diff options
| -rw-r--r-- | changelog.d/8595.misc | 1 | ||||
| -rw-r--r-- | synapse/push/bulk_push_rule_evaluator.py | 37 | ||||
| -rw-r--r-- | synapse/util/caches/descriptors.py | 235 | ||||
| -rw-r--r-- | tests/util/caches/test_descriptors.py | 60 |
4 files changed, 272 insertions, 61 deletions
diff --git a/changelog.d/8595.misc b/changelog.d/8595.misc new file mode 100644 index 0000000000..24fab65cda --- /dev/null +++ b/changelog.d/8595.misc @@ -0,0 +1 @@ +Implement and use an @lru_cache decorator. diff --git a/synapse/push/bulk_push_rule_evaluator.py b/synapse/push/bulk_push_rule_evaluator.py index d9b5478b53..82a72dc34f 100644 --- a/synapse/push/bulk_push_rule_evaluator.py +++ b/synapse/push/bulk_push_rule_evaluator.py @@ -15,8 +15,8 @@ # limitations under the License. import logging -from collections import namedtuple +import attr from prometheus_client import Counter from synapse.api.constants import EventTypes, Membership, RelationTypes @@ -26,7 +26,8 @@ from synapse.events.snapshot import EventContext from synapse.state import POWER_KEY from synapse.util.async_helpers import Linearizer from synapse.util.caches import register_cache -from synapse.util.caches.descriptors import cached +from synapse.util.caches.descriptors import lru_cache +from synapse.util.caches.lrucache import LruCache from .push_rule_evaluator import PushRuleEvaluatorForEvent @@ -120,7 +121,7 @@ class BulkPushRuleEvaluator: dict of user_id -> push_rules """ room_id = event.room_id - rules_for_room = await self._get_rules_for_room(room_id) + rules_for_room = self._get_rules_for_room(room_id) rules_by_user = await rules_for_room.get_rules(event, context) @@ -138,7 +139,7 @@ class BulkPushRuleEvaluator: return rules_by_user - @cached() + @lru_cache() def _get_rules_for_room(self, room_id): """Get the current RulesForRoom object for the given room id @@ -275,12 +276,14 @@ class RulesForRoom: the entire cache for the room. """ - def __init__(self, hs, room_id, rules_for_room_cache, room_push_rule_cache_metrics): + def __init__( + self, hs, room_id, rules_for_room_cache: LruCache, room_push_rule_cache_metrics + ): """ Args: hs (HomeServer) room_id (str) - rules_for_room_cache(Cache): The cache object that caches these + rules_for_room_cache: The cache object that caches these RoomsForUser objects. room_push_rule_cache_metrics (CacheMetric) """ @@ -489,13 +492,21 @@ class RulesForRoom: self.state_group = state_group -class _Invalidation(namedtuple("_Invalidation", ("cache", "room_id"))): - # We rely on _CacheContext implementing __eq__ and __hash__ sensibly, - # which namedtuple does for us (i.e. two _CacheContext are the same if - # their caches and keys match). This is important in particular to - # dedupe when we add callbacks to lru cache nodes, otherwise the number - # of callbacks would grow. +@attr.attrs(slots=True, frozen=True) +class _Invalidation: + # _Invalidation is passed as an `on_invalidate` callback to bulk_get_push_rules, + # which means that it it is stored on the bulk_get_push_rules cache entry. In order + # to ensure that we don't accumulate lots of redunant callbacks on the cache entry, + # we need to ensure that two _Invalidation objects are "equal" if they refer to the + # same `cache` and `room_id`. + # + # attrs provides suitable __hash__ and __eq__ methods, provided we remember to + # set `frozen=True`. + + cache = attr.ib(type=LruCache) + room_id = attr.ib(type=str) + def __call__(self): - rules = self.cache.get_immediate(self.room_id, None, update_metrics=False) + rules = self.cache.get(self.room_id, None, update_metrics=False) if rules: rules.invalidate_all() diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py index 5d7fffee66..a924140cdf 100644 --- a/synapse/util/caches/descriptors.py +++ b/synapse/util/caches/descriptors.py @@ -13,10 +13,23 @@ # 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. +import enum import functools import inspect import logging -from typing import Any, Callable, Generic, Optional, Tuple, TypeVar, Union, cast +from typing