From 690cb4f3b32938f5ced5590abe9429733040a129 Mon Sep 17 00:00:00 2001 From: Patrick Cloke Date: Wed, 9 Mar 2022 13:07:41 -0500 Subject: Allow for ignoring some arguments when caching. (#12189) * `@cached` can now take an `uncached_args` which is an iterable of names to not use in the cache key. * Requires `@cached`, @cachedList` and `@lru_cache` to use keyword arguments for clarity. * Asserts that keyword-only arguments in cached functions are not accepted. (I tested this briefly and I don't believe this works properly.) --- tests/util/caches/test_descriptors.py | 84 +++++++++++++++++++++++++++++++++-- 1 file changed, 81 insertions(+), 3 deletions(-) (limited to 'tests/util/caches') diff --git a/tests/util/caches/test_descriptors.py b/tests/util/caches/test_descriptors.py index 19741ffcda..6a4b17527a 100644 --- a/tests/util/caches/test_descriptors.py +++ b/tests/util/caches/test_descriptors.py @@ -141,6 +141,84 @@ class DescriptorTestCase(unittest.TestCase): self.assertEqual(r, "chips") obj.mock.assert_not_called() + @defer.inlineCallbacks + def test_cache_uncached_args(self): + """ + Only the arguments not named in uncached_args should matter to the cache + + Note that this is identical to test_cache_num_args, but provides the + arguments differently. + """ + + class Cls: + # Note that it is important that this is not the last argument to + # test behaviour of skipping arguments properly. + @descriptors.cached(uncached_args=("arg2",)) + def fn(self, arg1, arg2, arg3): + return self.mock(arg1, arg2, arg3) + + def __init__(self): + self.mock = mock.Mock() + + obj = Cls() + obj.mock.return_value = "fish" + r = yield obj.fn(1, 2, 3) + self.assertEqual(r, "fish") + obj.mock.assert_called_once_with(1, 2, 3) + obj.mock.reset_mock() + + # a call with different params should call the mock again + obj.mock.return_value = "chips" + r = yield obj.fn(2, 3, 4) + self.assertEqual(r, "chips") + obj.mock.assert_called_once_with(2, 3, 4) + obj.mock.reset_mock() + + # the two values should now be cached; we should be able to vary + # the second argument and still get the cached result. + r = yield obj.fn(1, 4, 3) + self.assertEqual(r, "fish") + r = yield obj.fn(2, 5, 4) + self.assertEqual(r, "chips") + obj.mock.assert_not_called() + + @defer.inlineCallbacks + def test_cache_kwargs(self): + """Test that keyword arguments are treated properly""" + + class Cls: + def __init__(self): + self.mock = mock.Mock() + + @descriptors.cached() + def fn(self, arg1, kwarg1=2): + return self.mock(arg1, kwarg1=kwarg1) + + obj = Cls() + obj.mock.return_value = "fish" + r = yield obj.fn(1, kwarg1=2) + self.assertEqual(r, "fish") + obj.mock.assert_called_once_with(1, kwarg1=2) + obj.mock.reset_mock() + + # a call with different params should call the mock again + obj.mock.return_value = "chips" + r = yield obj.fn(1, kwarg1=3) + self.assertEqual(r, "chips") + obj.mock.assert_called_once_with(1, kwarg1=3) + obj.mock.reset_mock() + + # the values should now be cached. + r = yield obj.fn(1, kwarg1=2) + self.assertEqual(r, "fish") + # We should be able to not provide kwarg1 and get the cached value back. + r = yield obj.fn(1) + self.assertEqual(r, "fish") + # Keyword arguments can be in any order. + r = yield obj.fn(kwarg1=2, arg1=1) + self.assertEqual(r, "fish") + obj.mock.assert_not_called() + def test_cache_with_sync_exception(self): """If the wrapped function throws synchronously, things should continue to work""" @@ -656,7 +734,7 @@ class CachedListDescriptorTestCase(unittest.TestCase): def fn(self, arg1, arg2): pass - @descriptors.cachedList("fn", "args1") + @descriptors.cachedList(cached_method_name="fn", list_name="args1") async def list_fn(self, args1, arg2): assert current_context().name == "c1" # we want this to behave like an asynchronous function @@ -715,7 +793,7 @@ class CachedListDescriptorTestCase(unittest.TestCase): def fn(self, arg1): pass - @descriptors.cachedList("fn", "args1") + @descriptors.cachedList(cached_method_name="fn", list_name="args1") def