internal/imports: fix typos in documentation

Fix typos and fix descriptions of methods where the behavior described
in the comment is not implemented by that method.

Change-Id: I2c34caff43399dcb4f0e5e41b67189d8d8404fd5
Reviewed-on: https://go-review.googlesource.com/c/tools/+/184697
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>

cmd/digraph/digraph.go

@@ -1,18 +1,83 @@
-// The digraph command performs queries over unlabelled directed graphs
-// represented in text form.  It is intended to integrate nicely with
-// typical UNIX command pipelines.
-//
-// Since directed graphs (import graphs, reference graphs, call graphs,
-// etc) often arise during software tool development and debugging, this
-// command is included in the go.tools repository.
-//
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+The digraph command performs queries over unlabelled directed graphs
+represented in text form.  It is intended to integrate nicely with
+typical UNIX command pipelines.
+
+Usage:
+
+	your-application | digraph [command]
+
+The support commands are:
+
+	nodes
+		the set of all nodes
+	degree
+		the in-degree and out-degree of each node
+	preds <node> ...
+		the set of immediate predecessors of the specified nodes
+	succs <node> ...
+		the set of immediate successors of the specified nodes
+	forward <node> ...
+		the set of nodes transitively reachable from the specified nodes
+	reverse <node> ...
+		the set of nodes that transitively reach the specified nodes
+	somepath <node> <node>
+		the list of nodes on some arbitrary path from the first node to the second
+	allpaths <node> <node>
+		the set of nodes on all paths from the first node to the second
+	sccs
+		all strongly connected components (one per line)
+	scc <node>
+		the set of nodes nodes strongly connected to the specified one
+
+Input format:
+
+Each line contains zero or more words. Words are separated by unquoted
+whitespace; words may contain Go-style double-quoted portions, allowing spaces
+and other characters to be expressed.
+
+Each word declares a node, and if there are more than one, an edge from the
+first to each subsequent one. The graph is provided on the standard input.
+
+For instance, the following (acyclic) graph specifies a partial order among the
+subtasks of getting dressed:
+
+	$ cat clothes.txt
+	socks shoes
+	"boxer shorts" pants
+	pants belt shoes
+	shirt tie sweater
+	sweater jacket
+	hat
+
+The line "shirt tie sweater" indicates the two edges shirt -> tie and
+shirt -> sweater, not shirt -> tie -> sweater.
+
+Example usage:
+
+Using digraph with existing Go tools:
+
+	$ go mod graph | digraph nodes # Operate on the Go module graph.
+	$ go list -m all | digraph nodes # Operate on the Go package graph.
+
+Show the transitive closure of imports of the digraph tool itself:
+	$ go list -f '{{.ImportPath}} {{join .Imports " "}}' ... | digraph forward golang.org/x/tools/cmd/digraph
+
+Show which clothes (see above) must be donned before a jacket:
+	$ digraph reverse jacket
+
+*/
+package main // import "golang.org/x/tools/cmd/digraph"
+
 // TODO(adonovan):
 // - support input files other than stdin
 // - support alternative formats (AT&T GraphViz, CSV, etc),
 //   a comment syntax, etc.
 // - allow queries to nest, like Blaze query language.
-//
-package main // import "golang.org/x/tools/cmd/digraph"
 
 import (
 	"bufio"
@@ -28,74 +93,41 @@ import (
 	"unicode/utf8"
 )
 
-const Usage = `digraph: queries over directed graphs in text form.
+func usage() {
+	fmt.Fprintf(os.Stderr, `Usage: your-application | digraph [command]
 
-Graph format:
-
-  Each line contains zero or more words.  Words are separated by
-  unquoted whitespace; words may contain Go-style double-quoted portions,
-  allowing spaces and other characters to be expressed.
-
-  Each field declares a node, and if there are more than one,
-  an edge from the first to each subsequent one.
-  The graph is provided on the standard input.
-
-  For instance, the following (acyclic) graph specifies a partial order
-  among the subtasks of getting dressed:
-
-	% cat clothes.txt
-	socks shoes
-	"boxer shorts" pants
-	pants belt shoes
-	shirt tie sweater
-	sweater jacket
-	hat
-
-  The line "shirt tie sweater" indicates the two edges shirt -> tie and
-  shirt -> sweater, not shirt -> tie -> sweater.
-
-Supported queries:
-
-  nodes
-	the set of all nodes
-  degree
-	the in-degree and out-degree of each node.
-  preds <label> ...
-	the set of immediate predecessors of the specified nodes
-  succs <label> ...
-	the set of immediate successors of the specified nodes
-  forward <label> ...
-	the set of nodes transitively reachable from the specified nodes
-  reverse <label> ...
-	the set of nodes that transitively reach the specified nodes
-  somepath <label> <label>
-	the list of nodes on some arbitrary path from the first node to the second
-  allpaths <label> <label>
-	the set of nodes on all paths from the first node to the second
-  sccs
-	all strongly connected components (one per line)
-  scc <label>
-	the set of nodes nodes strongly connected to the specified one
-
-Example usage:
-
-   Show the transitive closure of imports of the digraph tool itself:
-   % go list -f '{{.ImportPath}}{{.Imports}}' ... | tr '[]' '  ' |
-         digraph forward golang.org/x/tools/cmd/digraph
-
-   Show which clothes (see above) must be donned before a jacket:
-   %  digraph reverse jacket <clothes.txt
-
-`
+The support commands are:
+	nodes
+		the set of all nodes
+	degree
+		the in-degree and out-degree of each node
+	preds <node> ...
+		the set of immediate predecessors of the specified nodes
+	succs <node> ...
+		the set of immediate successors of the specified nodes
+	forward <node> ...
+		the set of nodes transitively reachable from the specified nodes
+	reverse <node> ...
+		the set of nodes that transitively reach the specified nodes
+	somepath <node> <node>
+		the list of nodes on some arbitrary path from the first node to the second
+	allpaths <node> <node>
+		the set of nodes on all paths from the first node to the second
+	sccs
+		all strongly connected components (one per line)
+	scc <node>
+		the set of nodes nodes strongly connected to the specified one
+`)
+	os.Exit(2)
+}
 
 func main() {
-	flag.Usage = func() { fmt.Fprintln(os.Stderr, Usage) }
+	flag.Usage = usage
 	flag.Parse()
 
 	args := flag.Args()
 	if len(args) == 0 {
-		fmt.Fprintln(os.Stderr, Usage)
-		return
+		usage()
 	}
 
 	if err := digraph(args[0], args[1:]); err != nil {
@@ -230,6 +262,47 @@ func (g graph) sccs() []nodeset {
 	return sccs
 }
 
+func (g graph) allpaths(from, to string) error {
+	// Mark all nodes to "to".
+	seen := make(nodeset) // value of seen[x] indicates whether x is on some path to "to"
+	var visit func(node string) bool
+	visit = func(node string) bool {
+		reachesTo, ok := seen[node]
+		if !ok {
+			reachesTo = node == to
+			seen[node] = reachesTo
+			for e := range g[node] {
+				if visit(e) {
+					reachesTo = true
+				}
+			}
+			if reachesTo && node != to {
+				seen[node] = true
+			}
+		}
+		return reachesTo
+	}
+	visit(from)
+
+	// For each marked node, collect its marked successors.
+	var edges []string
+	for n := range seen {
+		for succ := range g[n] {
+			if seen[succ] {
+				edges = append(edges, n+" "+succ)
+			}
+		}
+	}
+
+	// Sort (so that this method is deterministic) and print edges.
+	sort.Strings(edges)
+	for _, e := range edges {
+		fmt.Fprintln(stdout, e)
+	}
+
+	return nil
+}
+
 func parse(rd io.Reader) (graph, error) {
 	g := make(graph)
 
@@ -252,6 +325,7 @@ func parse(rd io.Reader) (graph, error) {
 	return g, nil
 }
 
+// Overridable for testing purposes.
 var stdin io.Reader = os.Stdin
 var stdout io.Writer = os.Stdout
 
@@ -366,33 +440,7 @@ func digraph(cmd string, args []string) error {
 		if g[to] == nil {
 			return fmt.Errorf("no such 'to' node %q", to)
 		}
-
-		seen := make(nodeset) // value of seen[x] indicates whether x is on some path to 'to'
-		var visit func(label string) bool
-		visit = func(label string) bool {
-			reachesTo, ok := seen[label]
-			if !ok {
-				reachesTo = label == to
-
-				seen[label] = reachesTo
-				for e := range g[label] {
-					if visit(e) {
-						reachesTo = true
-					}
-				}
-				seen[label] = reachesTo
-			}
-			return reachesTo
-		}
-		if !visit(from) {
-			return fmt.Errorf("no path from %q to %q", from, to)
-		}
-		for label, reachesTo := range seen {
-			if !reachesTo {
-				delete(seen, label)
-			}
-		}
-		seen.sort().println("\n")
+		g.allpaths(from, to)
 
 	case "sccs":
 		if len(args) != 0 {

cmd/digraph/digraph_test.go

@@ -1,3 +1,6 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
 package main
 
 import (
@@ -26,35 +29,34 @@ d c
 `
 
 	for _, test := range []struct {
+		name  string
 		input string
 		cmd   string
 		args  []string
 		want  string
 	}{
-		{g1, "nodes", nil, "belt\nhat\njacket\npants\nshirt\nshoes\nshorts\nsocks\nsweater\ntie\n"},
-		{g1, "reverse", []string{"jacket"}, "jacket\nshirt\nsweater\n"},
-		{g1, "forward", []string{"socks"}, "shoes\nsocks\n"},
-		{g1, "forward", []string{"socks", "sweater"}, "jacket\nshoes\nsocks\nsweater\n"},
-
-		{g2, "allpaths", []string{"a", "d"}, "a\nb\nc\nd\n"},
-
-		{g2, "sccs", nil, "a\nb\nc d\n"},
-		{g2, "scc", []string{"d"}, "c\nd\n"},
-		{g2, "succs", []string{"a"}, "b\nc\n"},
-		{g2, "preds", []string{"c"}, "a\nd\n"},
-		{g2, "preds", []string{"c", "d"}, "a\nb\nc\nd\n"},
+		{"nodes", g1, "nodes", nil, "belt\nhat\njacket\npants\nshirt\nshoes\nshorts\nsocks\nsweater\ntie\n"},
+		{"reverse", g1, "reverse", []string{"jacket"}, "jacket\nshirt\nsweater\n"},
+		{"forward", g1, "forward", []string{"socks"}, "shoes\nsocks\n"},
+		{"forward multiple args", g1, "forward", []string{"socks", "sweater"}, "jacket\nshoes\nsocks\nsweater\n"},
+		{"scss", g2, "sccs", nil, "a\nb\nc d\n"},
+		{"scc", g2, "scc", []string{"d"}, "c\nd\n"},
+		{"succs", g2, "succs", []string{"a"}, "b\nc\n"},
+		{"preds", g2, "preds", []string{"c"}, "a\nd\n"},
+		{"preds multiple args", g2, "preds", []string{"c", "d"}, "a\nb\nc\nd\n"},
 	} {
-		stdin = strings.NewReader(test.input)
-		stdout = new(bytes.Buffer)
-		if err := digraph(test.cmd, test.args); err != nil {
-			t.Error(err)
-			continue
-		}
+		t.Run(test.name, func(t *testing.T) {
+			stdin = strings.NewReader(test.input)
+			stdout = new(bytes.Buffer)
+			if err := digraph(test.cmd, test.args); err != nil {
+				t.Fatal(err)
+			}
 
-		got := stdout.(fmt.Stringer).String()
-		if got != test.want {
-			t.Errorf("digraph(%s, %s) = %q, want %q", test.cmd, test.args, got, test.want)
-		}
+			got := stdout.(fmt.Stringer).String()
+			if got != test.want {
+				t.Errorf("digraph(%s, %s) = got %q, want %q", test.cmd, test.args, got, test.want)
+			}
+		})
 	}
 
 	// TODO(adonovan):
@@ -62,6 +64,110 @@ d c
 	// - test errors
 }
 
+func TestAllpaths(t *testing.T) {
+	for _, test := range []struct {
+		name string
+		in   string
+		to   string // from is always "A"
+		want string
+	}{
+		{
+			name: "Basic",
+			in:   "A B\nB C",
+			to:   "B",
+			want: "A B\n",
+		},
+		{
+			name: "Long",
+			in:   "A B\nB C\n",
+			to:   "C",
+			want: "A B\nB C\n",
+		},
+		{
+			name: "Cycle Basic",
+			in:   "A B\nB A",
+			to:   "B",
+			want: "A B\nB A\n",
+		},
+		{
+			name: "Cycle Path Out",
+			// A <-> B -> C -> D
+			in:   "A B\nB A\nB C\nC D",
+			to:   "C",
+			want: "A B\nB A\nB C\n",
+		},
+		{
+			name: "Cycle Path Out Further Out",
+			// A -> B <-> C -> D -> E
+			in:   "A B\nB C\nC D\nC B\nD E",
+			to:   "D",
+			want: "A B\nB C\nC B\nC D\n",
+		},
+		{
+			name: "Two Paths Basic",
+			//           /-> C --\
+			// A -> B --          -> E -> F
+			//           \-> D --/
+			in:   "A B\nB C\nC E\nB D\nD E\nE F",
+			to:   "E",
+			want: "A B\nB C\nB D\nC E\nD E\n",
+		},
+		{
+			name: "Two Paths With One Immediately From Start",
+			//      /-> B -+ -> D
+			// A --        |
+			//      \-> C <+
+			in:   "A B\nA C\nB C\nB D",
+			to:   "C",
+			want: "A B\nA C\nB C\n",
+		},
+		{
+			name: "Two Paths Further Up",
+			//      /-> B --\
+			// A --          -> D -> E -> F
+			//      \-> C --/
+			in:   "A B\nA C\nB D\nC D\nD E\nE F",
+			to:   "E",
+			want: "A B\nA C\nB D\nC D\nD E\n",
+		},
+		{
+			// We should include A - C  - D even though it's further up the
+			// second path than D (which would already be in the graph by
+			// the time we get around to integrating the second path).
+			name: "Two Splits",
+			//      /-> B --\         /-> E --\
+			// A --           -> D --          -> G -> H
+			//      \-> C --/         \-> F --/
+			in:   "A B\nA C\nB D\nC D\nD E\nD F\nE G\nF G\nG H",
+			to:   "G",
+			want: "A B\nA C\nB D\nC D\nD E\nD F\nE G\nF G\n",
+		},
+		{
+			// D - E should not be duplicated.
+			name: "Two Paths - Two Splits With Gap",
+			//      /-> B --\              /-> F --\
+			// A --           -> D -> E --          -> H -> I
+			//      \-> C --/              \-> G --/
+			in:   "A B\nA C\nB D\nC D\nD E\nE F\nE G\nF H\nG H\nH I",
+			to:   "H",
+			want: "A B\nA C\nB D\nC D\nD E\nE F\nE G\nF H\nG H\n",
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			stdin = strings.NewReader(test.in)
+			stdout = new(bytes.Buffer)
+			if err := digraph("allpaths", []string{"A", test.to}); err != nil {
+				t.Fatal(err)
+			}
+
+			got := stdout.(fmt.Stringer).String()
+			if got != test.want {
+				t.Errorf("digraph(allpaths, A, %s) = got %q, want %q", test.to, got, test.want)
+			}
+		})
+	}
+}
+
 func TestSplit(t *testing.T) {
 	for _, test := range []struct {
 		line string

cmd/gopls/main.go

@@ -19,5 +19,5 @@ import (
 
 func main() {
 	debug.Version += "-cmd.gopls"
-	tool.Main(context.Background(), cmd.New("", nil), os.Args[1:])
+	tool.Main(context.Background(), cmd.New("gopls-legacy", "", nil), os.Args[1:])
 }

go/analysis/internal/facts/facts.go

@@ -99,6 +99,16 @@ func (s *Set) ExportObjectFact(obj types.Object, fact analysis.Fact) {
 	s.mu.Unlock()
 }
 
+func (s *Set) AllObjectFacts() []analysis.ObjectFact {
+	var facts []analysis.ObjectFact
+	for k, v := range s.m {
+		if k.obj != nil {
+			facts = append(facts, analysis.ObjectFact{k.obj, v})
+		}
+	}
+	return facts
+}
+
 // ImportPackageFact implements analysis.Pass.ImportPackageFact.
 func (s *Set) ImportPackageFact(pkg *types.Package, ptr analysis.Fact) bool {
 	if pkg == nil {
@@ -122,6 +132,16 @@ func (s *Set) ExportPackageFact(fact analysis.Fact) {
 	s.mu.Unlock()
 }
 
+func (s *Set) AllPackageFacts() []analysis.PackageFact {
+	var facts []analysis.PackageFact
+	for k, v := range s.m {
+		if k.obj == nil {
+			facts = append(facts, analysis.PackageFact{k.pkg, v})
+		}
+	}
+	return facts
+}
+
 // gobFact is the Gob declaration of a serialized fact.
 type gobFact struct {
 	PkgPath string          // path of package

go/analysis/unitchecker/unitchecker.go

@@ -334,8 +334,10 @@ func run(fset *token.FileSet, cfg *Config, analyzers []*analysis.Analyzer) ([]re
 				Report:            func(d analysis.Diagnostic) { act.diagnostics = append(act.diagnostics, d) },
 				ImportObjectFact:  facts.ImportObjectFact,
 				ExportObjectFact:  facts.ExportObjectFact,
+				AllObjectFacts:    facts.AllObjectFacts,
 				ImportPackageFact: facts.ImportPackageFact,
 				ExportPackageFact: facts.ExportPackageFact,
+				AllPackageFacts:   facts.AllPackageFacts,
 			}
 
 			t0 := time.Now()

go/cfg/builder.go

@@ -149,7 +149,7 @@ func (b *builder) branchStmt(s *ast.BranchStmt) {
 		}
 
 	case token.FALLTHROUGH:
-		for t := b.targets; t != nil; t = t.tail {
+		for t := b.targets; t != nil && block == nil; t = t.tail {
 			block = t._fallthrough
 		}
 

go/loader/loader.go

@@ -811,7 +811,15 @@ func (imp *importer) doImport(from *PackageInfo, to string) (*types.Package, err
 	// Import of incomplete package: this indicates a cycle.
 	fromPath := from.Pkg.Path()
 	if cycle := imp.findPath(path, fromPath); cycle != nil {
-		cycle = append([]string{fromPath}, cycle...)
+		// Normalize cycle: start from alphabetically largest node.
+		pos, start := -1, ""
+		for i, s := range cycle {
+			if pos < 0 || s > start {
+				pos, start = i, s
+			}
+		}
+		cycle = append(cycle, cycle[:pos]...)[pos:] // rotate cycle to start from largest
+		cycle = append(cycle, cycle[0])             // add start node to end to show cycliness
 		return nil, fmt.Errorf("import cycle: %s", strings.Join(cycle, " -> "))
 	}
 

go/packages/golist.go

@@ -316,9 +316,7 @@ func runNamedQueries(cfg *Config, driver driver, response *responseDeduper, quer
 
 	startWalk := time.Now()
 	gopathwalk.Walk(roots, add, gopathwalk.Options{ModulesEnabled: modRoot != "", Debug: debug})
-	if debug {
-		log.Printf("%v for walk", time.Since(startWalk))
-	}
+	cfg.Logf("%v for walk", time.Since(startWalk))
 
 	// Weird special case: the top-level package in a module will be in
 	// whatever directory the user checked the repository out into. It's
@@ -759,11 +757,9 @@ func invokeGo(cfg *Config, args ...string) (*bytes.Buffer, error) {
 	cmd.Dir = cfg.Dir
 	cmd.Stdout = stdout
 	cmd.Stderr = stderr
-	if debug {
-		defer func(start time.Time) {
-			log.Printf("%s for %v, stderr: <<%s>>\n", time.Since(start), cmdDebugStr(cmd, args...), stderr)
-		}(time.Now())
-	}
+	defer func(start time.Time) {
+		cfg.Logf("%s for %v, stderr: <<%s>>\n", time.Since(start), cmdDebugStr(cmd, args...), stderr)
+	}(time.Now())
 
 	if err := cmd.Run(); err != nil {
 		// Check for 'go' executable not being found.

go/packages/packages.go

@@ -103,6 +103,12 @@ type Config struct {
 	// If Context is nil, the load cannot be cancelled.
 	Context context.Context
 
+	// Logf is the logger for the config.
+	// If the user provides a logger, debug logging is enabled.
+	// If the GOPACKAGESDEBUG environment variable is set to true,
+	// but the logger is nil, default to log.Printf.
+	Logf func(format string, args ...interface{})
+
 	// Dir is the directory in which to run the build system's query tool
 	// that provides information about the packages.
 	// If Dir is empty, the tool is run in the current directory.
@@ -429,6 +435,17 @@ func newLoader(cfg *Config) *loader {
 	}
 	if cfg != nil {
 		ld.Config = *cfg
+		// If the user has provided a logger, use it.
+		ld.Config.Logf = cfg.Logf
+	}
+	if ld.Config.Logf == nil {
+		// If the GOPACKAGESDEBUG environment variable is set to true,
+		// but the user has not provided a logger, default to log.Printf.
+		if debug {
+			ld.Config.Logf = log.Printf
+		} else {
+			ld.Config.Logf = func(format string, args ...interface{}) {}
+		}
 	}
 	if ld.Config.Mode == 0 {
 		ld.Config.Mode = NeedName | NeedFiles | NeedCompiledGoFiles // Preserve zero behavior of Mode for backwards compatibility.

go/packages/packages_test.go

@@ -930,6 +930,12 @@ func testNewPackagesInOverlay(t *testing.T, exporter packagestest.Exporter) {
 			"b/b.go": `package b; import "golang.org/fake/c"; const B = "b" + c.C`,
 			"c/c.go": `package c; const C = "c"`,
 			"d/d.go": `package d; const D = "d"`,
+
+			// TODO: Remove these temporary files when golang.org/issue/33157 is resolved.
+			filepath.Join("e/e_temp.go"): ``,
+			filepath.Join("f/f_temp.go"): ``,
+			filepath.Join("g/g_temp.go"): ``,
+			filepath.Join("h/h_temp.go"): ``,
 		}}})
 	defer exported.Cleanup()
 
@@ -986,7 +992,11 @@ func testNewPackagesInOverlay(t *testing.T, exporter packagestest.Exporter) {
 	} {
 		exported.Config.Overlay = test.overlay
 		exported.Config.Mode = packages.LoadAllSyntax
-		initial, err := packages.Load(exported.Config, "golang.org/fake/e")
+		exported.Config.Logf = t.Logf
+
+		// With an overlay, we don't know the expected import path,
+		// so load with the absolute path of the directory.
+		initial, err := packages.Load(exported.Config, filepath.Join(dir, "e"))
 		if err != nil {
 			t.Error(err)
 			continue

gopls/go.mod

@@ -2,6 +2,6 @@ module golang.org/x/tools/gopls
 
 go 1.11
 
-require golang.org/x/tools v0.0.0-20190628153133-6cdbf07be9d0
+require golang.org/x/tools v0.0.0-20190723021737-8bb11ff117ca
 
 replace golang.org/x/tools => ../

gopls/go.sum

@@ -1,8 +1,8 @@
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58 h1:8gQV6CLnAEikrhgkHFbMAEhagSSnXWGV915qUMm9mrU=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-golang.org/x/tools v0.0.0-20190628153133-6cdbf07be9d0/go.mod h1:/rFqwRUd4F7ZHNgwSSTFct+R/Kf4OFW1sUzUTQQTgfc=
+golang.org/x/tools v0.0.0-20190723021737-8bb11ff117ca h1:SqwJrz6xPBlCUltcEHz2/p01HRPR+VGD+aYLikk8uas=
+golang.org/x/tools v0.0.0-20190723021737-8bb11ff117ca/go.mod h1:jcCCGcm9btYwXyDqrUWc6MKQKKGJCWEQ3AfLSRIbEuI=

gopls/main.go

@@ -17,5 +17,5 @@ import (
 )
 
 func main() {
-	tool.Main(context.Background(), cmd.New("", nil), os.Args[1:])
+	tool.Main(context.Background(), cmd.New("gopls", "", nil), os.Args[1:])
 }

internal/imports/fix.go

@@ -181,8 +181,8 @@ func collectReferences(f *ast.File) references {
 	return refs
 }
 
-// collectImports returns all the imports in f, keyed by their package name as
-// determined by pathToName. Unnamed imports (., _) and "C" are ignored.
+// collectImports returns all the imports in f.
+// Unnamed imports (., _) and "C" are ignored.
 func collectImports(f *ast.File) []*importInfo {
 	var imports []*importInfo
 	for _, imp := range f.Imports {
@@ -272,7 +272,7 @@ func (p *pass) loadPackageNames(imports []*importInfo) error {
 		unknown = append(unknown, imp.importPath)
 	}
 
-	names, err := p.env.getResolver().loadPackageNames(unknown, p.srcDir)
+	names, err := p.env.GetResolver().loadPackageNames(unknown, p.srcDir)
 	if err != nil {
 		return err
 	}
@@ -444,7 +444,7 @@ func apply(fset *token.FileSet, f *ast.File, fixes []*importFix) bool {
 		case setImportName:
 			// Find the matching import path and change the name.
 			for _, spec := range f.Imports {
-				path := strings.Trim(spec.Path.Value, `""`)
+				path := strings.Trim(spec.Path.Value, `"`)
 				if path == fix.info.importPath {
 					spec.Name = &ast.Ident{
 						Name:    fix.info.name,
@@ -514,7 +514,7 @@ func fixImportsDefault(fset *token.FileSet, f *ast.File, filename string, env *P
 	return err
 }
 
-// getFixes gets the getFixes that need to be made to f in order to fix the imports.
+// getFixes gets the import fixes that need to be made to f in order to fix the imports.
 // It does not modify the ast.
 func getFixes(fset *token.FileSet, f *ast.File, filename string, env *ProcessEnv) ([]*importFix, error) {
 	abs, err := filepath.Abs(filename)
@@ -595,7 +595,7 @@ type ProcessEnv struct {
 	// Logf is the default logger for the ProcessEnv.
 	Logf func(format string, args ...interface{})
 
-	resolver resolver
+	resolver Resolver
 }
 
 func (e *ProcessEnv) env() []string {
@@ -617,7 +617,7 @@ func (e *ProcessEnv) env() []string {
 	return env
 }
 
-func (e *ProcessEnv) getResolver() resolver {
+func (e *ProcessEnv) GetResolver() Resolver {
 	if e.resolver != nil {
 		return e.resolver
 	}
@@ -631,7 +631,7 @@ func (e *ProcessEnv) getResolver() resolver {
 		e.resolver = &gopathResolver{env: e}
 		return e.resolver
 	}
-	e.resolver = &moduleResolver{env: e}
+	e.resolver = &ModuleResolver{env: e}
 	return e.resolver
 }
 
@@ -700,20 +700,23 @@ func addStdlibCandidates(pass *pass, refs references) {
 	}
 }
 
-// A resolver does the build-system-specific parts of goimports.
-type resolver interface {
+// A Resolver does the build-system-specific parts of goimports.
+type Resolver interface {
 	// loadPackageNames loads the package names in importPaths.
 	loadPackageNames(importPaths []string, srcDir string) (map[string]string, error)
 	// scan finds (at least) the packages satisfying refs. The returned slice is unordered.
 	scan(refs references) ([]*pkg, error)
 }
 
-// gopathResolver implements resolver for GOPATH and module workspaces using go/packages.
+// gopackagesResolver implements resolver for GOPATH and module workspaces using go/packages.
 type goPackagesResolver struct {
 	env *ProcessEnv
 }
 
 func (r *goPackagesResolver) loadPackageNames(importPaths []string, srcDir string) (map[string]string, error) {
+	if len(importPaths) == 0 {
+		return nil, nil
+	}
 	cfg := r.env.newPackagesConfig(packages.LoadFiles)
 	pkgs, err := packages.Load(cfg, importPaths...)
 	if err != nil {
@@ -758,7 +761,7 @@ func (r *goPackagesResolver) scan(refs references) ([]*pkg, error) {
 }
 
 func addExternalCandidates(pass *pass, refs references, filename string) error {
-	dirScan, err := pass.env.getResolver().scan(refs)
+	dirScan, err := pass.env.GetResolver().scan(refs)
 	if err != nil {
 		return err
 	}
@@ -867,7 +870,7 @@ func (r *gopathResolver) loadPackageNames(importPaths []string, srcDir string) (
 	return names, nil
 }
 
-// importPathToNameGoPath finds out the actual package name, as declared in its .go files.
+// importPathToName finds out the actual package name, as declared in its .go files.
 // If there's a problem, it returns "".
 func importPathToName(env *ProcessEnv, importPath, srcDir string) (packageName string) {
 	// Fast path for standard library without going to disk.
@@ -887,8 +890,8 @@ func importPathToName(env *ProcessEnv, importPath, srcDir string) (packageName s
 }
 
 // packageDirToName is a faster version of build.Import if
-// the only thing desired is the package name. It uses build.FindOnly
-// to find the directory and then only parses one file in the package,
+// the only thing desired is the package name. Given a directory,
+// packageDirToName then only parses one file in the package,
 // trusting that the files in the directory are consistent.
 func packageDirToName(dir string) (packageName string, err error) {
 	d, err := os.Open(dir)

internal/imports/fix_test.go

@@ -1855,7 +1855,7 @@ func TestImportPathToNameGoPathParse(t *testing.T) {
 		if strings.Contains(t.Name(), "GoPackages") {
 			t.Skip("go/packages does not ignore package main")
 		}
-		r := t.env.getResolver()
+		r := t.env.GetResolver()
 		srcDir := filepath.Dir(t.exported.File("example.net/pkg", "z.go"))
 		names, err := r.loadPackageNames([]string{"example.net/pkg"}, srcDir)
 		if err != nil {

internal/imports/mod.go

@@ -18,37 +18,39 @@ import (
 	"golang.org/x/tools/internal/module"
 )
 
-// moduleResolver implements resolver for modules using the go command as little
+// ModuleResolver implements resolver for modules using the go command as little
 // as feasible.
-type moduleResolver struct {
+type ModuleResolver struct {
 	env *ProcessEnv
 
-	initialized   bool
-	main          *moduleJSON
-	modsByModPath []*moduleJSON // All modules, ordered by # of path components in module Path...
-	modsByDir     []*moduleJSON // ...or Dir.
+	Initialized   bool
+	Main          *ModuleJSON
+	ModsByModPath []*ModuleJSON // All modules, ordered by # of path components in module Path...
+	ModsByDir     []*ModuleJSON // ...or Dir.
+
+	ModCachePkgs map[string]*pkg // Packages in the mod cache, keyed by absolute directory.
 }
 
-type moduleJSON struct {
+type ModuleJSON struct {
 	Path     string           // module path
 	Version  string           // module version
 	Versions []string         // available module versions (with -versions)
-	Replace  *moduleJSON      // replaced by this module
+	Replace  *ModuleJSON      // replaced by this module
 	Time     *time.Time       // time version was created
-	Update   *moduleJSON      // available update, if any (with -u)
+	Update   *ModuleJSON      // available update, if any (with -u)
 	Main     bool             // is this the main module?
 	Indirect bool             // is this module only an indirect dependency of main module?
 	Dir      string           // directory holding files for this module, if any
 	GoMod    string           // path to go.mod file for this module, if any
-	Error    *moduleErrorJSON // error loading module
+	Error    *ModuleErrorJSON // error loading module
 }
 
-type moduleErrorJSON struct {
+type ModuleErrorJSON struct {
 	Err string // the error itself
 }
 
-func (r *moduleResolver) init() error {
-	if r.initialized {
+func (r *ModuleResolver) init() error {
+	if r.Initialized {
 		return nil
 	}
 	stdout, err := r.env.invokeGo("list", "-m", "-json", "...")
@@ -56,7 +58,7 @@ func (r *moduleResolver) init() error {
 		return err
 	}
 	for dec := json.NewDecoder(stdout); dec.More(); {
-		mod := &moduleJSON{}
+		mod := &ModuleJSON{}
 		if err := dec.Decode(mod); err != nil {
 			return err
 		}
@@ -67,34 +69,36 @@ func (r *moduleResolver) init() error {
 			// Can't do anything with a module that's not downloaded.
 			continue
 		}
-		r.modsByModPath = append(r.modsByModPath, mod)
-		r.modsByDir = append(r.modsByDir, mod)
+		r.ModsByModPath = append(r.ModsByModPath, mod)
+		r.ModsByDir = append(r.ModsByDir, mod)
 		if mod.Main {
-			r.main = mod
+			r.Main = mod
 		}
 	}
 
-	sort.Slice(r.modsByModPath, func(i, j int) bool {
+	sort.Slice(r.ModsByModPath, func(i, j int) bool {
 		count := func(x int) int {
-			return strings.Count(r.modsByModPath[x].Path, "/")
+			return strings.Count(r.ModsByModPath[x].Path, "/")
 		}
 		return count(j) < count(i) // descending order
 	})
-	sort.Slice(r.modsByDir, func(i, j int) bool {
+	sort.Slice(r.ModsByDir, func(i, j int) bool {
 		count := func(x int) int {
-			return strings.Count(r.modsByDir[x].Dir, "/")
+			return strings.Count(r.ModsByDir[x].Dir, "/")
 		}
 		return count(j) < count(i) // descending order
 	})
 
-	r.initialized = true
+	r.ModCachePkgs = make(map[string]*pkg)
+
+	r.Initialized = true
 	return nil
 }
 
 // findPackage returns the module and directory that contains the package at
 // the given import path, or returns nil, "" if no module is in scope.
-func (r *moduleResolver) findPackage(importPath string) (*moduleJSON, string) {
-	for _, m := range r.modsByModPath {
+func (r *ModuleResolver) findPackage(importPath string) (*ModuleJSON, string) {
+	for _, m := range r.ModsByModPath {
 		if !strings.HasPrefix(importPath, m.Path) {
 			continue
 		}
@@ -123,7 +127,7 @@ func (r *moduleResolver) findPackage(importPath string) (*moduleJSON, string) {
 
 // findModuleByDir returns the module that contains dir, or nil if no such
 // module is in scope.
-func (r *moduleResolver) findModuleByDir(dir string) *moduleJSON {
+func (r *ModuleResolver) findModuleByDir(dir string) *ModuleJSON {
 	// This is quite tricky and may not be correct. dir could be:
 	// - a package in the main module.
 	// - a replace target underneath the main module's directory.
@@ -134,7 +138,7 @@ func (r *moduleResolver) findModuleByDir(dir string) *moduleJSON {
 	// - in /vendor/ in -mod=vendor mode.
 	//    - nested module? Dunno.
 	// Rumor has it that replace targets cannot contain other replace targets.
-	for _, m := range r.modsByDir {
+	for _, m := range r.ModsByDir {
 		if !strings.HasPrefix(dir, m.Dir) {
 			continue
 		}
@@ -150,7 +154,7 @@ func (r *moduleResolver) findModuleByDir(dir string) *moduleJSON {
 
 // dirIsNestedModule reports if dir is contained in a nested module underneath
 // mod, not actually in mod.
-func dirIsNestedModule(dir string, mod *moduleJSON) bool {
+func dirIsNestedModule(dir string, mod *ModuleJSON) bool {
 	if !strings.HasPrefix(dir, mod.Dir) {
 		return false
 	}
@@ -176,7 +180,7 @@ func findModFile(dir string) string {
 	}
 }
 
-func (r *moduleResolver) loadPackageNames(importPaths []string, srcDir string) (map[string]string, error) {
+func (r *ModuleResolver) loadPackageNames(importPaths []string, srcDir string) (map[string]string, error) {
 	if err := r.init(); err != nil {
 		return nil, err
 	}
@@ -195,7 +199,7 @@ func (r *moduleResolver) loadPackageNames(importPaths []string, srcDir string) (
 	return names, nil
 }
 
-func (r *moduleResolver) scan(_ references) ([]*pkg, error) {
+func (r *ModuleResolver) scan(_ references) ([]*pkg, error) {
 	if err := r.init(); err != nil {
 		return nil, err
 	}
@@ -204,15 +208,15 @@ func (r *moduleResolver) scan(_ references) ([]*pkg, error) {
 	roots := []gopathwalk.Root{
 		{filepath.Join(r.env.GOROOT, "/src"), gopathwalk.RootGOROOT},
 	}
-	if r.main != nil {
-		roots = append(roots, gopathwalk.Root{r.main.Dir, gopathwalk.RootCurrentModule})
+	if r.Main != nil {
+		roots = append(roots, gopathwalk.Root{r.Main.Dir, gopathwalk.RootCurrentModule})
 	}
 	for _, p := range filepath.SplitList(r.env.GOPATH) {
 		roots = append(roots, gopathwalk.Root{filepath.Join(p, "/pkg/mod"), gopathwalk.RootModuleCache})
 	}
 
 	// Walk replace targets, just in case they're not in any of the above.
-	for _, mod := range r.modsByModPath {
+	for _, mod := range r.ModsByModPath {
 		if mod.Replace != nil {
 			roots = append(roots, gopathwalk.Root{mod.Dir, gopathwalk.RootOther})
 		}
@@ -232,6 +236,15 @@ func (r *moduleResolver) scan(_ references) ([]*pkg, error) {
 
 		dupCheck[dir] = true
 
+		absDir := dir
+		// Packages in the module cache are immutable. If we have
+		// already seen this package on a previous scan of the module
+		// cache, return that result.
+		if p, ok := r.ModCachePkgs[absDir]; ok {
+			result = append(result, p)
+			return
+		}
+
 		subdir := ""
 		if dir != root.Path {
 			subdir = dir[len(root.Path)+len("/"):]
@@ -247,7 +260,7 @@ func (r *moduleResolver) scan(_ references) ([]*pkg, error) {
 		}
 		switch root.Type {
 		case gopathwalk.RootCurrentModule:
-			importPath = path.Join(r.main.Path, filepath.ToSlash(subdir))
+			importPath = path.Join(r.Main.Path, filepath.ToSlash(subdir))
 		case gopathwalk.RootModuleCache:
 			matches := modCacheRegexp.FindStringSubmatch(subdir)
 			modPath, err := module.DecodePath(filepath.ToSlash(matches[1]))
@@ -298,10 +311,18 @@ func (r *moduleResolver) scan(_ references) ([]*pkg, error) {
 			dir = canonicalDir
 		}
 