import ( + Any, + Callable, + Generic, + Iterable, + Mapping, + Optional, + Sequence, + Tuple, + TypeVar, + Union, + cast, +) from weakref import WeakValueDictionary from twisted.internet import defer @@ -24,6 +37,7 @@ from twisted.internet import defer from synapse.logging.context import make_deferred_yieldable, preserve_fn from synapse.util import unwrapFirstError from synapse.util.caches.deferred_cache import DeferredCache +from synapse.util.caches.lrucache import LruCache logger = logging.getLogger(__name__) @@ -48,7 +62,7 @@ class _CachedFunction(Generic[F]): class _CacheDescriptorBase: - def __init__(self, orig: _CachedFunction, num_args, cache_context=False): + def __init__(self, orig: Callable[..., Any], num_args, cache_context=False): self.orig = orig arg_spec = inspect.getfullargspec(orig) @@ -97,8 +111,107 @@ class _CacheDescriptorBase: self.add_cache_context = cache_context + self.cache_key_builder = get_cache_key_builder( + self.arg_names, self.arg_defaults + ) + + +class _LruCachedFunction(Generic[F]): + cache = None # type: LruCache[CacheKey, Any] + __call__ = None # type: F + + +def lru_cache( + max_entries: int = 1000, cache_context: bool = False, +) -> Callable[[F], _LruCachedFunction[F]]: + """A method decorator that applies a memoizing cache around the function. + + This is more-or-less a drop-in equivalent to functools.lru_cache, although note + that the signature is slightly different. + + The main differences with functools.lru_cache are: + (a) the size of the cache can be controlled via the cache_factor mechanism + (b) the wrapped function can request a "cache_context" which provides a + callback mechanism to indicate that the result is no longer valid + (c) prometheus metrics are exposed automatically. + + The function should take zero or more arguments, which are used as the key for the + cache. Single-argument functions use that argument as the cache key; otherwise the + arguments are built into a tuple. + + Cached functions can be "chained" (i.e. a cached function can call other cached + functions and get appropriately invalidated when they called caches are + invalidated) by adding a special "cache_context" argument to the function + and passing that as a kwarg to all caches called. For example: + + @lru_cache(cache_context=True) + def foo(self, key, cache_context): + r1 = self.bar1(key, on_invalidate=cache_context.invalidate) + r2 = self.bar2(key, on_invalidate=cache_context.invalidate) + return r1 + r2 + + The wrapped function also has a 'cache' property which offers direct access to the + underlying LruCache. + """ + + def func(orig: F) -> _LruCachedFunction[F]: + desc = LruCacheDescriptor( + orig, max_entries=max_entries, cache_context=cache_context, + ) + return cast(_LruCachedFunction[F], desc) + + return func + + +class LruCacheDescriptor(_CacheDescriptorBase): + """Helper for @lru_cache""" + + class _Sentinel(enum.Enum): + sentinel = object() + + def __init__( + self, orig, max_entries: int = 1000, cache_context: bool = False, + ): + super().__init__(orig, num_args=None, cache_context=cache_context) + self.max_entries = max_entries + + def __get__(self, obj, owner): + cache = LruCache( + cache_name=self.orig.__name__, max_size=self.max_entries, + ) # type: LruCache[CacheKey, Any] + + get_cache_key = self.cache_key_builder + sentinel = LruCacheDescriptor._Sentinel.sentinel + + @functools.wraps(self.orig) + def _wrapped(*args, **kwargs): + invalidate_callback = kwargs.pop("on_invalidate", None) + callbacks = (invalidate_callback,) if invalidate_callback else () + + cache_key = get_cache_key(args, kwargs) -class CacheDescriptor(_CacheDescriptorBase): + ret = cache.get(cache_key, default=sentinel, callbacks=callbacks) + if ret != sentinel: + return ret + + # Add our own `cache_context` to argument list if the wrapped function + # has asked for one + if self.add_cache_context: + kwargs["cache_context"] = _CacheContext.get_instance(cache, cache_key) + + ret2 = self.orig(obj, *args, **kwargs) + cache.set(cache_key, ret2, callbacks=callbacks) + + return ret2 + + wrapped = cast(_CachedFunction, _wrapped) + wrapped.cache = cache + obj.