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move DeferredCache into its own module

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This commit is contained in:
Richard van der Hoff 2020-10-14 23:25:23 +01:00
parent 9f87da0a84
commit 4182bb812f
10 changed files with 367 additions and 332 deletions
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2
synapse/replication/slave/storage/client_ips.py
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@ -15,7 +15,7 @@
from synapse.storage.database import DatabasePool
from synapse.storage.databases.main.client_ips import LAST_SEEN_GRANULARITY
from synapse.util.caches.descriptors import DeferredCache
from synapse.util.caches.deferred_cache import DeferredCache
from ._base import BaseSlavedStore

2
synapse/storage/databases/main/client_ips.py
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@ -19,7 +19,7 @@ from typing import Dict, Optional, Tuple
from synapse.metrics.background_process_metrics import wrap_as_background_process
from synapse.storage._base import SQLBaseStore
from synapse.storage.database import DatabasePool, make_tuple_comparison_clause
from synapse.util.caches.descriptors import DeferredCache
from synapse.util.caches.deferred_cache import DeferredCache
logger = logging.getLogger(__name__)

3
synapse/storage/databases/main/devices.py
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@ -34,7 +34,8 @@ from synapse.storage.database import (
)
from synapse.types import Collection, JsonDict, get_verify_key_from_cross_signing_key
from synapse.util import json_decoder, json_encoder
from synapse.util.caches.descriptors import DeferredCache, cached, cachedList
from synapse.util.caches.deferred_cache import DeferredCache
from synapse.util.caches.descriptors import cached, cachedList
from synapse.util.iterutils import batch_iter
from synapse.util.stringutils import shortstr

3
synapse/storage/databases/main/events_worker.py
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@ -42,7 +42,8 @@ from synapse.storage.database import DatabasePool
from synapse.storage.engines import PostgresEngine
from synapse.storage.util.id_generators import MultiWriterIdGenerator, StreamIdGenerator
from synapse.types import Collection, get_domain_from_id
from synapse.util.caches.descriptors import DeferredCache, cached
from synapse.util.caches.deferred_cache import DeferredCache
from synapse.util.caches.descriptors import cached
from synapse.util.iterutils import batch_iter
from synapse.util.metrics import Measure