-		result = append(result, &pkg{
+		res := &pkg{
 			importPathShort: VendorlessPath(importPath),
 			dir:             dir,
-		})
+		}
+
+		switch root.Type {
+		case gopathwalk.RootModuleCache:
+			// Save the results of processing this directory.
+			r.ModCachePkgs[absDir] = res
+		}
+
+		result = append(result, res)
 	}, gopathwalk.Options{Debug: r.env.Debug, ModulesEnabled: true})
 	return result, nil
 }

internal/imports/mod_test.go

@@ -118,6 +118,25 @@ import _ "example.com"
 	mt.assertFound("example.com", "x")
 }
 
+// Tests that scanning the module cache > 1 time is able to find the same module.
+func TestModMultipleScans(t *testing.T) {
+	mt := setup(t, `
+-- go.mod --
+module x
+
+require example.com v1.0.0
+
+-- x.go --
+package x
+import _ "example.com"
+`, "")
+	defer mt.cleanup()
+
+	mt.assertScanFinds("example.com", "x")
+	mt.assertScanFinds("example.com", "x")
+
+}
+
 // Tests that -mod=vendor sort of works. Adapted from mod_getmode_vendor.txt.
 func TestModeGetmodeVendor(t *testing.T) {
 	mt := setup(t, `
@@ -140,7 +159,7 @@ import _ "rsc.io/quote"
 
 	mt.env.GOFLAGS = ""
 	// Clear out the resolver's cache, since we've changed the environment.
-	mt.resolver = &moduleResolver{env: mt.env}
+	mt.resolver = &ModuleResolver{env: mt.env}
 	mt.assertModuleFoundInDir("rsc.io/quote", "quote", `pkg.*mod.*/quote@.*$`)
 }
 
@@ -486,7 +505,7 @@ var proxyDir string
 type modTest struct {
 	*testing.T
 	env      *ProcessEnv
-	resolver *moduleResolver
+	resolver *ModuleResolver
 	cleanup  func()
 }
 
@@ -538,7 +557,7 @@ func setup(t *testing.T, main, wd string) *modTest {
 	return &modTest{
 		T:        t,
 		env:      env,
-		resolver: &moduleResolver{env: env},
+		resolver: &ModuleResolver{env: env},
 		cleanup: func() {
 			_ = filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
 				if err != nil {

internal/jsonrpc2/handler.go

@@ -0,0 +1,124 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package jsonrpc2
+
+import (
+	"context"
+)
+
+// Handler is the interface used to hook into the mesage handling of an rpc
+// connection.
+type Handler interface {
+	// Deliver is invoked to handle incoming requests.
+	// If the request returns false from IsNotify then the Handler must eventually
+	// call Reply on the Conn with the supplied request.
+	// Handlers are called synchronously, they should pass the work off to a go
+	// routine if they are going to take a long time.
+	// If Deliver returns true all subsequent handlers will be invoked with
+	// delivered set to true, and should not attempt to deliver the message.
+	Deliver(ctx context.Context, r *Request, delivered bool) bool
+
+	// Cancel is invoked for cancelled outgoing requests.
+	// It is okay to use the connection to send notifications, but the context will
+	// be in the cancelled state, so you must do it with the background context
+	// instead.
+	// If Cancel returns true all subsequent handlers will be invoked with
+	// cancelled set to true, and should not attempt to cancel the message.
+	Cancel(ctx context.Context, conn *Conn, id ID, cancelled bool) bool
+
+	// Log is invoked for all messages flowing through a Conn.
+	// direction indicates if the message being received or sent
+	// id is the message id, if not set it was a notification
+	// elapsed is the time between a call being seen and the response, and is
+	// negative for anything that is not a response.
+	// method is the method name specified in the message
+	// payload is the parameters for a call or notification, and the result for a
+	// response
+
+	// Request is called near the start of processing any request.
+	Request(ctx context.Context, direction Direction, r *WireRequest) context.Context
+	// Response is called near the start of processing any response.
+	Response(ctx context.Context, direction Direction, r *WireResponse) context.Context
+	// Done is called when any request is fully processed.
+	// For calls, this means the response has also been processed, for notifies
+	// this is as soon as the message has been written to the stream.
+	// If err is set, it implies the request failed.
+	Done(ctx context.Context, err error)
+	// Read is called with a count each time some data is read from the stream.
+	// The read calls are delayed until after the data has been interpreted so
+	// that it can be attributed to a request/response.
+	Read(ctx context.Context, bytes int64) context.Context
+	// Wrote is called each time some data is written to the stream.
+	Wrote(ctx context.Context, bytes int64) context.Context
+	// Error is called with errors that cannot be delivered through the normal
+	// mechanisms, for instance a failure to process a notify cannot be delivered
+	// back to the other party.
+	Error(ctx context.Context, err error)
+}
+
+// Direction is used to indicate to a logger whether the logged message was being
+// sent or received.
+type Direction bool
+
+const (
+	// Send indicates the message is outgoing.
+	Send = Direction(true)
+	// Receive indicates the message is incoming.
+	Receive = Direction(false)
+)
+
+func (d Direction) String() string {
+	switch d {
+	case Send:
+		return "send"
+	case Receive:
+		return "receive"
+	default:
+		panic("unreachable")
+	}
+}
+
+type EmptyHandler struct{}
+
+func (EmptyHandler) Deliver(ctx context.Context, r *Request, delivered bool) bool {
+	return false
+}
+
+func (EmptyHandler) Cancel(ctx context.Context, conn *Conn, id ID, cancelled bool) bool {
+	return false
+}
+
+func (EmptyHandler) Request(ctx context.Context, direction Direction, r *WireRequest) context.Context {
+	return ctx
+}
+
+func (EmptyHandler) Response(ctx context.Context, direction Direction, r *WireResponse) context.Context {
+	return ctx
+}
+
+func (EmptyHandler) Done(ctx context.Context, err error) {
+}
+
+func (EmptyHandler) Read(ctx context.Context, bytes int64) context.Context {
+	return ctx
+}
+
+func (EmptyHandler) Wrote(ctx context.Context, bytes int64) context.Context {
+	return ctx
+}
+
+func (EmptyHandler) Error(ctx context.Context, err error) {}
+
+type defaultHandler struct{ EmptyHandler }
+
+func (defaultHandler) Deliver(ctx context.Context, r *Request, delivered bool) bool {
+	if delivered {
+		return false
+	}
+	if !r.IsNotify() {
+		r.Reply(ctx, nil, NewErrorf(CodeMethodNotFound, "method %q not found", r.Method))
+	}
+	return true
+}

internal/jsonrpc2/jsonrpc2.go

@@ -13,28 +13,19 @@ import (
 	"fmt"
 	"sync"
 	"sync/atomic"
-	"time"
-
-	"golang.org/x/tools/internal/lsp/telemetry"
-	"golang.org/x/tools/internal/lsp/telemetry/tag"
-	"golang.org/x/tools/internal/lsp/telemetry/trace"
 )
 
 // Conn is a JSON RPC 2 client server connection.
 // Conn is bidirectional; it does not have a designated server or client end.
 type Conn struct {
-	seq                int64 // must only be accessed using atomic operations
-	Handler            Handler
-	Canceler           Canceler
-	Logger             Logger
-	Capacity           int
-	RejectIfOverloaded bool
-	stream             Stream
-	err                error
-	pendingMu          sync.Mutex // protects the pending map
-	pending            map[ID]chan *wireResponse
-	handlingMu         sync.Mutex // protects the handling map
-	handling           map[ID]*Request
+	seq        int64 // must only be accessed using atomic operations
+	handlers   []Handler
+	stream     Stream
+	err        error
+	pendingMu  sync.Mutex // protects the pending map
+	pending    map[ID]chan *WireResponse
+	handlingMu sync.Mutex // protects the handling map
+	handling   map[ID]*Request
 }
 
 type requestState int
@@ -51,73 +42,11 @@ const (
 type Request struct {
 	conn        *Conn
 	cancel      context.CancelFunc
-	start       time.Time
 	state       requestState
 	nextRequest chan struct{}
 
-	// Method is a string containing the method name to invoke.
-	Method string
-	// Params is either a struct or an array with the parameters of the method.
-	Params *json.RawMessage
-	// The id of this request, used to tie the response back to the request.
-	// Will be either a string or a number. If not set, the request is a notify,
-	// and no response is possible.
-	ID *ID
-}
-
-// Handler is an option you can pass to NewConn to handle incoming requests.
-// If the request returns false from IsNotify then the Handler must eventually
-// call Reply on the Conn with the supplied request.
-// Handlers are called synchronously, they should pass the work off to a go
-// routine if they are going to take a long time.
-type Handler func(context.Context, *Request)
-
-// Canceler is an option you can pass to NewConn which is invoked for
-// cancelled outgoing requests.
-// It is okay to use the connection to send notifications, but the context will
-// be in the cancelled state, so you must do it with the background context
-// instead.
-type Canceler func(context.Context, *Conn, ID)
-
-type rpcStats struct {
-	server bool
-	method string
-	span   trace.Span
-	start  time.Time
-}
-
-func start(ctx context.Context, server bool, method string, id *ID) (context.Context, *rpcStats) {
-	if method == "" {
-		panic("no method in rpc stats")
-	}
-	s := &rpcStats{
-		server: server,
-		method: method,
-		start:  time.Now(),
-	}
-	mode := telemetry.Outbound
-	if server {
-		mode = telemetry.Inbound
-	}
-	ctx, s.span = trace.StartSpan(ctx, method,
-		tag.Tag{Key: telemetry.Method, Value: method},
-		tag.Tag{Key: telemetry.RPCDirection, Value: mode},
-		tag.Tag{Key: telemetry.RPCID, Value: id},
-	)
-	telemetry.Started.Record(ctx, 1)
-	return ctx, s
-}
-
-func (s *rpcStats) end(ctx context.Context, err *error) {
-	if err != nil && *err != nil {
-		ctx = telemetry.StatusCode.With(ctx, "ERROR")
-	} else {
-		ctx = telemetry.StatusCode.With(ctx, "OK")
-	}
-	elapsedTime := time.Since(s.start)
-	latencyMillis := float64(elapsedTime) / float64(time.Millisecond)
-	telemetry.Latency.Record(ctx, latencyMillis)
-	s.span.End()
+	// The Wire values of the request.
+	WireRequest
 }
 
 // NewErrorf builds a Error struct for the suppied message and code.
@@ -133,23 +62,23 @@ func NewErrorf(code int64, format string, args ...interface{}) *Error {
 // You must call Run for the connection to be active.
 func NewConn(s Stream) *Conn {
 	conn := &Conn{
+		handlers: []Handler{defaultHandler{}},
 		stream:   s,
-		pending:  make(map[ID]chan *wireResponse),
+		pending:  make(map[ID]chan *WireResponse),
 		handling: make(map[ID]*Request),
 	}
-	// the default handler reports a method error
-	conn.Handler = func(ctx context.Context, r *Request) {
-		if !r.IsNotify() {
-			r.Reply(ctx, nil, NewErrorf(CodeMethodNotFound, "method %q not found", r.Method))
-		}
-	}
-	// the default canceler does nothing
-	conn.Canceler = func(context.Context, *Conn, ID) {}
-	// the default logger does nothing
-	conn.Logger = func(Direction, *ID, time.Duration, string, *json.RawMessage, *Error) {}
 	return conn
 }
 
+// AddHandler adds a new handler to the set the connection will invoke.
+// Handlers are invoked in the reverse order of how they were added, this
+// allows the most recent addition to be the first one to attempt to handle a
+// message.
+func (c *Conn) AddHandler(handler Handler) {
+	// prepend the new handlers so we use them first
+	c.handlers = append([]Handler{handler}, c.handlers...)
+}
+
 // Cancel cancels a pending Call on the server side.
 // The call is identified by its id.
 // JSON RPC 2 does not specify a cancel message, so cancellation support is not
@@ -168,14 +97,11 @@ func (c *Conn) Cancel(id ID) {
 // It will return as soon as the notification has been sent, as no response is
 // possible.
 func (c *Conn) Notify(ctx context.Context, method string, params interface{}) (err error) {
-	ctx, rpcStats := start(ctx, false, method, nil)
-	defer rpcStats.end(ctx, &err)
-
 	jsonParams, err := marshalToRaw(params)
 	if err != nil {
 		return fmt.Errorf("marshalling notify parameters: %v", err)
 	}
-	request := &wireRequest{
+	request := &WireRequest{
 		Method: method,
 		Params: jsonParams,
 	}
@@ -183,9 +109,18 @@ func (c *Conn) Notify(ctx context.Context, method string, params interface{}) (e
 	if err != nil {
 		return fmt.Errorf("marshalling notify request: %v", err)
 	}
-	c.Logger(Send, nil, -1, request.Method, request.Params, nil)
+	for _, h := range c.handlers {
+		ctx = h.Request(ctx, Send, request)
+	}
+	defer func() {
+		for _, h := range c.handlers {
+			h.Done(ctx, err)
+		}
+	}()
 	n, err := c.stream.Write(ctx, data)
-	telemetry.SentBytes.Record(ctx, n)
+	for _, h := range c.handlers {
+		ctx = h.Wrote(ctx, n)
+	}
 	return err
 }
 
@@ -195,13 +130,11 @@ func (c *Conn) Notify(ctx context.Context, method string, params interface{}) (e
 func (c *Conn) Call(ctx context.Context, method string, params, result interface{}) (err error) {
 	// generate a new request identifier
 	id := ID{Number: atomic.AddInt64(&c.seq, 1)}
-	ctx, rpcStats := start(ctx, false, method, &id)
-	defer rpcStats.end(ctx, &err)
 	jsonParams, err := marshalToRaw(params)
 	if err != nil {
 		return fmt.Errorf("marshalling call parameters: %v", err)
 	}
-	request := &wireRequest{
+	request := &WireRequest{
 		ID:     &id,
 		Method: method,
 		Params: jsonParams,
@@ -211,9 +144,12 @@ func (c *Conn) Call(ctx context.Context, method string, params, result interface
 	if err != nil {
 		return fmt.Errorf("marshalling call request: %v", err)
 	}
+	for _, h := range c.handlers {
+		ctx = h.Request(ctx, Send, request)
+	}
 	// we have to add ourselves to the pending map before we send, otherwise we
 	// are racing the response
-	rchan := make(chan *wireResponse)
+	rchan := make(chan *WireResponse)
 	c.pendingMu.Lock()
 	c.pending[id] = rchan
 	c.pendingMu.Unlock()
@@ -222,12 +158,15 @@ func (c *Conn) Call(ctx context.Context, method string, params, result interface
 		c.pendingMu.Lock()
 		delete(c.pending, id)
 		c.pendingMu.Unlock()
+		for _, h := range c.handlers {
+			h.Done(ctx, err)
+		}
 	}()
 	// now we are ready to send
-	before := time.Now()
-	c.Logger(Send, request.ID, -1, request.Method, request.Params, nil)
 	n, err := c.stream.Write(ctx, data)
-	telemetry.SentBytes.Record(ctx, n)
+	for _, h := range c.handlers {
+		ctx = h.Wrote(ctx, n)
+	}
 	if err != nil {
 		// sending failed, we will never get a response, so don't leave it pending
 		return err
@@ -235,8 +174,9 @@ func (c *Conn) Call(ctx context.Context, method string, params, result interface
 	// now wait for the response
 	select {
 	case response := <-rchan:
-		elapsed := time.Since(before)
-		c.Logger(Receive, response.ID, elapsed, request.Method, response.Result, response.Error)
+		for _, h := range c.handlers {
+			ctx = h.Response(ctx, Receive, response)
+		}
 		// is it an error response?
 		if response.Error != nil {
 			return response.Error
@@ -250,7 +190,12 @@ func (c *Conn) Call(ctx context.Context, method string, params, result interface
 		return nil
 	case <-ctx.Done():
 		// allow the handler to propagate the cancel
-		c.Canceler(ctx, c, id)
+		cancelled := false
+		for _, h := range c.handlers {
+			if h.Cancel(ctx, c, id, cancelled) {
+				cancelled = true
+			}
+		}
 		return ctx.Err()
 	}
 }
@@ -290,9 +235,6 @@ func (r *Request) Reply(ctx context.Context, result interface{}, err error) erro
 	if r.IsNotify() {
 		return fmt.Errorf("reply not invoked with a valid call")
 	}
-	ctx, st := trace.StartSpan(ctx, r.Method+":reply")
-	defer st.End()
-
 	// reply ends the handling phase of a call, so if we are not yet
 	// parallel we should be now. The go routine is allowed to continue
 	// to do work after replying, which is why it is important to unlock
@@ -300,12 +242,11 @@ func (r *Request) Reply(ctx context.Context, result interface{}, err error) erro
 	r.Parallel()
 	r.state = requestReplied
 
-	elapsed := time.Since(r.start)
 	var raw *json.RawMessage
 	if err == nil {
 		raw, err = marshalToRaw(result)
 	}
-	response := &wireResponse{
+	response := &WireResponse{
 		Result: raw,
 		ID:     r.ID,
 	}
@@ -320,9 +261,13 @@ func (r *Request) Reply(ctx context.Context, result interface{}, err error) erro
 	if err != nil {
 		return err
 	}
-	r.conn.Logger(Send, response.ID, elapsed, r.Method, response.Result, response.Error)
+	for _, h := range r.conn.handlers {
+		ctx = h.Response(ctx, Send, response)
+	}
 	n, err := r.conn.stream.Write(ctx, data)
-	telemetry.SentBytes.Record(ctx, n)
+	for _, h := range r.conn.handlers {
+		ctx = h.Wrote(ctx, n)
+	}
 
 	if err != nil {
 		// TODO(iancottrell): if a stream write fails, we really need to shut down
@@ -360,7 +305,7 @@ type combined struct {
 // caused the termination.
 // It must be called exactly once for each Conn.
 // It returns only when the reader is closed or there is an error in the stream.
-func (c *Conn) Run(ctx context.Context) error {
+func (c *Conn) Run(runCtx context.Context) error {
 	// we need to make the next request "lock" in an unlocked state to allow
 	// the first incoming request to proceed. All later requests are unlocked
 	// by the preceding request going to parallel mode.
@@ -368,7 +313,7 @@ func (c *Conn) Run(ctx context.Context) error {
 	close(nextRequest)
 	for {
 		// get the data for a message
-		data, n, err := c.stream.Read(ctx)
+		data, n, err := c.stream.Read(runCtx)
 		if err != nil {
 			// the stream failed, we cannot continue
 			return err
@@ -378,26 +323,32 @@ func (c *Conn) Run(ctx context.Context) error {
 		if err := json.Unmarshal(data, msg); err != nil {
 			// a badly formed message arrived, log it and continue
 			// we trust the stream to have isolated the error to just this message
-			c.Logger(Receive, nil, -1, "", nil, NewErrorf(0, "unmarshal failed: %v", err))
+			for _, h := range c.handlers {
+				h.Error(runCtx, fmt.Errorf("unmarshal failed: %v", err))
+			}
 			continue
 		}
 		// work out which kind of message we have
 		switch {
 		case msg.Method != "":
 			// if method is set it must be a request
-			reqCtx, cancelReq := context.WithCancel(ctx)
-			reqCtx, rpcStats := start(reqCtx, true, msg.Method, msg.ID)
-			telemetry.ReceivedBytes.Record(ctx, n)
+			reqCtx, cancelReq := context.WithCancel(runCtx)
 			thisRequest := nextRequest
 			nextRequest = make(chan struct{})
 			req := &Request{
 				conn:        c,
 				cancel:      cancelReq,
 				nextRequest: nextRequest,
-				start:       time.Now(),
-				Method:      msg.Method,
-				Params:      msg.Params,
-				ID:          msg.ID,
+				WireRequest: WireRequest{
+					VersionTag: msg.VersionTag,
+					Method:     msg.Method,
+					Params:     msg.Params,
+					ID:         msg.ID,
+				},
+			}
+			for _, h := range c.handlers {
+				reqCtx = h.Request(reqCtx, Receive, &req.WireRequest)
+				reqCtx = h.Read(reqCtx, n)
 			}
 			c.setHandling(req, true)
 			go func() {
@@ -409,11 +360,17 @@ func (c *Conn) Run(ctx context.Context) error {
 						req.Reply(reqCtx, nil, NewErrorf(CodeInternalError, "method %q did not reply", req.Method))
 					}
 					req.Parallel()
-					rpcStats.end(reqCtx, nil)
+					for _, h := range c.handlers {
+						h.Done(reqCtx, err)
+					}
 					cancelReq()
 				}()
-				c.Logger(Receive, req.ID, -1, req.Method, req.Params, nil)
-				c.Handler(reqCtx, req)
+				delivered := false
+				for _, h := range c.handlers {
+					if h.Deliver(reqCtx, req, delivered) {
+						delivered = true
+					}
+				}
 			}()
 		case msg.ID != nil:
 			// we have a response, get the pending entry from the map
@@ -424,7 +381,7 @@ func (c *Conn) Run(ctx context.Context) error {
 			}
 			c.pendingMu.Unlock()
 			// and send the reply to the channel
-			response := &wireResponse{
+			response := &WireResponse{
 				Result: msg.Result,
 				Error:  msg.Error,
 				ID:     msg.ID,
@@ -432,7 +389,9 @@ func (c *Conn) Run(ctx context.Context) error {
 			rchan <- response
 			close(rchan)
 		default:
-			c.Logger(Receive, nil, -1, "", nil, NewErrorf(0, "message not a call, notify or response, ignoring"))
+			for _, h := range c.handlers {
+				h.Error(runCtx, fmt.Errorf("message not a call, notify or response, ignoring"))
+			}
 		}
 	}
 }

internal/jsonrpc2/jsonrpc2_test.go

@@ -10,9 +10,11 @@ import (
 	"flag"
 	"fmt"
 	"io"
+	"log"
 	"path"
 	"reflect"
 	"testing"
+	"time"
 
 	"golang.org/x/tools/internal/jsonrpc2"
 )
@@ -106,10 +108,7 @@ func run(ctx context.Context, t *testing.T, withHeaders bool, r io.ReadCloser, w
 		stream = jsonrpc2.NewStream(r, w)
 	}
 	conn := jsonrpc2.NewConn(stream)
-	conn.Handler = handle
-	if *logRPC {
-		conn.Logger = jsonrpc2.Log
-	}
+	conn.AddHandler(&handle{log: *logRPC})
 	go func() {
 		defer func() {
 			r.Close()
@@ -122,36 +121,82 @@ func run(ctx context.Context, t *testing.T, withHeaders bool, r io.ReadCloser, w
 	return conn
 }
 
-func handle(ctx context.Context, r *jsonrpc2.Request) {
+type handle struct {
+	log bool
+}
+
+func (h *handle) Deliver(ctx context.Context, r *jsonrpc2.Request, delivered bool) bool {
 	switch r.Method {
 	case "no_args":
 		if r.Params != nil {
 			r.Reply(ctx, nil, jsonrpc2.NewErrorf(jsonrpc2.CodeInvalidParams, "Expected no params"))
-			return
+			return true
 		}
 		r.Reply(ctx, true, nil)
 	case "one_string":
 		var v string
 		if err := json.Unmarshal(*r.Params, &v); err != nil {
 			r.Reply(ctx, nil, jsonrpc2.NewErrorf(jsonrpc2.CodeParseError, "%v", err.Error()))
-			return
+			return true
 		}
 		r.Reply(ctx, "got:"+v, nil)
 	case "one_number":
 		var v int
 		if err := json.Unmarshal(*r.Params, &v); err != nil {
 			r.Reply(ctx, nil, jsonrpc2.NewErrorf(jsonrpc2.CodeParseError, "%v", err.Error()))
-			return
+			return true
 		}
 		r.Reply(ctx, fmt.Sprintf("got:%d", v), nil)
 	case "join":
 		var v []string
 		if err := json.Unmarshal(*r.Params, &v); err != nil {
 			r.Reply(ctx, nil, jsonrpc2.NewErrorf(jsonrpc2.CodeParseError, "%v", err.Error()))
-			return
+			return true
 		}
 		r.Reply(ctx, path.Join(v...), nil)
 	default:
 		r.Reply(ctx, nil, jsonrpc2.NewErrorf(jsonrpc2.CodeMethodNotFound, "method %q not found", r.Method))
 	}
+	return true
+}
+
+func (h *handle) Cancel(ctx context.Context, conn *jsonrpc2.Conn, id jsonrpc2.ID, cancelled bool) bool {
+	return false
+}
+
+func (h *handle) Request(ctx context.Context, direction jsonrpc2.Direction, r *jsonrpc2.WireRequest) context.Context {
+	if h.log {
+		if r.ID != nil {
+			log.Printf("%v call [%v] %s %v", direction, r.ID, r.Method, r.Params)
+		} else {
+			log.Printf("%v notification %s %v", direction, r.Method, r.Params)
+		}
+		ctx = context.WithValue(ctx, "method", r.Method)
+		ctx = context.WithValue(ctx, "start", time.Now())
+	}
+	return ctx
+}
+
+func (h *handle) Response(ctx context.Context, direction jsonrpc2.Direction, r *jsonrpc2.WireResponse) context.Context {
+	if h.log {
+		method := ctx.Value("method")
+		elapsed := time.Since(ctx.Value("start").(time.Time))
+		log.Printf("%v response in %v [%v] %s %v", direction, elapsed, r.ID, method, r.Result)
+	}
+	return ctx
+}
+
+func (h *handle) Done(ctx context.Context, err error) {
+}
+
+func (h *handle) Read(ctx context.Context, bytes int64) context.Context {
+	return ctx
+}
+
+func (h *handle) Wrote(ctx context.Context, bytes int64) context.Context {
+	return ctx
+}
+
+func (h *handle) Error(ctx context.Context, err error) {
+	log.Printf("%v", err)
 }

internal/jsonrpc2/log.go

@@ -1,59 +0,0 @@
-// Copyright 2018 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package jsonrpc2
-
-import (
-	"encoding/json"
-	"log"
-	"time"
-)
-
-// Logger is an option you can pass to NewConn which is invoked for
-// all messages flowing through a Conn.
-// direction indicates if the message being recieved or sent
-// id is the message id, if not set it was a notification
-// elapsed is the time between a call being seen and the response, and is
-// negative for anything that is not a response.
-// method is the method name specified in the message
-// payload is the parameters for a call or notification, and the result for a
-// response
-type Logger = func(direction Direction, id *ID, elapsed time.Duration, method string, payload *json.RawMessage, err *Error)
-
-// Direction is used to indicate to a logger whether the logged message was being
-// sent or received.
-type Direction bool
-
-const (
-	// Send indicates the message is outgoing.
-	Send = Direction(true)
-	// Receive indicates the message is incoming.
-	Receive = Direction(false)
-)
-
-func (d Direction) String() string {
-	switch d {
-	case Send:
-		return "send"
-	case Receive:
-		return "receive"
-	default:
-		panic("unreachable")
-	}
-}
-
-// Log is an implementation of Logger that outputs using log.Print
-// It is not used by default, but is provided for easy logging in users code.
-func Log(direction Direction, id *ID, elapsed time.Duration, method string, payload *json.RawMessage, err *Error) {
-	switch {
-	case err != nil:
-		log.Printf("%v failure [%v] %s %v", direction, id, method, err)
-	case id == nil:
-		log.Printf("%v notification %s %s", direction, method, *payload)
-	case elapsed >= 0:
-		log.Printf("%v response in %v [%v] %s %s", direction, elapsed, id, method, *payload)
-	default:
-		log.Printf("%v call [%v] %s %s", direction, id, method, *payload)
-	}
-}

internal/jsonrpc2/wire.go

@@ -34,8 +34,8 @@ const (
 	CodeServerOverloaded = -32000
 )
 
-// wireRequest is sent to a server to represent a Call or Notify operaton.
-type wireRequest struct {
+// WireRequest is sent to a server to represent a Call or Notify operaton.
+type WireRequest struct {
 	// VersionTag is always encoded as the string "2.0"
 	VersionTag VersionTag `json:"jsonrpc"`
 	// Method is a string containing the method name to invoke.
@@ -48,11 +48,11 @@ type wireRequest struct {
 	ID *ID `json:"id,omitempty"`
 }
 
-// wireResponse is a reply to a Request.
+// WireResponse is a reply to a Request.
 // It will always have the ID field set to tie it back to a request, and will
 // have either the Result or Error fields set depending on whether it is a
 // success or failure response.
-type wireResponse struct {
+type WireResponse struct {
 	// VersionTag is always encoded as the string "2.0"
 	VersionTag VersionTag `json:"jsonrpc"`
 	// Result is the response value, and is required on success.

internal/lsp/cache/cache.go

@@ -14,7 +14,6 @@ import (
 
 	"golang.org/x/tools/internal/lsp/debug"
 	"golang.org/x/tools/internal/lsp/source"
-	"golang.org/x/tools/internal/lsp/xlog"
 	"golang.org/x/tools/internal/memoize"
 	"golang.org/x/tools/internal/span"
 )
@@ -72,12 +71,11 @@ func (c *cache) GetFile(uri span.URI) source.FileHandle {
 	}
 }
 
-func (c *cache) NewSession(log xlog.Logger) source.Session {
+func (c *cache) NewSession(ctx context.Context) source.Session {
 	index := atomic.AddInt64(&sessionIndex, 1)
 	s := &session{
 		cache:         c,
 		id:            strconv.FormatInt(index, 10),
-		log:           log,
 		overlays:      make(map[span.URI]*overlay),
 		filesWatchMap: NewWatchMap(),
 	}

internal/lsp/cache/check.go

@@ -16,6 +16,8 @@ import (
 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/packages"
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
 	"golang.org/x/tools/internal/lsp/telemetry/trace"
 	"golang.org/x/tools/internal/span"
 )
@@ -68,18 +70,22 @@ func (imp *importer) getPkg(ctx context.Context, id packageID) (*pkg, error) {
 		// This goroutine becomes responsible for populating
 		// the entry and broadcasting its readiness.
 		e.pkg, e.err = imp.typeCheck(ctx, id)
+		if e.err != nil {
+			// Don't cache failed packages. If we didn't successfully cache the package
+			// in each file, then this pcache entry won't get invalidated as those files
+			// change.
+			imp.view.pcache.mu.Lock()
+			if imp.view.pcache.packages[id] == e {
+				delete(imp.view.pcache.packages, id)
+			}
+			imp.view.pcache.mu.Unlock()
+		}
 		close(e.ready)
 	}
 
 	if e.err != nil {
 		// If the import had been previously canceled, and that error cached, try again.
 		if e.err == context.Canceled && ctx.Err() == nil {
-			imp.view.pcache.mu.Lock()
-			// Clear out canceled cache entry if it is still there.
-			if imp.view.pcache.packages[id] == e {
-				delete(imp.view.pcache.packages, id)
-			}
-			imp.view.pcache.mu.Unlock()
 			return imp.getPkg(ctx, id)
 		}
 		return nil, e.err
@@ -89,8 +95,8 @@ func (imp *importer) getPkg(ctx context.Context, id packageID) (*pkg, error) {
 }
 
 func (imp *importer) typeCheck(ctx context.Context, id packageID) (*pkg, error) {
-	ctx, ts := trace.StartSpan(ctx, "cache.importer.typeCheck")
-	defer ts.End()
+	ctx, done := trace.StartSpan(ctx, "cache.importer.typeCheck", telemetry.Package.Of(id))
+	defer done()
 	meta, ok := imp.view.mcache.packages[id]
 	if !ok {
 		return nil, fmt.Errorf("no metadata for %v", id)
@@ -117,42 +123,42 @@ func (imp *importer) typeCheck(ctx context.Context, id packageID) (*pkg, error)
 		mode = source.ParseExported
 	}
 	var (
-		files []*astFile
-		phs   []source.ParseGoHandle
-		wg    sync.WaitGroup
+		files  = make([]*ast.File, len(meta.files))
+		errors = make([]error, len(meta.files))
+		wg     sync.WaitGroup
 	)
 	for _, filename := range meta.files {
 		uri := span.FileURI(filename)
 		f, err := imp.view.getFile(ctx, uri)
 		if err != nil {
+			log.Error(ctx, "unable to get file", err, telemetry.File.Of(f.URI()))
 			continue
 		}
-		ph := imp.view.session.cache.ParseGoHandle(f.Handle(ctx), mode)
-		phs = append(phs, ph)
-		files = append(files, &astFile{
-			uri:       ph.File().Identity().URI,
-			isTrimmed: mode == source.ParseExported,
-			ph:        ph,
-		})
+		pkg.files = append(pkg.files, imp.view.session.cache.ParseGoHandle(f.Handle(ctx), mode))
 	}
-	for i, ph := range phs {
+	for i, ph := range pkg.files {
 		wg.Add(1)
 		go func(i int, ph source.ParseGoHandle) {
 			defer wg.Done()
 
-			files[i].file, files[i].err = ph.Parse(ctx)
+			files[i], errors[i] = ph.Parse(ctx)
 		}(i, ph)
 	}
 	wg.Wait()
 
+	var i int
 	for _, f := range files {
-		pkg.files = append(pkg.files, f)
-
-		if f.err != nil {
-			if f.err == context.Canceled {
-				return nil, f.err
-			}
-			imp.view.session.cache.appendPkgError(pkg, f.err)
+		if f != nil {
+			files[i] = f
+			i++
+		}
+	}
+	for _, err := range errors {
+		if err == context.Canceled {
+			return nil, err
+		}
+		if err != nil {
+			imp.view.session.cache.appendPkgError(pkg, err)
 		}
 	}
 
@@ -188,7 +194,7 @@ func (imp *importer) typeCheck(ctx context.Context, id packageID) (*pkg, error)
 	check := types.NewChecker(cfg, imp.fset, pkg.types, pkg.typesInfo)
 
 	// Ignore type-checking errors.
-	check.Files(pkg.GetSyntax())
+	check.Files(files)
 
 	// Add every file in this package to our cache.
 	if err := imp.cachePackage(ctx, pkg, meta, mode); err != nil {
@@ -199,16 +205,17 @@ func (imp *importer) typeCheck(ctx context.Context, id packageID) (*pkg, error)
 }
 
 func (imp *importer) cachePackage(ctx context.Context, pkg *pkg, meta *metadata, mode source.ParseMode) error {
-	for _, file := range pkg.files {
-		f, err := imp.view.getFile(ctx, file.uri)
+	for _, ph := range pkg.files {
+		uri := ph.File().Identity().URI
+		f, err := imp.view.getFile(ctx, uri)
 		if err != nil {
-			return fmt.Errorf("no such file %s: %v", file.uri, err)
+			return fmt.Errorf("no such file %s: %v", uri, err)
 		}
 		gof, ok := f.(*goFile)
 		if !ok {
-			return fmt.Errorf("non Go file %s", file.uri)
+			return fmt.Errorf("non Go file %s", uri)
 		}
-		if err := imp.cachePerFile(gof, file, pkg); err != nil {
+		if err := imp.cachePerFile(gof, ph, pkg); err != nil {
 			return fmt.Errorf("failed to cache file %s: %v", gof.URI(), err)
 		}
 	}
@@ -227,7 +234,7 @@ func (imp *importer) cachePackage(ctx context.Context, pkg *pkg, meta *metadata,
 	return nil
 }
 
-func (imp *importer) cachePerFile(gof *goFile, file *astFile, p *pkg) error {
+func (imp *importer) cachePerFile(gof *goFile, ph source.ParseGoHandle, p *pkg) error {
 	gof.mu.Lock()
 	defer gof.mu.Unlock()
 
@@ -237,25 +244,11 @@ func (imp *importer) cachePerFile(gof *goFile, file *astFile, p *pkg) error {
 	}
 	gof.pkgs[p.id] = p
 
-	// Get the AST for the file.
-	gof.ast = file
-	if gof.ast == nil {
-		return fmt.Errorf("no AST information for %s", file.uri)
+	file, err := ph.Parse(imp.ctx)
+	if file == nil {
+		return fmt.Errorf("no AST for %s: %v", ph.File().Identity().URI, err)
 	}
-	if gof.ast.file == nil {
-		return fmt.Errorf("no AST for %s", file.uri)
-	}
-	// Get the *token.File directly from the AST.
-	pos := gof.ast.file.Pos()
-	if !pos.IsValid() {
-		return fmt.Errorf("AST for %s has an invalid position", file.uri)
-	}
-	tok := imp.view.session.cache.FileSet().File(pos)
-	if tok == nil {
-		return fmt.Errorf("no *token.File for %s", file.uri)
-	}
-	gof.token = tok
-	gof.imports = gof.ast.file.Imports
+	gof.imports = file.Imports
 	return nil
 }
 

internal/lsp/cache/external.go

@@ -10,6 +10,7 @@ import (
 	"os"
 
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry"
 	"golang.org/x/tools/internal/lsp/telemetry/trace"
 	"golang.org/x/tools/internal/span"
 )
@@ -51,8 +52,8 @@ func (h *nativeFileHandle) Kind() source.FileKind {
 }
 
 func (h *nativeFileHandle) Read(ctx context.Context) ([]byte, string, error) {
-	ctx, ts := trace.StartSpan(ctx, "cache.nativeFileHandle.Read")
-	defer ts.End()
+	ctx, done := trace.StartSpan(ctx, "cache.nativeFileHandle.Read", telemetry.File.Of(h.identity.URI.Filename()))
+	defer done()
 	//TODO: this should fail if the version is not the same as the handle
 	data, err := ioutil.ReadFile(h.identity.URI.Filename())
 	if err != nil {

internal/lsp/cache/file.go

@@ -34,8 +34,6 @@ type fileBase struct {
 
 	handleMu sync.Mutex
 	handle   source.FileHandle
-
-	token *token.File
 }
 
 func basename(filename string) string {

internal/lsp/cache/gofile.go

@@ -6,11 +6,14 @@ package cache
 
 import (
 	"context"
+	"fmt"
 	"go/ast"
 	"go/token"
 	"sync"
 