__dict__[self.orig.__name__] = wrapped + + return wrapped + + +class DeferredCacheDescriptor(_CacheDescriptorBase): """ A method decorator that applies a memoizing cache around the function. This caches deferreds, rather than the results themselves. Deferreds that @@ -141,7 +254,6 @@ class CacheDescriptor(_CacheDescriptorBase): cache_context=False, iterable=False, ): - super().__init__(orig, num_args=num_args, cache_context=cache_context) self.max_entries = max_entries @@ -157,41 +269,7 @@ class CacheDescriptor(_CacheDescriptorBase): iterable=self.iterable, ) # type: DeferredCache[CacheKey, Any] - def get_cache_key_gen(args, kwargs): - """Given some args/kwargs return a generator that resolves into - the cache_key. - - We loop through each arg name, looking up if its in the `kwargs`, - otherwise using the next argument in `args`. If there are no more - args then we try looking the arg name up in the defaults - """ - pos = 0 - for nm in self.arg_names: - if nm in kwargs: - yield kwargs[nm] - elif pos < len(args): - yield args[pos] - pos += 1 - else: - yield self.arg_defaults[nm] - - # By default our cache key is a tuple, but if there is only one item - # then don't bother wrapping in a tuple. This is to save memory. - if self.num_args == 1: - nm = self.arg_names[0] - - def get_cache_key(args, kwargs): - if nm in kwargs: - return kwargs[nm] - elif len(args): - return args[0] - else: - return self.arg_defaults[nm] - - else: - - def get_cache_key(args, kwargs): - return tuple(get_cache_key_gen(args, kwargs)) + get_cache_key = self.cache_key_builder @functools.wraps(self.orig) def _wrapped(*args, **kwargs): @@ -223,7 +301,6 @@ class CacheDescriptor(_CacheDescriptorBase): wrapped.prefill = lambda key, val: cache.prefill(key[0], val) else: wrapped.invalidate = cache.invalidate - wrapped.invalidate_all = cache.invalidate_all wrapped.invalidate_many = cache.invalidate_many wrapped.prefill = cache.prefill @@ -236,7 +313,7 @@ class CacheDescriptor(_CacheDescriptorBase): return wrapped -class CacheListDescriptor(_CacheDescriptorBase): +class DeferredCacheListDescriptor(_CacheDescriptorBase): """Wraps an existing cache to support bulk fetching of keys. Given a list of keys it looks in the cache to find any hits, then passes @@ -382,11 +459,13 @@ class _CacheContext: on a lower level. """ + Cache = Union[DeferredCache, LruCache] + _cache_context_objects = ( WeakValueDictionary() - ) # type: WeakValueDictionary[Tuple[DeferredCache, CacheKey], _CacheContext] + ) # type: WeakValueDictionary[Tuple[_CacheContext.Cache, CacheKey], _CacheContext] - def __init__(self, cache, cache_key): # type: (DeferredCache, CacheKey) -> None + def __init__(self, cache: "_CacheContext.Cache", cache_key: CacheKey) -> None: self._cache = cache self._cache_key = cache_key @@ -396,8 +475,8 @@ class _CacheContext: @classmethod def get_instance( - cls, cache, cache_key - ): # type: (DeferredCache, CacheKey) -> _CacheContext + cls, cache: "_CacheContext.Cache", cache_key: CacheKey + ) -> "_CacheContext": """Returns an instance constructed with the given arguments. A new instance is only created if none already exists. @@ -418,7 +497,7 @@ def cached( cache_context: bool = False, iterable: bool = False, ) -> Callable[[F], _CachedFunction[F]]: - func = lambda orig: CacheDescriptor( + func = lambda orig: DeferredCacheDescriptor( orig, max_entries=max_entries, num_args=num_args, @@ -460,7 +539,7 @@ def cachedList( def batch_do_something(self, first_arg, second_args): ... """ - func = lambda orig: CacheListDescriptor( + func = lambda orig: DeferredCacheListDescriptor( orig, cached_method_name=cached_method_name, list_name=list_name, @@ -468,3 +547,65 @@ def cachedList( ) return cast(Callable[[F], _CachedFunction[F]], func) + + +def get_cache_key_builder( + param_names: Sequence[str], param_defaults: Mapping[str, Any] +) -> Callable[[Sequence[Any], Mapping[str, Any]], CacheKey]: + """Construct a function