292
synapse/util/caches/deferred_cache.py Normal file
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@ -0,0 +1,292 @@
# -*- coding: utf-8 -*-
# Copyright 2015, 2016 OpenMarket Ltd
# Copyright 2018 New Vector Ltd
# Copyright 2020 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.
import enum
import threading
from typing import Callable, Generic, Iterable, MutableMapping, Optional, TypeVar, cast
from prometheus_client import Gauge
from twisted.internet import defer
from synapse.util.async_helpers import ObservableDeferred
from synapse.util.caches import register_cache
from synapse.util.caches.lrucache import LruCache
from synapse.util.caches.treecache import TreeCache, iterate_tree_cache_entry
cache_pending_metric = Gauge(
"synapse_util_caches_cache_pending",
"Number of lookups currently pending for this cache",
["name"],
)
KT = TypeVar("KT")
VT = TypeVar("VT")
class _Sentinel(enum.Enum):
# defining a sentinel in this way allows mypy to correctly handle the
# type of a dictionary lookup.
sentinel = object()
class DeferredCache(Generic[KT, VT]):
"""Wraps an LruCache, adding support for Deferred results.
It expects that each entry added with set() will be a Deferred; likewise get()
may return an ObservableDeferred.
"""
__slots__ = (
"cache",
"name",
"keylen",
"thread",
"metrics",
"_pending_deferred_cache",
)
def __init__(
self,
name: str,
max_entries: int = 1000,
keylen: int = 1,
tree: bool = False,
iterable: bool = False,
apply_cache_factor_from_config: bool = True,
):
"""
Args:
name: The name of the cache
max_entries: Maximum amount of entries that the cache will hold
keylen: The length of the tuple used as the cache key. Ignored unless
`tree` is True.
tree: Use a TreeCache instead of a dict as the underlying cache type
iterable: If True, count each item in the cached object as an entry,
rather than each cached object
apply_cache_factor_from_config: Whether cache factors specified in the
config file affect `max_entries`
"""
cache_type = TreeCache if tree else dict
# _pending_deferred_cache maps from the key value to a `CacheEntry` object.
self._pending_deferred_cache = (
cache_type()
) # type: MutableMapping[KT, CacheEntry]
# cache is used for completed results and maps to the result itself, rather than
# a Deferred.
self.cache = LruCache(
max_size=max_entries,
keylen=keylen,
cache_type=cache_type,
size_callback=(lambda d: len(d)) if iterable else None,
evicted_callback=self._on_evicted,
apply_cache_factor_from_config=apply_cache_factor_from_config,
)
self.name = name
self.keylen = keylen
self.thread = None # type: Optional[threading.Thread]
self.metrics = register_cache(
"cache",
name,
self.cache,
collect_callback=self._metrics_collection_callback,
)
@property
def max_entries(self):
return self.cache.max_size
def _on_evicted(self, evicted_count):
self.metrics.inc_evictions(evicted_count)
def _metrics_collection_callback(self):
cache_pending_metric.labels(self.name).set(len(self._pending_deferred_cache))
def check_thread(self):
expected_thread = self.thread
if expected_thread is None:
self.thread = threading.current_thread()
else:
if expected_thread is not threading.current_thread():
raise ValueError(
"Cache objects can only be accessed from the main thread"
)
def get(
self,
key: KT,
default=_Sentinel.sentinel,
callback: Optional[Callable[[], None]] = None,
update_metrics: bool = True,
):
"""Looks the key up in the caches.
Args:
key(tuple)
default: What is returned if key is not in the caches. If not
specified then function throws KeyError instead
callback(fn): Gets called when the entry in the cache is invalidated
update_metrics (bool): whether to update the cache hit rate metrics
Returns:
Either an ObservableDeferred or the result itself
"""
callbacks = [callback] if callback else []
val = self._pending_deferred_cache.get(key, _Sentinel.sentinel)
if val is not _Sentinel.sentinel:
val.callbacks.update(callbacks)
if update_metrics:
self.metrics.inc_hits()
return val.deferred
val = self.cache.get(key, _Sentinel.sentinel, callbacks=callbacks)
if val is not _Sentinel.sentinel:
self.metrics.inc_hits()
return val
if update_metrics:
self.metrics.inc_misses()
if default is _Sentinel.sentinel:
raise KeyError()
else:
return default
def set(
self,
key: KT,
value: defer.Deferred,
callback: Optional[Callable[[], None]] = None,
) -> ObservableDeferred:
if not isinstance(value, defer.Deferred):
raise TypeError("not a Deferred")
callbacks = [callback] if callback else []
self.check_thread()
observable = ObservableDeferred(value, consumeErrors=True)
observer = observable.observe()
entry = CacheEntry(deferred=observable, callbacks=callbacks)
existing_entry = self._pending_deferred_cache.pop(key, None)
if existing_entry:
existing_entry.invalidate()
self._pending_deferred_cache[key] = entry
def compare_and_pop():
"""Check if our entry is still the one in _pending_deferred_cache, and
if so, pop it.
Returns true if the entries matched.
"""
existing_entry = self._pending_deferred_cache.pop(key, None)
if existing_entry is entry:
return True
# oops, the _pending_deferred_cache has been updated since
# we started our query, so we are out of date.
#
# Better put back whatever we took out. (We do it this way
# round, rather than peeking into the _pending_deferred_cache
# and then removing on a match, to make the common case faster)
if existing_entry is not None:
self._pending_deferred_cache[key] = existing_entry
return False
def cb(result):
if compare_and_pop():
self.cache.set(key, result, entry.callbacks)
else:
# we're not going to put this entry into the cache, so need
# to make sure that the invalidation callbacks are called.
# That was probably done when _pending_deferred_cache was
# updated, but it's possible that `set` was called without
# `invalidate` being previously called, in which case it may
# not have been. Either way, let's double-check now.
entry.invalidate()
def eb(_fail):
compare_and_pop()
entry.invalidate()
# once the deferred completes, we can move the entry from the
# _pending_deferred_cache to the real cache.
#
observer.addCallbacks(cb, eb)
return observable
def prefill(self, key: KT, value: VT, callback: Callable[[], None] = None):
callbacks = [callback] if callback else []
self.cache.set(key, value, callbacks=callbacks)
def invalidate(self, key):
self.check_thread()
self.cache.pop(key, None)
# if we have a pending lookup for this key, remove it from the
# _pending_deferred_cache, which will (a) stop it being returned
# for future queries and (b) stop it being persisted as a proper entry
# in self.cache.
entry = self._pending_deferred_cache.pop(key, None)
# run the invalidation callbacks now, rather than waiting for the
# deferred to resolve.
if entry:
entry.invalidate()
def invalidate_many(self, key: KT):
self.check_thread()
if not isinstance(key, tuple):
raise TypeError("The cache key must be a tuple not %r" % (type(key),))
self.cache.del_multi(key)
# if we have a pending lookup for this key, remove it from the
# _pending_deferred_cache, as above
entry_dict = self._pending_deferred_cache.pop(cast(KT, key), None)
if entry_dict is not None:
for entry in iterate_tree_cache_entry(entry_dict):
entry.invalidate()
def invalidate_all(self):
self.check_thread()
self.cache.clear()
for entry in self._pending_deferred_cache.values():
entry.invalidate()
self._pending_deferred_cache.clear()
class CacheEntry:
__slots__ = ["deferred", "callbacks", "invalidated"]
def __init__(
self, deferred: ObservableDeferred, callbacks: Iterable[Callable[[], None]]
):
self.deferred = deferred
self.callbacks = set(callbacks)
self.invalidated = False
def invalidate(self):
if not self.invalidated:
self.invalidated = True
for callback in self.callbacks:
callback()
self.callbacks.clear()