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -33,7 +36,6 @@ type goFile struct {
 
 	imports []*ast.ImportSpec
 
-	ast  *astFile
 	pkgs map[packageID]*pkg
 	meta map[packageID]*metadata
 }
@@ -46,71 +48,53 @@ type astFile struct {
 	isTrimmed bool
 }
 
-func (f *goFile) GetToken(ctx context.Context) *token.File {
-	f.view.mu.Lock()
-	defer f.view.mu.Unlock()
-
-	if f.isDirty() || f.astIsTrimmed() {
-		if _, err := f.view.loadParseTypecheck(ctx, f); err != nil {
-			f.View().Session().Logger().Errorf(ctx, "unable to check package for %s: %v", f.URI(), err)
-			return nil
-		}
+func (f *goFile) GetToken(ctx context.Context) (*token.File, error) {
+	file, err := f.GetAST(ctx, source.ParseFull)
+	if file == nil {
+		return nil, err
 	}
-	f.mu.Lock()
-	defer f.mu.Unlock()
-
-	if unexpectedAST(ctx, f) {
-		return nil
-	}
-	return f.token
+	return f.view.session.cache.fset.File(file.Pos()), nil
 }
 
-func (f *goFile) GetAnyAST(ctx context.Context) *ast.File {
+func (f *goFile) GetAST(ctx context.Context, mode source.ParseMode) (*ast.File, error) {
 	f.view.mu.Lock()
 	defer f.view.mu.Unlock()
+	ctx = telemetry.File.With(ctx, f.URI())
 
-	if f.isDirty() {
+	if f.isDirty(ctx) || f.wrongParseMode(ctx, mode) {
 		if _, err := f.view.loadParseTypecheck(ctx, f); err != nil {
-			f.View().Session().Logger().Errorf(ctx, "unable to check package for %s: %v", f.URI(), err)
-			return nil
+			return nil, fmt.Errorf("GetAST: unable to check package for %s: %v", f.URI(), err)
 		}
 	}
-
-	f.mu.Lock()
-	defer f.mu.Unlock()
-
-	if f.ast == nil {
-		return nil
-	}
-	return f.ast.file
-}
-
-func (f *goFile) GetAST(ctx context.Context) *ast.File {
-	f.view.mu.Lock()
-	defer f.view.mu.Unlock()
-
-	if f.isDirty() || f.astIsTrimmed() {
-		if _, err := f.view.loadParseTypecheck(ctx, f); err != nil {
-			f.View().Session().Logger().Errorf(ctx, "unable to check package for %s: %v", f.URI(), err)
-			return nil
+	fh := f.Handle(ctx)
+	// Check for a cached AST first, in case getting a trimmed version would actually cause a re-parse.
+	for _, m := range []source.ParseMode{
+		source.ParseHeader,
+		source.ParseExported,
+		source.ParseFull,
+	} {
+		if m < mode {
+			continue
+		}
+		if v, ok := f.view.session.cache.store.Cached(parseKey{
+			file: fh.Identity(),
+			mode: m,
+		}).(*parseGoData); ok {
+			return v.ast, v.err
 		}
 	}
-	f.mu.Lock()
-	defer f.mu.Unlock()
-
-	if unexpectedAST(ctx, f) {
-		return nil
-	}
-	return f.ast.file
+	ph := f.view.session.cache.ParseGoHandle(fh, mode)
+	return ph.Parse(ctx)
 }
 
 func (f *goFile) GetPackages(ctx context.Context) []source.Package {
 	f.view.mu.Lock()
 	defer f.view.mu.Unlock()
+	ctx = telemetry.File.With(ctx, f.URI())
 
-	if f.isDirty() || f.astIsTrimmed() {
+	if f.isDirty(ctx) || f.wrongParseMode(ctx, source.ParseFull) {
 		if errs, err := f.view.loadParseTypecheck(ctx, f); err != nil {
-			f.View().Session().Logger().Errorf(ctx, "unable to check package for %s: %v", f.URI(), err)
+			log.Error(ctx, "unable to check package", err, telemetry.File)
 
 			// Create diagnostics for errors if we are able to.
 			if len(errs) > 0 {
@@ -123,9 +107,6 @@ func (f *goFile) GetPackages(ctx context.Context) []source.Package {
 	f.mu.Lock()
 	defer f.mu.Unlock()
 
-	if unexpectedAST(ctx, f) {
-		return nil
-	}
 	var pkgs []source.Package
 	for _, pkg := range f.pkgs {
 		pkgs = append(pkgs, pkg)
@@ -148,23 +129,24 @@ func (f *goFile) GetPackage(ctx context.Context) source.Package {
 	return result
 }
 
-func unexpectedAST(ctx context.Context, f *goFile) bool {
-	// If the AST comes back nil, something has gone wrong.
-	if f.ast == nil {
-		f.View().Session().Logger().Errorf(ctx, "expected full AST for %s, returned nil", f.URI())
-		return true
-	}
-	// If the AST comes back trimmed, something has gone wrong.
-	if f.ast.isTrimmed {
-		f.View().Session().Logger().Errorf(ctx, "expected full AST for %s, returned trimmed", f.URI())
-		return true
+func (f *goFile) wrongParseMode(ctx context.Context, mode source.ParseMode) bool {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+
+	fh := f.Handle(ctx)
+	for _, pkg := range f.pkgs {
+		for _, ph := range pkg.files {
+			if fh.Identity() == ph.File().Identity() {
+				return ph.Mode() < mode
+			}
+		}
 	}
 	return false
 }
 
 // isDirty is true if the file needs to be type-checked.
 // It assumes that the file's view's mutex is held by the caller.
-func (f *goFile) isDirty() bool {
+func (f *goFile) isDirty(ctx context.Context) bool {
 	f.mu.Lock()
 	defer f.mu.Unlock()
 
@@ -184,14 +166,16 @@ func (f *goFile) isDirty() bool {
 	if len(f.missingImports) > 0 {
 		return true
 	}
-	return f.token == nil || f.ast == nil
-}
-
-func (f *goFile) astIsTrimmed() bool {
-	f.mu.Lock()
-	defer f.mu.Unlock()
-
-	return f.ast != nil && f.ast.isTrimmed
+	fh := f.Handle(ctx)
+	for _, pkg := range f.pkgs {
+		for _, file := range pkg.files {
+			// There is a type-checked package for the current file handle.
+			if file.File().Identity() == fh.Identity() {
+				return false
+			}
+		}
+	}
+	return true
 }
 
 func (f *goFile) GetActiveReverseDeps(ctx context.Context) []source.GoFile {

internal/lsp/cache/load.go

@@ -10,6 +10,10 @@ import (
 
 	"golang.org/x/tools/go/packages"
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
+	"golang.org/x/tools/internal/lsp/telemetry/trace"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -19,7 +23,7 @@ func (v *view) loadParseTypecheck(ctx context.Context, f *goFile) ([]packages.Er
 
 	// If the AST for this file is trimmed, and we are explicitly type-checking it,
 	// don't ignore function bodies.
-	if f.astIsTrimmed() {
+	if f.wrongParseMode(ctx, source.ParseFull) {
 		v.pcache.mu.Lock()
 		f.invalidateAST(ctx)
 		v.pcache.mu.Unlock()
@@ -84,7 +88,9 @@ func (v *view) checkMetadata(ctx context.Context, f *goFile) (map[packageID]*met
 		return nil, nil, ctx.Err()
 	}
 
-	pkgs, err := packages.Load(v.Config(), fmt.Sprintf("file=%s", f.filename()))
+	ctx, done := trace.StartSpan(ctx, "packages.Load", telemetry.File.Of(f.filename()))
+	defer done()
+	pkgs, err := packages.Load(v.Config(ctx), fmt.Sprintf("file=%s", f.filename()))
 	if len(pkgs) == 0 {
 		if err == nil {
 			err = fmt.Errorf("go/packages.Load: no packages found for %s", f.filename())
@@ -99,7 +105,10 @@ func (v *view) checkMetadata(ctx context.Context, f *goFile) (map[packageID]*met
 	}
 	// Track missing imports as we look at the package's errors.
 	missingImports := make(map[packagePath]struct{})
+
+	log.Print(ctx, "go/packages.Load", tag.Of("packages", len(pkgs)))
 	for _, pkg := range pkgs {
+		log.Print(ctx, "go/packages.Load", tag.Of("package", pkg.PkgPath), tag.Of("files", pkg.CompiledGoFiles))
 		// If the package comes back with errors from `go list`,
 		// don't bother type-checking it.
 		if len(pkg.Errors) > 0 {
@@ -224,11 +233,13 @@ func (v *view) link(ctx context.Context, pkgPath packagePath, pkg *packages.Pack
 	for _, filename := range m.files {
 		f, err := v.getFile(ctx, span.FileURI(filename))
 		if err != nil {
-			v.session.log.Errorf(ctx, "no file %s: %v", filename, err)
+			log.Error(ctx, "no file", err, telemetry.File.Of(filename))
+			continue
 		}
 		gof, ok := f.(*goFile)
 		if !ok {
-			v.session.log.Errorf(ctx, "not a Go file: %s", f.URI())
+			log.Error(ctx, "not a Go file", nil, telemetry.File.Of(filename))
+			continue
 		}
 		if gof.meta == nil {
 			gof.meta = make(map[packageID]*metadata)
@@ -252,7 +263,7 @@ func (v *view) link(ctx context.Context, pkgPath packagePath, pkg *packages.Pack
 		}
 		if _, ok := m.children[packageID(importPkg.ID)]; !ok {
 			if err := v.link(ctx, importPkgPath, importPkg, m, missingImports); err != nil {
-				v.session.log.Errorf(ctx, "error in dependency %s: %v", importPkgPath, err)
+				log.Error(ctx, "error in dependency", err, telemetry.Package.Of(importPkgPath))
 			}
 		}
 	}

internal/lsp/cache/modfile.go

@@ -6,6 +6,7 @@ package cache
 
 import (
 	"context"
+	"fmt"
 	"go/token"
 )
 
@@ -14,7 +15,10 @@ type modFile struct {
 	fileBase
 }
 
-func (*modFile) GetToken(context.Context) *token.File { return nil }
-func (*modFile) setContent(content []byte)            {}
-func (*modFile) filename() string                     { return "" }
-func (*modFile) isActive() bool                       { return false }
+func (*modFile) GetToken(context.Context) (*token.File, error) {
+	return nil, fmt.Errorf("GetToken: not implemented")
+}
+
+func (*modFile) setContent(content []byte) {}
+func (*modFile) filename() string          { return "" }
+func (*modFile) isActive() bool            { return false }

internal/lsp/cache/parse.go

@@ -13,12 +13,13 @@ import (
 	"go/token"
 
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry"
 	"golang.org/x/tools/internal/lsp/telemetry/trace"
 	"golang.org/x/tools/internal/memoize"
 )
 
 // Limits the number of parallel parser calls per process.
-var parseLimit = make(chan bool, 20)
+var parseLimit = make(chan struct{}, 20)
 
 // parseKey uniquely identifies a parsed Go file.
 type parseKey struct {
@@ -74,13 +75,13 @@ func (h *parseGoHandle) Parse(ctx context.Context) (*ast.File, error) {
 }
 
 func parseGo(ctx context.Context, c *cache, fh source.FileHandle, mode source.ParseMode) (*ast.File, error) {
-	ctx, ts := trace.StartSpan(ctx, "cache.parseGo")
-	defer ts.End()
+	ctx, done := trace.StartSpan(ctx, "cache.parseGo", telemetry.File.Of(fh.Identity().URI.Filename()))
+	defer done()
 	buf, _, err := fh.Read(ctx)
 	if err != nil {
 		return nil, err
 	}
-	parseLimit <- true
+	parseLimit <- struct{}{}
 	defer func() { <-parseLimit }()
 	parserMode := parser.AllErrors | parser.ParseComments
 	if mode == source.ParseHeader {
@@ -140,8 +141,8 @@ func isEllipsisArray(n ast.Expr) bool {
 	return ok
 }
 
-// fix inspects and potentially modifies any *ast.BadStmts or *ast.BadExprs in the AST.
-// We attempt to modify the AST such that we can type-check it more effectively.
+// fix inspects the AST and potentially modifies any *ast.BadStmts so that it can be
+// type-checked more effectively.
 func fix(ctx context.Context, file *ast.File, tok *token.File, src []byte) error {
 	var parent ast.Node
 	var err error
@@ -207,7 +208,7 @@ func parseDeferOrGoStmt(bad *ast.BadStmt, parent ast.Node, tok *token.File, src
 	var to, curr token.Pos
 FindTo:
 	for {
-		curr, tkn, lit = s.Scan()
+		curr, tkn, _ = s.Scan()
 		// TODO(rstambler): This still needs more handling to work correctly.
 		// We encounter a specific issue with code that looks like this:
 		//

internal/lsp/cache/pkg.go

@@ -22,7 +22,7 @@ type pkg struct {
 	id      packageID
 	pkgPath packagePath
 
-	files      []*astFile
+	files      []source.ParseGoHandle
 	errors     []packages.Error
 	imports    map[packagePath]*pkg
 	types      *types.Package
@@ -149,17 +149,18 @@ func (pkg *pkg) PkgPath() string {
 
 func (pkg *pkg) GetFilenames() []string {
 	filenames := make([]string, 0, len(pkg.files))
-	for _, f := range pkg.files {
-		filenames = append(filenames, f.uri.Filename())
+	for _, ph := range pkg.files {
+		filenames = append(filenames, ph.File().Identity().URI.Filename())
 	}
 	return filenames
 }
 
-func (pkg *pkg) GetSyntax() []*ast.File {
+func (pkg *pkg) GetSyntax(ctx context.Context) []*ast.File {
 	var syntax []*ast.File
-	for _, f := range pkg.files {
-		if f.file != nil {
-			syntax = append(syntax, f.file)
+	for _, ph := range pkg.files {
+		file, _ := ph.Parse(ctx)
+		if file != nil {
+			syntax = append(syntax, file)
 		}
 	}
 	return syntax

internal/lsp/cache/session.go

@@ -16,15 +16,16 @@ import (
 
 	"golang.org/x/tools/internal/lsp/debug"
 	"golang.org/x/tools/internal/lsp/source"
-	"golang.org/x/tools/internal/lsp/xlog"
+	"golang.org/x/tools/internal/lsp/telemetry"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
+	"golang.org/x/tools/internal/lsp/telemetry/trace"
 	"golang.org/x/tools/internal/span"
+	"golang.org/x/tools/internal/xcontext"
 )
 
 type session struct {
 	cache *cache
 	id    string
-	// the logger to use to communicate back with the client
-	log xlog.Logger
 
 	viewMu  sync.Mutex
 	views   []*view
@@ -64,16 +65,18 @@ func (s *session) Cache() source.Cache {
 	return s.cache
 }
 
-func (s *session) NewView(name string, folder span.URI) source.View {
+func (s *session) NewView(ctx context.Context, name string, folder span.URI) source.View {
 	index := atomic.AddInt64(&viewIndex, 1)
 	s.viewMu.Lock()
 	defer s.viewMu.Unlock()
-	ctx := context.Background()
-	backgroundCtx, cancel := context.WithCancel(ctx)
+	// We want a true background context and not a detatched context here
+	// the spans need to be unrelated and no tag values should pollute it.
+	baseCtx := trace.Detach(xcontext.Detach(ctx))
+	backgroundCtx, cancel := context.WithCancel(baseCtx)
 	v := &view{
 		session:       s,
 		id:            strconv.FormatInt(index, 10),
-		baseCtx:       ctx,
+		baseCtx:       baseCtx,
 		backgroundCtx: backgroundCtx,
 		cancel:        cancel,
 		name:          name,
@@ -92,7 +95,7 @@ func (s *session) NewView(name string, folder span.URI) source.View {
 	}
 	// Preemptively build the builtin package,
 	// so we immediately add builtin.go to the list of ignored files.
-	v.buildBuiltinPkg()
+	v.buildBuiltinPkg(ctx)
 
 	s.views = append(s.views, v)
 	// we always need to drop the view map
@@ -178,11 +181,9 @@ func (s *session) removeView(ctx context.Context, view *view) error {
 	return fmt.Errorf("view %s for %v not found", view.Name(), view.Folder())
 }
 
-func (s *session) Logger() xlog.Logger {
-	return s.log
-}
-
-func (s *session) DidOpen(ctx context.Context, uri span.URI, text []byte) {
+// TODO: Propagate the language ID through to the view.
+func (s *session) DidOpen(ctx context.Context, uri span.URI, _ source.FileKind, text []byte) {
+	ctx = telemetry.File.With(ctx, uri)
 	// Mark the file as open.
 	s.openFiles.Store(uri, true)
 
@@ -197,12 +198,12 @@ func (s *session) DidOpen(ctx context.Context, uri span.URI, text []byte) {
 		if strings.HasPrefix(string(uri), string(view.Folder())) {
 			f, err := view.GetFile(ctx, uri)
 			if err != nil {
-				s.log.Errorf(ctx, "error getting file for %s", uri)
+				log.Error(ctx, "error getting file", nil, telemetry.File)
 				return
 			}
 			gof, ok := f.(*goFile)
 			if !ok {
-				s.log.Errorf(ctx, "%s is not a Go file", uri)
+				log.Error(ctx, "not a Go file", nil, telemetry.File)
 				return
 			}
 			// Mark file as open.
@@ -274,7 +275,7 @@ func (s *session) openOverlay(ctx context.Context, uri span.URI, data []byte) {
 	}
 	_, hash, err := s.cache.GetFile(uri).Read(ctx)
 	if err != nil {
-		s.log.Errorf(ctx, "failed to read %s: %v", uri, err)
+		log.Error(ctx, "failed to read", err, telemetry.File)
 		return
 	}
 	if hash == s.overlays[uri].hash {

internal/lsp/cache/sumfile.go

@@ -6,6 +6,7 @@ package cache
 
 import (
 	"context"
+	"fmt"
 	"go/token"
 )
 
@@ -14,7 +15,10 @@ type sumFile struct {
 	fileBase
 }
 
-func (*sumFile) GetToken(context.Context) *token.File { return nil }
-func (*sumFile) setContent(content []byte)            {}
-func (*sumFile) filename() string                     { return "" }
-func (*sumFile) isActive() bool                       { return false }
+func (*sumFile) GetToken(context.Context) (*token.File, error) {
+	return nil, fmt.Errorf("GetToken: not implemented")
+}
+
+func (*sumFile) setContent(content []byte) {}
+func (*sumFile) filename() string          { return "" }
+func (*sumFile) isActive() bool            { return false }

internal/lsp/cache/view.go

@@ -6,17 +6,22 @@ package cache
 
 import (
 	"context"
+	"fmt"
 	"go/ast"
 	"go/parser"
 	"go/token"
 	"go/types"
 	"os"
 	"path/filepath"
+	"strings"
 	"sync"
 
 	"golang.org/x/tools/go/packages"
+	"golang.org/x/tools/internal/imports"
 	"golang.org/x/tools/internal/lsp/debug"
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -48,6 +53,19 @@ type view struct {
 	// env is the environment to use when invoking underlying tools.
 	env []string
 
+	// process is the process env for this view.
+	// Note: this contains cached module and filesystem state.
+	//
+	// TODO(suzmue): the state cached in the process env is specific to each view,
+	// however, there is state that can be shared between views that is not currently
+	// cached, like the module cache.
+	processEnv *imports.ProcessEnv
+
+	// modFileVersions stores the last seen versions of the module files that are used
+	// by processEnvs resolver.
+	// TODO(suzmue): These versions may not actually be on disk.
+	modFileVersions map[string]string
+
 	// buildFlags is the build flags to use when invoking underlying tools.
 	buildFlags []string
 
@@ -111,7 +129,7 @@ func (v *view) Folder() span.URI {
 
 // Config returns the configuration used for the view's interaction with the
 // go/packages API. It is shared across all views.
-func (v *view) Config() *packages.Config {
+func (v *view) Config(ctx context.Context) *packages.Config {
 	// TODO: Should we cache the config and/or overlay somewhere?
 	return &packages.Config{
 		Dir:        v.folder.Filename(),
@@ -128,10 +146,112 @@ func (v *view) Config() *packages.Config {
 		ParseFile: func(*token.FileSet, string, []byte) (*ast.File, error) {
 			panic("go/packages must not be used to parse files")
 		},
+		Logf: func(format string, args ...interface{}) {
+			log.Print(ctx, fmt.Sprintf(format, args...))
+		},
 		Tests: true,
 	}
 }
 
+func (v *view) RunProcessEnvFunc(ctx context.Context, fn func(*imports.Options) error, opts *imports.Options) error {
+	v.mu.Lock()
+	defer v.mu.Unlock()
+	if v.processEnv == nil {
+		v.processEnv = v.buildProcessEnv(ctx)
+	}
+
+	// Before running the user provided function, clear caches in the resolver.
+	if v.modFilesChanged() {
+		if r, ok := v.processEnv.GetResolver().(*imports.ModuleResolver); ok {
+			// Clear the resolver cache and set Initialized to false.
+			r.Initialized = false
+			r.Main = nil
+			r.ModsByModPath = nil
+			r.ModsByDir = nil
+			// Reset the modFileVersions.
+			v.modFileVersions = nil
+		}
+	}
+
+	// Run the user function.
+	opts.Env = v.processEnv
+	if err := fn(opts); err != nil {
+		return err
+	}
+
+	// If applicable, store the file versions of the 'go.mod' files that are
+	// looked at by the resolver.
+	v.storeModFileVersions()
+
+	return nil
+}
+
+func (v *view) buildProcessEnv(ctx context.Context) *imports.ProcessEnv {
+	cfg := v.Config(ctx)
+	env := &imports.ProcessEnv{
+		WorkingDir: cfg.Dir,
+		Logf: func(format string, args ...interface{}) {
+			log.Print(ctx, fmt.Sprintf(format, args...))
+		},
+	}
+	for _, kv := range cfg.Env {
+		split := strings.Split(kv, "=")
+		if len(split) < 2 {
+			continue
+		}
+		switch split[0] {
+		case "GOPATH":
+			env.GOPATH = split[1]
+		case "GOROOT":
+			env.GOROOT = split[1]
+		case "GO111MODULE":
+			env.GO111MODULE = split[1]
+		case "GOPROXY":
+			env.GOROOT = split[1]
+		case "GOFLAGS":
+			env.GOFLAGS = split[1]
+		case "GOSUMDB":
+			env.GOSUMDB = split[1]
+		}
+	}
+	return env
+}
+
+func (v *view) modFilesChanged() bool {
+	// Check the versions of the 'go.mod' files of the main module
+	// and modules included by a replace directive. Return true if
+	// any of these file versions do not match.
+	for filename, version := range v.modFileVersions {
+		if version != v.fileVersion(filename) {
+			return true
+		}
+	}
+	return false
+}
+
+func (v *view) storeModFileVersions() {
+	// Store the mod files versions, if we are using a ModuleResolver.
+	r, moduleMode := v.processEnv.GetResolver().(*imports.ModuleResolver)
+	if !moduleMode || !r.Initialized {
+		return
+	}
+	v.modFileVersions = make(map[string]string)
+
+	// Get the file versions of the 'go.mod' files of the main module
+	// and modules included by a replace directive in the resolver.
+	for _, mod := range r.ModsByModPath {
+		if (mod.Main || mod.Replace != nil) && mod.GoMod != "" {
+			v.modFileVersions[mod.GoMod] = v.fileVersion(mod.GoMod)
+		}
+	}
+}
+
+func (v *view) fileVersion(filename string) string {
+	uri := span.FileURI(filename)
+	f := v.session.GetFile(uri)
+	return f.Identity().Version
+}
+
 func (v *view) Env() []string {
 	v.mu.Lock()
 	defer v.mu.Unlock()
@@ -143,6 +263,7 @@ func (v *view) SetEnv(env []string) {
 	defer v.mu.Unlock()
 	//TODO: this should invalidate the entire view
 	v.env = env
+	v.processEnv = nil // recompute process env
 }
 
 func (v *view) SetBuildFlags(buildFlags []string) {
@@ -186,9 +307,12 @@ func (v *view) BuiltinPackage() *ast.Package {
 // buildBuiltinPkg builds the view's builtin package.
 // It assumes that the view is not active yet,
 // i.e. it has not been added to the session's list of views.
-func (v *view) buildBuiltinPkg() {
-	cfg := *v.Config()
-	pkgs, _ := packages.Load(&cfg, "builtin")
+func (v *view) buildBuiltinPkg(ctx context.Context) {
+	cfg := *v.Config(ctx)
+	pkgs, err := packages.Load(&cfg, "builtin")
+	if err != nil {
+		log.Error(ctx, "error getting package metadata for \"builtin\" package", err)
+	}
 	if len(pkgs) != 1 {
 		v.builtinPkg, _ = ast.NewPackage(cfg.Fset, nil, nil, nil)
 		return
@@ -244,8 +368,6 @@ func (f *goFile) invalidateContent(ctx context.Context) {
 // including any position and type information that depends on it.
 func (f *goFile) invalidateAST(ctx context.Context) {
 	f.mu.Lock()
-	f.ast = nil
-	f.token = nil
 	pkgs := f.pkgs
 	f.mu.Unlock()
 
@@ -277,15 +399,25 @@ func (v *view) remove(ctx context.Context, id packageID, seen map[packageID]stru
 	for _, filename := range m.files {
 		f, err := v.findFile(span.FileURI(filename))
 		if err != nil {
-			v.session.log.Errorf(ctx, "cannot find file %s: %v", f.URI(), err)
+			log.Error(ctx, "cannot find file", err, telemetry.File.Of(f.URI()))
 			continue
 		}
 		gof, ok := f.(*goFile)
 		if !ok {
-			v.session.log.Errorf(ctx, "non-Go file %v", f.URI())
+			log.Error(ctx, "non-Go file", nil, telemetry.File.Of(f.URI()))
 			continue
 		}
 		gof.mu.Lock()
+		if pkg, ok := gof.pkgs[id]; ok {
+			// TODO: Ultimately, we shouldn't need this.
+			// Preemptively delete all of the cached keys if we are invalidating a package.
+			for _, ph := range pkg.files {
+				v.session.cache.store.Delete(parseKey{
+					file: ph.File().Identity(),
+					mode: ph.Mode(),
+				})
+			}
+		}
 		delete(gof.pkgs, id)
 		gof.mu.Unlock()
 	}

internal/lsp/cmd/check_test.go

@@ -5,7 +5,6 @@
 package cmd_test
 
 import (
-	"context"
 	"fmt"
 	"strings"
 	"testing"
@@ -23,7 +22,7 @@ func (r *runner) Diagnostics(t *testing.T, data tests.Diagnostics) {
 		fname := uri.Filename()
 		args := []string{"-remote=internal", "check", fname}
 		out := captureStdOut(t, func() {
-			tool.Main(context.Background(), r.app, args)
+			tool.Main(r.ctx, r.app, args)
 		})
 		// parse got into a collection of reports
 		got := map[string]struct{}{}

internal/lsp/cmd/cmd.go

@@ -24,8 +24,10 @@ import (
 	"golang.org/x/tools/internal/lsp/cache"
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry/ocagent"
 	"golang.org/x/tools/internal/span"
 	"golang.org/x/tools/internal/tool"
+	"golang.org/x/tools/internal/xcontext"
 )
 
 // Application is the main application as passed to tool.Main
@@ -44,6 +46,9 @@ type Application struct {
 	// The base cache to use for sessions from this application.
 	cache source.Cache
 
+	// The name of the binary, used in help and telemetry.
+	name string
+
 	// The working directory to run commands in.
 	wd string
 
@@ -55,23 +60,28 @@ type Application struct {
 
 	// Enable verbose logging
 	Verbose bool `flag:"v" help:"Verbose output"`
+
+	// Control ocagent export of telemetry
+	OCAgent string `flag:"ocagent" help:"The address of the ocagent, or off"`
 }
 
 // Returns a new Application ready to run.
-func New(wd string, env []string) *Application {
+func New(name, wd string, env []string) *Application {
 	if wd == "" {
 		wd, _ = os.Getwd()
 	}
 	app := &Application{
-		cache: cache.New(),
-		wd:    wd,
-		env:   env,
+		cache:   cache.New(),
+		name:    name,
+		wd:      wd,
+		env:     env,
+		OCAgent: "off", //TODO: Remove this line to default the exporter to on
 	}
 	return app
 }
 
 // Name implements tool.Application returning the binary name.
-func (app *Application) Name() string { return "gopls" }
+func (app *Application) Name() string { return app.name }
 
 // Usage implements tool.Application returning empty extra argument usage.
 func (app *Application) Usage() string { return "<command> [command-flags] [command-args]" }
@@ -101,6 +111,7 @@ gopls flags are:
 // If no arguments are passed it will invoke the server sub command, as a
 // temporary measure for compatibility.
 func (app *Application) Run(ctx context.Context, args ...string) error {
+	ocagent.Export(app.name, app.OCAgent)
 	app.Serve.app = app
 	if len(args) == 0 {
 		tool.Main(ctx, &app.Serve, args)
@@ -139,7 +150,7 @@ func (app *Application) connect(ctx context.Context) (*connection, error) {
 	switch app.Remote {
 	case "":
 		connection := newConnection(app)
-		connection.Server = lsp.NewClientServer(app.cache, connection.Client)
+		ctx, connection.Server = lsp.NewClientServer(ctx, app.cache, connection.Client)
 		return connection, connection.initialize(ctx)
 	case "internal":
 		internalMu.Lock()
@@ -148,13 +159,16 @@ func (app *Application) connect(ctx context.Context) (*connection, error) {
 			return c, nil
 		}
 		connection := newConnection(app)
-		ctx := context.Background() //TODO:a way of shutting down the internal server
+		ctx := xcontext.Detach(ctx) //TODO:a way of shutting down the internal server
 		cr, sw, _ := os.Pipe()
 		sr, cw, _ := os.Pipe()
 		var jc *jsonrpc2.Conn
-		jc, connection.Server, _ = protocol.NewClient(jsonrpc2.NewHeaderStream(cr, cw), connection.Client)
+		ctx, jc, connection.Server = protocol.NewClient(ctx, jsonrpc2.NewHeaderStream(cr, cw), connection.Client)
 		go jc.Run(ctx)
-		go lsp.NewServer(app.cache, jsonrpc2.NewHeaderStream(sr, sw)).Run(ctx)
+		go func() {
+			ctx, srv := lsp.NewServer(ctx, app.cache, jsonrpc2.NewHeaderStream(sr, sw))
+			srv.Run(ctx)
+		}()
 		if err := connection.initialize(ctx); err != nil {
 			return nil, err
 		}
@@ -168,7 +182,7 @@ func (app *Application) connect(ctx context.Context) (*connection, error) {
 		}
 		stream := jsonrpc2.NewHeaderStream(conn, conn)
 		var jc *jsonrpc2.Conn
-		jc, connection.Server, _ = protocol.NewClient(stream, connection.Client)
+		ctx, jc, connection.Server = protocol.NewClient(ctx, stream, connection.Client)
 		go jc.Run(ctx)
 		return connection, connection.initialize(ctx)
 	}
@@ -334,12 +348,14 @@ func (c *cmdClient) getFile(ctx context.Context, uri span.URI) *cmdFile {
 func (c *connection) AddFile(ctx context.Context, uri span.URI) *cmdFile {
 	c.Client.filesMu.Lock()
 	defer c.Client.filesMu.Unlock()
+
 	file := c.Client.getFile(ctx, uri)
 	if !file.added {
 		file.added = true
 		p := &protocol.DidOpenTextDocumentParams{}
 		p.TextDocument.URI = string(uri)
 		p.TextDocument.Text = string(file.mapper.Content)
+		p.TextDocument.LanguageID = source.DetectLanguage("", file.uri.Filename()).String()
 		if err := c.Server.DidOpen(ctx, p); err != nil {
 			file.err = fmt.Errorf("%v: %v", uri, err)
 		}

internal/lsp/cmd/cmd_test.go

@@ -6,6 +6,7 @@ package cmd_test
 
 import (
 	"bytes"
+	"context"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -24,6 +25,7 @@ type runner struct {
 	exporter packagestest.Exporter
 	data     *tests.Data
 	app      *cmd.Application
+	ctx      context.Context
 }
 
 func TestCommandLine(t *testing.T) {
@@ -37,7 +39,8 @@ func testCommandLine(t *testing.T, exporter packagestest.Exporter) {
 	r := &runner{
 		exporter: exporter,
 		data:     data,
-		app:      cmd.New(data.Config.Dir, data.Exported.Config.Env),
+		app:      cmd.New("gopls-test", data.Config.Dir, data.Exported.Config.Env),
+		ctx:      tests.Context(t),
 	}
 	tests.Run(t, r, data)
 }

internal/lsp/cmd/definition_test.go

@@ -5,7 +5,6 @@
 package cmd_test
 
 import (
-	"context"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -56,7 +55,7 @@ func TestDefinitionHelpExample(t *testing.T) {
 		fmt.Sprintf("%v:#%v", thisFile, cmd.ExampleOffset)} {
 		args := append(baseArgs, query)
 		got := captureStdOut(t, func() {
-			tool.Main(context.Background(), cmd.New("", nil), args)
+			tool.Main(tests.Context(t), cmd.New("gopls-test", "", nil), args)
 		})
 		if !expect.MatchString(got) {
 			t.Errorf("test with %v\nexpected:\n%s\ngot:\n%s", args, expect, got)
@@ -84,7 +83,7 @@ func (r *runner) Definition(t *testing.T, data tests.Definitions) {
 			uri := d.Src.URI()
 			args = append(args, fmt.Sprint(d.Src))
 			got := captureStdOut(t, func() {
-				tool.Main(context.Background(), r.app, args)
+				tool.Main(r.ctx, r.app, args)
 			})
 			got = normalizePaths(r.data, got)
 			if mode&jsonGoDef != 0 && runtime.GOOS == "windows" {

internal/lsp/cmd/format_test.go

@@ -5,7 +5,6 @@
 package cmd_test
 
 import (
-	"context"
 	"os/exec"
 	"regexp"
 	"strings"
@@ -38,9 +37,9 @@ func (r *runner) Format(t *testing.T, data tests.Formats) {
 				//TODO: our error handling differs, for now just skip unformattable files
 				continue
 			}
-			app := cmd.New(r.data.Config.Dir, r.data.Config.Env)
+			app := cmd.New("gopls-test", r.data.Config.Dir, r.data.Config.Env)
 			got := captureStdOut(t, func() {
-				tool.Main(context.Background(), app, append([]string{"-remote=internal", "format"}, args...))
+				tool.Main(r.ctx, app, append([]string{"-remote=internal", "format"}, args...))
 			})
 			got = normalizePaths(r.data, got)
 			// check the first two lines are the expected file header

internal/lsp/cmd/serve.go

@@ -20,6 +20,9 @@ import (
 	"golang.org/x/tools/internal/jsonrpc2"
 	"golang.org/x/tools/internal/lsp"
 	"golang.org/x/tools/internal/lsp/debug"
+	"golang.org/x/tools/internal/lsp/telemetry"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
+	"golang.org/x/tools/internal/lsp/telemetry/trace"
 	"golang.org/x/tools/internal/tool"
 )
 
@@ -79,8 +82,8 @@ func (s *Serve) Run(ctx context.Context, args ...string) error {
 	}
 
 	// For debugging purposes only.
-	run := func(srv *lsp.Server) {
-		srv.Conn.Logger = logger(s.Trace, out)
+	run := func(ctx context.Context, srv *lsp.Server) {
+		srv.Conn.AddHandler(&handler{loggingRPCs: s.Trace, out: out})
 		go srv.Run(ctx)
 	}
 	if s.Address != "" {
@@ -90,8 +93,8 @@ func (s *Serve) Run(ctx context.Context, args ...string) error {
 		return lsp.RunServerOnPort(ctx, s.app.cache, s.Port, run)
 	}
 	stream := jsonrpc2.NewHeaderStream(os.Stdin, os.Stdout)
-	srv := lsp.NewServer(s.app.cache, stream)
-	srv.Conn.Logger = logger(s.Trace, out)
+	ctx, srv := lsp.NewServer(ctx, s.app.cache, stream)
+	srv.Conn.AddHandler(&handler{loggingRPCs: s.Trace, out: out})
 	return srv.Run(ctx)
 }
 