list_fn(self, args1) -> "Deferred[dict]": return self.mock(args1) @@ -758,7 +836,7 @@ class CachedListDescriptorTestCase(unittest.TestCase): def fn(self, arg1, arg2): pass - @descriptors.cachedList("fn", "args1") + @descriptors.cachedList(cached_method_name="fn", list_name="args1") async def list_fn(self, args1, arg2): # we want this to behave like an asynchronous function await run_on_reactor() -- cgit 1.5.1 From 2fcf4b3f6cd2a0be6597622664636d2219957c2a Mon Sep 17 00:00:00 2001 From: Sean Quah <8349537+squahtx@users.noreply.github.com> Date: Mon, 14 Mar 2022 19:04:29 +0000 Subject: Add cancellation support to `@cached` and `@cachedList` decorators (#12183) These decorators mostly support cancellation already. Add cancellation tests and fix use of finished logging contexts by delaying cancellation, as suggested by @erikjohnston. Signed-off-by: Sean Quah --- changelog.d/12183.misc | 1 + synapse/util/caches/descriptors.py | 11 +++ tests/util/caches/test_descriptors.py | 147 +++++++++++++++++++++++++++++++++- 3 files changed, 157 insertions(+), 2 deletions(-) create mode 100644 changelog.d/12183.misc (limited to 'tests/util/caches') diff --git a/changelog.d/12183.misc b/changelog.d/12183.misc new file mode 100644 index 0000000000..dd441bb64f --- /dev/null +++ b/changelog.d/12183.misc @@ -0,0 +1 @@ +Add cancellation support to `@cached` and `@cachedList` decorators. diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py index c3c5c16db9..eda92d864d 100644 --- a/synapse/util/caches/descriptors.py +++ b/synapse/util/caches/descriptors.py @@ -41,6 +41,7 @@ from twisted.python.failure import Failure from synapse.logging.context import make_deferred_yieldable, preserve_fn from synapse.util import unwrapFirstError +from synapse.util.async_helpers import delay_cancellation from synapse.util.caches.deferred_cache import DeferredCache from synapse.util.caches.lrucache import LruCache @@ -350,6 +351,11 @@ class DeferredCacheDescriptor(_CacheDescriptorBase): ret = defer.maybeDeferred(preserve_fn(self.orig), obj, *args, **kwargs) ret = cache.set(cache_key, ret, callback=invalidate_callback) + # We started a new call to `self.orig`, so we must always wait for it to + # complete. Otherwise we might mark our current logging context as + # finished while `self.orig` is still using it in the background. + ret = delay_cancellation(ret) + return make_deferred_yieldable(ret) wrapped = cast(_CachedFunction, _wrapped) @@ -510,6 +516,11 @@ class DeferredCacheListDescriptor(_CacheDescriptorBase): d = defer.gatherResults(cached_defers, consumeErrors=True).addCallbacks( lambda _: results, unwrapFirstError ) + if missing: + # We started a new call to `self.orig`, so we must always wait for it to + # complete. Otherwise we might mark our current logging context as + # finished while `self.orig` is still using it in the background. + d = delay_cancellation(d) return make_deferred_yieldable(d) else: return defer.succeed(results) diff --git a/tests/util/caches/test_descriptors.py b/tests/util/caches/test_descriptors.py index 6a4b17527a..48e616ac74 100644 --- a/tests/util/caches/test_descriptors.py +++ b/tests/util/caches/test_descriptors.py @@ -17,7 +17,7 @@ from typing import Set from unittest import mock from twisted.internet import defer, reactor -from twisted.internet.defer import Deferred +from twisted.internet.defer import CancelledError, Deferred from synapse.api.errors import SynapseError from synapse.logging.context import ( @@ -28,7 +28,7 @@ from synapse.logging.context import ( make_deferred_yieldable, ) from synapse.util.caches import descriptors -from synapse.util.caches.descriptors import cached, lru_cache +from synapse.util.caches.descriptors import cached, cachedList, lru_cache from tests import unittest from tests.test_utils import get_awaitable_result @@ -493,6 +493,74 @@ class DescriptorTestCase(unittest.TestCase): obj.invalidate() top_invalidate.assert_called_once() + def test_cancel(self): + """Test