284
synapse/util/caches/descriptors.py
View File

@ -13,44 +13,24 @@
# 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
import threading
from typing import (
Any,
Callable,
Generic,
Iterable,
MutableMapping,
Optional,
Tuple,
TypeVar,
Union,
cast,
)
from typing import Any, Callable, Generic, Optional, Tuple, TypeVar, Union, cast
from weakref import WeakValueDictionary
from prometheus_client import Gauge
from twisted.internet import defer
from synapse.logging.context import make_deferred_yieldable, preserve_fn
from synapse.util import unwrapFirstError
from synapse.util.async_helpers import ObservableDeferred
from synapse.util.caches.lrucache import LruCache
from synapse.util.caches.treecache import TreeCache, iterate_tree_cache_entry
from . import register_cache
from synapse.util.caches.deferred_cache import DeferredCache
logger = logging.getLogger(__name__)
CacheKey = Union[Tuple, Any]
F = TypeVar("F", bound=Callable[..., Any])
KT = TypeVar("KT")
VT = TypeVar("VT")
class _CachedFunction(Generic[F]):
@ -68,266 +48,6 @@ class _CachedFunction(Generic[F]):
__call__ = None # type: F
cache_pending_metric = Gauge(
"synapse_util_caches_cache_pending",
"Number of lookups currently pending for this cache",
["name"],
)
class _Sentinel(enum.Enum):
# defining a sentinel in this way allows mypy to correctly handle the
# type of a dictionary lookup.
sentinel = object()
class CacheEntry:
__slots__ = ["deferred", "callbacks", "invalidated"]
def __init__(
self, deferred: ObservableDeferred, callbacks: Iterable[Callable[[], None]]
):
self.deferred = deferred
self.callbacks = set(callbacks)
self.invalidated = False
def invalidate(self):
if not self.invalidated:
self.invalidated = True
for callback in self.callbacks:
callback()
self.callbacks.clear()
class DeferredCache(Generic[KT, VT]):
"""Wraps an LruCache, adding support for Deferred results.
It expects that each entry added with set() will be a Deferred; likewise get()
may return an ObservableDeferred.
"""
__slots__ = (
"cache",
"name",
"keylen",
"thread",
"metrics",
"_pending_deferred_cache",
)
def __init__(
self,
name: str,
max_entries: int = 1000,
keylen: int = 1,
tree: bool = False,
iterable: bool = False,
apply_cache_factor_from_config: bool = True,
):
"""
Args:
name: The name of the cache
max_entries: Maximum amount of entries that the cache will hold
keylen: The length of the tuple used as the cache key. Ignored unless
`tree` is True.
tree: Use a TreeCache instead of a dict as the underlying cache type
iterable: If True, count each item in the cached object as an entry,
rather than each cached object
apply_cache_factor_from_config: Whether cache factors specified in the
config file affect `max_entries`
"""
cache_type = TreeCache if tree else dict
# _pending_deferred_cache maps from the key value to a `CacheEntry` object.
self._pending_deferred_cache = (
cache_type()
) # type: MutableMapping[KT, CacheEntry]
# cache is used for completed results and maps to the result itself, rather than
# a Deferred.
self.cache = LruCache(
max_size=max_entries,
keylen=keylen,
cache_type=cache_type,
size_callback=(lambda d: len(d)) if iterable else None,
evicted_callback=self._on_evicted,
apply_cache_factor_from_config=apply_cache_factor_from_config,
)
self.name = name
self.keylen = keylen
self.thread = None # type: Optional[threading.Thread]
self.metrics = register_cache(
"cache",
name,
self.cache,
collect_callback=self._metrics_collection_callback,
)
@property
def max_entries(self):
return self.cache.max_size
def _on_evicted(self, evicted_count):
self.metrics.inc_evictions(evicted_count)
def _metrics_collection_callback(self):
cache_pending_metric.labels(self.name).set(len(self._pending_deferred_cache))
def check_thread(self):
expected_thread = self.thread
if expected_thread is None:
self.thread = threading.current_thread()
else:
if expected_thread is not threading.current_thread():
raise ValueError(
"Cache objects can only be accessed from the main thread"
)
def get(
self,
key: KT,
default=_Sentinel.sentinel,
callback: Optional[Callable[[], None]] = None,
update_metrics: bool = True,