@@ -115,55 +118,161 @@ func (s *Serve) forward() error {
 	return <-errc
 }
 
-func logger(trace bool, out io.Writer) jsonrpc2.Logger {
-	return func(direction jsonrpc2.Direction, id *jsonrpc2.ID, elapsed time.Duration, method string, payload *json.RawMessage, err *jsonrpc2.Error) {
-		if !trace {
-			return
-		}
-		const eol = "\r\n\r\n\r\n"
-		if err != nil {
-			fmt.Fprintf(out, "[Error - %v] %s %s%s %v%s", time.Now().Format("3:04:05 PM"),
-				direction, method, id, err, eol)
-			return
-		}
-		outx := new(strings.Builder)
-		fmt.Fprintf(outx, "[Trace - %v] ", time.Now().Format("3:04:05 PM"))
-		switch direction {
-		case jsonrpc2.Send:
-			fmt.Fprint(outx, "Received ")
-		case jsonrpc2.Receive:
-			fmt.Fprint(outx, "Sending ")
-		}
-		switch {
-		case id == nil:
-			fmt.Fprint(outx, "notification ")
-		case elapsed >= 0:
-			fmt.Fprint(outx, "response ")
-		default:
-			fmt.Fprint(outx, "request ")
-		}
-		fmt.Fprintf(outx, "'%s", method)
-		switch {
-		case id == nil:
-			// do nothing
-		case id.Name != "":
-			fmt.Fprintf(outx, " - (%s)", id.Name)
-		default:
-			fmt.Fprintf(outx, " - (%d)", id.Number)
-		}
-		fmt.Fprint(outx, "'")
-		if elapsed >= 0 {
-			msec := int(elapsed.Round(time.Millisecond) / time.Millisecond)
-			fmt.Fprintf(outx, " in %dms", msec)
-		}
-		params := "null"
-		if payload != nil {
-			params = string(*payload)
-		}
-		if params == "null" {
-			params = "{}"
-		}
-		fmt.Fprintf(outx, ".\r\nParams: %s%s", params, eol)
-		fmt.Fprintf(out, "%s", outx.String())
-	}
+type handler struct {
+	loggingRPCs bool
+	out         io.Writer
+}
+
+type rpcStats struct {
+	method     string
+	direction  jsonrpc2.Direction
+	id         *jsonrpc2.ID
+	payload    *json.RawMessage
+	start      time.Time
+	delivering func()
+	close      func()
+}
+
+type statsKeyType int
+
+const statsKey = statsKeyType(0)
+
+func (h *handler) Deliver(ctx context.Context, r *jsonrpc2.Request, delivered bool) bool {
+	stats := h.getStats(ctx)
+	if stats != nil {
+		stats.delivering()
+	}
+	return false
+}
+
+func (h *handler) Cancel(ctx context.Context, conn *jsonrpc2.Conn, id jsonrpc2.ID, cancelled bool) bool {
+	return false
+}
+
+func (h *handler) Request(ctx context.Context, direction jsonrpc2.Direction, r *jsonrpc2.WireRequest) context.Context {
+	if r.Method == "" {
+		panic("no method in rpc stats")
+	}
+	stats := &rpcStats{
+		method:    r.Method,
+		start:     time.Now(),
+		direction: direction,
+		payload:   r.Params,
+	}
+	ctx = context.WithValue(ctx, statsKey, stats)
+	mode := telemetry.Outbound
+	if direction == jsonrpc2.Receive {
+		mode = telemetry.Inbound
+	}
+	ctx, stats.close = trace.StartSpan(ctx, r.Method,
+		tag.Tag{Key: telemetry.Method, Value: r.Method},
+		tag.Tag{Key: telemetry.RPCDirection, Value: mode},
+		tag.Tag{Key: telemetry.RPCID, Value: r.ID},
+	)
+	telemetry.Started.Record(ctx, 1)
+	_, stats.delivering = trace.StartSpan(ctx, "queued")
+	return ctx
+}
+
+func (h *handler) Response(ctx context.Context, direction jsonrpc2.Direction, r *jsonrpc2.WireResponse) context.Context {
+	stats := h.getStats(ctx)
+	h.logRPC(direction, r.ID, 0, stats.method, r.Result, nil)
+	return ctx
+}
+
+func (h *handler) Done(ctx context.Context, err error) {
+	stats := h.getStats(ctx)
+	h.logRPC(stats.direction, stats.id, time.Since(stats.start), stats.method, stats.payload, err)
+	if err != nil {
+		ctx = telemetry.StatusCode.With(ctx, "ERROR")
+	} else {
+		ctx = telemetry.StatusCode.With(ctx, "OK")
+	}
+	elapsedTime := time.Since(stats.start)
+	latencyMillis := float64(elapsedTime) / float64(time.Millisecond)
+	telemetry.Latency.Record(ctx, latencyMillis)
+	stats.close()
+}
+
+func (h *handler) Read(ctx context.Context, bytes int64) context.Context {
+	telemetry.SentBytes.Record(ctx, bytes)
+	return ctx
+}
+
+func (h *handler) Wrote(ctx context.Context, bytes int64) context.Context {
+	telemetry.ReceivedBytes.Record(ctx, bytes)
+	return ctx
+}
+
+const eol = "\r\n\r\n\r\n"
+
+func (h *handler) Error(ctx context.Context, err error) {
+	stats := h.getStats(ctx)
+	h.logRPC(stats.direction, stats.id, 0, stats.method, nil, err)
+}
+
+func (h *handler) getStats(ctx context.Context) *rpcStats {
+	stats, ok := ctx.Value(statsKey).(*rpcStats)
+	if !ok || stats == nil {
+		method, ok := ctx.Value(telemetry.Method).(string)
+		if !ok {
+			method = "???"
+		}
+		stats = &rpcStats{
+			method: method,
+			close:  func() {},
+		}
+	}
+	return stats
+}
+
+func (h *handler) logRPC(direction jsonrpc2.Direction, id *jsonrpc2.ID, elapsed time.Duration, method string, payload *json.RawMessage, err error) {
+	if !h.loggingRPCs {
+		return
+	}
+	const eol = "\r\n\r\n\r\n"
+	if err != nil {
+		fmt.Fprintf(h.out, "[Error - %v] %s %s%s %v%s", time.Now().Format("3:04:05 PM"),
+			direction, method, id, err, eol)
+		return
+	}
+	outx := new(strings.Builder)
+	fmt.Fprintf(outx, "[Trace - %v] ", time.Now().Format("3:04:05 PM"))
+	switch direction {
+	case jsonrpc2.Send:
+		fmt.Fprint(outx, "Received ")
+	case jsonrpc2.Receive:
+		fmt.Fprint(outx, "Sending ")
+	}
+	switch {
+	case id == nil:
+		fmt.Fprint(outx, "notification ")
+	case elapsed >= 0:
+		fmt.Fprint(outx, "response ")
+	default:
+		fmt.Fprint(outx, "request ")
+	}
+	fmt.Fprintf(outx, "'%s", method)
+	switch {
+	case id == nil:
+		// do nothing
+	case id.Name != "":
+		fmt.Fprintf(outx, " - (%s)", id.Name)
+	default:
+		fmt.Fprintf(outx, " - (%d)", id.Number)
+	}
+	fmt.Fprint(outx, "'")
+	if elapsed >= 0 {
+		msec := int(elapsed.Round(time.Millisecond) / time.Millisecond)
+		fmt.Fprintf(outx, " in %dms", msec)
+	}
+	params := "null"
+	if payload != nil {
+		params = string(*payload)
+	}
+	if params == "null" {
+		params = "{}"
+	}
+	fmt.Fprintf(outx, ".\r\nParams: %s%s", params, eol)
+	fmt.Fprintf(h.out, "%s", outx.String())
 }

internal/lsp/code_action.go

@@ -11,6 +11,8 @@ import (
 
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -57,7 +59,7 @@ func (s *Server) codeAction(ctx context.Context, params *protocol.CodeActionPara
 		if s.wantSuggestedFixes {
 			qf, err := quickFixes(ctx, view, gof)
 			if err != nil {
-				view.Session().Logger().Errorf(ctx, "quick fixes failed for %s: %v", uri, err)
+				log.Error(ctx, "quick fixes failed", err, telemetry.File.Of(uri))
 			}
 			codeActions = append(codeActions, qf...)
 		}
@@ -121,7 +123,8 @@ func findImportErrors(diagnostics []protocol.Diagnostic) bool {
 			return true
 		}
 		// "X imported but not used" is an unused import.
-		if strings.HasSuffix(diagnostic.Message, " imported but not used") {
+		// "X imported but not used as Y" is an unused import.
+		if strings.Contains(diagnostic.Message, " imported but not used") {
 			return true
 		}
 	}

internal/lsp/completion.go

@@ -12,6 +12,8 @@ import (
 
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -35,7 +37,7 @@ func (s *Server) completion(ctx context.Context, params *protocol.CompletionPara
 		WantDocumentaton: s.wantCompletionDocumentation,
 	})
 	if err != nil {
-		s.session.Logger().Infof(ctx, "no completions found for %s:%v:%v: %v", uri, int(params.Position.Line), int(params.Position.Character), err)
+		log.Print(ctx, "no completions found", tag.Of("At", rng), tag.Of("Failure", err))
 	}
 	return &protocol.CompletionList{
 		IsIncomplete: false,
@@ -62,11 +64,11 @@ func (s *Server) toProtocolCompletionItems(ctx context.Context, view source.View
 		prefix = strings.ToLower(surrounding.Prefix())
 		spn, err := surrounding.Range.Span()
 		if err != nil {
-			s.session.Logger().Infof(ctx, "failed to get span for surrounding position: %s:%v:%v: %v", m.URI, int(pos.Line), int(pos.Character), err)
+			log.Print(ctx, "failed to get span for surrounding position: %s:%v:%v: %v", tag.Of("Position", pos), tag.Of("Failure", err))
 		} else {
 			rng, err := m.Range(spn)
 			if err != nil {
-				s.session.Logger().Infof(ctx, "failed to convert surrounding position: %s:%v:%v: %v", m.URI, int(pos.Line), int(pos.Character), err)
+				log.Print(ctx, "failed to convert surrounding position", tag.Of("Position", pos), tag.Of("Failure", err))
 			} else {
 				insertionRange = rng
 			}

internal/lsp/debug/info.go

@@ -20,7 +20,7 @@ const (
 )
 
 // Version is a manually-updated mechanism for tracking versions.
-var Version = "v0.1.2"
+var Version = "v0.1.3"
 
 // This writes the version and environment information to a writer.
 func PrintVersionInfo(w io.Writer, verbose bool, mode PrintMode) {

internal/lsp/debug/metrics.go

@@ -0,0 +1,49 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package debug
+
+import (
+	"golang.org/x/tools/internal/lsp/telemetry"
+	"golang.org/x/tools/internal/lsp/telemetry/metric"
+)
+
+var (
+	// the distributions we use for histograms
+	bytesDistribution        = []int64{1 << 10, 1 << 11, 1 << 12, 1 << 14, 1 << 16, 1 << 20}
+	millisecondsDistribution = []float64{0.1, 0.5, 1, 2, 5, 10, 50, 100, 500, 1000, 5000, 10000, 50000, 100000}
+
+	receivedBytes = metric.HistogramInt64{
+		Name:        "received_bytes",
+		Description: "Distribution of received bytes, by method.",
+		Keys:        []interface{}{telemetry.RPCDirection, telemetry.Method},
+		Buckets:     bytesDistribution,
+	}.Record(telemetry.ReceivedBytes)
+
+	sentBytes = metric.HistogramInt64{
+		Name:        "sent_bytes",
+		Description: "Distribution of sent bytes, by method.",
+		Keys:        []interface{}{telemetry.RPCDirection, telemetry.Method},
+		Buckets:     bytesDistribution,
+	}.Record(telemetry.SentBytes)
+
+	latency = metric.HistogramFloat64{
+		Name:        "latency",
+		Description: "Distribution of latency in milliseconds, by method.",
+		Keys:        []interface{}{telemetry.RPCDirection, telemetry.Method},
+		Buckets:     millisecondsDistribution,
+	}.Record(telemetry.Latency)
+
+	started = metric.Scalar{
+		Name:        "started",
+		Description: "Count of RPCs started by method.",
+		Keys:        []interface{}{telemetry.RPCDirection, telemetry.Method},
+	}.CountInt64(telemetry.Started)
+
+	completed = metric.Scalar{
+		Name:        "completed",
+		Description: "Count of RPCs completed by method and status.",
+		Keys:        []interface{}{telemetry.RPCDirection, telemetry.Method, telemetry.StatusCode},
+	}.CountFloat64(telemetry.Latency)
+)

internal/lsp/debug/prometheus.go

@@ -0,0 +1,111 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package debug
+
+import (
+	"bytes"
+	"fmt"
+	"net/http"
+	"sort"
+
+	"golang.org/x/tools/internal/lsp/telemetry/metric"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
+	"golang.org/x/tools/internal/lsp/telemetry/worker"
+)
+
+type prometheus struct {
+	metrics []metric.Data
+}
+
+func (p *prometheus) observeMetric(data metric.Data) {
+	name := data.Handle().Name()
+	index := sort.Search(len(p.metrics), func(i int) bool {
+		return p.metrics[i].Handle().Name() >= name
+	})
+	if index >= len(p.metrics) || p.metrics[index].Handle().Name() != name {
+		old := p.metrics
+		p.metrics = make([]metric.Data, len(old)+1)
+		copy(p.metrics, old[:index])
+		copy(p.metrics[index+1:], old[index:])
+	}
+	p.metrics[index] = data
+}
+
+func (p *prometheus) header(w http.ResponseWriter, name, description string, isGauge, isHistogram bool) {
+	kind := "counter"
+	if isGauge {
+		kind = "gauge"
+	}
+	if isHistogram {
+		kind = "histogram"
+	}
+	fmt.Fprintf(w, "# HELP %s %s\n", name, description)
+	fmt.Fprintf(w, "# TYPE %s %s\n", name, kind)
+}
+
+func (p *prometheus) row(w http.ResponseWriter, name string, group tag.List, extra string, value interface{}) {
+	fmt.Fprint(w, name)
+	buf := &bytes.Buffer{}
+	fmt.Fprint(buf, group)
+	if extra != "" {
+		if buf.Len() > 0 {
+			fmt.Fprint(buf, ",")
+		}
+		fmt.Fprint(buf, extra)
+	}
+	if buf.Len() > 0 {
+		fmt.Fprint(w, "{")
+		buf.WriteTo(w)
+		fmt.Fprint(w, "}")
+	}
+	fmt.Fprintf(w, " %v\n", value)
+}
+
+func (p *prometheus) serve(w http.ResponseWriter, r *http.Request) {
+	done := make(chan struct{})
+	worker.Do(func() {
+		defer close(done)
+		for _, data := range p.metrics {
+			switch data := data.(type) {
+			case *metric.Int64Data:
+				p.header(w, data.Info.Name, data.Info.Description, data.IsGauge, false)
+				for i, group := range data.Groups() {
+					p.row(w, data.Info.Name, group, "", data.Rows[i])
+				}
+
+			case *metric.Float64Data:
+				p.header(w, data.Info.Name, data.Info.Description, data.IsGauge, false)
+				for i, group := range data.Groups() {
+					p.row(w, data.Info.Name, group, "", data.Rows[i])
+				}
+
+			case *metric.HistogramInt64Data:
+				p.header(w, data.Info.Name, data.Info.Description, false, true)
+				for i, group := range data.Groups() {
+					row := data.Rows[i]
+					for j, b := range data.Info.Buckets {
+						p.row(w, data.Info.Name+"_bucket", group, fmt.Sprintf(`le="%v"`, b), row.Values[j])
+					}
+					p.row(w, data.Info.Name+"_bucket", group, `le="+Inf"`, row.Count)
+					p.row(w, data.Info.Name+"_count", group, "", row.Count)
+					p.row(w, data.Info.Name+"_sum", group, "", row.Sum)
+				}
+
+			case *metric.HistogramFloat64Data:
+				p.header(w, data.Info.Name, data.Info.Description, false, true)
+				for i, group := range data.Groups() {
+					row := data.Rows[i]
+					for j, b := range data.Info.Buckets {
+						p.row(w, data.Info.Name+"_bucket", group, fmt.Sprintf(`le="%v"`, b), row.Values[j])
+					}
+					p.row(w, data.Info.Name+"_bucket", group, `le="+Inf"`, row.Count)
+					p.row(w, data.Info.Name+"_count", group, "", row.Count)
+					p.row(w, data.Info.Name+"_sum", group, "", row.Sum)
+				}
+			}
+		}
+	})
+	<-done
+}

internal/lsp/debug/rpc.go

@@ -0,0 +1,209 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package debug
+
+import (
+	"fmt"
+	"html/template"
+	"log"
+	"net/http"
+	"sort"
+
+	"golang.org/x/tools/internal/lsp/telemetry"
+	"golang.org/x/tools/internal/lsp/telemetry/metric"
+)
+
+var rpcTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
+{{define "title"}}RPC Information{{end}}
+{{define "body"}}
+	<H2>Inbound</H2>
+	{{template "rpcSection" .Inbound}}
+	<H2>Outbound</H2>
+	{{template "rpcSection" .Outbound}}
+{{end}}
+{{define "rpcSection"}}
+	{{range .}}<P>
+		<b>{{.Method}}</b> {{.Started}} <a href="/trace/{{.Method}}">traces</a> ({{.InProgress}} in progress)
+		<br>
+		<i>Latency</i> {{with .Latency}}{{.Mean}} ({{.Min}}<{{.Max}}){{end}}
+		<i>By bucket</i> 0s {{range .Latency.Values}}<b>{{.Count}}</b> {{.Limit}} {{end}}
+		<br>
+		<i>Received</i> {{with .Received}}{{.Mean}} ({{.Min}}<{{.Max}}){{end}}
+		<i>Sent</i> {{with .Sent}}{{.Mean}} ({{.Min}}<{{.Max}}){{end}}
+		<br>
+		<i>Result codes</i> {{range .Codes}}{{.Key}}={{.Count}} {{end}}
+		</P>
+	{{end}}
+{{end}}
+`))
+
+type rpcs struct {
+	Inbound  []*rpcStats
+	Outbound []*rpcStats
+}
+
+type rpcStats struct {
+	Method     string
+	Started    int64
+	Completed  int64
+	InProgress int64
+	Latency    rpcTimeHistogram
+	Received   rpcBytesHistogram
+	Sent       rpcBytesHistogram
+	Codes      []*rpcCodeBucket
+}
+
+type rpcTimeHistogram struct {
+	Sum    timeUnits
+	Count  int64
+	Mean   timeUnits
+	Min    timeUnits
+	Max    timeUnits
+	Values []rpcTimeBucket
+}
+
+type rpcTimeBucket struct {
+	Limit timeUnits
+	Count int64
+}
+
+type rpcBytesHistogram struct {
+	Sum    byteUnits
+	Count  int64
+	Mean   byteUnits
+	Min    byteUnits
+	Max    byteUnits
+	Values []rpcBytesBucket
+}
+
+type rpcBytesBucket struct {
+	Limit byteUnits
+	Count int64
+}
+
+type rpcCodeBucket struct {
+	Key   string
+	Count int64
+}
+
+func (r *rpcs) observeMetric(data metric.Data) {
+	for i, group := range data.Groups() {
+		set := &r.Inbound
+		if group.Get(telemetry.RPCDirection) == telemetry.Outbound {
+			set = &r.Outbound
+		}
+		method, ok := group.Get(telemetry.Method).(string)
+		if !ok {
+			log.Printf("Not a method... %v", group)
+			continue
+		}
+		index := sort.Search(len(*set), func(i int) bool {
+			return (*set)[i].Method >= method
+		})
+		if index >= len(*set) || (*set)[index].Method != method {
+			old := *set
+			*set = make([]*rpcStats, len(old)+1)
+			copy(*set, old[:index])
+			copy((*set)[index+1:], old[index:])
+			(*set)[index] = &rpcStats{Method: method}
+		}
+		stats := (*set)[index]
+		switch data.Handle() {
+		case started:
+			stats.Started = data.(*metric.Int64Data).Rows[i]
+		case completed:
+			status, ok := group.Get(telemetry.StatusCode).(string)
+			if !ok {
+				log.Printf("Not status... %v", group)
+				continue
+			}
+			var b *rpcCodeBucket
+			for c, entry := range stats.Codes {
+				if entry.Key == status {
+					b = stats.Codes[c]
+					break
+				}
+			}
+			if b == nil {
+				b = &rpcCodeBucket{Key: status}
+				stats.Codes = append(stats.Codes, b)
+				sort.Slice(stats.Codes, func(i int, j int) bool {
+					return stats.Codes[i].Key < stats.Codes[i].Key
+				})
+			}
+			b.Count = data.(*metric.Int64Data).Rows[i]
+		case latency:
+			data := data.(*metric.HistogramFloat64Data)
+			row := data.Rows[i]
+			stats.Latency.Count = row.Count
+			stats.Latency.Sum = timeUnits(row.Sum)
+			stats.Latency.Min = timeUnits(row.Min)
+			stats.Latency.Max = timeUnits(row.Max)
+			stats.Latency.Mean = timeUnits(row.Sum) / timeUnits(row.Count)
+			stats.Latency.Values = make([]rpcTimeBucket, len(data.Info.Buckets))
+			last := int64(0)
+			for i, b := range data.Info.Buckets {
+				stats.Latency.Values[i].Limit = timeUnits(b)
+				stats.Latency.Values[i].Count = row.Values[i] - last
+				last = row.Values[i]
+			}
+		case sentBytes:
+			data := data.(*metric.HistogramInt64Data)
+			row := data.Rows[i]
+			stats.Sent.Count = row.Count
+			stats.Sent.Sum = byteUnits(row.Sum)
+			stats.Sent.Min = byteUnits(row.Min)
+			stats.Sent.Max = byteUnits(row.Max)
+			stats.Sent.Mean = byteUnits(row.Sum) / byteUnits(row.Count)
+		case receivedBytes:
+			data := data.(*metric.HistogramInt64Data)
+			row := data.Rows[i]
+			stats.Received.Count = row.Count
+			stats.Received.Sum = byteUnits(row.Sum)
+			stats.Sent.Min = byteUnits(row.Min)
+			stats.Sent.Max = byteUnits(row.Max)
+			stats.Received.Mean = byteUnits(row.Sum) / byteUnits(row.Count)
+		}
+	}
+
+	for _, set := range [][]*rpcStats{r.Inbound, r.Outbound} {
+		for _, stats := range set {
+			stats.Completed = 0
+			for _, b := range stats.Codes {
+				stats.Completed += b.Count
+			}
+			stats.InProgress = stats.Started - stats.Completed
+		}
+	}
+}
+
+func (r *rpcs) getData(req *http.Request) interface{} {
+	return r
+}
+
+func units(v float64, suffixes []string) string {
+	s := ""
+	for _, s = range suffixes {
+		n := v / 1000
+		if n < 1 {
+			break
+		}
+		v = n
+	}
+	return fmt.Sprintf("%.2f%s", v, s)
+}
+
+type timeUnits float64
+
+func (v timeUnits) String() string {
+	v = v * 1000 * 1000
+	return units(float64(v), []string{"ns", "μs", "ms", "s"})
+}
+
+type byteUnits float64
+
+func (v byteUnits) String() string {
+	return units(float64(v), []string{"B", "KB", "MB", "GB", "TB"})
+}

internal/lsp/debug/serve.go

@@ -9,7 +9,6 @@ import (
 	"context"
 	"go/token"
 	"html/template"
-	"log"
 	"net"
 	"net/http"
 	"net/http/pprof"
@@ -19,6 +18,11 @@ import (
 	"strconv"
 	"sync"
 
+	"golang.org/x/tools/internal/lsp/telemetry/log"
+	"golang.org/x/tools/internal/lsp/telemetry/metric"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
+	"golang.org/x/tools/internal/lsp/telemetry/trace"
+	"golang.org/x/tools/internal/lsp/telemetry/worker"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -211,7 +215,13 @@ func Serve(ctx context.Context, addr string) error {
 	if err != nil {
 		return err
 	}
-	log.Printf("Debug serving on port: %d", listener.Addr().(*net.TCPAddr).Port)
+	log.Print(ctx, "Debug serving", tag.Of("Port", listener.Addr().(*net.TCPAddr).Port))
+	prometheus := prometheus{}
+	metric.RegisterObservers(prometheus.observeMetric)
+	rpcs := rpcs{}
+	metric.RegisterObservers(rpcs.observeMetric)
+	traces := traces{}
+	trace.RegisterObservers(traces.export)
 	go func() {
 		mux := http.NewServeMux()
 		mux.HandleFunc("/", Render(mainTmpl, func(*http.Request) interface{} { return data }))
@@ -221,6 +231,9 @@ func Serve(ctx context.Context, addr string) error {
 		mux.HandleFunc("/debug/pprof/profile", pprof.Profile)
 		mux.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
 		mux.HandleFunc("/debug/pprof/trace", pprof.Trace)
+		mux.HandleFunc("/metrics/", prometheus.serve)
+		mux.HandleFunc("/rpc/", Render(rpcTmpl, rpcs.getData))
+		mux.HandleFunc("/trace/", Render(traceTmpl, traces.getData))
 		mux.HandleFunc("/cache/", Render(cacheTmpl, getCache))
 		mux.HandleFunc("/session/", Render(sessionTmpl, getSession))
 		mux.HandleFunc("/view/", Render(viewTmpl, getView))
@@ -228,23 +241,28 @@ func Serve(ctx context.Context, addr string) error {
 		mux.HandleFunc("/info", Render(infoTmpl, getInfo))
 		mux.HandleFunc("/memory", Render(memoryTmpl, getMemory))
 		if err := http.Serve(listener, mux); err != nil {
-			log.Printf("Debug server failed with %v", err)
+			log.Error(ctx, "Debug server failed", err)
 			return
 		}
-		log.Printf("Debug server finished")
+		log.Print(ctx, "Debug server finished")
 	}()
 	return nil
 }
 
 func Render(tmpl *template.Template, fun func(*http.Request) interface{}) func(http.ResponseWriter, *http.Request) {
 	return func(w http.ResponseWriter, r *http.Request) {
-		var data interface{}
-		if fun != nil {
-			data = fun(r)
-		}
-		if err := tmpl.Execute(w, data); err != nil {
-			log.Print(err)
-		}
+		done := make(chan struct{})
+		worker.Do(func() {
+			defer close(done)
+			var data interface{}
+			if fun != nil {
+				data = fun(r)
+			}
+			if err := tmpl.Execute(w, data); err != nil {
+				log.Error(context.Background(), "", err)
+			}
+		})
+		<-done
 	}
 }
 
@@ -276,6 +294,10 @@ var BaseTemplate = template.Must(template.New("").Parse(`
 td.value {
   text-align: right;
 }
+ul.events {
+	list-style-type: none;
+}
+
 </style>
 {{block "head" .}}{{end}}
 </head>
@@ -283,7 +305,9 @@ td.value {
 <a href="/">Main</a>
 <a href="/info">Info</a>
 <a href="/memory">Memory</a>
-<a href="/debug/">Debug</a>
+<a href="/metrics">Metrics</a>
+<a href="/rpc">RPC</a>
+<a href="/trace">Trace</a>
 <hr>
 <h1>{{template "title" .}}</h1>
 {{block "body" .}}
@@ -354,8 +378,6 @@ var debugTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
 {{define "title"}}GoPls Debug pages{{end}}
 {{define "body"}}
 <a href="/debug/pprof">Profiling</a>
-<a href="/debug/rpcz">RPCz</a>
-<a href="/debug/tracez">Tracez</a>
 {{end}}
 `))
 

internal/lsp/debug/trace.go

@@ -0,0 +1,172 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package debug
+
+import (
+	"bytes"
+	"fmt"
+	"html/template"
+	"net/http"
+	"sort"
+	"strings"
+	"time"
+
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
+	"golang.org/x/tools/internal/lsp/telemetry/trace"
+)
+
+var traceTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
+{{define "title"}}Trace Information{{end}}
+{{define "body"}}
+	{{range .Traces}}<a href="/trace/{{.Name}}">{{.Name}}</a> last: {{.Last.Duration}}, longest: {{.Longest.Duration}}<br>{{end}}
+	{{if .Selected}}
+		<H2>{{.Selected.Name}}</H2>
+		{{if .Selected.Last}}<H3>Last</H3><ul>{{template "details" .Selected.Last}}</ul>{{end}}
+		{{if .Selected.Longest}}<H3>Longest</H3><ul>{{template "details" .Selected.Longest}}</ul>{{end}}
+	{{end}}
+{{end}}
+{{define "details"}}
+	<li>{{.Offset}} {{.Name}} {{.Duration}} {{.Tags}}</li>
+	{{if .Events}}<ul class=events>{{range .Events}}<li>{{.Offset}} {{.Tags}}</li>{{end}}</ul>{{end}}
+	{{if .Children}}<ul>{{range .Children}}{{template "details" .}}{{end}}</ul>{{end}}
+{{end}}
+`))
+
+type traces struct {
+	sets       map[string]*traceSet
+	unfinished map[trace.SpanID]*traceData
+}
+
+type traceResults struct {
+	Traces   []*traceSet
+	Selected *traceSet
+}
+
+type traceSet struct {
+	Name    string
+	Last    *traceData
+	Longest *traceData
+}
+
+type traceData struct {
+	ID       trace.SpanID
+	ParentID trace.SpanID
+	Name     string
+	Start    time.Time
+	Finish   time.Time
+	Offset   time.Duration
+	Duration time.Duration
+	Tags     string
+	Events   []traceEvent
+	Children []*traceData
+}
+
+type traceEvent struct {
+	Time   time.Time
+	Offset time.Duration
+	Tags   string
+}
+
+func (t *traces) export(span *trace.Span) {
+	if t.sets == nil {
+		t.sets = make(map[string]*traceSet)
+		t.unfinished = make(map[trace.SpanID]*traceData)
+	}
+	// is this a completed span?
+	if span.Finish.IsZero() {
+		t.start(span)
+	} else {
+		t.finish(span)
+	}
+}
+
+func (t *traces) start(span *trace.Span) {
+	// just starting, add it to the unfinished map
+	td := &traceData{
+		ID:       span.SpanID,
+		ParentID: span.ParentID,
+		Name:     span.Name,
+		Start:    span.Start,
+		Tags:     renderTags(span.Tags),
+	}
+	t.unfinished[span.SpanID] = td
+	// and wire up parents if we have them
+	if !span.ParentID.IsValid() {
+		return
+	}
+	parent, found := t.unfinished[span.ParentID]
+	if !found {
+		// trace had an invalid parent, so it cannot itself be valid
+		return
+	}
+	parent.Children = append(parent.Children, td)
+
+}
+
+func (t *traces) finish(span *trace.Span) {
+	// finishing, must be already in the map
+	td, found := t.unfinished[span.SpanID]
+	if !found {
+		return // if this happens we are in a bad place
+	}
+	delete(t.unfinished, span.SpanID)
+
+	td.Finish = span.Finish
+	td.Duration = span.Finish.Sub(span.Start)
+	td.Events = make([]traceEvent, len(span.Events))
+	for i, event := range span.Events {
+		td.Events[i] = traceEvent{
+			Time: event.Time,
+			Tags: renderTags(event.Tags),
+		}
+	}
+
+	set, ok := t.sets[span.Name]
+	if !ok {
+		set = &traceSet{Name: span.Name}
+		t.sets[span.Name] = set
+	}
+	set.Last = td
+	if set.Longest == nil || set.Last.Duration > set.Longest.Duration {
+		set.Longest = set.Last
+	}
+	if !td.ParentID.IsValid() {
+		fillOffsets(td, td.Start)
+	}
+}
+
+func (t *traces) getData(req *http.Request) interface{} {
+	if len(t.sets) == 0 {
+		return nil
+	}
+	data := traceResults{}
+	data.Traces = make([]*traceSet, 0, len(t.sets))
+	for _, set := range t.sets {
+		data.Traces = append(data.Traces, set)
+	}
+	sort.Slice(data.Traces, func(i, j int) bool { return data.Traces[i].Name < data.Traces[j].Name })
+	if bits := strings.SplitN(req.URL.Path, "/trace/", 2); len(bits) > 1 {
+		data.Selected = t.sets[bits[1]]
+	}
+	return data
+}
+
+func fillOffsets(td *traceData, start time.Time) {
+	td.Offset = td.Start.Sub(start)
+	for i := range td.Events {
+		td.Events[i].Offset = td.Events[i].Time.Sub(start)
+	}
+	for _, child := range td.Children {
+		fillOffsets(child, start)
+	}
+}
+
+func renderTags(tags tag.List) string {
+	buf := &bytes.Buffer{}
+	for _, tag := range tags {
+		fmt.Fprintf(buf, "%v=%q ", tag.Key, tag.Value)
+	}
+	return buf.String()
+}

internal/lsp/diagnostics.go

@@ -10,13 +10,16 @@ import (
 
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
 	"golang.org/x/tools/internal/span"
 )
 
 func (s *Server) Diagnostics(ctx context.Context, view source.View, uri span.URI) {
+	ctx = telemetry.File.With(ctx, uri)
 	f, err := view.GetFile(ctx, uri)
 	if err != nil {
-		s.session.Logger().Errorf(ctx, "no file for %s: %v", uri, err)
+		log.Error(ctx, "no file", err, telemetry.File)
 		return
 	}
 	// For non-Go files, don't return any diagnostics.
@@ -26,7 +29,7 @@ func (s *Server) Diagnostics(ctx context.Context, view source.View, uri span.URI
 	}
 	reports, err := source.Diagnostics(ctx, view, gof, s.disabledAnalyses)
 	if err != nil {
-		s.session.Logger().Errorf(ctx, "failed to compute diagnostics for %s: %v", gof.URI(), err)
+		log.Error(ctx, "failed to compute diagnostics", err, telemetry.File)
 		return
 	}
 
@@ -38,7 +41,7 @@ func (s *Server) Diagnostics(ctx context.Context, view source.View, uri span.URI
 			if s.undelivered == nil {
 				s.undelivered = make(map[span.URI][]source.Diagnostic)
 			}
-			s.session.Logger().Errorf(ctx, "failed to deliver diagnostic for %s (will retry): %v", uri, err)
+			log.Error(ctx, "failed to deliver diagnostic (will retry)", err, telemetry.File)
 			s.undelivered[uri] = diagnostics
 			continue
 		}
@@ -49,7 +52,7 @@ func (s *Server) Diagnostics(ctx context.Context, view source.View, uri span.URI
 	// undelivered ones (only for remaining URIs).
 	for uri, diagnostics := range s.undelivered {
 		if err := s.publishDiagnostics(ctx, view, uri, diagnostics); err != nil {
-			s.session.Logger().Errorf(ctx, "failed to deliver diagnostic for %s (will not retry): %v", uri, err)
+			log.Error(ctx, "failed to deliver diagnostic for (will not retry)", err, telemetry.File)
 		}
 		// If we fail to deliver the same diagnostics twice, just give up.
 		delete(s.undelivered, uri)

internal/lsp/format.go

@@ -6,7 +6,6 @@ package lsp
 
 import (
 	"context"
-	"fmt"
 
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
@@ -39,9 +38,9 @@ func spanToRange(ctx context.Context, view source.View, s span.Span) (source.GoF
 	}
 	if rng.Start == rng.End {
 		// If we have a single point, assume we want the whole file.
-		tok := f.GetToken(ctx)
-		if tok == nil {
-			return nil, nil, span.Range{}, fmt.Errorf("no file information for %s", f.URI())
+		tok, err := f.GetToken(ctx)
+		if err != nil {
+			return nil, nil, span.Range{}, err
 		}
 		rng.End = tok.Pos(tok.Size())
 	}

internal/lsp/general.go

@@ -15,16 +15,21 @@ import (
 	"golang.org/x/tools/internal/lsp/debug"
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
 	"golang.org/x/tools/internal/span"
 )
 
 func (s *Server) initialize(ctx context.Context, params *protocol.InitializeParams) (*protocol.InitializeResult, error) {
-	s.initializedMu.Lock()
-	defer s.initializedMu.Unlock()
-	if s.isInitialized {
+	s.stateMu.Lock()
+	state := s.state
+	s.stateMu.Unlock()
+	if state >= serverInitializing {
 		return nil, jsonrpc2.NewErrorf(jsonrpc2.CodeInvalidRequest, "server already initialized")
 	}
-	s.isInitialized = true // mark server as initialized now
+	s.stateMu.Lock()
+	s.state = serverInitializing
+	s.stateMu.Unlock()
 
 	// TODO: Remove the option once we are certain there are no issues here.
 	s.textDocumentSyncKind = protocol.Incremental
@@ -125,6 +130,10 @@ func (s *Server) setClientCapabilities(caps protocol.ClientCapabilities) {
 }
 
 func (s *Server) initialized(ctx context.Context, params *protocol.InitializedParams) error {
+	s.stateMu.Lock()
+	s.state = serverInitialized
+	s.stateMu.Unlock()
+
 	if s.configurationSupported {
 		if s.dynamicConfigurationSupported {
 			s.client.RegisterCapability(ctx, &protocol.RegistrationParams{
@@ -138,23 +147,36 @@ func (s *Server) initialized(ctx context.Context, params *protocol.InitializedPa
 			})
 		}
 		for _, view := range s.session.Views() {
-			config, err := s.client.Configuration(ctx, &protocol.ConfigurationParams{
-				Items: []protocol.ConfigurationItem{{
-					ScopeURI: protocol.NewURI(view.Folder()),
-					Section:  "gopls",
-				}},
-			})
-			if err != nil {
-				return err
-			}
-			if err := s.processConfig(ctx, view, config[0]); err != nil {
+			if err := s.fetchConfig(ctx, view); err != nil {
 				return err
 			}
 		}
 	}
 	buf := &bytes.Buffer{}
 	debug.PrintVersionInfo(buf, true, debug.PlainText)
-	s.session.Logger().Infof(ctx, "%s", buf)
+	log.Print(ctx, buf.String())
+	return nil
+}
+
+func (s *Server) fetchConfig(ctx context.Context, view source.View) error {
+	configs, err := s.client.Configuration(ctx, &protocol.ConfigurationParams{
+		Items: []protocol.ConfigurationItem{{
+			ScopeURI: protocol.NewURI(view.Folder()),
+			Section:  "gopls",
+		}, {
+			ScopeURI: protocol.NewURI(view.Folder()),
+			Section:  view.Name(),
+		},
+		},
+	})
+	if err != nil {
+		return err
+	}
+	for _, config := range configs {
+		if err := s.processConfig(ctx, view, config); err != nil {
+			return err
+		}
+	}
 	return nil
 }
 