which will build cache keys suitable for a cached function + + Args: + param_names: list of formal parameter names for the cached function + param_defaults: a mapping from parameter name to default value for that param + + Returns: + A function which will take an (args, kwargs) pair and return a cache key + """ + + # By default our cache key is a tuple, but if there is only one item + # then don't bother wrapping in a tuple. This is to save memory. + + if len(param_names) == 1: + nm = param_names[0] + + def get_cache_key(args: Sequence[Any], kwargs: Mapping[str, Any]) -> CacheKey: + if nm in kwargs: + return kwargs[nm] + elif len(args): + return args[0] + else: + return param_defaults[nm] + + else: + + def get_cache_key(args: Sequence[Any], kwargs: Mapping[str, Any]) -> CacheKey: + return tuple(_get_cache_key_gen(param_names, param_defaults, args, kwargs)) + + return get_cache_key + + +def _get_cache_key_gen( + param_names: Iterable[str], + param_defaults: Mapping[str, Any], + args: Sequence[Any], + kwargs: Mapping[str, Any], +) -> Iterable[Any]: + """Given some args/kwargs return a generator that resolves into + the cache_key. + + This is essentially the same operation as `inspect.getcallargs`, but optimised so + that we don't need to inspect the target function for each call. + """ + + # We loop through each arg name, looking up if its in the `kwargs`, + # otherwise using the next argument in `args`. If there are no more + # args then we try looking the arg name up in the defaults. + pos = 0 + for nm in param_names: + if nm in kwargs: + yield kwargs[nm] + elif pos < len(args): + yield args[pos] + pos += 1 + else: + yield param_defaults[nm] diff --git a/tests/util/caches/test_descriptors.py b/tests/util/caches/test_descriptors.py index 2ad08f541b..cf1e3203a4 100644 --- a/tests/util/caches/test_descriptors.py +++ b/tests/util/caches/test_descriptors.py @@ -29,13 +29,46 @@ from synapse.logging.context import ( make_deferred_yieldable, ) from synapse.util.caches import descriptors -from synapse.util.caches.descriptors import cached +from synapse.util.caches.descriptors import cached, lru_cache from tests import unittest +from tests.test_utils import get_awaitable_result logger = logging.getLogger(__name__) +class LruCacheDecoratorTestCase(unittest.TestCase): + def test_base(self): + class Cls: + def __init__(self): + self.mock = mock.Mock() + + @lru_cache() + def fn(self, arg1, arg2): + return self.mock(arg1, arg2) + + obj = Cls() + obj.mock.return_value = "fish" + r = obj.fn(1, 2) + self.assertEqual(r, "fish") + obj.mock.assert_called_once_with(1, 2) + obj.mock.reset_mock() + + # a call with different params should call the mock again + obj.mock.return_value = "chips" + r = obj.fn(1, 3) + self.assertEqual(r, "chips") + obj.mock.assert_called_once_with(1, 3) + obj.mock.reset_mock() + + # the two values should now be cached + r = obj.fn(1, 2) + self.assertEqual(r, "fish") + r = obj.fn(1, 3) + self.assertEqual(r, "chips") + obj.mock.assert_not_called() + + def run_on_reactor(): d = defer.Deferred() reactor.callLater(0, d.callback, 0) @@ -362,6 +395,31 @@ class DescriptorTestCase(unittest.TestCase): d = obj.fn(1) self.failureResultOf(d, SynapseError) + def test_invalidate_cascade(self): + """Invalidations should cascade up through cache contexts""" + + class Cls: + @cached(cache_context=True) + async def func1(self, key, cache_context): + return await self.func2(key, on_invalidate=cache_context.invalidate) + + @cached(cache_context=True) + async def func2(self, key, cache_context): + return self.func3(key, on_invalidate=cache_context.invalidate) + + @lru_cache(cache_context=True) + def func3(self, key, cache_context): + self.invalidate = cache_context.invalidate + return 42 + + obj = Cls() + + top_invalidate = mock.Mock() + r = get_awaitable_result(obj.func1("k1", on_invalidate=top_invalidate)) + self.assertEqual(r, 42) + obj.invalidate() + top_invalidate.assert_called_once() + class CacheDecoratorTestCase(unittest.HomeserverTestCase): """More tests for @cached |