Take named arguments to @cached() decorator, add a 'max_entries' limit

tests/storage/test__base.py

@@ -0,0 +1,89 @@
+# -*- coding: utf-8 -*-
+# Copyright 2015 OpenMarket Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+from tests import unittest
+from twisted.internet import defer
+
+from synapse.storage._base import cached
+
+
+class CacheDecoratorTestCase(unittest.TestCase):
+
+    @defer.inlineCallbacks
+    def test_passthrough(self):
+        @cached()
+        def func(self, key):
+            return key
+
+        self.assertEquals((yield func(self, "foo")), "foo")
+        self.assertEquals((yield func(self, "bar")), "bar")
+
+    @defer.inlineCallbacks
+    def test_hit(self):
+        callcount = [0]
+
+        @cached()
+        def func(self, key):
+            callcount[0] += 1
+            return key
+
+        yield func(self, "foo")
+
+        self.assertEquals(callcount[0], 1)
+
+        self.assertEquals((yield func(self, "foo")), "foo")
+        self.assertEquals(callcount[0], 1)
+
+    @defer.inlineCallbacks
+    def test_invalidate(self):
+        callcount = [0]
+
+        @cached()
+        def func(self, key):
+            callcount[0] += 1
+            return key
+
+        yield func(self, "foo")
+
+        self.assertEquals(callcount[0], 1)
+
+        func.invalidate("foo")
+
+        yield func(self, "foo")
+
+        self.assertEquals(callcount[0], 2)
+
+    @defer.inlineCallbacks
+    def test_max_entries(self):
+        callcount = [0]
+
+        @cached(max_entries=10)
+        def func(self, key):
+            callcount[0] += 1
+            return key
+
+        for k in range(0,12):
+            yield func(self, k)
+
+        self.assertEquals(callcount[0], 12)
+
+        # There must have been at least 2 evictions, meaning if we calculate
+        # all 12 values again, we must get called at least 2 more times
+        for k in range(0,12):
+            yield func(self, k)
+
+        self.assertTrue(callcount[0] >= 14,
+            msg="Expected callcount >= 14, got %d" % (callcount[0]))