@@ -209,7 +231,7 @@ func (s *Server) processConfig(ctx context.Context, view source.View, config int
 		case "FullDocumentation":
 			s.hoverKind = source.FullDocumentation
 		default:
-			view.Session().Logger().Errorf(ctx, "unsupported hover kind %s", hoverKind)
+			log.Error(ctx, "unsupported hover kind", nil, tag.Of("HoverKind", hoverKind))
 			// The default value is already be set to synopsis.
 		}
 	}
@@ -234,19 +256,21 @@ func (s *Server) processConfig(ctx context.Context, view source.View, config int
 }
 
 func (s *Server) shutdown(ctx context.Context) error {
-	s.initializedMu.Lock()
-	defer s.initializedMu.Unlock()
-	if !s.isInitialized {
+	s.stateMu.Lock()
+	defer s.stateMu.Unlock()
+	if s.state < serverInitialized {
 		return jsonrpc2.NewErrorf(jsonrpc2.CodeInvalidRequest, "server not initialized")
 	}
 	// drop all the active views
 	s.session.Shutdown(ctx)
-	s.isInitialized = false
+	s.state = serverShutDown
 	return nil
 }
 
 func (s *Server) exit(ctx context.Context) error {
-	if s.isInitialized {
+	s.stateMu.Lock()
+	defer s.stateMu.Unlock()
+	if s.state != serverShutDown {
 		os.Exit(1)
 	}
 	os.Exit(0)

internal/lsp/highlight.go

@@ -9,6 +9,8 @@ import (
 
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -29,7 +31,7 @@ func (s *Server) documentHighlight(ctx context.Context, params *protocol.TextDoc
 	}
 	spans, err := source.Highlight(ctx, f, rng.Start)
 	if err != nil {
-		view.Session().Logger().Errorf(ctx, "no highlight for %s: %v", spn, err)
+		log.Error(ctx, "no highlight", err, tag.Of("Span", spn))
 	}
 	return toProtocolHighlight(m, spans), nil
 }

internal/lsp/hover.go

@@ -28,7 +28,7 @@ func (s *Server) hover(ctx context.Context, params *protocol.TextDocumentPositio
 	}
 	ident, err := source.Identifier(ctx, view, f, identRange.Start)
 	if err != nil {
-		return nil, err
+		return nil, nil
 	}
 	hover, err := ident.Hover(ctx, s.preferredContentFormat == protocol.Markdown, s.hoverKind)
 	if err != nil {

internal/lsp/link.go

@@ -7,9 +7,16 @@ package lsp
 import (
 	"context"
 	"fmt"
+	"go/ast"
+	"go/token"
+	"regexp"
 	"strconv"
+	"sync"
 
 	"golang.org/x/tools/internal/lsp/protocol"
+	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -20,30 +27,105 @@ func (s *Server) documentLink(ctx context.Context, params *protocol.DocumentLink
 	if err != nil {
 		return nil, err
 	}
-	file := f.GetAST(ctx)
+	file, err := f.GetAST(ctx, source.ParseFull)
 	if file == nil {
-		return nil, fmt.Errorf("no AST for %v", uri)
+		return nil, err
 	}
-	// Add a Godoc link for each imported package.
-	var result []protocol.DocumentLink
-	for _, imp := range file.Imports {
-		spn, err := span.NewRange(view.Session().Cache().FileSet(), imp.Pos(), imp.End()).Span()
-		if err != nil {
-			return nil, err
+
+	var links []protocol.DocumentLink
+	ast.Inspect(file, func(node ast.Node) bool {
+		switch n := node.(type) {
+		case *ast.ImportSpec:
+			target, err := strconv.Unquote(n.Path.Value)
+			if err != nil {
+				log.Error(ctx, "cannot unquote import path", err, tag.Of("Path", n.Path.Value))
+				return false
+			}
+			target = "https://godoc.org/" + target
+			l, err := toProtocolLink(view, m, target, n.Pos(), n.End())
+			if err != nil {
+				log.Error(ctx, "cannot initialize DocumentLink", err, tag.Of("Path", n.Path.Value))
+				return false
+			}
+			links = append(links, l)
+			return false
+		case *ast.BasicLit:
+			if n.Kind != token.STRING {
+				return false
+			}
+			l, err := findLinksInString(n.Value, n.Pos(), view, m)
+			if err != nil {
+				log.Error(ctx, "cannot find links in string", err)
+				return false
+			}
+			links = append(links, l...)
+			return false
 		}
-		rng, err := m.Range(spn)
-		if err != nil {
-			return nil, err
+		return true
+	})
+
+	for _, commentGroup := range file.Comments {
+		for _, comment := range commentGroup.List {
+			l, err := findLinksInString(comment.Text, comment.Pos(), view, m)
+			if err != nil {
+				log.Error(ctx, "cannot find links in comment", err)
+				continue
+			}
+			links = append(links, l...)
 		}
-		target, err := strconv.Unquote(imp.Path.Value)
-		if err != nil {
-			continue
-		}
-		target = "https://godoc.org/" + target
-		result = append(result, protocol.DocumentLink{
-			Range:  rng,
-			Target: target,
-		})
 	}
-	return result, nil
+
+	return links, nil
+}
+
+func findLinksInString(src string, pos token.Pos, view source.View, mapper *protocol.ColumnMapper) ([]protocol.DocumentLink, error) {
+	var links []protocol.DocumentLink
+	re, err := getURLRegexp()
+	if err != nil {
+		return nil, fmt.Errorf("cannot create regexp for links: %s", err.Error())
+	}
+	for _, urlIndex := range re.FindAllIndex([]byte(src), -1) {
+		start := urlIndex[0]
+		end := urlIndex[1]
+		startPos := token.Pos(int(pos) + start)
+		endPos := token.Pos(int(pos) + end)
+		target := src[start:end]
+		l, err := toProtocolLink(view, mapper, target, startPos, endPos)
+		if err != nil {
+			return nil, err
+		}
+		links = append(links, l)
+	}
+	return links, nil
+}
+
+const urlRegexpString = "(http|ftp|https)://([\\w_-]+(?:(?:\\.[\\w_-]+)+))([\\w.,@?^=%&:/~+#-]*[\\w@?^=%&/~+#-])?"
+
+var (
+	urlRegexp  *regexp.Regexp
+	regexpOnce sync.Once
+	regexpErr  error
+)
+
+func getURLRegexp() (*regexp.Regexp, error) {
+	regexpOnce.Do(func() {
+		urlRegexp, regexpErr = regexp.Compile(urlRegexpString)
+	})
+	return urlRegexp, regexpErr
+}
+
+func toProtocolLink(view source.View, mapper *protocol.ColumnMapper, target string, start, end token.Pos) (protocol.DocumentLink, error) {
+	spn, err := span.NewRange(view.Session().Cache().FileSet(), start, end).Span()
+	if err != nil {
+		return protocol.DocumentLink{}, err
+	}
+	rng, err := mapper.Range(spn)
+	if err != nil {
+		return protocol.DocumentLink{}, err
+	}
+	l := protocol.DocumentLink{
+		Range:  rng,
+		Target: target,
+	}
+	return l, nil
 }

internal/lsp/lsp_test.go

@@ -21,7 +21,6 @@ import (
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/lsp/tests"
-	"golang.org/x/tools/internal/lsp/xlog"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -32,18 +31,19 @@ func TestLSP(t *testing.T) {
 type runner struct {
 	server *Server
 	data   *tests.Data
+	ctx    context.Context
 }
 
 const viewName = "lsp_test"
 
 func testLSP(t *testing.T, exporter packagestest.Exporter) {
+	ctx := tests.Context(t)
 	data := tests.Load(t, exporter, "testdata")
 	defer data.Exported.Cleanup()
 
-	log := xlog.New(xlog.StdSink{})
 	cache := cache.New()
-	session := cache.NewSession(log)
-	view := session.NewView(viewName, span.FileURI(data.Config.Dir))
+	session := cache.NewSession(ctx)
+	view := session.NewView(ctx, viewName, span.FileURI(data.Config.Dir))
 	view.SetEnv(data.Config.Env)
 	for filename, content := range data.Config.Overlay {
 		session.SetOverlay(span.FileURI(filename), content)
@@ -59,6 +59,7 @@ func testLSP(t *testing.T, exporter packagestest.Exporter) {
 			hoverKind: source.SynopsisDocumentation,
 		},
 		data: data,
+		ctx:  ctx,
 	}
 	tests.Run(t, r, data)
 }
@@ -67,7 +68,7 @@ func testLSP(t *testing.T, exporter packagestest.Exporter) {
 func (r *runner) Diagnostics(t *testing.T, data tests.Diagnostics) {
 	v := r.server.session.View(viewName)
 	for uri, want := range data {
-		f, err := v.GetFile(context.Background(), uri)
+		f, err := v.GetFile(r.ctx, uri)
 		if err != nil {
 			t.Fatalf("no file for %s: %v", f, err)
 		}
@@ -75,7 +76,7 @@ func (r *runner) Diagnostics(t *testing.T, data tests.Diagnostics) {
 		if !ok {
 			t.Fatalf("%s is not a Go file: %v", uri, err)
 		}
-		results, err := source.Diagnostics(context.Background(), v, gof, nil)
+		results, err := source.Diagnostics(r.ctx, v, gof, nil)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -218,7 +219,7 @@ func (r *runner) Completion(t *testing.T, data tests.Completions, snippets tests
 
 func (r *runner) runCompletion(t *testing.T, src span.Span) *protocol.CompletionList {
 	t.Helper()
-	list, err := r.server.Completion(context.Background(), &protocol.CompletionParams{
+	list, err := r.server.Completion(r.ctx, &protocol.CompletionParams{
 		TextDocumentPositionParams: protocol.TextDocumentPositionParams{
 			TextDocument: protocol.TextDocumentIdentifier{
 				URI: protocol.NewURI(src.URI()),
@@ -295,7 +296,6 @@ func summarizeCompletionItems(i int, want []source.CompletionItem, got []protoco
 }
 
 func (r *runner) Format(t *testing.T, data tests.Formats) {
-	ctx := context.Background()
 	for _, spn := range data {
 		uri := spn.URI()
 		filename := uri.Filename()
@@ -305,7 +305,7 @@ func (r *runner) Format(t *testing.T, data tests.Formats) {
 			return out, nil
 		}))
 
-		edits, err := r.server.Formatting(context.Background(), &protocol.DocumentFormattingParams{
+		edits, err := r.server.Formatting(r.ctx, &protocol.DocumentFormattingParams{
 			TextDocument: protocol.TextDocumentIdentifier{
 				URI: protocol.NewURI(uri),
 			},
@@ -316,7 +316,7 @@ func (r *runner) Format(t *testing.T, data tests.Formats) {
 			}
 			continue
 		}
-		_, m, err := getSourceFile(ctx, r.server.session.ViewOf(uri), uri)
+		_, m, err := getSourceFile(r.ctx, r.server.session.ViewOf(uri), uri)
 		if err != nil {
 			t.Error(err)
 		}
@@ -333,7 +333,6 @@ func (r *runner) Format(t *testing.T, data tests.Formats) {
 }
 
 func (r *runner) Import(t *testing.T, data tests.Imports) {
-	ctx := context.Background()
 	for _, spn := range data {
 		uri := spn.URI()
 		filename := uri.Filename()
@@ -343,7 +342,7 @@ func (r *runner) Import(t *testing.T, data tests.Imports) {
 			return out, nil
 		}))
 
-		actions, err := r.server.CodeAction(context.Background(), &protocol.CodeActionParams{
+		actions, err := r.server.CodeAction(r.ctx, &protocol.CodeActionParams{
 			TextDocument: protocol.TextDocumentIdentifier{
 				URI: protocol.NewURI(uri),
 			},
@@ -354,7 +353,7 @@ func (r *runner) Import(t *testing.T, data tests.Imports) {
 			}
 			continue
 		}
-		_, m, err := getSourceFile(ctx, r.server.session.ViewOf(uri), uri)
+		_, m, err := getSourceFile(r.ctx, r.server.session.ViewOf(uri), uri)
 		if err != nil {
 			t.Error(err)
 		}
@@ -393,13 +392,13 @@ func (r *runner) Definition(t *testing.T, data tests.Definitions) {
 		var locs []protocol.Location
 		var hover *protocol.Hover
 		if d.IsType {
-			locs, err = r.server.TypeDefinition(context.Background(), params)
+			locs, err = r.server.TypeDefinition(r.ctx, params)
 		} else {
-			locs, err = r.server.Definition(context.Background(), params)
+			locs, err = r.server.Definition(r.ctx, params)
 			if err != nil {
 				t.Fatalf("failed for %v: %v", d.Src, err)
 			}
-			hover, err = r.server.Hover(context.Background(), params)
+			hover, err = r.server.Hover(r.ctx, params)
 		}
 		if err != nil {
 			t.Fatalf("failed for %v: %v", d.Src, err)
@@ -446,7 +445,7 @@ func (r *runner) Highlight(t *testing.T, data tests.Highlights) {
 			TextDocument: protocol.TextDocumentIdentifier{URI: loc.URI},
 			Position:     loc.Range.Start,
 		}
-		highlights, err := r.server.DocumentHighlight(context.Background(), params)
+		highlights, err := r.server.DocumentHighlight(r.ctx, params)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -492,7 +491,7 @@ func (r *runner) Reference(t *testing.T, data tests.References) {
 				Position:     loc.Range.Start,
 			},
 		}
-		got, err := r.server.References(context.Background(), params)
+		got, err := r.server.References(r.ctx, params)
 		if err != nil {
 			t.Fatalf("failed for %v: %v", src, err)
 		}
@@ -509,7 +508,6 @@ func (r *runner) Reference(t *testing.T, data tests.References) {
 }
 
 func (r *runner) Rename(t *testing.T, data tests.Renames) {
-	ctx := context.Background()
 	for spn, newText := range data {
 		tag := fmt.Sprintf("%s-rename", newText)
 
@@ -524,7 +522,7 @@ func (r *runner) Rename(t *testing.T, data tests.Renames) {
 			t.Fatalf("failed for %v: %v", spn, err)
 		}
 
-		workspaceEdits, err := r.server.Rename(ctx, &protocol.RenameParams{
+		workspaceEdits, err := r.server.Rename(r.ctx, &protocol.RenameParams{
 			TextDocument: protocol.TextDocumentIdentifier{
 				URI: protocol.NewURI(uri),
 			},
@@ -544,7 +542,7 @@ func (r *runner) Rename(t *testing.T, data tests.Renames) {
 		var res []string
 		for uri, edits := range *workspaceEdits.Changes {
 			spnURI := span.URI(uri)
-			_, m, err := getSourceFile(ctx, r.server.session.ViewOf(span.URI(spnURI)), spnURI)
+			_, m, err := getSourceFile(r.ctx, r.server.session.ViewOf(span.URI(spnURI)), spnURI)
 			if err != nil {
 				t.Error(err)
 			}
@@ -582,7 +580,6 @@ func (r *runner) Rename(t *testing.T, data tests.Renames) {
 
 func applyEdits(contents string, edits []source.TextEdit) string {
 	res := contents
-	sortSourceTextEdits(edits)
 
 	// Apply the edits from the end of the file forward
 	// to preserve the offsets
@@ -596,15 +593,6 @@ func applyEdits(contents string, edits []source.TextEdit) string {
 	return res
 }
 
-func sortSourceTextEdits(d []source.TextEdit) {
-	sort.Slice(d, func(i int, j int) bool {
-		if r := span.Compare(d[i].Span, d[j].Span); r != 0 {
-			return r < 0
-		}
-		return d[i].NewText < d[j].NewText
-	})
-}
-
 func (r *runner) Symbol(t *testing.T, data tests.Symbols) {
 	for uri, expectedSymbols := range data {
 		params := &protocol.DocumentSymbolParams{
@@ -612,7 +600,7 @@ func (r *runner) Symbol(t *testing.T, data tests.Symbols) {
 				URI: string(uri),
 			},
 		}
-		symbols, err := r.server.DocumentSymbol(context.Background(), params)
+		symbols, err := r.server.DocumentSymbol(r.ctx, params)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -688,7 +676,7 @@ func (r *runner) SignatureHelp(t *testing.T, data tests.Signatures) {
 		if err != nil {
 			t.Fatalf("failed for %v: %v", loc, err)
 		}
-		gotSignatures, err := r.server.SignatureHelp(context.Background(), &protocol.TextDocumentPositionParams{
+		gotSignatures, err := r.server.SignatureHelp(r.ctx, &protocol.TextDocumentPositionParams{
 			TextDocument: protocol.TextDocumentIdentifier{
 				URI: protocol.NewURI(spn.URI()),
 			},
@@ -754,7 +742,7 @@ func (r *runner) Link(t *testing.T, data tests.Links) {
 		if err != nil {
 			t.Fatal(err)
 		}
-		gotLinks, err := r.server.DocumentLink(context.Background(), &protocol.DocumentLinkParams{
+		gotLinks, err := r.server.DocumentLink(r.ctx, &protocol.DocumentLinkParams{
 			TextDocument: protocol.TextDocumentIdentifier{
 				URI: protocol.NewURI(uri),
 			},
@@ -762,15 +750,30 @@ func (r *runner) Link(t *testing.T, data tests.Links) {
 		if err != nil {
 			t.Fatal(err)
 		}
+		var notePositions []token.Position
 		links := make(map[span.Span]string, len(wantLinks))
 		for _, link := range wantLinks {
 			links[link.Src] = link.Target
+			notePositions = append(notePositions, link.NotePosition)
 		}
+
 		for _, link := range gotLinks {
 			spn, err := m.RangeSpan(link.Range)
 			if err != nil {
 				t.Fatal(err)
 			}
+			linkInNote := false
+			for _, notePosition := range notePositions {
+				// Drop the links found inside expectation notes arguments as this links are not collected by expect package
+				if notePosition.Line == spn.Start().Line() &&
+					notePosition.Column <= spn.Start().Column() {
+					delete(links, spn)
+					linkInNote = true
+				}
+			}
+			if linkInNote {
+				continue
+			}
 			if target, ok := links[spn]; ok {
 				delete(links, spn)
 				if target != link.Target {

internal/lsp/protocol/context.go

@@ -0,0 +1,40 @@
+package protocol
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"golang.org/x/tools/internal/lsp/telemetry/log"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
+	"golang.org/x/tools/internal/xcontext"
+)
+
+func init() {
+	log.AddLogger(logger)
+}
+
+type contextKey int
+
+const (
+	clientKey = contextKey(iota)
+)
+
+func WithClient(ctx context.Context, client Client) context.Context {
+	return context.WithValue(ctx, clientKey, client)
+}
+
+// logger implements log.Logger in terms of the LogMessage call to a client.
+func logger(ctx context.Context, at time.Time, tags tag.List) bool {
+	client, ok := ctx.Value(clientKey).(Client)
+	if !ok {
+		return false
+	}
+	entry := log.ToEntry(ctx, time.Time{}, tags)
+	msg := &LogMessageParams{Type: Info, Message: fmt.Sprint(entry)}
+	if entry.Error != nil {
+		msg.Type = Error
+	}
+	go client.LogMessage(xcontext.Detach(ctx), msg)
+	return true
+}

internal/lsp/protocol/detatch.go

@@ -1,21 +0,0 @@
-// Copyright 2019 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package protocol
-
-import (
-	"context"
-	"time"
-)
-
-// detatch returns a context that keeps all the values of its parent context
-// but detatches from the cancellation and error handling.
-func detatchContext(ctx context.Context) context.Context { return detatchedContext{ctx} }
-
-type detatchedContext struct{ parent context.Context }
-
-func (v detatchedContext) Deadline() (time.Time, bool)       { return time.Time{}, false }
-func (v detatchedContext) Done() <-chan struct{}             { return nil }
-func (v detatchedContext) Err() error                        { return nil }
-func (v detatchedContext) Value(key interface{}) interface{} { return v.parent.Value(key) }

internal/lsp/protocol/enums.go

@@ -13,7 +13,7 @@ var (
 	namesInitializeError        [int(UnknownProtocolVersion) + 1]string
 	namesMessageType            [int(Log) + 1]string
 	namesFileChangeType         [int(Deleted) + 1]string
-	namesWatchKind              [int(Change) + 1]string
+	namesWatchKind              [int(WatchDelete) + 1]string
 	namesCompletionTriggerKind  [int(TriggerForIncompleteCompletions) + 1]string
 	namesDiagnosticSeverity     [int(SeverityHint) + 1]string
 	namesDiagnosticTag          [int(Unnecessary) + 1]string
@@ -40,7 +40,9 @@ func init() {
 	namesFileChangeType[int(Changed)] = "Changed"
 	namesFileChangeType[int(Deleted)] = "Deleted"
 
-	namesWatchKind[int(Change)] = "Change"
+	namesWatchKind[int(WatchCreate)] = "WatchCreate"
+	namesWatchKind[int(WatchChange)] = "WatchChange"
+	namesWatchKind[int(WatchDelete)] = "WatchDelete"
 
 	namesCompletionTriggerKind[int(Invoked)] = "Invoked"
 	namesCompletionTriggerKind[int(TriggerCharacter)] = "TriggerCharacter"

internal/lsp/protocol/log.go

@@ -1,32 +0,0 @@
-package protocol
-
-import (
-	"context"
-
-	"golang.org/x/tools/internal/lsp/xlog"
-)
-
-// logSink implements xlog.Sink in terms of the LogMessage call to a client.
-type logSink struct {
-	client Client
-}
-
-// NewLogger returns an xlog.Sink that sends its messages using client.LogMessage.
-// It maps Debug to the Log level, Info and Error to their matching levels, and
-// does not support warnings.
-func NewLogger(client Client) xlog.Sink {
-	return logSink{client: client}
-}
-
-func (s logSink) Log(ctx context.Context, level xlog.Level, message string) {
-	typ := Log
-	switch level {
-	case xlog.ErrorLevel:
-		typ = Error
-	case xlog.InfoLevel:
-		typ = Info
-	case xlog.DebugLevel:
-		typ = Log
-	}
-	s.client.LogMessage(ctx, &LogMessageParams{Type: typ, Message: message})
-}

internal/lsp/protocol/protocol.go

@@ -8,46 +8,56 @@ import (
 	"context"
 
 	"golang.org/x/tools/internal/jsonrpc2"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
 	"golang.org/x/tools/internal/lsp/telemetry/trace"
-	"golang.org/x/tools/internal/lsp/xlog"
+	"golang.org/x/tools/internal/xcontext"
 )
 
-const defaultMessageBufferSize = 20
-const defaultRejectIfOverloaded = false
+type DocumentUri = string
 
-func canceller(ctx context.Context, conn *jsonrpc2.Conn, id jsonrpc2.ID) {
-	ctx = detatchContext(ctx)
-	ctx, span := trace.StartSpan(ctx, "protocol.canceller")
-	defer span.End()
+type canceller struct{ jsonrpc2.EmptyHandler }
+
+type clientHandler struct {
+	canceller
+	client Client
+}
+
+type serverHandler struct {
+	canceller
+	server Server
+}
+
+func (canceller) Cancel(ctx context.Context, conn *jsonrpc2.Conn, id jsonrpc2.ID, cancelled bool) bool {
+	if cancelled {
+		return false
+	}
+	ctx = xcontext.Detach(ctx)
+	ctx, done := trace.StartSpan(ctx, "protocol.canceller")
+	defer done()
 	conn.Notify(ctx, "$/cancelRequest", &CancelParams{ID: id})
+	return true
 }
 
-func NewClient(stream jsonrpc2.Stream, client Client) (*jsonrpc2.Conn, Server, xlog.Logger) {
-	log := xlog.New(NewLogger(client))
+func NewClient(ctx context.Context, stream jsonrpc2.Stream, client Client) (context.Context, *jsonrpc2.Conn, Server) {
+	ctx = WithClient(ctx, client)
 	conn := jsonrpc2.NewConn(stream)
-	conn.Capacity = defaultMessageBufferSize
-	conn.RejectIfOverloaded = defaultRejectIfOverloaded
-	conn.Handler = clientHandler(log, client)
-	conn.Canceler = jsonrpc2.Canceler(canceller)
-	return conn, &serverDispatcher{Conn: conn}, log
+	conn.AddHandler(&clientHandler{client: client})
+	return ctx, conn, &serverDispatcher{Conn: conn}
 }
 
-func NewServer(stream jsonrpc2.Stream, server Server) (*jsonrpc2.Conn, Client, xlog.Logger) {
+func NewServer(ctx context.Context, stream jsonrpc2.Stream, server Server) (context.Context, *jsonrpc2.Conn, Client) {
 	conn := jsonrpc2.NewConn(stream)
 	client := &clientDispatcher{Conn: conn}
-	log := xlog.New(NewLogger(client))
-	conn.Capacity = defaultMessageBufferSize
-	conn.RejectIfOverloaded = defaultRejectIfOverloaded
-	conn.Handler = serverHandler(log, server)
-	conn.Canceler = jsonrpc2.Canceler(canceller)
-	return conn, client, log
+	ctx = WithClient(ctx, client)
+	conn.AddHandler(&serverHandler{server: server})
+	return ctx, conn, client
 }
 
-func sendParseError(ctx context.Context, log xlog.Logger, req *jsonrpc2.Request, err error) {
+func sendParseError(ctx context.Context, req *jsonrpc2.Request, err error) {
 	if _, ok := err.(*jsonrpc2.Error); !ok {
 		err = jsonrpc2.NewErrorf(jsonrpc2.CodeParseError, "%v", err)
 	}
 	if err := req.Reply(ctx, nil, err); err != nil {
-		log.Errorf(ctx, "%v", err)
+		log.Error(ctx, "", err)
 	}
 }

internal/lsp/protocol/tsclient.go

@@ -7,7 +7,7 @@ import (
 	"encoding/json"
 
 	"golang.org/x/tools/internal/jsonrpc2"
-	"golang.org/x/tools/internal/lsp/xlog"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
 )
 
 type Client interface {
@@ -23,117 +23,127 @@ type Client interface {
 	ApplyEdit(context.Context, *ApplyWorkspaceEditParams) (*ApplyWorkspaceEditResponse, error)
 }
 
-func clientHandler(log xlog.Logger, client Client) jsonrpc2.Handler {
-	return func(ctx context.Context, r *jsonrpc2.Request) {
-		switch r.Method {
-		case "$/cancelRequest":
-			var params CancelParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			r.Conn().Cancel(params.ID)
-		case "window/showMessage": // notif
-			var params ShowMessageParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := client.ShowMessage(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "window/logMessage": // notif
-			var params LogMessageParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := client.LogMessage(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "telemetry/event": // notif
-			var params interface{}
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := client.Event(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/publishDiagnostics": // notif
-			var params PublishDiagnosticsParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := client.PublishDiagnostics(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "workspace/workspaceFolders": // req
-			if r.Params != nil {
-				r.Reply(ctx, nil, jsonrpc2.NewErrorf(jsonrpc2.CodeInvalidParams, "Expected no params"))
-				return
-			}
-			resp, err := client.WorkspaceFolders(ctx)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "workspace/configuration": // req
-			var params ConfigurationParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := client.Configuration(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "client/registerCapability": // req
-			var params RegistrationParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			err := client.RegisterCapability(ctx, &params)
-			if err := r.Reply(ctx, nil, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "client/unregisterCapability": // req
-			var params UnregistrationParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			err := client.UnregisterCapability(ctx, &params)
-			if err := r.Reply(ctx, nil, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "window/showMessageRequest": // req
-			var params ShowMessageRequestParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := client.ShowMessageRequest(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "workspace/applyEdit": // req
-			var params ApplyWorkspaceEditParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := client.ApplyEdit(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-
-		default:
-			if r.IsNotify() {
-				r.Reply(ctx, nil, jsonrpc2.NewErrorf(jsonrpc2.CodeMethodNotFound, "method %q not found", r.Method))
-			}
+func (h clientHandler) Deliver(ctx context.Context, r *jsonrpc2.Request, delivered bool) bool {
+	if delivered {
+		return false
+	}
+	switch r.Method {
+	case "$/cancelRequest":
+		var params CancelParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
 		}
+		r.Conn().Cancel(params.ID)
+		return true
+	case "window/showMessage": // notif
+		var params ShowMessageParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.client.ShowMessage(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "window/logMessage": // notif
+		var params LogMessageParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.client.LogMessage(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "telemetry/event": // notif
+		var params interface{}
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.client.Event(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/publishDiagnostics": // notif
+		var params PublishDiagnosticsParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.client.PublishDiagnostics(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "workspace/workspaceFolders": // req
+		if r.Params != nil {
+			r.Reply(ctx, nil, jsonrpc2.NewErrorf(jsonrpc2.CodeInvalidParams, "Expected no params"))
+			return true
+		}
+		resp, err := h.client.WorkspaceFolders(ctx)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "workspace/configuration": // req
+		var params ConfigurationParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.client.Configuration(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "client/registerCapability": // req
+		var params RegistrationParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		err := h.client.RegisterCapability(ctx, &params)
+		if err := r.Reply(ctx, nil, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "client/unregisterCapability": // req
+		var params UnregistrationParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		err := h.client.UnregisterCapability(ctx, &params)
+		if err := r.Reply(ctx, nil, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "window/showMessageRequest": // req
+		var params ShowMessageRequestParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.client.ShowMessageRequest(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "workspace/applyEdit": // req
+		var params ApplyWorkspaceEditParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.client.ApplyEdit(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+
+	default:
+		return false
 	}
 }
 

internal/lsp/protocol/tsprotocol.go

@@ -1,7 +1,7 @@
 // Package protocol contains data types and code for LSP jsonrpcs
 // generated automatically from vscode-languageserver-node
-// commit: c1e8923f8ea3b1f9c61dadf97448244d9ffbf7ae
-// last fetched Tue May 21 2019 07:36:27 GMT-0400 (Eastern Daylight Time)
+// commit: 8801c20b667945f455d7e023c71d2f741caeda25
+// last fetched Sat Jul 13 2019 18:33:10 GMT-0700 (Pacific Daylight Time)
 package protocol
 
 // Code generated (see typescript/README.md) DO NOT EDIT.
@@ -155,6 +155,26 @@ type FoldingRangeParams struct {
 	TextDocument TextDocumentIdentifier `json:"textDocument"`
 }
 
+// SelectionRangeProviderOptions is
+type SelectionRangeProviderOptions struct {
+}
+
+/*SelectionRangeParams defined:
+ * A parameter literal used in selection range requests.
+ */
+type SelectionRangeParams struct {
+
+	/*TextDocument defined:
+	 * The text document.
+	 */
+	TextDocument TextDocumentIdentifier `json:"textDocument"`
+
+	/*Positions defined:
+	 * The positions inside the text document.
+	 */
+	Positions []Position `json:"positions"`
+}
+
 /*Registration defined:
  * General parameters to to register for an notification or to register a provider.
  */
@@ -1241,6 +1261,19 @@ type ClientCapabilities struct {
 			 */
 			LinkSupport bool `json:"linkSupport,omitempty"`
 		} `json:"declaration,omitempty"`
+
+		/*SelectionRange defined:
+		 * Capabilities specific to `textDocument/selectionRange` requests
+		 */
+		SelectionRange struct {
+
+			/*DynamicRegistration defined:
+			 * Whether implementation supports dynamic registration for selection range providers. If this is set to `true`
+			 * the client supports the new `(SelectionRangeProviderOptions & TextDocumentRegistrationOptions & StaticRegistrationOptions)`
+			 * return value for the corresponding server capability as well.
+			 */
+			DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
+		} `json:"selectionRange,omitempty"`
 	} `json:"textDocument,omitempty"`
 
 	/*Window defined:
@@ -1600,6 +1633,11 @@ type ServerCapabilities struct {
 	 * The server provides Goto Type Definition support.
 	 */
 	DeclarationProvider bool `json:"declarationProvider,omitempty"` // boolean | (TextDocumentRegistrationOptions & StaticRegistrationOptions)
+
+	/*SelectionRangeProvider defined:
+	 * The server provides selection range support.
+	 */
+	SelectionRangeProvider bool `json:"selectionRangeProvider,omitempty"` // boolean | (TextDocumentRegistrationOptions & StaticRegistrationOptions & SelectionRangeProviderOptions)
 }
 
 // InitializeParams is
@@ -1626,7 +1664,7 @@ type InitializeParams struct {
 	 *
 	 * @deprecated in favour of workspaceFolders.
 	 */
-	RootURI string `json:"rootUri"`
+	RootURI DocumentUri `json:"rootUri"`
 
 	/*Capabilities defined:
 	 * The capabilities provided by the client (editor or tool)
@@ -1861,7 +1899,7 @@ type FileEvent struct {
 	/*URI defined:
 	 * The file's uri.
 	 */
-	URI string `json:"uri"`
+	URI DocumentUri `json:"uri"`
 
 	/*Type defined:
 	 * The change type.
@@ -1910,10 +1948,12 @@ type PublishDiagnosticsParams struct {
 	/*URI defined:
 	 * The URI for which diagnostic information is reported.
 	 */
-	URI string `json:"uri"`
+	URI DocumentUri `json:"uri"`
 
 	/*Version defined:
 	 * Optional the version number of the document the diagnostics are published for.
+	 *
+	 * @since 3.15
 	 */
 	Version float64 `json:"version,omitempty"`
 
@@ -2264,7 +2304,7 @@ type Range struct {
 type Location struct {
 
 	// URI is
-	URI string `json:"uri"`
+	URI DocumentUri `json:"uri"`
 
 	// Range is
 	Range Range `json:"range"`
@@ -2287,7 +2327,7 @@ type LocationLink struct {
 	/*TargetURI defined:
 	 * The target resource identifier of this link.
 	 */
-	TargetURI string `json:"targetUri"`
+	TargetURI DocumentUri `json:"targetUri"`
 
 	/*TargetRange defined:
 	 * The full target range of this link. If the target for example is a symbol then target range is the
@@ -2528,7 +2568,7 @@ type CreateFile struct {
 	/*URI defined:
 	 * The resource to create.
 	 */
-	URI string `json:"uri"`
+	URI DocumentUri `json:"uri"`
 
 	/*Options defined:
 	 * Additional options
@@ -2565,12 +2605,12 @@ type RenameFile struct {
 	/*OldURI defined:
 	 * The old (existing) location.
 	 */
-	OldURI string `json:"oldUri"`
+	OldURI DocumentUri `json:"oldUri"`
 
 	/*NewURI defined:
 	 * The new location.
 	 */
-	NewURI string `json:"newUri"`
+	NewURI DocumentUri `json:"newUri"`
 
 	/*Options defined:
 	 * Rename options.
@@ -2607,7 +2647,7 @@ type DeleteFile struct {
 	/*URI defined:
 	 * The file to delete.
 	 */
-	URI string `json:"uri"`
+	URI DocumentUri `json:"uri"`
 
 	/*Options defined:
 	 * Delete options.
@@ -2656,7 +2696,7 @@ type TextDocumentIdentifier struct {
 	/*URI defined:
 	 * The text document's uri.
 	 */
-	URI string `json:"uri"`
+	URI DocumentUri `json:"uri"`
 }
 
 /*VersionedTextDocumentIdentifier defined:
@@ -2684,7 +2724,7 @@ type TextDocumentItem struct {
 	/*URI defined:
 	 * The text document's uri.
 	 */
-	URI string `json:"uri"`
+	URI DocumentUri `json:"uri"`
 
 	/*LanguageID defined:
 	 * The text document's language identifier
@@ -2809,8 +2849,6 @@ type CompletionItem struct {
 	 * and a completion item with an `insertText` of `console` is provided it
 	 * will only insert `sole`. Therefore it is recommended to use `textEdit` instead
 	 * since it avoids additional client side interpretation.
-	 *
-	 * @deprecated Use textEdit instead.
 	 */
 	InsertText string `json:"insertText,omitempty"`
 
@@ -3262,6 +3300,23 @@ type DocumentLink struct {
 	Data interface{} `json:"data,omitempty"`
 }
 
+/*SelectionRange defined:
+ * A selection range represents a part of a selection hierarchy. A selection range
+ * may have a parent selection range that contains it.
+ */
+type SelectionRange struct {
+
+	/*Range defined:
+	 * The [range](#Range) of this selection range.
+	 */
+	Range Range `json:"range"`
+
+	/*Parent defined:
+	 * The parent selection range containing this range. Therefore `parent.range` must contain `this.range`.
+	 */
+	Parent *SelectionRange `json:"parent,omitempty"`
+}
+
 /*TextDocument defined:
  * A simple text document. Not to be implemented.
  */
@@ -3274,7 +3329,7 @@ type TextDocument struct {
 	 *
 	 * @readonly
 	 */
-	URI string `json:"uri"`
+	URI DocumentUri `json:"uri"`
 
 	/*LanguageID defined:
 	 * The identifier of the language associated with this document.
@@ -3556,10 +3611,20 @@ const (
 	 */
 	Deleted FileChangeType = 3
 
-	/*Change defined:
+	/*WatchCreate defined:
+	 * Interested in create events.
+	 */
+	WatchCreate WatchKind = 1
+
+	/*WatchChange defined:
 	 * Interested in change events
 	 */
-	Change WatchKind = 2
+	WatchChange WatchKind = 2
+
+	/*WatchDelete defined:
+	 * Interested in delete events
+	 */
+	WatchDelete WatchKind = 4
 
 	/*Invoked defined:
 	 * Completion was triggered by typing an identifier (24x7 code
@@ -3952,6 +4017,12 @@ type DocumentFilter struct {
  */
 type DocumentSelector []DocumentFilter
 
+// DocumentURI is a type
+/**
+ * A tagging type for string properties that are actually URIs.
+ */
+type DocumentURI string
+
 // DefinitionLink is a type
 /**
  * Information about where a symbol is defined.

internal/lsp/protocol/tsserver.go

@@ -7,7 +7,7 @@ import (
 	"encoding/json"
 
 	"golang.org/x/tools/internal/jsonrpc2"
-	"golang.org/x/tools/internal/lsp/xlog"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
 )
 
 type Server interface {
@@ -29,6 +29,7 @@ type Server interface {
 	ColorPresentation(context.Context, *ColorPresentationParams) ([]ColorPresentation, error)
 	FoldingRange(context.Context, *FoldingRangeParams) ([]FoldingRange, error)
 	Declaration(context.Context, *TextDocumentPositionParams) ([]DeclarationLink, error)
+	SelectionRange(context.Context, *SelectionRangeParams) ([]SelectionRange, error)
 	Initialize(context.Context, *InitializeParams) (*InitializeResult, error)
 	Shutdown(context.Context) error
 	WillSaveWaitUntil(context.Context, *WillSaveTextDocumentParams) ([]TextEdit, error)
@@ -54,414 +55,466 @@ type Server interface {
 	ExecuteCommand(context.Context, *ExecuteCommandParams) (interface{}, error)
 }
 
