MatrixSynapse/tests/util/caches/test_response_cache.py

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# 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 unittest.mock import Mock
from parameterized import parameterized
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from twisted.internet import defer
from synapse.util.caches.response_cache import ResponseCache, ResponseCacheContext
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from tests.server import get_clock
from tests.unittest import TestCase
class ResponseCacheTestCase(TestCase):
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"""
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) -> None:
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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) -> None:
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cache = self.with_cache("keeping_cache", ms=9001)
expected_result = "howdy"
wrap_d = defer.ensureDeferred(
cache.wrap(0, self.instant_return, expected_result)
)
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self.assertEqual(
expected_result,
self.successResultOf(wrap_d),
"initial wrap result should be the same",
)
# a second call should return the result without a call to the wrapped function
unexpected = Mock(spec=())
wrap2_d = defer.ensureDeferred(cache.wrap(0, unexpected))
unexpected.assert_not_called()
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self.assertEqual(
expected_result,
self.successResultOf(wrap2_d),
"cache should still have the result",
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)
def test_cache_miss(self) -> None:
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cache = self.with_cache("trashing_cache", ms=0)
expected_result = "howdy"
wrap_d = defer.ensureDeferred(
cache.wrap(0, self.instant_return, expected_result)
)
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self.assertEqual(
expected_result,
self.successResultOf(wrap_d),
"initial wrap result should be the same",
)
self.assertCountEqual([], cache.keys(), "cache should not have the result now")
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def test_cache_expire(self) -> None:
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cache = self.with_cache("short_cache", ms=1000)
expected_result = "howdy"
wrap_d = defer.ensureDeferred(
cache.wrap(0, self.instant_return, expected_result)
)
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self.assertEqual(expected_result, self.successResultOf(wrap_d))
# a second call should return the result without a call to the wrapped function
unexpected = Mock(spec=())
wrap2_d = defer.ensureDeferred(cache.wrap(0, unexpected))
unexpected.assert_not_called()
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self.assertEqual(
expected_result,
self.successResultOf(wrap2_d),
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"cache should still have the result",
)
# cache eviction timer is handled
self.reactor.pump((2,))
self.assertCountEqual([], cache.keys(), "cache should not have the result now")
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def test_cache_wait_hit(self) -> None:
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cache = self.with_cache("neutral_cache")
expected_result = "howdy"
wrap_d = defer.ensureDeferred(
cache.wrap(0, self.delayed_return, expected_result)
)
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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) -> None:
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cache = self.with_cache("medium_cache", ms=3000)
expected_result = "howdy"
wrap_d = defer.ensureDeferred(
cache.wrap(0, self.delayed_return, expected_result)
)
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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))
# a second call should immediately return the result without a call to the
# wrapped function
unexpected = Mock(spec=())
wrap2_d = defer.ensureDeferred(cache.wrap(0, unexpected))
unexpected.assert_not_called()
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self.assertEqual(
expected_result,
self.successResultOf(wrap2_d),
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"cache should still have the result",
)
# (1 + 1 + 2) > 3.0, cache eviction timer is handled
self.reactor.pump((2,))
self.assertCountEqual([], cache.keys(), "cache should not have the result now")
@parameterized.expand([(True,), (False,)])
def test_cache_context_nocache(self, should_cache: bool) -> None:
"""If the callback clears the should_cache bit, the result should not be cached"""
cache = self.with_cache("medium_cache", ms=3000)
expected_result = "howdy"
call_count = 0
async def non_caching(o: str, cache_context: ResponseCacheContext[int]) -> str:
nonlocal call_count
call_count += 1
await self.clock.sleep(1)
cache_context.should_cache = should_cache
return o
wrap_d = defer.ensureDeferred(
cache.wrap(0, non_caching, expected_result, cache_context=True)
)
# there should be no result to start with
self.assertNoResult(wrap_d)
# a second call should also return a pending deferred
wrap2_d = defer.ensureDeferred(
cache.wrap(0, non_caching, expected_result, cache_context=True)
)
self.assertNoResult(wrap2_d)
# and there should have been exactly one call
self.assertEqual(call_count, 1)
# let the call complete
self.reactor.advance(1)
# both results should have completed
self.assertEqual(expected_result, self.successResultOf(wrap_d))
self.assertEqual(expected_result, self.successResultOf(wrap2_d))
if should_cache:
unexpected = Mock(spec=())
wrap3_d = defer.ensureDeferred(cache.wrap(0, unexpected))
unexpected.assert_not_called()
self.assertEqual(
expected_result,
self.successResultOf(wrap3_d),
"cache should still have the result",
)
else:
self.assertCountEqual(
[], cache.keys(), "cache should not have the result now"
)