that cancelling a lookup does not cancel other lookups""" + complete_lookup: "Deferred[None]" = Deferred() + + class Cls: + @cached() + async def fn(self, arg1): + await complete_lookup + return str(arg1) + + obj = Cls() + + d1 = obj.fn(123) + d2 = obj.fn(123) + self.assertFalse(d1.called) + self.assertFalse(d2.called) + + # Cancel `d1`, which is the lookup that caused `fn` to run. + d1.cancel() + + # `d2` should complete normally. + complete_lookup.callback(None) + self.failureResultOf(d1, CancelledError) + self.assertEqual(d2.result, "123") + + def test_cancel_logcontexts(self): + """Test that cancellation does not break logcontexts. + + * The `CancelledError` must be raised with the correct logcontext. + * The inner lookup must not resume with a finished logcontext. + * The inner lookup must not restore a finished logcontext when done. + """ + complete_lookup: "Deferred[None]" = Deferred() + + class Cls: + inner_context_was_finished = False + + @cached() + async def fn(self, arg1): + await make_deferred_yieldable(complete_lookup) + self.inner_context_was_finished = current_context().finished + return str(arg1) + + obj = Cls() + + async def do_lookup(): + with LoggingContext("c1") as c1: + try: + await obj.fn(123) + self.fail("No CancelledError thrown") + except CancelledError: + self.assertEqual( + current_context(), + c1, + "CancelledError was not raised with the correct logcontext", + ) + # suppress the error and succeed + + d = defer.ensureDeferred(do_lookup()) + d.cancel() + + complete_lookup.callback(None) + self.successResultOf(d) + self.assertFalse( + obj.inner_context_was_finished, "Tried to restart a finished logcontext" + ) + self.assertEqual(current_context(), SENTINEL_CONTEXT) + class CacheDecoratorTestCase(unittest.HomeserverTestCase): """More tests for @cached @@ -865,3 +933,78 @@ class CachedListDescriptorTestCase(unittest.TestCase): obj.fn.invalidate((10, 2)) invalidate0.assert_called_once() invalidate1.assert_called_once() + + def test_cancel(self): + """Test that cancelling a lookup does not cancel other lookups""" + complete_lookup: "Deferred[None]" = Deferred() + + class Cls: + @cached() + def fn(self, arg1): + pass + + @cachedList(cached_method_name="fn", list_name="args") + async def list_fn(self, args): + await complete_lookup + return {arg: str(arg) for arg in args} + + obj = Cls() + + d1 = obj.list_fn([123, 456]) + d2 = obj.list_fn([123, 456, 789]) + self.assertFalse(d1.called) + self.assertFalse(d2.called) + + d1.cancel() + + # `d2` should complete normally. + complete_lookup.callback(None) + self.failureResultOf(d1, CancelledError) + self.assertEqual(d2.result, {123: "123", 456: "456", 789: "789"}) + + def test_cancel_logcontexts(self): + """Test that cancellation does not break logcontexts. + + * The `CancelledError` must be raised with the correct logcontext. + * The inner lookup must not resume with a finished logcontext. + * The inner lookup must not restore a finished logcontext when done. + """ + complete_lookup: "Deferred[None]" = Deferred() + + class Cls: + inner_context_was_finished = False + + @cached() + def fn(self, arg1): + pass + + @cachedList(cached_method_name="fn", list_name="args") + async def list_fn(self, args): + await make_deferred_yieldable(complete_lookup) + self.inner_context_was_finished = current_context().finished + return {arg: str(arg) for arg in args} + + obj = Cls() + + async def do_lookup(): + with LoggingContext("c1") as c1: + try: + await obj.list_fn([123]) + self.fail("No CancelledError thrown") + except CancelledError: + self.assertEqual( + current_context(), + c1, + "CancelledError was not raised with the correct logcontext", + ) + # suppress the error and succeed + + d = defer.ensureDeferred(do_lookup()) + d.cancel() + + complete_lookup.callback(None) + self.successResultOf(d) + self.assertFalse( + obj.inner_context_was_finished, "Tried to restart a finished logcontext" + ) + self.assertEqual(current_context(), SENTINEL_CONTEXT) -- cgit 1.5.1