-func serverHandler(log xlog.Logger, server Server) jsonrpc2.Handler {
-	return func(ctx context.Context, r *jsonrpc2.Request) {
-		switch r.Method {
-		case "$/cancelRequest":
-			var params CancelParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			r.Conn().Cancel(params.ID)
-		case "workspace/didChangeWorkspaceFolders": // notif
-			var params DidChangeWorkspaceFoldersParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := server.DidChangeWorkspaceFolders(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "initialized": // notif
-			var params InitializedParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := server.Initialized(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "exit": // notif
-			if err := server.Exit(ctx); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "workspace/didChangeConfiguration": // notif
-			var params DidChangeConfigurationParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := server.DidChangeConfiguration(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/didOpen": // notif
-			var params DidOpenTextDocumentParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := server.DidOpen(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/didChange": // notif
-			var params DidChangeTextDocumentParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := server.DidChange(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/didClose": // notif
-			var params DidCloseTextDocumentParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := server.DidClose(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/didSave": // notif
-			var params DidSaveTextDocumentParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := server.DidSave(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/willSave": // notif
-			var params WillSaveTextDocumentParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := server.WillSave(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "workspace/didChangeWatchedFiles": // notif
-			var params DidChangeWatchedFilesParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := server.DidChangeWatchedFiles(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "$/setTraceNotification": // notif
-			var params SetTraceParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := server.SetTraceNotification(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "$/logTraceNotification": // notif
-			var params LogTraceParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			if err := server.LogTraceNotification(ctx, &params); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/implementation": // req
-			var params TextDocumentPositionParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.Implementation(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/typeDefinition": // req
-			var params TextDocumentPositionParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.TypeDefinition(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/documentColor": // req
-			var params DocumentColorParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.DocumentColor(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/colorPresentation": // req
-			var params ColorPresentationParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.ColorPresentation(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/foldingRange": // req
-			var params FoldingRangeParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.FoldingRange(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/declaration": // req
-			var params TextDocumentPositionParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.Declaration(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "initialize": // req
-			var params InitializeParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.Initialize(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "shutdown": // req
-			if r.Params != nil {
-				r.Reply(ctx, nil, jsonrpc2.NewErrorf(jsonrpc2.CodeInvalidParams, "Expected no params"))
-				return
-			}
-			err := server.Shutdown(ctx)
-			if err := r.Reply(ctx, nil, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/willSaveWaitUntil": // req
-			var params WillSaveTextDocumentParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.WillSaveWaitUntil(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/completion": // req
-			var params CompletionParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.Completion(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "completionItem/resolve": // req
-			var params CompletionItem
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.Resolve(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/hover": // req
-			var params TextDocumentPositionParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.Hover(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/signatureHelp": // req
-			var params TextDocumentPositionParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.SignatureHelp(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/definition": // req
-			var params TextDocumentPositionParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.Definition(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/references": // req
-			var params ReferenceParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.References(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/documentHighlight": // req
-			var params TextDocumentPositionParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.DocumentHighlight(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/documentSymbol": // req
-			var params DocumentSymbolParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.DocumentSymbol(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "workspace/symbol": // req
-			var params WorkspaceSymbolParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.Symbol(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/codeAction": // req
-			var params CodeActionParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.CodeAction(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/codeLens": // req
-			var params CodeLensParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.CodeLens(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "codeLens/resolve": // req
-			var params CodeLens
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.ResolveCodeLens(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/formatting": // req
-			var params DocumentFormattingParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.Formatting(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/rangeFormatting": // req
-			var params DocumentRangeFormattingParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.RangeFormatting(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/onTypeFormatting": // req
-			var params DocumentOnTypeFormattingParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.OnTypeFormatting(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/rename": // req
-			var params RenameParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.Rename(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/prepareRename": // req
-			var params TextDocumentPositionParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.PrepareRename(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "textDocument/documentLink": // req
-			var params DocumentLinkParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.DocumentLink(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "documentLink/resolve": // req
-			var params DocumentLink
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.ResolveDocumentLink(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-		case "workspace/executeCommand": // req
-			var params ExecuteCommandParams
-			if err := json.Unmarshal(*r.Params, &params); err != nil {
-				sendParseError(ctx, log, r, err)
-				return
-			}
-			resp, err := server.ExecuteCommand(ctx, &params)
-			if err := r.Reply(ctx, resp, err); err != nil {
-				log.Errorf(ctx, "%v", err)
-			}
-
-		default:
-			if r.IsNotify() {
-				r.Reply(ctx, nil, jsonrpc2.NewErrorf(jsonrpc2.CodeMethodNotFound, "method %q not found", r.Method))
-			}
+func (h serverHandler) Deliver(ctx context.Context, r *jsonrpc2.Request, delivered bool) bool {
+	if delivered {
+		return false
+	}
+	switch r.Method {
+	case "$/cancelRequest":
+		var params CancelParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
 		}
+		r.Conn().Cancel(params.ID)
+		return true
+	case "workspace/didChangeWorkspaceFolders": // notif
+		var params DidChangeWorkspaceFoldersParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.server.DidChangeWorkspaceFolders(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "initialized": // notif
+		var params InitializedParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.server.Initialized(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "exit": // notif
+		if err := h.server.Exit(ctx); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "workspace/didChangeConfiguration": // notif
+		var params DidChangeConfigurationParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.server.DidChangeConfiguration(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/didOpen": // notif
+		var params DidOpenTextDocumentParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.server.DidOpen(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/didChange": // notif
+		var params DidChangeTextDocumentParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.server.DidChange(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/didClose": // notif
+		var params DidCloseTextDocumentParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.server.DidClose(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/didSave": // notif
+		var params DidSaveTextDocumentParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.server.DidSave(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/willSave": // notif
+		var params WillSaveTextDocumentParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.server.WillSave(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "workspace/didChangeWatchedFiles": // notif
+		var params DidChangeWatchedFilesParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.server.DidChangeWatchedFiles(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "$/setTraceNotification": // notif
+		var params SetTraceParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.server.SetTraceNotification(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "$/logTraceNotification": // notif
+		var params LogTraceParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.server.LogTraceNotification(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/implementation": // req
+		var params TextDocumentPositionParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.Implementation(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/typeDefinition": // req
+		var params TextDocumentPositionParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.TypeDefinition(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/documentColor": // req
+		var params DocumentColorParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.DocumentColor(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/colorPresentation": // req
+		var params ColorPresentationParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.ColorPresentation(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/foldingRange": // req
+		var params FoldingRangeParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.FoldingRange(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/declaration": // req
+		var params TextDocumentPositionParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.Declaration(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/selectionRange": // req
+		var params SelectionRangeParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.SelectionRange(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "initialize": // req
+		var params InitializeParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.Initialize(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "shutdown": // req
+		if r.Params != nil {
+			r.Reply(ctx, nil, jsonrpc2.NewErrorf(jsonrpc2.CodeInvalidParams, "Expected no params"))
+			return true
+		}
+		err := h.server.Shutdown(ctx)
+		if err := r.Reply(ctx, nil, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/willSaveWaitUntil": // req
+		var params WillSaveTextDocumentParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.WillSaveWaitUntil(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/completion": // req
+		var params CompletionParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.Completion(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "completionItem/resolve": // req
+		var params CompletionItem
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.Resolve(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/hover": // req
+		var params TextDocumentPositionParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.Hover(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/signatureHelp": // req
+		var params TextDocumentPositionParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.SignatureHelp(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/definition": // req
+		var params TextDocumentPositionParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.Definition(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/references": // req
+		var params ReferenceParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.References(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/documentHighlight": // req
+		var params TextDocumentPositionParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.DocumentHighlight(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/documentSymbol": // req
+		var params DocumentSymbolParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.DocumentSymbol(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "workspace/symbol": // req
+		var params WorkspaceSymbolParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.Symbol(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/codeAction": // req
+		var params CodeActionParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.CodeAction(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/codeLens": // req
+		var params CodeLensParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.CodeLens(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "codeLens/resolve": // req
+		var params CodeLens
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.ResolveCodeLens(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/formatting": // req
+		var params DocumentFormattingParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.Formatting(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/rangeFormatting": // req
+		var params DocumentRangeFormattingParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.RangeFormatting(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/onTypeFormatting": // req
+		var params DocumentOnTypeFormattingParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.OnTypeFormatting(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/rename": // req
+		var params RenameParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.Rename(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/prepareRename": // req
+		var params TextDocumentPositionParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.PrepareRename(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "textDocument/documentLink": // req
+		var params DocumentLinkParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.DocumentLink(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "documentLink/resolve": // req
+		var params DocumentLink
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.ResolveDocumentLink(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+	case "workspace/executeCommand": // req
+		var params ExecuteCommandParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		resp, err := h.server.ExecuteCommand(ctx, &params)
+		if err := r.Reply(ctx, resp, err); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
+
+	default:
+		return false
 	}
 }
 
@@ -564,6 +617,14 @@ func (s *serverDispatcher) Declaration(ctx context.Context, params *TextDocument
 	return result, nil
 }
 
+func (s *serverDispatcher) SelectionRange(ctx context.Context, params *SelectionRangeParams) ([]SelectionRange, error) {
+	var result []SelectionRange
+	if err := s.Conn.Call(ctx, "textDocument/selectionRange", params, &result); err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
 func (s *serverDispatcher) Initialize(ctx context.Context, params *InitializeParams) (*InitializeResult, error) {
 	var result InitializeResult
 	if err := s.Conn.Call(ctx, "initialize", params, &result); err != nil {

internal/lsp/protocol/typescript/README.md

@@ -4,10 +4,10 @@
 
 1. Make sure `node` is installed.
   As explained at the [node site](<https://nodejs.org> Node)
-  you may need `node install @types/node` for the node runtime types
-2. Install the typescript compiler, with `node install typescript`.
+  you may need `npm install @types/node` for the node runtime types
+2. Install the typescript compiler, with `npm install typescript`.
 3. Make sure `tsc` and `node` are in your execution path.
-4. Get the typescript code for the jsonrpc protocol with `git clone vscode-lanuageserver-node.git`
+4. Get the typescript code for the jsonrpc protocol with `git clone git@github.com:microsoft/vscode-languageserver-node.git`
 
 ## Usage
 
@@ -31,4 +31,4 @@ To generate the client and server boilerplate (tsclient.go and tsserver.go)
 
 ## Note
 
-`go.ts` uses the Typescript compiler's API, which is [introduced](<https://github.com/Microsoft/TypeScript/wiki/Architectural-Overview> API) in their wiki.
+`go.ts` uses the Typescript compiler's API, which is [introduced](<https://github.com/Microsoft/TypeScript/wiki/Architectural-Overview> API) in their wiki.

internal/lsp/protocol/typescript/go.ts

@@ -582,7 +582,7 @@ function generate(files: string[], options: ts.CompilerOptions): void {
       }
       if (x[0].goType == 'bool') {  // take it
         if (x[1].goType == 'RenameOptions') {
-          return ({goType: 'RenameOptions', gostuff: getText(node)})
+          return ({goType: 'interface{}', gostuff: getText(node)})
         }
         return ({goType: 'bool', gostuff: getText(node)})
       }
@@ -927,7 +927,7 @@ let byName = new Map<string, Struct>();
     // consts are unique. (Go consts are package-level, but Typescript's are
     // not.) Use suffixes to minimize changes to gopls.
     let pref = new Map<string, string>(
-        [['DiagnosticSeverity', 'Severity']])  // typeName->prefix
+      [['DiagnosticSeverity', 'Severity'], ['WatchKind', 'Watch']])  // typeName->prefix
     let suff = new Map<string, string>([
       ['CompletionItemKind', 'Completion'], ['InsertTextFormat', 'TextFormat']
     ])

internal/lsp/protocol/typescript/requests.ts

@@ -59,7 +59,7 @@ function generate(files: string[], options: ts.CompilerOptions): void {
   setReceives();  // distinguish client and server
   // for each of Client and Server there are 3 parts to the output:
   // 1. type X interface {methods}
-  // 2. serverHandler(...) { return func(...) { switch r.method}}
+  // 2. func (h *serverHandler) Deliver(...) { switch r.method }
   // 3. func (x *xDispatcher) Method(ctx, parm)
   not.forEach(
     (v, k) => {
@@ -99,7 +99,7 @@ function sig(nm: string, a: string, b: string, names?: boolean): string {
 
 const notNil = `if r.Params != nil {
 				r.Reply(ctx, nil, jsonrpc2.NewErrorf(jsonrpc2.CodeInvalidParams, "Expected no params"))
-				return
+				return true
 			}`;
 // Go code for notifications. Side is client or server, m is the request method
 function goNot(side: side, m: string) {
@@ -113,16 +113,18 @@ function goNot(side: side, m: string) {
   if (a != '') {
     case1 = `var params ${a}
     if err := json.Unmarshal(*r.Params, &params); err != nil {
-      sendParseError(ctx, log, r, err)
-      return
+      sendParseError(ctx, r, err)
+      return true
     }
-    if err := ${side.name}.${nm}(ctx, &params); err != nil {
-      log.Errorf(ctx, "%v", err)
-    }`;
+    if err := h.${side.name}.${nm}(ctx, &params); err != nil {
+      log.Error(ctx, "", err)
+    }
+    return true`;
   } else {
-    case1 = `if err := ${side.name}.${nm}(ctx); err != nil {
-      log.Errorf(ctx, "%v", err)
-    }`;
+    case1 = `if err := h.${side.name}.${nm}(ctx); err != nil {
+      log.Error(ctx, "", err)
+    }
+    return true`;
   }
   side.cases.push(`${caseHdr}\n${case1}`);
 
@@ -152,24 +154,26 @@ function goReq(side: side, m: string) {
   if (a != '') {
     case1 = `var params ${a}
     if err := json.Unmarshal(*r.Params, &params); err != nil {
-      sendParseError(ctx, log, r, err)
-      return
+      sendParseError(ctx, r, err)
+      return true
     }`;
   }
   const arg2 = a == '' ? '' : ', &params';
-  let case2 = `if err := ${side.name}.${nm}(ctx${arg2}); err != nil {
-    log.Errorf(ctx, "%v", err)
+  let case2 = `if err := h.${side.name}.${nm}(ctx${arg2}); err != nil {
+    log.Error(ctx, "", err)
   }`;
   if (b != '') {
-    case2 = `resp, err := ${side.name}.${nm}(ctx${arg2})
+    case2 = `resp, err := h.${side.name}.${nm}(ctx${arg2})
     if err := r.Reply(ctx, resp, err); err != nil {
-      log.Errorf(ctx, "%v", err)
-    }`;
+      log.Error(ctx, "", err)
+    }
+    return true`;
   } else {  // response is nil
-    case2 = `err := ${side.name}.${nm}(ctx${arg2})
+    case2 = `err := h.${side.name}.${nm}(ctx${arg2})
     if err := r.Reply(ctx, nil, err); err != nil {
-      log.Errorf(ctx, "%v", err)
-    }`
+      log.Error(ctx, "", err)
+    }
+    return true`
   }
 
   side.cases.push(`${caseHdr}\n${case1}\n${case2}`);
@@ -222,32 +226,31 @@ function output(side: side) {
     "encoding/json"
 
     "golang.org/x/tools/internal/jsonrpc2"
-    "golang.org/x/tools/internal/lsp/xlog"
+    "golang.org/x/tools/internal/lsp/telemetry/log"
   )
   `);
   const a = side.name[0].toUpperCase() + side.name.substring(1)
   f(`type ${a} interface {`);
   side.methods.forEach((v) => { f(v) });
   f('}\n');
-  f(`func ${side.name}Handler(log xlog.Logger, ${side.name} ${
-    side.goName}) jsonrpc2.Handler {
-    return func(ctx context.Context, r *jsonrpc2.Request) {
+  f(`func (h ${side.name}Handler) Deliver(ctx context.Context, r *jsonrpc2.Request, delivered bool) bool {
+      if delivered {
+        return false
+      }
       switch r.Method {
       case "$/cancelRequest":
         var params CancelParams
         if err := json.Unmarshal(*r.Params, &params); err != nil {
-          sendParseError(ctx, log, r, err)
-          return
+          sendParseError(ctx, r, err)
+          return true
         }
-        r.Conn().Cancel(params.ID)`);
+        r.Conn().Cancel(params.ID)
+        return true`);
   side.cases.forEach((v) => { f(v) });
   f(`
   default:
-    if r.IsNotify() {
-      r.Reply(ctx, nil, jsonrpc2.NewErrorf(jsonrpc2.CodeMethodNotFound, "method %q not found", r.Method))
-    }
+    return false
   }
-}
 }`);
   f(`
   type ${side.name}Dispatcher struct {

internal/lsp/references.go

@@ -9,6 +9,8 @@ import (
 
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -34,7 +36,7 @@ func (s *Server) references(ctx context.Context, params *protocol.ReferenceParam
 	}
 	references, err := ident.References(ctx)
 	if err != nil {
-		view.Session().Logger().Errorf(ctx, "no references for %s: %v", ident.Name, err)
+		log.Error(ctx, "no references", err, tag.Of("Identifier", ident.Name))
 	}
 	if params.Context.IncludeDeclaration {
 		// The declaration of this identifier may not be in the

internal/lsp/server.go

@@ -13,37 +13,36 @@ import (
 	"golang.org/x/tools/internal/jsonrpc2"
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
-	"golang.org/x/tools/internal/lsp/xlog"
 	"golang.org/x/tools/internal/span"
 )
 
 // NewClientServer
-func NewClientServer(cache source.Cache, client protocol.Client) *Server {
-	return &Server{
+func NewClientServer(ctx context.Context, cache source.Cache, client protocol.Client) (context.Context, *Server) {
+	ctx = protocol.WithClient(ctx, client)
+	return ctx, &Server{
 		client:  client,
-		session: cache.NewSession(xlog.New(protocol.NewLogger(client))),
+		session: cache.NewSession(ctx),
 	}
 }
 
 // NewServer starts an LSP server on the supplied stream, and waits until the
 // stream is closed.
-func NewServer(cache source.Cache, stream jsonrpc2.Stream) *Server {
+func NewServer(ctx context.Context, cache source.Cache, stream jsonrpc2.Stream) (context.Context, *Server) {
 	s := &Server{}
-	var log xlog.Logger
-	s.Conn, s.client, log = protocol.NewServer(stream, s)
-	s.session = cache.NewSession(log)
-	return s
+	ctx, s.Conn, s.client = protocol.NewServer(ctx, stream, s)
+	s.session = cache.NewSession(ctx)
+	return ctx, s
 }
 
 // RunServerOnPort starts an LSP server on the given port and does not exit.
 // This function exists for debugging purposes.
-func RunServerOnPort(ctx context.Context, cache source.Cache, port int, h func(s *Server)) error {
+func RunServerOnPort(ctx context.Context, cache source.Cache, port int, h func(ctx context.Context, s *Server)) error {
 	return RunServerOnAddress(ctx, cache, fmt.Sprintf(":%v", port), h)
 }
 
 // RunServerOnPort starts an LSP server on the given port and does not exit.
 // This function exists for debugging purposes.
-func RunServerOnAddress(ctx context.Context, cache source.Cache, addr string, h func(s *Server)) error {
+func RunServerOnAddress(ctx context.Context, cache source.Cache, addr string, h func(ctx context.Context, s *Server)) error {
 	ln, err := net.Listen("tcp", addr)
 	if err != nil {
 		return err
@@ -53,7 +52,7 @@ func RunServerOnAddress(ctx context.Context, cache source.Cache, addr string, h
 		if err != nil {
 			return err
 		}
-		h(NewServer(cache, jsonrpc2.NewHeaderStream(conn, conn)))
+		h(NewServer(ctx, cache, jsonrpc2.NewHeaderStream(conn, conn)))
 	}
 }
 
@@ -61,12 +60,21 @@ func (s *Server) Run(ctx context.Context) error {
 	return s.Conn.Run(ctx)
 }
 
+type serverState int
+
+const (
+	serverCreated      = serverState(iota)
+	serverInitializing // set once the server has received "initialize" request
+	serverInitialized  // set once the server has received "initialized" request
+	serverShutDown
+)
+
 type Server struct {
 	Conn   *jsonrpc2.Conn
 	client protocol.Client
 
-	initializedMu sync.Mutex
-	isInitialized bool // set once the server has received "initialize" request
+	stateMu sync.Mutex
+	state   serverState
 
 	// Configurations.
 	// TODO(rstambler): Separate these into their own struct?
@@ -264,6 +272,11 @@ func (s *Server) PrepareRename(context.Context, *protocol.TextDocumentPositionPa
 func (s *Server) SetTraceNotification(context.Context, *protocol.SetTraceParams) error {
 	return notImplemented("SetTraceNotification")
 }
+
+func (s *Server) SelectionRange(context.Context, *protocol.SelectionRangeParams) ([]protocol.SelectionRange, error) {
+	return nil, notImplemented("SelectionRange")
+}
+
 func notImplemented(method string) *jsonrpc2.Error {
 	return jsonrpc2.NewErrorf(jsonrpc2.CodeMethodNotFound, "method %q not yet implemented", method)
 }

internal/lsp/signature_help.go

@@ -9,6 +9,8 @@ import (
 
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -29,7 +31,7 @@ func (s *Server) signatureHelp(ctx context.Context, params *protocol.TextDocumen
 	}
 	info, err := source.SignatureHelp(ctx, f, rng.Start)
 	if err != nil {
-		s.session.Logger().Infof(ctx, "no signature help for %s:%v:%v : %s", uri, int(params.Position.Line), int(params.Position.Character), err)
+		log.Print(ctx, "no signature help", tag.Of("At", rng), tag.Of("Failure", err))
 		return nil, nil
 	}
 	return toProtocolSignatureHelp(info), nil

internal/lsp/source/analysis.go

@@ -11,7 +11,6 @@ import (
 	"fmt"
 	"go/token"
 	"go/types"
-	"log"
 	"reflect"
 	"sort"
 	"strings"
@@ -24,8 +23,8 @@ import (
 )
 
 func analyze(ctx context.Context, v View, pkgs []Package, analyzers []*analysis.Analyzer) ([]*Action, error) {
-	ctx, ts := trace.StartSpan(ctx, "source.analyze")
-	defer ts.End()
+	ctx, done := trace.StartSpan(ctx, "source.analyze")
+	defer done()
 	if ctx.Err() != nil {
 		return nil, ctx.Err()
 	}
@@ -148,7 +147,7 @@ func (act *Action) execOnce(ctx context.Context, fset *token.FileSet) error {
 	pass := &analysis.Pass{
 		Analyzer:          act.Analyzer,
 		Fset:              fset,
-		Files:             act.Pkg.GetSyntax(),
+		Files:             act.Pkg.GetSyntax(ctx),
 		Pkg:               act.Pkg.GetTypes(),
 		TypesInfo:         act.Pkg.GetTypesInfo(),
 		TypesSizes:        act.Pkg.GetTypesSizes(),
@@ -245,12 +244,12 @@ func (act *Action) importObjectFact(obj types.Object, ptr analysis.Fact) bool {
 // exportObjectFact implements Pass.ExportObjectFact.
 func (act *Action) exportObjectFact(obj types.Object, fact analysis.Fact) {
 	if act.pass.ExportObjectFact == nil {
-		log.Panicf("%s: Pass.ExportObjectFact(%s, %T) called after Run", act, obj, fact)
+		panic(fmt.Sprintf("%s: Pass.ExportObjectFact(%s, %T) called after Run", act, obj, fact))
 	}
 
 	if obj.Pkg() != act.Pkg.GetTypes() {
-		log.Panicf("internal error: in analysis %s of package %s: Fact.Set(%s, %T): can't set facts on objects belonging another package",
-			act.Analyzer, act.Pkg, obj, fact)
+		panic(fmt.Sprintf("internal error: in analysis %s of package %s: Fact.Set(%s, %T): can't set facts on objects belonging another package",
+			act.Analyzer, act.Pkg, obj, fact))
 	}
 
 	key := objectFactKey{obj, factType(fact)}
@@ -284,7 +283,7 @@ func (act *Action) importPackageFact(pkg *types.Package, ptr analysis.Fact) bool
 // exportPackageFact implements Pass.ExportPackageFact.
 func (act *Action) exportPackageFact(fact analysis.Fact) {
 	if act.pass.ExportPackageFact == nil {
-		log.Panicf("%s: Pass.ExportPackageFact(%T) called after Run", act, fact)
+		panic(fmt.Sprintf("%s: Pass.ExportPackageFact(%T) called after Run", act, fact))
 	}
 
 	key := packageFactKey{act.pass.Pkg, factType(fact)}
@@ -294,7 +293,7 @@ func (act *Action) exportPackageFact(fact analysis.Fact) {
 func factType(fact analysis.Fact) reflect.Type {
 	t := reflect.TypeOf(fact)
 	if t.Kind() != reflect.Ptr {
-		log.Fatalf("invalid Fact type: got %T, want pointer", t)
+		panic(fmt.Sprintf("invalid Fact type: got %T, want pointer", t))
 	}
 	return t
 }

internal/lsp/source/completion.go

@@ -278,13 +278,13 @@ type CompletionOptions struct {
 // the client to score the quality of the completion. For instance, some clients
 // may tolerate imperfect matches as valid completion results, since users may make typos.
 func Completion(ctx context.Context, view View, f GoFile, pos token.Pos, opts CompletionOptions) ([]CompletionItem, *Selection, error) {
-	ctx, ts := trace.StartSpan(ctx, "source.Completion")
-	defer ts.End()
-	file := f.GetAST(ctx)
-	if file == nil {
-		return nil, nil, fmt.Errorf("no AST for %s", f.URI())
-	}
+	ctx, done := trace.StartSpan(ctx, "source.Completion")
+	defer done()
 
+	file, err := f.GetAST(ctx, ParseFull)
+	if file == nil {
+		return nil, nil, err
+	}
 	pkg := f.GetPackage(ctx)
 	if pkg == nil || pkg.IsIllTyped() {
 		return nil, nil, fmt.Errorf("package for %s is ill typed", f.URI())
@@ -509,6 +509,7 @@ func (c *completer) lexical() error {
 			if scope == types.Universe {
 				score *= 0.1
 			}
+
 			// If we haven't already added a candidate for an object with this name.
 			if _, ok := seen[obj.Name()]; !ok {
 				seen[obj.Name()] = struct{}{}

internal/lsp/source/completion_format.go

@@ -14,6 +14,8 @@ import (
 	"strings"
 
 	"golang.org/x/tools/internal/lsp/snippet"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -97,31 +99,38 @@ func (c *completer) item(cand candidate) (CompletionItem, error) {
 	if c.opts.WantDocumentaton {
 		declRange, err := objToRange(c.ctx, c.view.Session().Cache().FileSet(), obj)
 		if err != nil {
-			return CompletionItem{}, err
+			log.Error(c.ctx, "failed to get declaration range for object", err, tag.Of("Name", obj.Name()))
+			goto Return
 		}
 		pos := declRange.FileSet.Position(declRange.Start)
 		if !pos.IsValid() {
-			return CompletionItem{}, fmt.Errorf("invalid declaration position for %v", item.Label)
+			log.Error(c.ctx, "invalid declaration position", err, tag.Of("Label", item.Label))
+			goto Return
 		}
 		uri := span.FileURI(pos.Filename)
 		f, err := c.view.GetFile(c.ctx, uri)
 		if err != nil {
-			return CompletionItem{}, err
+			log.Error(c.ctx, "unable to get file", err, tag.Of("URI", uri))
+			goto Return
 		}
 		gof, ok := f.(GoFile)
 		if !ok {
-			return CompletionItem{}, fmt.Errorf("declaration for %s not in a Go file: %s", item.Label, uri)
+			log.Error(c.ctx, "declaration in a Go file", err, tag.Of("Label", item.Label))
+			goto Return
 		}
 		ident, err := Identifier(c.ctx, c.view, gof, declRange.Start)
 		if err != nil {
-			return CompletionItem{}, err
+			log.Error(c.ctx, "no identifier", err, tag.Of("Name", obj.Name()))
+			goto Return
 		}
 		documentation, err := ident.Documentation(c.ctx, SynopsisDocumentation)
 		if err != nil {
-			return CompletionItem{}, err
+			log.Error(c.ctx, "no documentation", err, tag.Of("Name", obj.Name()))
+			goto Return
 		}
 		item.Documentation = documentation
 	}
+Return:
 	return item, nil
 }
 
@@ -192,7 +201,7 @@ func formatFieldList(ctx context.Context, v View, list *ast.FieldList) ([]string
 		cfg := printer.Config{Mode: printer.UseSpaces | printer.TabIndent, Tabwidth: 4}
 		b := &bytes.Buffer{}
 		if err := cfg.Fprint(b, v.Session().Cache().FileSet(), p.Type); err != nil {
-			v.Session().Logger().Errorf(ctx, "unable to print type %v", p.Type)
+			log.Error(ctx, "unable to print type", nil, tag.Of("Type", p.Type))
 			continue
 		}
 		typ := replacer.Replace(b.String())

internal/lsp/source/diagnostics.go

@@ -34,6 +34,9 @@ import (
 	"golang.org/x/tools/go/analysis/passes/unsafeptr"
 	"golang.org/x/tools/go/analysis/passes/unusedresult"
 	"golang.org/x/tools/go/packages"
+	"golang.org/x/tools/internal/lsp/telemetry"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
+	"golang.org/x/tools/internal/lsp/telemetry/trace"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -59,6 +62,8 @@ const (
 )
 
 func Diagnostics(ctx context.Context, view View, f GoFile, disabledAnalyses map[string]struct{}) (map[span.URI][]Diagnostic, error) {
+	ctx, done := trace.StartSpan(ctx, "source.Diagnostics", telemetry.File.Of(f.URI()))
+	defer done()
 	pkg := f.GetPackage(ctx)
 	if pkg == nil {
 		return singleDiagnostic(f.URI(), "%s is not part of a package", f.URI()), nil
@@ -81,7 +86,7 @@ func Diagnostics(ctx context.Context, view View, f GoFile, disabledAnalyses map[
 	if !diagnostics(ctx, view, pkg, reports) {
 		// If we don't have any list, parse, or type errors, run analyses.
 		if err := analyses(ctx, view, pkg, disabledAnalyses, reports); err != nil {
-			view.Session().Logger().Errorf(ctx, "failed to run analyses for %s: %v", f.URI(), err)
+			log.Error(ctx, "failed to run analyses", err, telemetry.File)
 		}
 	}
 	// Updates to the diagnostics for this package may need to be propagated.
@@ -104,6 +109,8 @@ type diagnosticSet struct {
 }
 
 func diagnostics(ctx context.Context, v View, pkg Package, reports map[span.URI][]Diagnostic) bool {
+	ctx, done := trace.StartSpan(ctx, "source.diagnostics", telemetry.Package.Of(pkg.ID()))
+	defer done()
 	diagSets := make(map[span.URI]*diagnosticSet)
 	for _, err := range pkg.GetErrors() {
 		diag := Diagnostic{
@@ -229,30 +236,31 @@ func parseDiagnosticMessage(input string) span.Span {
 
 func pointToSpan(ctx context.Context, view View, spn span.Span) span.Span {
 	f, err := view.GetFile(ctx, spn.URI())
+	ctx = telemetry.File.With(ctx, spn.URI())
 	if err != nil {
-		view.Session().Logger().Errorf(ctx, "could not find file for diagnostic: %v", spn.URI())
+		log.Error(ctx, "could not find file for diagnostic", nil, telemetry.File)
 		return spn
 	}
 	diagFile, ok := f.(GoFile)
 	if !ok {
-		view.Session().Logger().Errorf(ctx, "%s is not a Go file", spn.URI())
+		log.Error(ctx, "not a Go file", nil, telemetry.File)
 		return spn
 	}
-	tok := diagFile.GetToken(ctx)
-	if tok == nil {
-		view.Session().Logger().Errorf(ctx, "could not find token.File for diagnostic: %v", spn.URI())
+	tok, err := diagFile.GetToken(ctx)
+	if err != nil {
+		log.Error(ctx, "could not find token.File for diagnostic", err, telemetry.File)
 		return spn
 	}
 	data, _, err := diagFile.Handle(ctx).Read(ctx)
 	if err != nil {
-		view.Session().Logger().Errorf(ctx, "could not find content for diagnostic: %v", spn.URI())
+		log.Error(ctx, "could not find content for diagnostic", err, telemetry.File)
 		return spn
 	}
 	c := span.NewTokenConverter(diagFile.FileSet(), tok)
 	s, err := spn.WithOffset(c)
 	//we just don't bother producing an error if this failed
 	if err != nil {
-		view.Session().Logger().Errorf(ctx, "invalid span for diagnostic: %v: %v", spn.URI(), err)
+		log.Error(ctx, "invalid span for diagnostic", err, telemetry.File)
 		return spn
 	}
 	start := s.Start()

internal/lsp/source/format.go

@@ -10,27 +10,36 @@ import (
 	"context"
 	"fmt"
 	"go/format"
-	"strings"
 
 	"golang.org/x/tools/go/ast/astutil"
 	"golang.org/x/tools/go/packages"
 	"golang.org/x/tools/internal/imports"
 	"golang.org/x/tools/internal/lsp/diff"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
 	"golang.org/x/tools/internal/lsp/telemetry/trace"
 	"golang.org/x/tools/internal/span"
 )
 
 // Format formats a file with a given range.
 func Format(ctx context.Context, f GoFile, rng span.Range) ([]TextEdit, error) {
-	ctx, ts := trace.StartSpan(ctx, "source.Format")
-	defer ts.End()
-	file := f.GetAST(ctx)
+	ctx, done := trace.StartSpan(ctx, "source.Format")
+	defer done()
+
+	file, err := f.GetAST(ctx, ParseFull)
 	if file == nil {
-		return nil, fmt.Errorf("no AST for %s", f.URI())
+		return nil, err
 	}
 	pkg := f.GetPackage(ctx)
 	if hasListErrors(pkg.GetErrors()) || hasParseErrors(pkg.GetErrors()) {
-		return nil, fmt.Errorf("%s has parse errors, not formatting", f.URI())
+		// Even if this package has list or parse errors, this file may not
+		// have any parse errors and can still be formatted. Using format.Node
+		// on an ast with errors may result in code being added or removed.
+		// Attempt to format the source of this file instead.
+		formatted, err := formatSource(ctx, f)
+		if err != nil {
+			return nil, err
+		}
+		return computeTextEdits(ctx, f, string(formatted)), nil
 	}
 	path, exact := astutil.PathEnclosingInterval(file, rng.Start, rng.End)
 	if !exact || len(path) == 0 {
@@ -51,10 +60,20 @@ func Format(ctx context.Context, f GoFile, rng span.Range) ([]TextEdit, error) {
 	return computeTextEdits(ctx, f, buf.String()), nil
 }
 
+func formatSource(ctx context.Context, file File) ([]byte, error) {
+	ctx, done := trace.StartSpan(ctx, "source.formatSource")
+	defer done()
+	data, _, err := file.Handle(ctx).Read(ctx)
+	if err != nil {
+		return nil, err
+	}
+	return format.Source(data)
+}
+
 // Imports formats a file using the goimports tool.
 func Imports(ctx context.Context, view View, f GoFile, rng span.Range) ([]TextEdit, error) {
-	ctx, ts := trace.StartSpan(ctx, "source.Imports")
-	defer ts.End()
+	ctx, done := trace.StartSpan(ctx, "source.Imports")
+	defer done()
 	data, _, err := f.Handle(ctx).Read(ctx)
 	if err != nil {
 		return nil, err
@@ -66,8 +85,8 @@ func Imports(ctx context.Context, view View, f GoFile, rng span.Range) ([]TextEd
 	if hasListErrors(pkg.GetErrors()) {
 		return nil, fmt.Errorf("%s has list errors, not running goimports", f.URI())
 	}
+
 	options := &imports.Options{
-		Env: buildProcessEnv(ctx, view),
 		// Defaults.
 		AllErrors:  true,
 		Comments:   true,
@@ -76,10 +95,16 @@ func Imports(ctx context.Context, view View, f GoFile, rng span.Range) ([]TextEd
 		TabIndent:  true,
 		TabWidth:   8,
 	}
-	formatted, err := imports.Process(f.URI().Filename(), data, options)
+	var formatted []byte
+	importFn := func(opts *imports.Options) error {
+		formatted, err = imports.Process(f.URI().Filename(), data, opts)
+		return err
+	}
+	err = view.RunProcessEnvFunc(ctx, importFn, options)
 	if err != nil {
 		return nil, err
 	}
+
 	return computeTextEdits(ctx, f, string(formatted)), nil
 }
 
@@ -101,43 +126,12 @@ func hasListErrors(errors []packages.Error) bool {
 	return false
 }
 
