simplify caching class

--HG--
branch : trunk

py/path/testing/test_cacheutil.py

@@ -0,0 +1,77 @@
+import py
+from py.__.path import cacheutil 
+
+class BasicCacheAPITest:
+    cache = None
+    def test_getorbuild(self):
+        val = self.cache.getorbuild(-42, lambda: 42)
+        assert val == 42
+        val = self.cache.getorbuild(-42, lambda: 23)
+        assert val == 42
+
+    def test_cache_get_key_error(self):
+        py.test.raises(KeyError, "self.cache._getentry(-23)")
+
+    def test_delentry_non_raising(self):
+        val = self.cache.getorbuild(100, lambda: 100)
+        self.cache.delentry(100)
+        py.test.raises(KeyError, "self.cache._getentry(100)")
+
+    def test_delentry_raising(self):
+        val = self.cache.getorbuild(100, lambda: 100)
+        self.cache.delentry(100)
+        py.test.raises(KeyError, "self.cache.delentry(100, raising=True)")
+
+class TestBuildcostAccess(BasicCacheAPITest):
+    cache = cacheutil.BuildcostAccessCache(maxentries=128)
+
+    def test_cache_works_somewhat_simple(self, monkeypatch):
+        cache = cacheutil.BuildcostAccessCache()
+        # the default gettime 
+        # BuildcostAccessCache.build can 
+        # result into time()-time() == 0 which makes the below
+        # test fail randomly.  Let's rather use incrementing
+        # numbers instead. 
+        monkeypatch.setattr(cacheutil, 'gettime', 
+                py.std.itertools.count().next)
+        for x in range(cache.maxentries):
+            y = cache.getorbuild(x, lambda: x)
+            assert x == y
+        for x in range(cache.maxentries):
+            assert cache.getorbuild(x, None) == x
+        for x in range(cache.maxentries/2):
+            assert cache.getorbuild(x, None) == x
+            assert cache.getorbuild(x, None) == x
+        # evict one entry 
+        val = cache.getorbuild(-1, lambda: 42)
+        assert val == 42
+        # check that recently used ones are still there
+        # and are not build again
+        for x in range(cache.maxentries/2):
+            assert cache.getorbuild(x, None) == x
+        assert cache.getorbuild(-1, None) == 42
+
+
+class TestAging(BasicCacheAPITest):
+    maxsecs = 0.10
+    cache = cacheutil.AgingCache(maxentries=128, maxseconds=maxsecs)
+
+    def test_cache_eviction(self):
+        self.cache.getorbuild(17, lambda: 17)
+        endtime = py.std.time.time() + self.maxsecs * 10 
+        while py.std.time.time() < endtime: 
+            try:
+                self.cache._getentry(17)
+            except KeyError:
+                break 
+            py.std.time.sleep(self.maxsecs*0.3) 
+        else: 
+            py.test.fail("waiting for cache eviction failed") 
+
+def test_prune_lowestweight(): 
+    maxsecs = 0.05 
+    cache = cacheutil.AgingCache(maxentries=10, maxseconds=maxsecs)
+    for x in range(cache.maxentries): 
+        cache.getorbuild(x, lambda: x) 
+    py.std.time.sleep(maxsecs*1.1) 
+    cache.getorbuild(cache.maxentries+1, lambda: 42)