):
"""Looks the key up in the caches.
Args:
key(tuple)
default: What is returned if key is not in the caches. If not
specified then function throws KeyError instead
callback(fn): Gets called when the entry in the cache is invalidated
update_metrics (bool): whether to update the cache hit rate metrics
Returns:
Either an ObservableDeferred or the result itself
"""
callbacks = [callback] if callback else []
val = self._pending_deferred_cache.get(key, _Sentinel.sentinel)
if val is not _Sentinel.sentinel:
val.callbacks.update(callbacks)
if update_metrics:
self.metrics.inc_hits()
return val.deferred
val = self.cache.get(key, _Sentinel.sentinel, callbacks=callbacks)
if val is not _Sentinel.sentinel:
self.metrics.inc_hits()
return val
if update_metrics:
self.metrics.inc_misses()
if default is _Sentinel.sentinel:
raise KeyError()
else:
return default
def set(
self,
key: KT,
value: defer.Deferred,
callback: Optional[Callable[[], None]] = None,
) -> ObservableDeferred:
if not isinstance(value, defer.Deferred):
raise TypeError("not a Deferred")
callbacks = [callback] if callback else []
self.check_thread()
observable = ObservableDeferred(value, consumeErrors=True)
observer = observable.observe()
entry = CacheEntry(deferred=observable, callbacks=callbacks)
existing_entry = self._pending_deferred_cache.pop(key, None)
if existing_entry:
existing_entry.invalidate()
self._pending_deferred_cache[key] = entry
def compare_and_pop():
"""Check if our entry is still the one in _pending_deferred_cache, and
if so, pop it.
Returns true if the entries matched.
"""
existing_entry = self._pending_deferred_cache.pop(key, None)
if existing_entry is entry:
return True
# oops, the _pending_deferred_cache has been updated since
# we started our query, so we are out of date.
#
# Better put back whatever we took out. (We do it this way
# round, rather than peeking into the _pending_deferred_cache
# and then removing on a match, to make the common case faster)
if existing_entry is not None:
self._pending_deferred_cache[key] = existing_entry
return False
def cb(result):
if compare_and_pop():
self.cache.set(key, result, entry.callbacks)
else:
# we're not going to put this entry into the cache, so need
# to make sure that the invalidation callbacks are called.
# That was probably done when _pending_deferred_cache was
# updated, but it's possible that `set` was called without
# `invalidate` being previously called, in which case it may
# not have been. Either way, let's double-check now.
entry.invalidate()
def eb(_fail):
compare_and_pop()
entry.invalidate()
# once the deferred completes, we can move the entry from the
# _pending_deferred_cache to the real cache.
#
observer.addCallbacks(cb, eb)
return observable
def prefill(self, key: KT, value: VT, callback: Callable[[], None] = None):
callbacks = [callback] if callback else []
self.cache.set(key, value, callbacks=callbacks)
def invalidate(self, key):
self.check_thread()
self.cache.pop(key, None)
# if we have a pending lookup for this key, remove it from the
# _pending_deferred_cache, which will (a) stop it being returned
# for future queries and (b) stop it being persisted as a proper entry
# in self.cache.
entry = self._pending_deferred_cache.pop(key, None)
# run the invalidation callbacks now, rather than waiting for the
# deferred to resolve.
if entry:
entry.invalidate()
def invalidate_many(self, key: KT):
self.check_thread()
if not isinstance(key, tuple):
raise TypeError("The cache key must be a tuple not %r" % (type(key),))
self.cache.del_multi(key)
# if we have a pending lookup for this key, remove it from the
# _pending_deferred_cache, as above
entry_dict = self._pending_deferred_cache.pop(cast(KT, key), None)
if entry_dict is not None:
for entry in iterate_tree_cache_entry(entry_dict):
entry.invalidate()
def invalidate_all(self):
self.check_thread()
self.cache.clear()
for entry in self._pending_deferred_cache.values():
entry.invalidate()
self._pending_deferred_cache.clear()
class _CacheDescriptorBase:
def __init__(self, orig: _CachedFunction, num_args, cache_context=False):
self.orig = orig

