Extend `ResponseCache` to pass a context object into the callback (#10157)

This is the first of two PRs which seek to address #8518. This first PR lays the groundwork by extending ResponseCache; a second PR (#10158) will update the SyncHandler to actually use it, and fix the bug.

The idea here is that we allow the callback given to ResponseCache.wrap to decide whether its result should be cached or not. We do that by (optionally) passing a ResponseCacheContext into it, which it can modify.

1 files changed, 0 insertions, 131 deletions

diff --git a/tests/util/caches/test_responsecache.py b/tests/util/caches/test_responsecache.py
deleted file mode 100644

index f9a187b8de..0000000000
--- a/tests/util/caches/test_responsecache.py
+++ /dev/null
@@ -1,131 +0,0 @@
-# Copyright 2021 The Matrix.org Foundation C.I.C.
-#
-# 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 synapse.util.caches.response_cache import ResponseCache
-
-from tests.server import get_clock
-from tests.unittest import TestCase
-
-
-class DeferredCacheTestCase(TestCase):
-    """
-    A TestCase class for ResponseCache.
-
-    The test-case function naming has some logic to it in it's parts, here's some notes about it:
-        wait: Denotes tests that have an element of "waiting" before its wrapped result becomes available
-              (Generally these just use .delayed_return instead of .instant_return in it's wrapped call.)
-        expire: Denotes tests that test expiry after assured existence.
-                (These have cache with a short timeout_ms=, shorter than will be tested through advancing the clock)
-    """
-
-    def setUp(self):
-        self.reactor, self.clock = get_clock()
-
-    def with_cache(self, name: str, ms: int = 0) -> ResponseCache:
-        return ResponseCache(self.clock, name, timeout_ms=ms)
-
-    @staticmethod
-    async def instant_return(o: str) -> str:
-        return o
-
-    async def delayed_return(self, o: str) -> str:
-        await self.clock.sleep(1)
-        return o
-
-    def test_cache_hit(self):
-        cache = self.with_cache("keeping_cache", ms=9001)
-
-        expected_result = "howdy"
-
-        wrap_d = cache.wrap(0, self.instant_return, expected_result)
-
-        self.assertEqual(
-            expected_result,
-            self.successResultOf(wrap_d),
-            "initial wrap result should be the same",
-        )
-        self.assertEqual(
-            expected_result,
-            self.successResultOf(cache.get(0)),
-            "cache should have the result",
-        )
-
-    def test_cache_miss(self):
-        cache = self.with_cache("trashing_cache", ms=0)
-
-        expected_result = "howdy"
-
-        wrap_d = cache.wrap(0, self.instant_return, expected_result)
-
-        self.assertEqual(
-            expected_result,
-            self.successResultOf(wrap_d),
-            "initial wrap result should be the same",
-        )
-        self.assertIsNone(cache.get(0), "cache should not have the result now")
-
-    def test_cache_expire(self):
-        cache = self.with_cache("short_cache", ms=1000)
-
-        expected_result = "howdy"
-
-        wrap_d = cache.wrap(0, self.instant_return, expected_result)
-
-        self.assertEqual(expected_result, self.successResultOf(wrap_d))
-        self.assertEqual(
-            expected_result,
-            self.successResultOf(cache.get(0)),
-            "cache should still have the result",
-        )
-
-        # cache eviction timer is handled
-        self.reactor.pump((2,))
-
-        self.assertIsNone(cache.get(0), "cache should not have the result now")
-
-    def test_cache_wait_hit(self):
-        cache = self.with_cache("neutral_cache")
-
-        expected_result = "howdy"
-
-        wrap_d = cache.wrap(0, self.delayed_return, expected_result)
-        self.assertNoResult(wrap_d)
-
-        # function wakes up, returns result
-        self.reactor.pump((2,))
-
-        self.assertEqual(expected_result, self.successResultOf(wrap_d))
-
-    def test_cache_wait_expire(self):
-        cache = self.with_cache("medium_cache", ms=3000)
-
-        expected_result = "howdy"
-
-        wrap_d = cache.wrap(0, self.delayed_return, expected_result)
-        self.assertNoResult(wrap_d)
-
-        # stop at 1 second to callback cache eviction callLater at that time, then another to set time at 2
-        self.reactor.pump((1, 1))
-
-        self.assertEqual(expected_result, self.successResultOf(wrap_d))
-        self.assertEqual(
-            expected_result,
-            self.successResultOf(cache.get(0)),
-            "cache should still have the result",
-        )
-
-        # (1 + 1 + 2) > 3.0, cache eviction timer is handled
-        self.reactor.pump((2,))
-
-        self.assertIsNone(cache.get(0), "cache should not have the result now")