-func buildProcessEnv(ctx context.Context, view View) *imports.ProcessEnv {
-	cfg := view.Config()
-	env := &imports.ProcessEnv{
-		WorkingDir: cfg.Dir,
-		Logf: func(format string, v ...interface{}) {
-			view.Session().Logger().Infof(ctx, format, v...)
-		},
-	}
-	for _, kv := range cfg.Env {
-		split := strings.Split(kv, "=")
-		if len(split) < 2 {
-			continue
-		}
-		switch split[0] {
-		case "GOPATH":
-			env.GOPATH = split[1]
-		case "GOROOT":
-			env.GOROOT = split[1]
-		case "GO111MODULE":
-			env.GO111MODULE = split[1]
-		case "GOPROXY":
-			env.GOROOT = split[1]
-		case "GOFLAGS":
-			env.GOFLAGS = split[1]
-		case "GOSUMDB":
-			env.GOSUMDB = split[1]
-		}
-	}
-	return env
-}
-
 func computeTextEdits(ctx context.Context, file File, formatted string) (edits []TextEdit) {
-	ctx, ts := trace.StartSpan(ctx, "source.computeTextEdits")
-	defer ts.End()
+	ctx, done := trace.StartSpan(ctx, "source.computeTextEdits")
+	defer done()
 	data, _, err := file.Handle(ctx).Read(ctx)
 	if err != nil {
-		file.View().Session().Logger().Errorf(ctx, "Cannot compute text edits: %v", err)
+		log.Error(ctx, "Cannot compute text edits", err)
 		return nil
 	}
 	u := diff.SplitLines(string(data))

internal/lsp/source/highlight.go

@@ -16,11 +16,12 @@ import (
 )
 
 func Highlight(ctx context.Context, f GoFile, pos token.Pos) ([]span.Span, error) {
-	ctx, ts := trace.StartSpan(ctx, "source.Highlight")
-	defer ts.End()
-	file := f.GetAST(ctx)
+	ctx, done := trace.StartSpan(ctx, "source.Highlight")
+	defer done()
+
+	file, err := f.GetAST(ctx, ParseFull)
 	if file == nil {
-		return nil, fmt.Errorf("no AST for %s", f.URI())
+		return nil, err
 	}
 	fset := f.FileSet()
 	path, _ := astutil.PathEnclosingInterval(file, pos, pos)

internal/lsp/source/hover.go

@@ -33,8 +33,8 @@ const (
 )
 
 func (i *IdentifierInfo) Hover(ctx context.Context, markdownSupported bool, hoverKind HoverKind) (string, error) {
-	ctx, ts := trace.StartSpan(ctx, "source.Hover")
-	defer ts.End()
+	ctx, done := trace.StartSpan(ctx, "source.Hover")
+	defer done()
 	h, err := i.decl.hover(ctx)
 	if err != nil {
 		return "", err
@@ -80,10 +80,12 @@ func (i *IdentifierInfo) Documentation(ctx context.Context, hoverKind HoverKind)
 }
 
 func (d declaration) hover(ctx context.Context) (*documentation, error) {
-	ctx, ts := trace.StartSpan(ctx, "source.hover")
-	defer ts.End()
+	ctx, done := trace.StartSpan(ctx, "source.hover")
+	defer done()
 	obj := d.obj
 	switch node := d.node.(type) {
+	case *ast.ImportSpec:
+		return &documentation{node, nil}, nil
 	case *ast.GenDecl:
 		switch obj := obj.(type) {
 		case *types.TypeName, *types.Var, *types.Const, *types.Func:

internal/lsp/source/identifier.go

@@ -63,11 +63,12 @@ func Identifier(ctx context.Context, view View, f GoFile, pos token.Pos) (*Ident
 
 // identifier checks a single position for a potential identifier.
 func identifier(ctx context.Context, view View, f GoFile, pos token.Pos) (*IdentifierInfo, error) {
-	ctx, ts := trace.StartSpan(ctx, "source.identifier")
-	defer ts.End()
-	file := f.GetAST(ctx)
+	ctx, done := trace.StartSpan(ctx, "source.identifier")
+	defer done()
+
+	file, err := f.GetAST(ctx, ParseFull)
 	if file == nil {
-		return nil, fmt.Errorf("no AST for %s", f.URI())
+		return nil, err
 	}
 	pkg := f.GetPackage(ctx)
 	if pkg == nil || pkg.IsIllTyped() {
@@ -121,8 +122,6 @@ func identifier(ctx context.Context, view View, f GoFile, pos token.Pos) (*Ident
 		}
 	}
 
-	var err error
-
 	// Handle builtins separately.
 	if result.decl.obj.Parent() == types.Universe {
 		decl, ok := lookupBuiltinDecl(f.View(), result.Name).(ast.Node)
@@ -235,14 +234,13 @@ func objToNode(ctx context.Context, view View, originPkg *types.Package, obj typ
 	}
 	// If the object is exported from a different package,
 	// we don't need its full AST to find the definition.
-	var declAST *ast.File
+	mode := ParseFull
 	if obj.Exported() && obj.Pkg() != originPkg {
-		declAST = declFile.GetAnyAST(ctx)
-	} else {
-		declAST = declFile.GetAST(ctx)
+		mode = ParseExported
 	}
+	declAST, err := declFile.GetAST(ctx, mode)
 	if declAST == nil {
-		return nil, fmt.Errorf("no AST for %s", f.URI())
+		return nil, err
 	}
 	path, _ := astutil.PathEnclosingInterval(declAST, rng.Start, rng.End)
 	if path == nil {
@@ -292,12 +290,12 @@ func importSpec(ctx context.Context, f GoFile, fAST *ast.File, pkg Package, pos
 	if importedPkg == nil {
 		return nil, fmt.Errorf("no import for %q", importPath)
 	}
-	if importedPkg.GetSyntax() == nil {
+	if importedPkg.GetSyntax(ctx) == nil {
 		return nil, fmt.Errorf("no syntax for for %q", importPath)
 	}
 	// Heuristic: Jump to the longest (most "interesting") file of the package.
 	var dest *ast.File
-	for _, f := range importedPkg.GetSyntax() {
+	for _, f := range importedPkg.GetSyntax(ctx) {
 		if dest == nil || f.End()-f.Pos() > dest.End()-dest.Pos() {
 			dest = f
 		}
@@ -306,6 +304,7 @@ func importSpec(ctx context.Context, f GoFile, fAST *ast.File, pkg Package, pos
 		return nil, fmt.Errorf("package %q has no files", importPath)
 	}
 	result.decl.rng = span.NewRange(f.FileSet(), dest.Name.Pos(), dest.Name.End())
+	result.decl.node = imp
 	return result, nil
 }
 

internal/lsp/source/references.go

@@ -27,8 +27,8 @@ type ReferenceInfo struct {
 // References returns a list of references for a given identifier within the packages
 // containing i.File. Declarations appear first in the result.
 func (i *IdentifierInfo) References(ctx context.Context) ([]*ReferenceInfo, error) {
-	ctx, ts := trace.StartSpan(ctx, "source.References")
-	defer ts.End()
+	ctx, done := trace.StartSpan(ctx, "source.References")
+	defer done()
 	var references []*ReferenceInfo
 
 	// If the object declaration is nil, assume it is an import spec and do not look for references.

internal/lsp/source/rename.go

@@ -37,8 +37,9 @@ type renamer struct {
 
 // Rename returns a map of TextEdits for each file modified when renaming a given identifier within a package.
 func (i *IdentifierInfo) Rename(ctx context.Context, newName string) (map[span.URI][]TextEdit, error) {
-	ctx, ts := trace.StartSpan(ctx, "source.Rename")
-	defer ts.End()
+	ctx, done := trace.StartSpan(ctx, "source.Rename")
+	defer done()
+
 	if i.Name == newName {
 		return nil, fmt.Errorf("old and new names are the same: %s", newName)
 	}
@@ -85,7 +86,16 @@ func (i *IdentifierInfo) Rename(ctx context.Context, newName string) (map[span.U
 		return nil, fmt.Errorf(r.errors)
 	}
 
-	return r.update()
+	changes, err := r.update()
+	if err != nil {
+		return nil, err
+	}
+
+	// Sort edits for each file.
+	for _, edits := range changes {
+		sortTextEdits(edits)
+	}
+	return changes, nil
 }
 
 // Rename all references to the identifier.

internal/lsp/source/rename_check.go

@@ -113,7 +113,7 @@ func (r *renamer) checkInPackageBlock(from types.Object) {
 	}
 
 	// Check for conflicts between package block and all file blocks.
-	for _, f := range pkg.GetSyntax() {
+	for _, f := range pkg.GetSyntax(r.ctx) {
 		fileScope := pkg.GetTypesInfo().Scopes[f]
 		b, prev := fileScope.LookupParent(r.to, token.NoPos)
 		if b == fileScope {
@@ -328,7 +328,7 @@ func forEachLexicalRef(ctx context.Context, pkg Package, obj types.Object, fn fu
 		return true
 	}
 
-	for _, f := range pkg.GetSyntax() {
+	for _, f := range pkg.GetSyntax(ctx) {
 		ast.Inspect(f, visit)
 		if len(stack) != 0 {
 			panic(stack)
@@ -802,7 +802,7 @@ func (r *renamer) satisfy() map[satisfy.Constraint]bool {
 					r.from, r.to, pkg.PkgPath())
 				return nil
 			}
-			f.Find(pkg.GetTypesInfo(), pkg.GetSyntax())
+			f.Find(pkg.GetTypesInfo(), pkg.GetSyntax(r.ctx))
 		}
 		r.satisfyConstraints = f.Result
 	}
@@ -835,7 +835,7 @@ func someUse(info *types.Info, obj types.Object) *ast.Ident {
 //
 func pathEnclosingInterval(ctx context.Context, fset *token.FileSet, pkg Package, start, end token.Pos) (resPkg Package, path []ast.Node, exact bool) {
 	var pkgs = []Package{pkg}
-	for _, f := range pkg.GetSyntax() {
+	for _, f := range pkg.GetSyntax(ctx) {
 		for _, imp := range f.Imports {
 			if imp == nil {
 				continue
@@ -848,7 +848,7 @@ func pathEnclosingInterval(ctx context.Context, fset *token.FileSet, pkg Package
 		}
 	}
 	for _, p := range pkgs {
-		for _, f := range p.GetSyntax() {
+		for _, f := range p.GetSyntax(ctx) {
 			if f.Pos() == token.NoPos {
 				// This can happen if the parser saw
 				// too many errors and bailed out.

internal/lsp/source/signature_help.go

@@ -26,11 +26,12 @@ type ParameterInformation struct {
 }
 
 func SignatureHelp(ctx context.Context, f GoFile, pos token.Pos) (*SignatureInformation, error) {
-	ctx, ts := trace.StartSpan(ctx, "source.SignatureHelp")
-	defer ts.End()
-	file := f.GetAST(ctx)
+	ctx, done := trace.StartSpan(ctx, "source.SignatureHelp")
+	defer done()
+
+	file, err := f.GetAST(ctx, ParseFull)
 	if file == nil {
-		return nil, fmt.Errorf("no AST for %s", f.URI())
+		return nil, err
 	}
 	pkg := f.GetPackage(ctx)
 	if pkg == nil || pkg.IsIllTyped() {

internal/lsp/source/source_test.go

@@ -19,7 +19,6 @@ import (
 	"golang.org/x/tools/internal/lsp/diff"
 	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/lsp/tests"
-	"golang.org/x/tools/internal/lsp/xlog"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -30,18 +29,20 @@ func TestSource(t *testing.T) {
 type runner struct {
 	view source.View
 	data *tests.Data
+	ctx  context.Context
 }
 
 func testSource(t *testing.T, exporter packagestest.Exporter) {
+	ctx := tests.Context(t)
 	data := tests.Load(t, exporter, "../testdata")
 	defer data.Exported.Cleanup()
 
-	log := xlog.New(xlog.StdSink{})
 	cache := cache.New()
-	session := cache.NewSession(log)
+	session := cache.NewSession(ctx)
 	r := &runner{
-		view: session.NewView("source_test", span.FileURI(data.Config.Dir)),
+		view: session.NewView(ctx, "source_test", span.FileURI(data.Config.Dir)),
 		data: data,
+		ctx:  ctx,
 	}
 	r.view.SetEnv(data.Config.Env)
 	for filename, content := range data.Config.Overlay {
@@ -52,11 +53,11 @@ func testSource(t *testing.T, exporter packagestest.Exporter) {
 
 func (r *runner) Diagnostics(t *testing.T, data tests.Diagnostics) {
 	for uri, want := range data {
-		f, err := r.view.GetFile(context.Background(), uri)
+		f, err := r.view.GetFile(r.ctx, uri)
 		if err != nil {
 			t.Fatal(err)
 		}
-		results, err := source.Diagnostics(context.Background(), r.view, f.(source.GoFile), nil)
+		results, err := source.Diagnostics(r.ctx, r.view, f.(source.GoFile), nil)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -132,7 +133,7 @@ func summarizeDiagnostics(i int, want []source.Diagnostic, got []source.Diagnost
 }
 
 func (r *runner) Completion(t *testing.T, data tests.Completions, snippets tests.CompletionSnippets, items tests.CompletionItems) {
-	ctx := context.Background()
+	ctx := r.ctx
 	for src, itemList := range data {
 		var want []source.CompletionItem
 		for _, pos := range itemList {
@@ -142,9 +143,9 @@ func (r *runner) Completion(t *testing.T, data tests.Completions, snippets tests
 		if err != nil {
 			t.Fatalf("failed for %v: %v", src, err)
 		}
-		tok := f.(source.GoFile).GetToken(ctx)
-		if tok == nil {
-			t.Fatalf("failed to get token for %v", src)
+		tok, err := f.(source.GoFile).GetToken(ctx)
+		if err != nil {
+			t.Fatalf("failed to get token for %s: %v", src.URI(), err)
 		}
 		pos := tok.Pos(src.Start().Offset())
 		list, surrounding, err := source.Completion(ctx, r.view, f.(source.GoFile), pos, source.CompletionOptions{
@@ -180,7 +181,10 @@ func (r *runner) Completion(t *testing.T, data tests.Completions, snippets tests
 			if err != nil {
 				t.Fatalf("failed for %v: %v", src, err)
 			}
-			tok := f.GetToken(ctx)
+			tok, err := f.(source.GoFile).GetToken(ctx)
+			if err != nil {
+				t.Fatalf("failed to get token for %s: %v", src.URI(), err)
+			}
 			pos := tok.Pos(src.Start().Offset())
 			list, _, err := source.Completion(ctx, r.view, f.(source.GoFile), pos, source.CompletionOptions{
 				DeepComplete: strings.Contains(string(src.URI()), "deepcomplete"),
@@ -289,7 +293,7 @@ func summarizeCompletionItems(i int, want []source.CompletionItem, got []source.
 }
 
 func (r *runner) Format(t *testing.T, data tests.Formats) {
-	ctx := context.Background()
+	ctx := r.ctx
 	for _, spn := range data {
 		uri := spn.URI()
 		filename := uri.Filename()
@@ -302,7 +306,11 @@ func (r *runner) Format(t *testing.T, data tests.Formats) {
 		if err != nil {
 			t.Fatalf("failed for %v: %v", spn, err)
 		}
-		rng, err := spn.Range(span.NewTokenConverter(f.FileSet(), f.GetToken(ctx)))
+		tok, err := f.(source.GoFile).GetToken(ctx)
+		if err != nil {
+			t.Fatalf("failed to get token for %s: %v", spn.URI(), err)
+		}
+		rng, err := spn.Range(span.NewTokenConverter(f.FileSet(), tok))
 		if err != nil {
 			t.Fatalf("failed for %v: %v", spn, err)
 		}
@@ -327,7 +335,7 @@ func (r *runner) Format(t *testing.T, data tests.Formats) {
 }
 
 func (r *runner) Import(t *testing.T, data tests.Imports) {
-	ctx := context.Background()
+	ctx := r.ctx
 	for _, spn := range data {
 		uri := spn.URI()
 		filename := uri.Filename()
@@ -340,7 +348,11 @@ func (r *runner) Import(t *testing.T, data tests.Imports) {
 		if err != nil {
 			t.Fatalf("failed for %v: %v", spn, err)
 		}
-		rng, err := spn.Range(span.NewTokenConverter(f.FileSet(), f.GetToken(ctx)))
+		tok, err := f.(source.GoFile).GetToken(ctx)
+		if err != nil {
+			t.Fatalf("failed to get token for %s: %v", spn.URI(), err)
+		}
+		rng, err := spn.Range(span.NewTokenConverter(f.FileSet(), tok))
 		if err != nil {
 			t.Fatalf("failed for %v: %v", spn, err)
 		}
@@ -365,13 +377,16 @@ func (r *runner) Import(t *testing.T, data tests.Imports) {
 }
 
 func (r *runner) Definition(t *testing.T, data tests.Definitions) {
-	ctx := context.Background()
+	ctx := r.ctx
 	for _, d := range data {
 		f, err := r.view.GetFile(ctx, d.Src.URI())
 		if err != nil {
 			t.Fatalf("failed for %v: %v", d.Src, err)
 		}
-		tok := f.GetToken(ctx)
+		tok, err := f.(source.GoFile).GetToken(ctx)
+		if err != nil {
+			t.Fatalf("failed to get token for %s: %v", d.Src.URI(), err)
+		}
 		pos := tok.Pos(d.Src.Start().Offset())
 		ident, err := source.Identifier(ctx, r.view, f.(source.GoFile), pos)
 		if err != nil {
@@ -407,14 +422,17 @@ func (r *runner) Definition(t *testing.T, data tests.Definitions) {
 }
 
 func (r *runner) Highlight(t *testing.T, data tests.Highlights) {
-	ctx := context.Background()
+	ctx := r.ctx
 	for name, locations := range data {
 		src := locations[0]
 		f, err := r.view.GetFile(ctx, src.URI())
 		if err != nil {
 			t.Fatalf("failed for %v: %v", src, err)
 		}
-		tok := f.GetToken(ctx)
+		tok, err := f.(source.GoFile).GetToken(ctx)
+		if err != nil {
+			t.Fatalf("failed to get token for %s: %v", src.URI(), err)
+		}
 		pos := tok.Pos(src.Start().Offset())
 		highlights, err := source.Highlight(ctx, f.(source.GoFile), pos)
 		if err != nil {
@@ -432,14 +450,16 @@ func (r *runner) Highlight(t *testing.T, data tests.Highlights) {
 }
 
 func (r *runner) Reference(t *testing.T, data tests.References) {
-	ctx := context.Background()
+	ctx := r.ctx
 	for src, itemList := range data {
 		f, err := r.view.GetFile(ctx, src.URI())
 		if err != nil {
 			t.Fatalf("failed for %v: %v", src, err)
 		}
-
-		tok := f.GetToken(ctx)
+		tok, err := f.(source.GoFile).GetToken(ctx)
+		if err != nil {
+			t.Fatalf("failed to get token for %s: %v", src.URI(), err)
+		}
 		pos := tok.Pos(src.Start().Offset())
 		ident, err := source.Identifier(ctx, r.view, f.(source.GoFile), pos)
 		if err != nil {
@@ -478,7 +498,7 @@ func (r *runner) Reference(t *testing.T, data tests.References) {
 }
 
 func (r *runner) Rename(t *testing.T, data tests.Renames) {
-	ctx := context.Background()
+	ctx := r.ctx
 	for spn, newText := range data {
 		tag := fmt.Sprintf("%s-rename", newText)
 
@@ -486,14 +506,18 @@ func (r *runner) Rename(t *testing.T, data tests.Renames) {
 		if err != nil {
 			t.Fatalf("failed for %v: %v", spn, err)
 		}
-		tok := f.GetToken(ctx)
+		tok, err := f.(source.GoFile).GetToken(ctx)
+		if err != nil {
+			t.Fatalf("failed to get token for %s: %v", spn.URI(), err)
+		}
 		pos := tok.Pos(spn.Start().Offset())
 
-		ident, err := source.Identifier(context.Background(), r.view, f.(source.GoFile), pos)
+		ident, err := source.Identifier(r.ctx, r.view, f.(source.GoFile), pos)
 		if err != nil {
 			t.Error(err)
+			continue
 		}
-		changes, err := ident.Rename(context.Background(), newText)
+		changes, err := ident.Rename(r.ctx, newText)
 		if err != nil {
 			renamed := string(r.data.Golden(tag, spn.URI().Filename(), func() ([]byte, error) {
 				return []byte(err.Error()), nil
@@ -544,7 +568,6 @@ func (r *runner) Rename(t *testing.T, data tests.Renames) {
 
 func applyEdits(contents string, edits []source.TextEdit) string {
 	res := contents
-	sortSourceTextEdits(edits)
 
 	// Apply the edits from the end of the file forward
 	// to preserve the offsets
@@ -558,17 +581,8 @@ func applyEdits(contents string, edits []source.TextEdit) string {
 	return res
 }
 
-func sortSourceTextEdits(d []source.TextEdit) {
-	sort.Slice(d, func(i int, j int) bool {
-		if r := span.Compare(d[i].Span, d[j].Span); r != 0 {
-			return r < 0
-		}
-		return d[i].NewText < d[j].NewText
-	})
-}
-
 func (r *runner) Symbol(t *testing.T, data tests.Symbols) {
-	ctx := context.Background()
+	ctx := r.ctx
 	for uri, expectedSymbols := range data {
 		f, err := r.view.GetFile(ctx, uri)
 		if err != nil {
@@ -632,13 +646,16 @@ func summarizeSymbols(i int, want []source.Symbol, got []source.Symbol, reason s
 }
 
 func (r *runner) SignatureHelp(t *testing.T, data tests.Signatures) {
-	ctx := context.Background()
+	ctx := r.ctx
 	for spn, expectedSignature := range data {
 		f, err := r.view.GetFile(ctx, spn.URI())
 		if err != nil {
 			t.Fatalf("failed for %v: %v", spn, err)
 		}
-		tok := f.GetToken(ctx)
+		tok, err := f.(source.GoFile).GetToken(ctx)
+		if err != nil {
+			t.Fatalf("failed to get token for %s: %v", spn.URI(), err)
+		}
 		pos := tok.Pos(spn.Start().Offset())
 		gotSignature, err := source.SignatureHelp(ctx, f.(source.GoFile), pos)
 		if err != nil {

internal/lsp/source/suggested_fix_experimental.go

@@ -8,10 +8,10 @@ import (
 	"golang.org/x/tools/internal/span"
 )
 
-func getCodeActions(fset *token.FileSet, diag analysis.Diagnostic) ([]CodeAction, error) {
-	var cas []CodeAction
+func getCodeActions(fset *token.FileSet, diag analysis.Diagnostic) ([]SuggestedFixes, error) {
+	var cas []SuggestedFixes
 	for _, fix := range diag.SuggestedFixes {
-		var ca CodeAction
+		var ca SuggestedFixes
 		ca.Title = fix.Message
 		for _, te := range fix.TextEdits {
 			span, err := span.NewRange(fset, te.Pos, te.End).Span()

internal/lsp/source/symbols.go

@@ -42,12 +42,13 @@ type Symbol struct {
 }
 
 func DocumentSymbols(ctx context.Context, f GoFile) ([]Symbol, error) {
-	ctx, ts := trace.StartSpan(ctx, "source.DocumentSymbols")
-	defer ts.End()
+	ctx, done := trace.StartSpan(ctx, "source.DocumentSymbols")
+	defer done()
+
 	fset := f.FileSet()
-	file := f.GetAST(ctx)
+	file, err := f.GetAST(ctx, ParseFull)
 	if file == nil {
-		return nil, fmt.Errorf("no AST for %s", f.URI())
+		return nil, err
 	}
 	pkg := f.GetPackage(ctx)
 	if pkg == nil || pkg.IsIllTyped() {

internal/lsp/source/util.go

@@ -9,9 +9,41 @@ import (
 	"go/ast"
 	"go/token"
 	"go/types"
+	"path/filepath"
 	"strings"
 )
 
+func DetectLanguage(langID, filename string) FileKind {
+	switch langID {
+	case "go":
+		return Go
+	case "go.mod":
+		return Mod
+	case "go.sum":
+		return Sum
+	}
+	// Fallback to detecting the language based on the file extension.
+	switch filepath.Ext(filename) {
+	case ".mod":
+		return Mod
+	case ".sum":
+		return Sum
+	default: // fallback to Go
+		return Go
+	}
+}
+
+func (k FileKind) String() string {
+	switch k {
+	case Mod:
+		return "go.mod"
+	case Sum:
+		return "go.sum"
+	default:
+		return "go"
+	}
+}
+
 // indexExprAtPos returns the index of the expression containing pos.
 func indexExprAtPos(pos token.Pos, args []ast.Expr) int {
 	for i, expr := range args {

internal/lsp/source/view.go

@@ -9,12 +9,13 @@ import (
 	"go/ast"
 	"go/token"
 	"go/types"
+	"sort"
 	"strings"
 
 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/packages"
+	"golang.org/x/tools/internal/imports"
 	"golang.org/x/tools/internal/lsp/diff"
-	"golang.org/x/tools/internal/lsp/xlog"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -111,7 +112,7 @@ type Cache interface {
 	FileSystem
 
 	// NewSession creates a new Session manager and returns it.
-	NewSession(log xlog.Logger) Session
+	NewSession(ctx context.Context) Session
 
 	// FileSet returns the shared fileset used by all files in the system.
 	FileSet() *token.FileSet
@@ -129,14 +130,11 @@ type Cache interface {
 // A session may have many active views at any given time.
 type Session interface {
 	// NewView creates a new View and returns it.
-	NewView(name string, folder span.URI) View
+	NewView(ctx context.Context, name string, folder span.URI) View
 
 	// Cache returns the cache that created this session.
 	Cache() Cache
 
-	// Returns the logger in use for this session.
-	Logger() xlog.Logger
-
 	// View returns a view with a mathing name, if the session has one.
 	View(name string) View
 
@@ -154,7 +152,7 @@ type Session interface {
 	FileSystem
 
 	// DidOpen is invoked each time a file is opened in the editor.
-	DidOpen(ctx context.Context, uri span.URI, text []byte)
+	DidOpen(ctx context.Context, uri span.URI, kind FileKind, text []byte)
 
 	// DidSave is invoked each time an open file is saved in the editor.
 	DidSave(uri span.URI)
@@ -210,7 +208,11 @@ type View interface {
 	// Ignore returns true if this file should be ignored by this view.
 	Ignore(span.URI) bool
 
-	Config() *packages.Config
+	Config(ctx context.Context) *packages.Config
+
+	// RunProcessEnvFunc runs fn with the process env for this view inserted into opts.
+	// Note: the process env contains cached module and filesystem state.
+	RunProcessEnvFunc(ctx context.Context, fn func(*imports.Options) error, opts *imports.Options) error
 }
 
 // File represents a source file of any type.
@@ -219,19 +221,15 @@ type File interface {
 	View() View
 	Handle(ctx context.Context) FileHandle
 	FileSet() *token.FileSet
-	GetToken(ctx context.Context) *token.File
+	GetToken(ctx context.Context) (*token.File, error)
 }
 
 // GoFile represents a Go source file that has been type-checked.
 type GoFile interface {
 	File
 
-	// GetAnyAST returns an AST that may or may not contain function bodies.
-	// It should be used in scenarios where function bodies are not necessary.
-	GetAnyAST(ctx context.Context) *ast.File
-
 	// GetAST returns the full AST for the file.
-	GetAST(ctx context.Context) *ast.File
+	GetAST(ctx context.Context, mode ParseMode) (*ast.File, error)
 
 	// GetPackage returns the package that this file belongs to.
 	GetPackage(ctx context.Context) Package
@@ -258,7 +256,7 @@ type Package interface {
 	ID() string
 	PkgPath() string
 	GetFilenames() []string
-	GetSyntax() []*ast.File
+	GetSyntax(context.Context) []*ast.File
 	GetErrors() []packages.Error
 	GetTypes() *types.Package
 	GetTypesInfo() *types.Info
@@ -322,3 +320,10 @@ func EditsToDiff(edits []TextEdit) []*diff.Op {
 	}
 	return ops
 }
+
+func sortTextEdits(d []TextEdit) {
+	// Use a stable sort to maintain the order of edits inserted at the same position.
+	sort.SliceStable(d, func(i int, j int) bool {
+		return span.Compare(d[i].Span, d[j].Span) < 0
+	})
+}

internal/lsp/symbols.go

@@ -14,8 +14,8 @@ import (
 )
 
 func (s *Server) documentSymbol(ctx context.Context, params *protocol.DocumentSymbolParams) ([]protocol.DocumentSymbol, error) {
-	ctx, ts := trace.StartSpan(ctx, "lsp.Server.documentSymbol")
-	defer ts.End()
+	ctx, done := trace.StartSpan(ctx, "lsp.Server.documentSymbol")
+	defer done()
 	uri := span.NewURI(params.TextDocument.URI)
 	view := s.session.ViewOf(uri)
 	f, m, err := getGoFile(ctx, view, uri)

internal/lsp/telemetry/log/entry.go

@@ -0,0 +1,51 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package log
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
+)
+
+type Entry struct {
+	At      time.Time
+	Message string
+	Error   error
+	Tags    tag.List
+}
+
+func ToEntry(ctx context.Context, at time.Time, tags tag.List) Entry {
+	//TODO: filter more efficiently for the common case of stripping prefixes only
+	entry := Entry{
+		At: at,
+	}
+	for _, t := range tags {
+		switch t.Key {
+		case MessageTag:
+			entry.Message = t.Value.(string)
+		case ErrorTag:
+			entry.Error = t.Value.(error)
+		default:
+			entry.Tags = append(entry.Tags, t)
+		}
+	}
+	return entry
+}
+
+func (e Entry) Format(f fmt.State, r rune) {
+	if !e.At.IsZero() {
+		fmt.Fprint(f, e.At.Format("2006/01/02 15:04:05 "))
+	}
+	fmt.Fprint(f, e.Message)
+	if e.Error != nil {
+		fmt.Fprintf(f, ": %v", e.Error)
+	}
+	for _, tag := range e.Tags {
+		fmt.Fprintf(f, "\n\t%v = %v", tag.Key, tag.Value)
+	}
+}

internal/lsp/telemetry/log/log.go

@@ -0,0 +1,92 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package log is a context based logging package, designed to interact well
+// with both the lsp protocol and the other telemetry packages.
+package log
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"time"
+
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
+	"golang.org/x/tools/internal/lsp/telemetry/worker"
+)
+
+const (
+	// The well known tag keys for the logging system.
+	MessageTag = tag.Key("message")
+	ErrorTag   = tag.Key("error")
+)
+
+// Logger is a function that handles logging messages.
+// Loggers are registered at start up, and may use information in the context
+// to decide what to do with a given log message.
+type Logger func(ctx context.Context, at time.Time, tags tag.List) bool
+
+// With sends a tag list to the installed loggers.
+func With(ctx context.Context, tags ...tag.Tag) {
+	at := time.Now()
+	worker.Do(func() {
+		deliver(ctx, at, tags)
+	})
+}
+
+// Print takes a message and a tag list and combines them into a single tag
+// list before delivering them to the loggers.
+func Print(ctx context.Context, message string, tags ...tag.Tagger) {
+	at := time.Now()
+	worker.Do(func() {
+		tags := append(tag.Tags(ctx, tags...), MessageTag.Of(message))
+		deliver(ctx, at, tags)
+	})
+}
+
+type errorString string
+
+// Error allows errorString to conform to the error interface.
+func (err errorString) Error() string { return string(err) }
+
+// Print takes a message and a tag list and combines them into a single tag
+// list before delivering them to the loggers.
+func Error(ctx context.Context, message string, err error, tags ...tag.Tagger) {
+	at := time.Now()
+	worker.Do(func() {
+		if err == nil {
+			err = errorString(message)
+			message = ""
+		}
+		tags := append(tag.Tags(ctx, tags...), MessageTag.Of(message), ErrorTag.Of(err))
+		deliver(ctx, at, tags)
+	})
+}
+
+func deliver(ctx context.Context, at time.Time, tags tag.List) {
+	delivered := false
+	for _, logger := range loggers {
+		if logger(ctx, at, tags) {
+			delivered = true
+		}
+	}
+	if !delivered {
+		// no logger processed the message, so we log to stderr just in case
+		Stderr(ctx, at, tags)
+	}
+}
+
+var loggers = []Logger{}
+
+func AddLogger(logger Logger) {
+	worker.Do(func() {
+		loggers = append(loggers, logger)
+	})
+}
+
+// Stderr is a logger that logs to stderr in the standard format.
+func Stderr(ctx context.Context, at time.Time, tags tag.List) bool {
+	fmt.Fprintf(os.Stderr, "%v\n", ToEntry(ctx, at, tags))
+	return true
+}