3
tests/storage/test__base.py
View File

@ -20,7 +20,8 @@ from mock import Mock
from twisted.internet import defer
from synapse.util.async_helpers import ObservableDeferred
from synapse.util.caches.descriptors import DeferredCache, cached
from synapse.util.caches.deferred_cache import DeferredCache
from synapse.util.caches.descriptors import cached
from tests import unittest

2
tests/test_metrics.py
View File

@ -15,7 +15,7 @@
# limitations under the License.
from synapse.metrics import REGISTRY, InFlightGauge, generate_latest
from synapse.util.caches.descriptors import DeferredCache
from synapse.util.caches.deferred_cache import DeferredCache
from tests import unittest

64
tests/util/caches/test_deferred_cache.py Normal file
View File

@ -0,0 +1,64 @@
# -*- coding: utf-8 -*-
# Copyright 2020 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.
import unittest
from functools import partial
from twisted.internet import defer
import synapse.util.caches.deferred_cache
class DeferredCacheTestCase(unittest.TestCase):
def test_invalidate_all(self):
cache = synapse.util.caches.deferred_cache.DeferredCache("testcache")
callback_record = [False, False]
def record_callback(idx):
callback_record[idx] = True
# add a couple of pending entries
d1 = defer.Deferred()
cache.set("key1", d1, partial(record_callback, 0))
d2 = defer.Deferred()
cache.set("key2", d2, partial(record_callback, 1))
# lookup should return observable deferreds
self.assertFalse(cache.get("key1").has_called())
self.assertFalse(cache.get("key2").has_called())
# let one of the lookups complete
d2.callback("result2")
# for now at least, the cache will return real results rather than an
# observabledeferred
self.assertEqual(cache.get("key2"), "result2")
# now do the invalidation
cache.invalidate_all()
# lookup should return none
self.assertIsNone(cache.get("key1", None))
self.assertIsNone(cache.get("key2", None))
# both callbacks should have been callbacked
self.assertTrue(callback_record[0], "Invalidation callback for key1 not called")
self.assertTrue(callback_record[1], "Invalidation callback for key2 not called")
# letting the other lookup complete should do nothing
d1.callback("result1")
self.assertIsNone(cache.get("key1", None))

44
tests/util/caches/test_descriptors.py
View File

@ -14,7 +14,6 @@
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
from functools import partial
import mock
@ -42,49 +41,6 @@ def run_on_reactor():
return make_deferred_yieldable(d)
class DeferredCacheTestCase(unittest.TestCase):
def test_invalidate_all(self):
cache = descriptors.DeferredCache("testcache")
callback_record = [False, False]
def record_callback(idx):
callback_record[idx] = True
# add a couple of pending entries
d1 = defer.Deferred()
cache.set("key1", d1, partial(record_callback, 0))
d2 = defer.Deferred()
cache.set("key2", d2, partial(record_callback, 1))
# lookup should return observable deferreds
self.assertFalse(cache.get("key1").has_called())
self.assertFalse(cache.get("key2").has_called())
# let one of the lookups complete
d2.callback("result2")
# for now at least, the cache will return real results rather than an
# observabledeferred
self.assertEqual(cache.get("key2"), "result2")
# now do the invalidation
cache.invalidate_all()
# lookup should return none
self.assertIsNone(cache.get("key1", None))
self.assertIsNone(cache.get("key2", None))
# both callbacks should have been callbacked
self.assertTrue(callback_record[0], "Invalidation callback for key1 not called")
self.assertTrue(callback_record[1], "Invalidation callback for key2 not called")
# letting the other lookup complete should do nothing
d1.callback("result1")
self.assertIsNone(cache.get("key1", None))
class DescriptorTestCase(unittest.TestCase):
@defer.inlineCallbacks
def test_cache(self):