dashboard: split key handler into key package, add TimeKey to cache

LGTM=dsymonds
R=golang-codereviews, dsymonds
CC=golang-codereviews
https://golang.org/cl/104780044

dashboard/app/build/handler.go

@@ -20,6 +20,7 @@ import (
 	"appengine/datastore"
 
 	"cache"
+	"key"
 )
 
 const commitsPerPage = 30
@@ -789,12 +790,12 @@ func validKey(c appengine.Context, key, builder string) bool {
 	return isMasterKey(c, key) || key == builderKey(c, builder)
 }
 
-func isMasterKey(c appengine.Context, key string) bool {
+func isMasterKey(c appengine.Context, k string) bool {
-	return appengine.IsDevAppServer() || key == secretKey(c)
+	return appengine.IsDevAppServer() || k == key.Secret(c)
 }
 
 func builderKey(c appengine.Context, builder string) string {
-	h := hmac.New(md5.New, []byte(secretKey(c)))
+	h := hmac.New(md5.New, []byte(key.Secret(c)))
 	h.Write([]byte(builder))
 	return fmt.Sprintf("%x", h.Sum(nil))
 }

dashboard/app/build/init.go

@@ -12,7 +12,9 @@ import (
 
 	"appengine"
 	"appengine/datastore"
+
 	"cache"
+	"key"
 )
 
 func initHandler(w http.ResponseWriter, r *http.Request) {
@@ -38,7 +40,7 @@ func initHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Create secret key.
-	secretKey(c)
+	key.Secret(c)
 
 	fmt.Fprint(w, "OK")
 }

dashboard/app/cache/cache.go

@@ -15,9 +15,11 @@ import (
 	"appengine/memcache"
 )
 
+// TimeKey specifies the memcache entity that keeps the logical datastore time.
+var TimeKey = "cachetime"
+
 const (
 	nocache = "nocache"
-	timeKey = "cachetime"
 	expiry  = 600 // 10 minutes
 )
 
@@ -25,7 +27,7 @@ func newTime() uint64 { return uint64(time.Now().Unix()) << 32 }
 
 // Now returns the current logical datastore time to use for cache lookups.
 func Now(c appengine.Context) uint64 {
-	t, err := memcache.Increment(c, timeKey, 0, newTime())
+	t, err := memcache.Increment(c, TimeKey, 0, newTime())
 	if err != nil {
 		c.Errorf("cache.Now: %v", err)
 		return 0
@@ -36,7 +38,7 @@ func Now(c appengine.Context) uint64 {
 // Tick sets the current logical datastore time to a never-before-used time
 // and returns that time. It should be called to invalidate the cache.
 func Tick(c appengine.Context) uint64 {
-	t, err := memcache.Increment(c, timeKey, 1, newTime())
+	t, err := memcache.Increment(c, TimeKey, 1, newTime())
 	if err != nil {
 		c.Errorf("cache.Tick: %v", err)
 		return 0

dashboard/app/key/key.go

@@ -4,7 +4,7 @@
 
 // +build appengine
 
-package build
+package key
 
 import (
 	"sync"
@@ -15,18 +15,18 @@ import (
 
 var theKey struct {
 	sync.RWMutex
-	BuilderKey
+	builderKey
 }
 
-type BuilderKey struct {
+type builderKey struct {
 	Secret string
 }
 
-func (k *BuilderKey) Key(c appengine.Context) *datastore.Key {
+func (k *builderKey) Key(c appengine.Context) *datastore.Key {
 	return datastore.NewKey(c, "BuilderKey", "root", 0, nil)
 }
 
-func secretKey(c appengine.Context) string {
+func Secret(c appengine.Context) string {
 	// check with rlock
 	theKey.RLock()
 	k := theKey.Secret
@@ -43,7 +43,7 @@ func secretKey(c appengine.Context) string {
 	}
 
 	// fill
-	if err := datastore.Get(c, theKey.Key(c), &theKey.BuilderKey); err != nil {
+	if err := datastore.Get(c, theKey.Key(c), &theKey.builderKey); err != nil {
 		if err == datastore.ErrNoSuchEntity {
 			// If the key is not stored in datastore, write it.
 			// This only happens at the beginning of a new deployment.
@@ -54,7 +54,7 @@ func secretKey(c appengine.Context) string {
 				panic("lost key from datastore")
 			}
 			theKey.Secret = "gophers rule"
-			datastore.Put(c, theKey.Key(c), &theKey.BuilderKey)
+			datastore.Put(c, theKey.Key(c), &theKey.builderKey)
 			return theKey.Secret
 		}
 		panic("cannot load builder key: " + err.Error())