internal/lsp/telemetry/metric/metric.go

@@ -0,0 +1,412 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package metric aggregates stats into metrics that can be exported.
+package metric
+
+import (
+	"context"
+	"sort"
+
+	"golang.org/x/tools/internal/lsp/telemetry/stats"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
+	"golang.org/x/tools/internal/lsp/telemetry/worker"
+)
+
+// Handle uniquely identifies a constructed metric.
+// It can be used to detect which observed data objects belong
+// to that metric.
+type Handle struct {
+	name string
+}
+
+// Data represents a single point in the time series of a metric.
+// This provides the common interface to all metrics no matter their data
+// format.
+// To get the actual values for the metric you must type assert to a concrete
+// metric type.
+type Data interface {
+	// Handle returns the metric handle this data is for.
+	Handle() Handle
+	// Groups reports the rows that currently exist for this metric.
+	Groups() []tag.List
+}
+
+// Scalar represents the construction information for a scalar metric.
+type Scalar struct {
+	// Name is the unique name of this metric.
+	Name string
+	// Description can be used by observers to describe the metric to users.
+	Description string
+	// Keys is the set of tags that collectively describe rows of the metric.
+	Keys []interface{}
+}
+
+// HistogramInt64 represents the construction information for an int64 histogram metric.
+type HistogramInt64 struct {
+	// Name is the unique name of this metric.
+	Name string
+	// Description can be used by observers to describe the metric to users.
+	Description string
+	// Keys is the set of tags that collectively describe rows of the metric.
+	Keys []interface{}
+	// Buckets holds the inclusive upper bound of each bucket in the histogram.
+	Buckets []int64
+}
+
+// HistogramFloat64 represents the construction information for an float64 histogram metric.
+type HistogramFloat64 struct {
+	// Name is the unique name of this metric.
+	Name string
+	// Description can be used by observers to describe the metric to users.
+	Description string
+	// Keys is the set of tags that collectively describe rows of the metric.
+	Keys []interface{}
+	// Buckets holds the inclusive upper bound of each bucket in the histogram.
+	Buckets []float64
+}
+
+// Observer is the type for functions that want to observe metric values
+// as they arrive.
+// Each data point delivered to an observer is immutable and can be stored if
+// needed.
+type Observer func(Data)
+
+// CountInt64 creates a new metric based on the Scalar information that counts
+// the number of times the supplied int64 measure is set.
+// Metrics of this type will use Int64Data.
+func (info Scalar) CountInt64(measure *stats.Int64Measure) Handle {
+	data := &Int64Data{Info: &info}
+	measure.Subscribe(data.countInt64)
+	return Handle{info.Name}
+}
+
+// SumInt64 creates a new metric based on the Scalar information that sums all
+// the values recorded on the int64 measure.
+// Metrics of this type will use Int64Data.
+func (info Scalar) SumInt64(measure *stats.Int64Measure) Handle {
+	data := &Int64Data{Info: &info}
+	measure.Subscribe(data.sum)
+	_ = data
+	return Handle{info.Name}
+}
+
+// LatestInt64 creates a new metric based on the Scalar information that tracks
+// the most recent value recorded on the int64 measure.
+// Metrics of this type will use Int64Data.
+func (info Scalar) LatestInt64(measure *stats.Int64Measure) Handle {
+	data := &Int64Data{Info: &info, IsGauge: true}
+	measure.Subscribe(data.latest)
+	return Handle{info.Name}
+}
+
+// CountFloat64 creates a new metric based on the Scalar information that counts
+// the number of times the supplied float64 measure is set.
+// Metrics of this type will use Int64Data.
+func (info Scalar) CountFloat64(measure *stats.Float64Measure) Handle {
+	data := &Int64Data{Info: &info}
+	measure.Subscribe(data.countFloat64)
+	return Handle{info.Name}
+}
+
+// SumFloat64 creates a new metric based on the Scalar information that sums all
+// the values recorded on the float64 measure.
+// Metrics of this type will use Float64Data.
+func (info Scalar) SumFloat64(measure *stats.Float64Measure) Handle {
+	data := &Float64Data{Info: &info}
+	measure.Subscribe(data.sum)
+	return Handle{info.Name}
+}
+
+// LatestFloat64 creates a new metric based on the Scalar information that tracks
+// the most recent value recorded on the float64 measure.
+// Metrics of this type will use Float64Data.
+func (info Scalar) LatestFloat64(measure *stats.Float64Measure) Handle {
+	data := &Float64Data{Info: &info, IsGauge: true}
+	measure.Subscribe(data.latest)
+	return Handle{info.Name}
+}
+
+// Record creates a new metric based on the HistogramInt64 information that
+// tracks the bucketized counts of values recorded on the int64 measure.
+// Metrics of this type will use HistogramInt64Data.
+func (info HistogramInt64) Record(measure *stats.Int64Measure) Handle {
+	data := &HistogramInt64Data{Info: &info}
+	measure.Subscribe(data.record)
+	return Handle{info.Name}
+}
+
+// Record creates a new metric based on the HistogramFloat64 information that
+// tracks the bucketized counts of values recorded on the float64 measure.
+// Metrics of this type will use HistogramFloat64Data.
+func (info HistogramFloat64) Record(measure *stats.Float64Measure) Handle {
+	data := &HistogramFloat64Data{Info: &info}
+	measure.Subscribe(data.record)
+	return Handle{info.Name}
+}
+
+// Int64Data is a concrete implementation of Data for int64 scalar metrics.
+type Int64Data struct {
+	// Info holds the original consruction information.
+	Info *Scalar
+	// IsGauge is true for metrics that track values, rather than increasing over time.
+	IsGauge bool
+	// Rows holds the per group values for the metric.
+	Rows []int64
+
+	groups []tag.List
+}
+
+// Float64Data is a concrete implementation of Data for float64 scalar metrics.
+type Float64Data struct {
+	// Info holds the original consruction information.
+	Info *Scalar
+	// IsGauge is true for metrics that track values, rather than increasing over time.
+	IsGauge bool
+	// Rows holds the per group values for the metric.
+	Rows []float64
+
+	groups []tag.List
+}
+
+// HistogramInt64Data is a concrete implementation of Data for int64 histogram metrics.
+type HistogramInt64Data struct {
+	// Info holds the original consruction information.
+	Info *HistogramInt64
+	// Rows holds the per group values for the metric.
+	Rows []*HistogramInt64Row
+
+	groups []tag.List
+}
+
+// HistogramInt64Row holds the values for a single row of a HistogramInt64Data.
+type HistogramInt64Row struct {
+	// Values is the counts per bucket.
+	Values []int64
+	// Count is the total count.
+	Count int64
+	// Sum is the sum of all the values recorded.
+	Sum int64
+	// Min is the smallest recorded value.
+	Min int64
+	// Max is the largest recorded value.
+	Max int64
+}
+
+// HistogramFloat64Data is a concrete implementation of Data for float64 histogram metrics.
+type HistogramFloat64Data struct {
+	// Info holds the original consruction information.
+	Info *HistogramFloat64
+	// Rows holds the per group values for the metric.
+	Rows []*HistogramFloat64Row
+
+	groups []tag.List
+}
+
+// HistogramFloat64Row holds the values for a single row of a HistogramFloat64Data.
+type HistogramFloat64Row struct {
+	// Values is the counts per bucket.
+	Values []int64
+	// Count is the total count.
+	Count int64
+	// Sum is the sum of all the values recorded.
+	Sum float64
+	// Min is the smallest recorded value.
+	Min float64
+	// Max is the largest recorded value.
+	Max float64
+}
+
+// Name returns the name of the metric this is a handle for.
+func (h Handle) Name() string { return h.name }
+
+var observers []Observer
+
+// RegisterObservers adds a new metric observer to the system.
+// There is no way to unregister an observer.
+func RegisterObservers(e ...Observer) {
+	worker.Do(func() {
+		observers = append(e, observers...)
+	})
+}
+
+// export must only be called from inside a worker
+func export(m Data) {
+	for _, e := range observers {
+		e(m)
+	}
+}
+
+func getGroup(ctx context.Context, g *[]tag.List, keys []interface{}) (int, bool) {
+	group := tag.Get(ctx, keys...)
+	old := *g
+	index := sort.Search(len(old), func(i int) bool {
+		return !old[i].Less(group)
+	})
+	if index < len(old) && group.Equal(old[index]) {
+		// not a new group
+		return index, false
+	}
+	*g = make([]tag.List, len(old)+1)
+	copy(*g, old[:index])
+	copy((*g)[index+1:], old[index:])
+	(*g)[index] = group
+	return index, true
+}
+
+func (data *Int64Data) Handle() Handle     { return Handle{data.Info.Name} }
+func (data *Int64Data) Groups() []tag.List { return data.groups }
+
+func (data *Int64Data) modify(ctx context.Context, f func(v int64) int64) {
+	worker.Do(func() {
+		index, insert := getGroup(ctx, &data.groups, data.Info.Keys)
+		old := data.Rows
+		if insert {
+			data.Rows = make([]int64, len(old)+1)
+			copy(data.Rows, old[:index])
+			copy(data.Rows[index+1:], old[index:])
+		} else {
+			data.Rows = make([]int64, len(old))
+			copy(data.Rows, old)
+		}
+		data.Rows[index] = f(data.Rows[index])
+		frozen := *data
+		export(&frozen)
+	})
+}
+
+func (data *Int64Data) countInt64(ctx context.Context, measure *stats.Int64Measure, value int64) {
+	data.modify(ctx, func(v int64) int64 { return v + 1 })
+}
+
+func (data *Int64Data) countFloat64(ctx context.Context, measure *stats.Float64Measure, value float64) {
+	data.modify(ctx, func(v int64) int64 { return v + 1 })
+}
+
+func (data *Int64Data) sum(ctx context.Context, measure *stats.Int64Measure, value int64) {
+	data.modify(ctx, func(v int64) int64 { return v + value })
+}
+
+func (data *Int64Data) latest(ctx context.Context, measure *stats.Int64Measure, value int64) {
+	data.modify(ctx, func(v int64) int64 { return value })
+}
+
+func (data *Float64Data) Handle() Handle     { return Handle{data.Info.Name} }
+func (data *Float64Data) Groups() []tag.List { return data.groups }
+
+func (data *Float64Data) modify(ctx context.Context, f func(v float64) float64) {
+	worker.Do(func() {
+		index, insert := getGroup(ctx, &data.groups, data.Info.Keys)
+		old := data.Rows
+		if insert {
+			data.Rows = make([]float64, len(old)+1)
+			copy(data.Rows, old[:index])
+			copy(data.Rows[index+1:], old[index:])
+		} else {
+			data.Rows = make([]float64, len(old))
+			copy(data.Rows, old)
+		}
+		data.Rows[index] = f(data.Rows[index])
+		frozen := *data
+		export(&frozen)
+	})
+}
+
+func (data *Float64Data) sum(ctx context.Context, measure *stats.Float64Measure, value float64) {
+	data.modify(ctx, func(v float64) float64 { return v + value })
+}
+
+func (data *Float64Data) latest(ctx context.Context, measure *stats.Float64Measure, value float64) {
+	data.modify(ctx, func(v float64) float64 { return value })
+}
+
+func (data *HistogramInt64Data) Handle() Handle     { return Handle{data.Info.Name} }
+func (data *HistogramInt64Data) Groups() []tag.List { return data.groups }
+
+func (data *HistogramInt64Data) modify(ctx context.Context, f func(v *HistogramInt64Row)) {
+	worker.Do(func() {
+		index, insert := getGroup(ctx, &data.groups, data.Info.Keys)
+		old := data.Rows
+		var v HistogramInt64Row
+		if insert {
+			data.Rows = make([]*HistogramInt64Row, len(old)+1)
+			copy(data.Rows, old[:index])
+			copy(data.Rows[index+1:], old[index:])
+		} else {
+			data.Rows = make([]*HistogramInt64Row, len(old))
+			copy(data.Rows, old)
+			v = *data.Rows[index]
+		}
+		oldValues := v.Values
+		v.Values = make([]int64, len(data.Info.Buckets))
+		copy(v.Values, oldValues)
+		f(&v)
+		data.Rows[index] = &v
+		frozen := *data
+		export(&frozen)
+	})
+}
+
+func (data *HistogramInt64Data) record(ctx context.Context, measure *stats.Int64Measure, value int64) {
+	data.modify(ctx, func(v *HistogramInt64Row) {
+		v.Sum += value
+		if v.Min > value || v.Count == 0 {
+			v.Min = value
+		}
+		if v.Max < value || v.Count == 0 {
+			v.Max = value
+		}
+		v.Count++
+		for i, b := range data.Info.Buckets {
+			if value <= b {
+				v.Values[i]++
+			}
+		}
+	})
+}
+
+func (data *HistogramFloat64Data) Handle() Handle     { return Handle{data.Info.Name} }
+func (data *HistogramFloat64Data) Groups() []tag.List { return data.groups }
+
+func (data *HistogramFloat64Data) modify(ctx context.Context, f func(v *HistogramFloat64Row)) {
+	worker.Do(func() {
+		index, insert := getGroup(ctx, &data.groups, data.Info.Keys)
+		old := data.Rows
+		var v HistogramFloat64Row
+		if insert {
+			data.Rows = make([]*HistogramFloat64Row, len(old)+1)
+			copy(data.Rows, old[:index])
+			copy(data.Rows[index+1:], old[index:])
+		} else {
+			data.Rows = make([]*HistogramFloat64Row, len(old))
+			copy(data.Rows, old)
+			v = *data.Rows[index]
+		}
+		oldValues := v.Values
+		v.Values = make([]int64, len(data.Info.Buckets))
+		copy(v.Values, oldValues)
+		f(&v)
+		data.Rows[index] = &v
+		frozen := *data
+		export(&frozen)
+	})
+}
+
+func (data *HistogramFloat64Data) record(ctx context.Context, measure *stats.Float64Measure, value float64) {
+	data.modify(ctx, func(v *HistogramFloat64Row) {
+		v.Sum += value
+		if v.Min > value || v.Count == 0 {
+			v.Min = value
+		}
+		if v.Max < value || v.Count == 0 {
+			v.Max = value
+		}
+		v.Count++
+		for i, b := range data.Info.Buckets {
+			if value <= b {
+				v.Values[i]++
+			}
+		}
+	})
+}

internal/lsp/telemetry/ocagent/ocagent.go

@@ -0,0 +1,242 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package ocagent adds the ability to export all telemetry to an ocagent.
+// This keeps the complie time dependencies to zero and allows the agent to
+// have the exporters needed for telemetry aggregation and viewing systems.
+package ocagent
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"os"
+	"time"
+
+	"golang.org/x/tools/internal/lsp/telemetry/log"
+	"golang.org/x/tools/internal/lsp/telemetry/metric"
+	"golang.org/x/tools/internal/lsp/telemetry/ocagent/wire"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
+	"golang.org/x/tools/internal/lsp/telemetry/trace"
+	"golang.org/x/tools/internal/lsp/telemetry/worker"
+)
+
+const DefaultAddress = "http://localhost:55678"
+const exportRate = 2 * time.Second
+
+type exporter struct {
+	address string
+	node    *wire.Node
+	spans   []*wire.Span
+	metrics []*wire.Metric
+}
+
+func Export(service, address string) {
+	if address == "off" {
+		return
+	}
+	hostname, _ := os.Hostname()
+	exporter := &exporter{
+		address: address,
+		node: &wire.Node{
+			Identifier: &wire.ProcessIdentifier{
+				HostName:       hostname,
+				Pid:            uint32(os.Getpid()),
+				StartTimestamp: convertTimestamp(time.Now()),
+			},
+			LibraryInfo: &wire.LibraryInfo{
+				Language:           wire.LanguageGo,
+				ExporterVersion:    "0.0.1",
+				CoreLibraryVersion: "x/tools",
+			},
+			ServiceInfo: &wire.ServiceInfo{
+				Name: service,
+			},
+		},
+	}
+	if exporter.address == "" {
+		exporter.address = DefaultAddress
+	}
+	//TODO: add metrics once the ocagent json metric interface works
+	trace.RegisterObservers(exporter.observeTrace)
+	go func() {
+		for _ = range time.Tick(exportRate) {
+			worker.Do(func() {
+				exporter.flush()
+			})
+		}
+	}()
+}
+
+func (e *exporter) observeTrace(span *trace.Span) {
+	// is this a completed span?
+	if span.Finish.IsZero() {
+		return
+	}
+	e.spans = append(e.spans, convertSpan(span))
+}
+
+func (e *exporter) observeMetric(data metric.Data) {
+	e.metrics = append(e.metrics, convertMetric(data))
+}
+
+func (e *exporter) flush() {
+	spans := e.spans
+	e.spans = nil
+	metrics := e.metrics
+	e.metrics = nil
+
+	if len(spans) > 0 {
+		e.send("/v1/trace", &wire.ExportTraceServiceRequest{
+			Node:  e.node,
+			Spans: spans,
+			//TODO: Resource?
+		})
+	}
+	if len(metrics) > 0 {
+		e.send("/v1/metrics", &wire.ExportMetricsServiceRequest{
+			Node:    e.node,
+			Metrics: metrics,
+			//TODO: Resource?
+		})
+	}
+}
+
+func (e *exporter) send(endpoint string, message interface{}) {
+	blob, err := json.Marshal(message)
+	if err != nil {
+		errorInExport("ocagent failed to marshal message for %v: %v", endpoint, err)
+		return
+	}
+	uri := e.address + endpoint
+	req, err := http.NewRequest("POST", uri, bytes.NewReader(blob))
+	if err != nil {
+		errorInExport("ocagent failed to build request for %v: %v", uri, err)
+		return
+	}
+	req.Header.Set("Content-Type", "application/json")
+	res, err := http.DefaultClient.Do(req)
+	if err != nil {
+		errorInExport("ocagent failed to send message: %v \n", err)
+		return
+	}
+	res.Body.Close()
+	return
+}
+
+func errorInExport(message string, args ...interface{}) {
+	// This function is useful when debugging the exporter, but in general we
+	// want to just drop any export
+}
+
+func convertTimestamp(t time.Time) wire.Timestamp {
+	return t.Format(time.RFC3339Nano)
+}
+
+func toTruncatableString(s string) *wire.TruncatableString {
+	return &wire.TruncatableString{Value: s}
+}
+
+func convertSpan(span *trace.Span) *wire.Span {
+	result := &wire.Span{
+		TraceId:                 span.TraceID[:],
+		SpanId:                  span.SpanID[:],
+		TraceState:              nil, //TODO?
+		ParentSpanId:            span.ParentID[:],
+		Name:                    toTruncatableString(span.Name),
+		Kind:                    wire.UnspecifiedSpanKind,
+		StartTime:               convertTimestamp(span.Start),
+		EndTime:                 convertTimestamp(span.Finish),
+		Attributes:              convertAttributes(span.Tags),
+		TimeEvents:              convertEvents(span.Events),
+		SameProcessAsParentSpan: true,
+		//TODO: StackTrace?
+		//TODO: Links?
+		//TODO: Status?
+		//TODO: Resource?
+	}
+	return result
+}
+
+func convertMetric(data metric.Data) *wire.Metric {
+	return nil //TODO:
+}
+
+func convertAttributes(tags tag.List) *wire.Attributes {
+	if len(tags) == 0 {
+		return nil
+	}
+	attributes := make(map[string]wire.Attribute)
+	for _, tag := range tags {
+		attributes[fmt.Sprint(tag.Key)] = convertAttribute(tag.Value)
+	}
+	return &wire.Attributes{AttributeMap: attributes}
+}
+
+func convertAttribute(v interface{}) wire.Attribute {
+	switch v := v.(type) {
+	case int8:
+		return wire.IntAttribute{IntValue: int64(v)}
+	case int16:
+		return wire.IntAttribute{IntValue: int64(v)}
+	case int32:
+		return wire.IntAttribute{IntValue: int64(v)}
+	case int64:
+		return wire.IntAttribute{IntValue: v}
+	case uint8:
+		return wire.IntAttribute{IntValue: int64(v)}
+	case uint16:
+		return wire.IntAttribute{IntValue: int64(v)}
+	case uint32:
+		return wire.IntAttribute{IntValue: int64(v)}
+	case uint64:
+		return wire.IntAttribute{IntValue: int64(v)}
+	case uint:
+		return wire.IntAttribute{IntValue: int64(v)}
+	case float32:
+		return wire.DoubleAttribute{DoubleValue: float64(v)}
+	case float64:
+		return wire.DoubleAttribute{DoubleValue: v}
+	case bool:
+		return wire.BoolAttribute{BoolValue: v}
+	case string:
+		return wire.StringAttribute{StringValue: toTruncatableString(v)}
+	default:
+		return wire.StringAttribute{StringValue: toTruncatableString(fmt.Sprint(v))}
+	}
+}
+
+func convertEvents(events []trace.Event) *wire.TimeEvents {
+	//TODO: MessageEvents?
+	result := make([]wire.TimeEvent, len(events))
+	for i, event := range events {
+		result[i] = convertEvent(event)
+	}
+	return &wire.TimeEvents{TimeEvent: result}
+}
+
+func convertEvent(event trace.Event) wire.TimeEvent {
+	return wire.TimeEvent{
+		Time:       convertTimestamp(event.Time),
+		Annotation: convertAnnotation(event.Tags),
+	}
+}
+
+func convertAnnotation(tags tag.List) *wire.Annotation {
+	entry := log.ToEntry(nil, time.Time{}, tags)
+	description := entry.Message
+	if description == "" && entry.Error != nil {
+		description = entry.Error.Error()
+		entry.Error = nil
+	}
+	tags = entry.Tags
+	if entry.Error != nil {
+		tags = append(tags, tag.Of("Error", entry.Error))
+	}
+	return &wire.Annotation{
+		Description: toTruncatableString(description),
+		Attributes:  convertAttributes(tags),
+	}
+}

internal/lsp/telemetry/ocagent/wire/common.go

@@ -0,0 +1,101 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package wire
+
+// This file holds common ocagent types
+
+type Node struct {
+	Identifier  *ProcessIdentifier `json:"identifier,omitempty"`
+	LibraryInfo *LibraryInfo       `json:"library_info,omitempty"`
+	ServiceInfo *ServiceInfo       `json:"service_info,omitempty"`
+	Attributes  map[string]string  `json:"attributes,omitempty"`
+}
+
+type Resource struct {
+	Type   string            `json:"type,omitempty"`
+	Labels map[string]string `json:"labels,omitempty"`
+}
+
+type TruncatableString struct {
+	Value              string `json:"value,omitempty"`
+	TruncatedByteCount int32  `json:"truncated_byte_count,omitempty"`
+}
+
+type Attributes struct {
+	AttributeMap           map[string]Attribute `json:"attributeMap,omitempty"`
+	DroppedAttributesCount int32                `json:"dropped_attributes_count,omitempty"`
+}
+
+type StringAttribute struct {
+	StringValue *TruncatableString `json:"stringValue,omitempty"`
+}
+
+type IntAttribute struct {
+	IntValue int64 `json:"intValue,omitempty"`
+}
+
+type BoolAttribute struct {
+	BoolValue bool `json:"boolValue,omitempty"`
+}
+
+type DoubleAttribute struct {
+	DoubleValue float64 `json:"doubleValue,omitempty"`
+}
+
+type Attribute interface {
+	tagAttribute()
+}
+
+func (StringAttribute) tagAttribute() {}
+func (IntAttribute) tagAttribute()    {}
+func (BoolAttribute) tagAttribute()   {}
+func (DoubleAttribute) tagAttribute() {}
+
+type StackTrace struct {
+	StackFrames      *StackFrames `json:"stack_frames,omitempty"`
+	StackTraceHashId uint64       `json:"stack_trace_hash_id,omitempty"`
+}
+
+type StackFrames struct {
+	Frame              []*StackFrame `json:"frame,omitempty"`
+	DroppedFramesCount int32         `json:"dropped_frames_count,omitempty"`
+}
+
+type StackFrame struct {
+	FunctionName         *TruncatableString `json:"function_name,omitempty"`
+	OriginalFunctionName *TruncatableString `json:"original_function_name,omitempty"`
+	FileName             *TruncatableString `json:"file_name,omitempty"`
+	LineNumber           int64              `json:"line_number,omitempty"`
+	ColumnNumber         int64              `json:"column_number,omitempty"`
+	LoadModule           *Module            `json:"load_module,omitempty"`
+	SourceVersion        *TruncatableString `json:"source_version,omitempty"`
+}
+
+type Module struct {
+	Module  *TruncatableString `json:"module,omitempty"`
+	BuildId *TruncatableString `json:"build_id,omitempty"`
+}
+
+type ProcessIdentifier struct {
+	HostName       string    `json:"host_name,omitempty"`
+	Pid            uint32    `json:"pid,omitempty"`
+	StartTimestamp Timestamp `json:"start_timestamp,omitempty"`
+}
+
+type LibraryInfo struct {
+	Language           Language `json:"language,omitempty"`
+	ExporterVersion    string   `json:"exporter_version,omitempty"`
+	CoreLibraryVersion string   `json:"core_library_version,omitempty"`
+}
+
+type Language int32
+
+const (
+	LanguageGo Language = 4
+)
+
+type ServiceInfo struct {
+	Name string `json:"name,omitempty"`
+}

internal/lsp/telemetry/ocagent/wire/core.go

@@ -0,0 +1,17 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package wire
+
+// This file contains type that match core proto types
+
+type Timestamp = string
+
+type Int64Value struct {
+	Value int64 `json:"value,omitempty"`
+}
+
+type DoubleValue struct {
+	Value float64 `json:"value,omitempty"`
+}

internal/lsp/telemetry/ocagent/wire/metrics.go

@@ -0,0 +1,130 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package wire
+
+type ExportMetricsServiceRequest struct {
+	Node     *Node     `json:"node,omitempty"`
+	Metrics  []*Metric `json:"metrics,omitempty"`
+	Resource *Resource `json:"resource,omitempty"`
+}
+
+type Metric struct {
+	MetricDescriptor *MetricDescriptor `json:"metric_descriptor,omitempty"`
+	Timeseries       []*TimeSeries     `json:"timeseries,omitempty"`
+	Resource         *Resource         `json:"resource,omitempty"`
+}
+
+type MetricDescriptor struct {
+	Name        string                `json:"name,omitempty"`
+	Description string                `json:"description,omitempty"`
+	Unit        string                `json:"unit,omitempty"`
+	Type        MetricDescriptor_Type `json:"type,omitempty"`
+	LabelKeys   []*LabelKey           `json:"label_keys,omitempty"`
+}
+
+type MetricDescriptor_Type int32
+
+const (
+	MetricDescriptor_UNSPECIFIED             MetricDescriptor_Type = 0
+	MetricDescriptor_GAUGE_INT64             MetricDescriptor_Type = 1
+	MetricDescriptor_GAUGE_DOUBLE            MetricDescriptor_Type = 2
+	MetricDescriptor_GAUGE_DISTRIBUTION      MetricDescriptor_Type = 3
+	MetricDescriptor_CUMULATIVE_INT64        MetricDescriptor_Type = 4
+	MetricDescriptor_CUMULATIVE_DOUBLE       MetricDescriptor_Type = 5
+	MetricDescriptor_CUMULATIVE_DISTRIBUTION MetricDescriptor_Type = 6
+	MetricDescriptor_SUMMARY                 MetricDescriptor_Type = 7
+)
+
+type LabelKey struct {
+	Key         string `json:"key,omitempty"`
+	Description string `json:"description,omitempty"`
+}
+
+type TimeSeries struct {
+	StartTimestamp *Timestamp    `json:"start_timestamp,omitempty"`
+	LabelValues    []*LabelValue `json:"label_values,omitempty"`
+	Points         []*Point      `json:"points,omitempty"`
+}
+
+type LabelValue struct {
+	Value    string `json:"value,omitempty"`
+	HasValue bool   `json:"has_value,omitempty"`
+}
+
+type Point struct {
+	Timestamp *Timestamp `json:"timestamp,omitempty"`
+	Value     PointValue `json:"value,omitempty"`
+}
+
+type PointInt64Value struct {
+	Int64Value int64 `json:"int64Value,omitempty"`
+}
+
+type PointDoubleValue struct {
+	DoubleValue float64 `json:"doubleValue,omitempty"`
+}
+
+type PointDistributionValue struct {
+	DistributionValue *DistributionValue `json:"distributionValue,omitempty"`
+}
+
+type PointSummaryValue struct {
+	SummaryValue *SummaryValue `json:"summaryValue,omitempty"`
+}
+
+type PointValue interface {
+	tagPointValue()
+}
+
+func (PointInt64Value) tagPointValue()        {}
+func (PointDoubleValue) tagPointValue()       {}
+func (PointDistributionValue) tagPointValue() {}
+func (PointSummaryValue) tagPointValue()      {}
+
+type DistributionValue struct {
+	Count                 int64         `json:"count,omitempty"`
+	Sum                   float64       `json:"sum,omitempty"`
+	SumOfSquaredDeviation float64       `json:"sum_of_squared_deviation,omitempty"`
+	BucketOptions         BucketOptions `json:"bucket_options,omitempty"`
+	Buckets               []*Bucket     `json:"buckets,omitempty"`
+}
+
+type BucketOptionsExplicit struct {
+	Bounds []float64 `json:"bounds,omitempty"`
+}
+
+type BucketOptions interface {
+	tagBucketOptions()
+}
+
+func (BucketOptionsExplicit) tagBucketOptions() {}
+
+type Bucket struct {
+	Count    int64     `json:"count,omitempty"`
+	Exemplar *Exemplar `json:"exemplar,omitempty"`
+}
+
+type Exemplar struct {
+	Value       float64           `json:"value,omitempty"`
+	Timestamp   *Timestamp        `json:"timestamp,omitempty"`
+	Attachments map[string]string `json:"attachments,omitempty"`
+}
+
+type SummaryValue struct {
+	Count    *Int64Value  `json:"count,omitempty"`
+	Sum      *DoubleValue `json:"sum,omitempty"`
+	Snapshot *Snapshot    `json:"snapshot,omitempty"`
+}
+
+type Snapshot struct {
+	Count            *Int64Value                  `json:"count,omitempty"`
+	Sum              *DoubleValue                 `json:"sum,omitempty"`
+	PercentileValues []*SnapshotValueAtPercentile `json:"percentile_values,omitempty"`
+}
+
+type SnapshotValueAtPercentile struct {
+	Percentile float64 `json:"percentile,omitempty"`
+	Value      float64 `json:"value,omitempty"`
+}

internal/lsp/telemetry/ocagent/wire/trace.go

@@ -0,0 +1,112 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package wire
+
+type ExportTraceServiceRequest struct {
+	Node     *Node     `json:"node,omitempty"`
+	Spans    []*Span   `json:"spans,omitempty"`
+	Resource *Resource `json:"resource,omitempty"`
+}
+
+type Span struct {
+	TraceId                 []byte             `json:"trace_id,omitempty"`
+	SpanId                  []byte             `json:"span_id,omitempty"`
+	TraceState              *TraceState        `json:"tracestate,omitempty"`
+	ParentSpanId            []byte             `json:"parent_span_id,omitempty"`
+	Name                    *TruncatableString `json:"name,omitempty"`
+	Kind                    SpanKind           `json:"kind,omitempty"`
+	StartTime               Timestamp          `json:"start_time,omitempty"`
+	EndTime                 Timestamp          `json:"end_time,omitempty"`
+	Attributes              *Attributes        `json:"attributes,omitempty"`
+	StackTrace              *StackTrace        `json:"stack_trace,omitempty"`
+	TimeEvents              *TimeEvents        `json:"time_events,omitempty"`
+	Links                   *Links             `json:"links,omitempty"`
+	Status                  *Status            `json:"status,omitempty"`
+	Resource                *Resource          `json:"resource,omitempty"`
+	SameProcessAsParentSpan bool               `json:"same_process_as_parent_span,omitempty"`
+	ChildSpanCount          bool               `json:"child_span_count,omitempty"`
+}
+
+type TraceState struct {
+	Entries []*TraceStateEntry `json:"entries,omitempty"`
+}
+
+type TraceStateEntry struct {
+	Key   string `json:"key,omitempty"`
+	Value string `json:"value,omitempty"`
+}
+
+type SpanKind int32
+
+const (
+	UnspecifiedSpanKind SpanKind = 0
+	ServerSpanKind      SpanKind = 1
+	ClientSpanKind      SpanKind = 2
+)
+
+type TimeEvents struct {
+	TimeEvent                 []TimeEvent `json:"timeEvent,omitempty"`
+	DroppedAnnotationsCount   int32       `json:"dropped_annotations_count,omitempty"`
+	DroppedMessageEventsCount int32       `json:"dropped_message_events_count,omitempty"`
+}
+
+type TimeEvent struct {
+	Time         Timestamp     `json:"time,omitempty"`
+	MessageEvent *MessageEvent `json:"messageEvent,omitempty"`
+	Annotation   *Annotation   `json:"annotation,omitempty"`
+}
+
+type Annotation struct {
+	Description *TruncatableString `json:"description,omitempty"`
+	Attributes  *Attributes        `json:"attributes,omitempty"`
+}
+
+type MessageEvent struct {
+	Type             MessageEventType `json:"type,omitempty"`
+	Id               uint64           `json:"id,omitempty"`
+	UncompressedSize uint64           `json:"uncompressed_size,omitempty"`
+	CompressedSize   uint64           `json:"compressed_size,omitempty"`
+}
+
+type MessageEventType int32
+
+const (
+	UnspecifiedMessageEvent MessageEventType = iota
+	SentMessageEvent
+	ReceivedMessageEvent
+)
+
+type TimeEventValue interface {
+	tagTimeEventValue()
+}
+
+func (Annotation) tagTimeEventValue()   {}
+func (MessageEvent) tagTimeEventValue() {}
+
+type Links struct {
+	Link              []*Link `json:"link,omitempty"`
+	DroppedLinksCount int32   `json:"dropped_links_count,omitempty"`
+}
+
+type Link struct {
+	TraceId    []byte      `json:"trace_id,omitempty"`
+	SpanId     []byte      `json:"span_id,omitempty"`
+	Type       LinkType    `json:"type,omitempty"`
+	Attributes *Attributes `json:"attributes,omitempty"`
+	TraceState *TraceState `json:"tracestate,omitempty"`
+}
+
+type LinkType int32
+
+const (
+	UnspecifiedLinkType LinkType = 0
+	ChildLinkType       LinkType = 1
+	ParentLinkType      LinkType = 2
+)
+
+type Status struct {
+	Code    int32  `json:"code,omitempty"`
+	Message string `json:"message,omitempty"`
+}

internal/lsp/telemetry/tag/key.go

@@ -17,12 +17,24 @@ import (
 // those values in the context.
 type Key string
 
+// Of returns a Tag for a key and value.
+// This is a trivial helper that makes common logging easier to read.
+func Of(key interface{}, value interface{}) Tag {
+	return Tag{Key: key, Value: value}
+}
+
 // Of creates a new Tag with this key and the supplied value.
 // You can use this when building a tag list.
 func (k Key) Of(v interface{}) Tag {
 	return Tag{Key: k, Value: v}
 }
 
+// Tag can be used to get a tag for the key from a context.
+// It makes Key conform to the Tagger interface.
+func (k Key) Tag(ctx context.Context) Tag {
+	return Tag{Key: k, Value: ctx.Value(k)}
+}
+
 // With applies sets this key to the supplied value on the context and
 // returns the new context generated.
 // It uses the With package level function so that observers are also notified.

internal/lsp/telemetry/tag/tag.go

@@ -25,6 +25,14 @@ type Tag struct {
 	Value interface{}
 }
 
+// Tagger is the interface to somthing that returns a Tag given a context.
+// Both Tag itself and Key support this interface, allowing methods that can
+// take either (and other implementations as well)
+type Tagger interface {
+	// Tag returns a Tag potentially using information from the Context.
+	Tag(context.Context) Tag
+}
+
 // List is a way of passing around a collection of key value pairs.
 // It is an alternative to the less efficient and unordered method of using
 // maps.
@@ -64,6 +72,15 @@ func Get(ctx context.Context, keys ...interface{}) List {
 	return tags
 }
 
+// Tags collects a list of tags for the taggers from the context.
+func Tags(ctx context.Context, taggers ...Tagger) List {
+	tags := make(List, len(taggers))
+	for i, t := range taggers {
+		tags[i] = t.Tag(ctx)
+	}
+	return tags
+}
+
 var observers = []Observer{}
 
 // Observe adds a new tag observer to the registered set.
@@ -80,6 +97,12 @@ func (t Tag) Format(f fmt.State, r rune) {
 	fmt.Fprintf(f, `%v="%v"`, t.Key, t.Value)
 }
 
+// Get returns the tag unmodified.
+// It makes Key conform to the Tagger interface.
+func (t Tag) Tag(ctx context.Context) Tag {
+	return t
+}
+
 // Get will get a single key's value from the list.
 func (l List) Get(k interface{}) interface{} {
 	for _, t := range l {

internal/lsp/telemetry/trace/id.go

@@ -0,0 +1,72 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package tag adds support for telemetry tracins.
+package trace
+
+import (
+	crand "crypto/rand"
+	"encoding/binary"
+	"fmt"
+	"math/rand"
+	"sync"
+	"sync/atomic"
+)
+
+type TraceID [16]byte
+type SpanID [8]byte
+
+func (t TraceID) String() string {
+	return fmt.Sprintf("%02x", t[:])
+}
+
+func (s SpanID) String() string {
+	return fmt.Sprintf("%02x", s[:])
+}
+
+func (s SpanID) IsValid() bool {
+	return s != SpanID{}
+}
+
+var (
+	generationMu sync.Mutex
+	nextSpanID   uint64
+	spanIDInc    uint64
+
+	traceIDAdd  [2]uint64
+	traceIDRand *rand.Rand
+)
+
+func initGenerator() {
+	var rngSeed int64
+	for _, p := range []interface{}{
+		&rngSeed, &traceIDAdd, &nextSpanID, &spanIDInc,
+	} {
+		binary.Read(crand.Reader, binary.LittleEndian, p)
+	}
+	traceIDRand = rand.New(rand.NewSource(rngSeed))
+	spanIDInc |= 1
+}
+
+func newTraceID() TraceID {
+	generationMu.Lock()
+	defer generationMu.Unlock()
+	if traceIDRand == nil {
+		initGenerator()
+	}
+	var tid [16]byte
+	binary.LittleEndian.PutUint64(tid[0:8], traceIDRand.Uint64()+traceIDAdd[0])
+	binary.LittleEndian.PutUint64(tid[8:16], traceIDRand.Uint64()+traceIDAdd[1])
+	return tid
+}
+
+func newSpanID() SpanID {
+	var id uint64
+	for id == 0 {
+		id = atomic.AddUint64(&nextSpanID, spanIDInc)
+	}
+	var sid [8]byte
+	binary.LittleEndian.PutUint64(sid[:], id)
+	return sid
+}

internal/lsp/telemetry/trace/trace.go

@@ -2,59 +2,139 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package tag adds support for telemetry tracins.
+// Package trace adds support for telemetry tracing.
 package trace
 
 import (
 	"context"
+	"fmt"
+	"time"
+
+	"golang.org/x/tools/internal/lsp/telemetry/log"
+	"golang.org/x/tools/internal/lsp/telemetry/tag"
+	"golang.org/x/tools/internal/lsp/telemetry/worker"
 )
 
-type Span interface {
-	AddAttributes(attributes ...Attribute)
-	AddMessageReceiveEvent(messageID, uncompressedByteSize, compressedByteSize int64)
-	AddMessageSendEvent(messageID, uncompressedByteSize, compressedByteSize int64)
-	Annotate(attributes []Attribute, str string)
-	Annotatef(attributes []Attribute, format string, a ...interface{})
-	End()
-	IsRecordingEvents() bool
-	SetName(name string)
-	SetStatus(status Status)
+type Span struct {
+	Name     string
+	TraceID  TraceID
+	SpanID   SpanID
+	ParentID SpanID
+	Start    time.Time
+	Finish   time.Time
+	Tags     tag.List
+	Events   []Event
+
+	ready bool
 }
 
-type Attribute interface{}
-
-type Status struct {
-	Code    int32
-	Message string
+type Event struct {
+	Time time.Time
+	Tags tag.List
 }
 
-type nullSpan struct{}
+type Observer func(*Span)
 
-func (nullSpan) AddAttributes(attributes ...Attribute)                                            {}
-func (nullSpan) AddMessageReceiveEvent(messageID, uncompressedByteSize, compressedByteSize int64) {}
-func (nullSpan) AddMessageSendEvent(messageID, uncompressedByteSize, compressedByteSize int64)    {}
-func (nullSpan) Annotate(attributes []Attribute, str string)                                      {}
-func (nullSpan) Annotatef(attributes []Attribute, format string, a ...interface{})                {}
-func (nullSpan) End()                                                                             {}
-func (nullSpan) IsRecordingEvents() bool                                                          { return false }
-func (nullSpan) SetName(name string)                                                              {}
-func (nullSpan) SetStatus(status Status)                                                          {}
+func RegisterObservers(o ...Observer) {
+	worker.Do(func() {
+		if !registered {
+			registered = true
+			tag.Observe(tagObserver)
+			log.AddLogger(logger)
+		}
+		observers = append(observers, o...)
+	})
+}
+
+func StartSpan(ctx context.Context, name string, tags ...tag.Tag) (context.Context, func()) {
+	span := &Span{
+		Name:  name,
+		Start: time.Now(),
+	}
+	if parent := fromContext(ctx); parent != nil {
+		span.TraceID = parent.TraceID
+		span.ParentID = parent.SpanID
+	} else {
+		span.TraceID = newTraceID()
+	}
+	span.SpanID = newSpanID()
+	ctx = context.WithValue(ctx, contextKey, span)
+	if len(tags) > 0 {
+		ctx = tag.With(ctx, tags...)
+	}
+	worker.Do(func() {
+		span.ready = true
+		for _, o := range observers {
+			o(span)
+		}
+	})
+	return ctx, span.close
+}
+
+func (s *Span) close() {
+	now := time.Now()
+	worker.Do(func() {
+		s.Finish = now
+		for _, o := range observers {
+			o(s)
+		}
+	})
+}
+
+func (s *Span) Format(f fmt.State, r rune) {
+	fmt.Fprintf(f, "%v %v:%v", s.Name, s.TraceID, s.SpanID)
+	if s.ParentID.IsValid() {
+		fmt.Fprintf(f, "[%v]", s.ParentID)
+	}
+	fmt.Fprintf(f, " %v->%v", s.Start, s.Finish)
+}
+
+type contextKeyType int
+
+var contextKey contextKeyType
+
+func fromContext(ctx context.Context) *Span {
+	v := ctx.Value(contextKey)
+	if v == nil {
+		return nil
+	}
+	return v.(*Span)
+}
 
 var (
-	FromContext = func(ctx context.Context) Span { return nullSpan{} }
-	NewContext  = func(ctx context.Context, span Span) context.Context { return ctx }
-	StartSpan   = func(ctx context.Context, name string, options ...interface{}) (context.Context, Span) {
-		return ctx, nullSpan{}
-	}
-	BoolAttribute    = func(key string, value bool) Attribute { return nil }
-	Float64Attribute = func(key string, value float64) Attribute { return nil }
-	Int64Attribute   = func(key string, value int64) Attribute { return nil }
-	StringAttribute  = func(key string, value string) Attribute { return nil }
-	WithSpanKind     = func(spanKind int) interface{} { return nil }
+	observers  []Observer
+	registered bool
 )
 
-const (
-	SpanKindUnspecified = iota
-	SpanKindServer
-	SpanKindClient
-)
+func tagObserver(ctx context.Context, at time.Time, tags tag.List) {
+	span := fromContext(ctx)
+	if span == nil {
+		return
+	}
+	if !span.ready {
+		span.Tags = append(span.Tags, tags...)
+		return
+	}
+	span.Events = append(span.Events, Event{
+		Time: at,
+		Tags: tags,
+	})
+}
+
+func logger(ctx context.Context, at time.Time, tags tag.List) bool {
+	span := fromContext(ctx)
+	if span == nil {
+		return false
+	}
+	span.Events = append(span.Events, Event{
+		Time: at,
+		Tags: tags,
+	})
+	return false
+}
+
+// Detach returns a context without an associated span.
+// This allows the creation of spans that are not children of the current span.
+func Detach(ctx context.Context) context.Context {
+	return context.WithValue(ctx, contextKey, nil)
+}

internal/lsp/telemetry/worker/worker.go

@@ -6,8 +6,13 @@
 // to work cooperatively and efficiently.
 package worker
 
+import (
+	"fmt"
+	"os"
+)
+
 var (
-	workQueue = make(chan func(), 100)
+	workQueue = make(chan func(), 1000)
 )
 
 func init() {
@@ -26,5 +31,10 @@ func init() {
 // This function may block, but in general it will return very quickly and
 // before the task has been run.
 func Do(task func()) {
-	workQueue <- task
+	select {
+	case workQueue <- task:
+	default:
+		fmt.Fprint(os.Stderr, "work queue is full\n")
+		workQueue <- task
+	}
 }