mirror of
https://git.anonymousland.org/anonymousland/synapse-product.git
synced 2024-12-18 09:44:21 -05:00
293 lines
9.9 KiB
Python
293 lines
9.9 KiB
Python
# -*- 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()
|