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https://mau.dev/maunium/synapse.git
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f85b6ca494
Instead of calculating the size of the cache repeatedly, which can take a long time now that it can use a callback, instead cache the size and update that on insertion and deletion. This requires changing the cache descriptors to have two caches, one for pending deferreds and the other for the actual values. There's no reason to evict from the pending deferreds as they won't take up any more memory.
139 lines
4.2 KiB
Python
139 lines
4.2 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2015, 2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from synapse.util.caches import register_cache
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from collections import OrderedDict
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import logging
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logger = logging.getLogger(__name__)
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class ExpiringCache(object):
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def __init__(self, cache_name, clock, max_len=0, expiry_ms=0,
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reset_expiry_on_get=False, iterable=False):
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"""
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Args:
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cache_name (str): Name of this cache, used for logging.
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clock (Clock)
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max_len (int): Max size of dict. If the dict grows larger than this
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then the oldest items get automatically evicted. Default is 0,
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which indicates there is no max limit.
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expiry_ms (int): How long before an item is evicted from the cache
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in milliseconds. Default is 0, indicating items never get
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evicted based on time.
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reset_expiry_on_get (bool): If true, will reset the expiry time for
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an item on access. Defaults to False.
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iterable (bool): If true, the size is calculated by summing the
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sizes of all entries, rather than the number of entries.
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"""
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self._cache_name = cache_name
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self._clock = clock
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self._max_len = max_len
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self._expiry_ms = expiry_ms
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self._reset_expiry_on_get = reset_expiry_on_get
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self._cache = OrderedDict()
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self.metrics = register_cache(cache_name, self)
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self.iterable = iterable
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self._size_estimate = 0
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def start(self):
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if not self._expiry_ms:
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# Don't bother starting the loop if things never expire
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return
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def f():
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self._prune_cache()
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self._clock.looping_call(f, self._expiry_ms / 2)
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def __setitem__(self, key, value):
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now = self._clock.time_msec()
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self._cache[key] = _CacheEntry(now, value)
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if self.iterable:
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self._size_estimate += len(value)
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# Evict if there are now too many items
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while self._max_len and len(self) > self._max_len:
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_key, value = self._cache.popitem(last=False)
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if self.iterable:
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self._size_estimate -= len(value.value)
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def __getitem__(self, key):
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try:
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entry = self._cache[key]
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self.metrics.inc_hits()
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except KeyError:
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self.metrics.inc_misses()
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raise
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if self._reset_expiry_on_get:
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entry.time = self._clock.time_msec()
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return entry.value
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def get(self, key, default=None):
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try:
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return self[key]
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except KeyError:
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return default
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def _prune_cache(self):
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if not self._expiry_ms:
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# zero expiry time means don't expire. This should never get called
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# since we have this check in start too.
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return
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begin_length = len(self)
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now = self._clock.time_msec()
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keys_to_delete = set()
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for key, cache_entry in self._cache.items():
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if now - cache_entry.time > self._expiry_ms:
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keys_to_delete.add(key)
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for k in keys_to_delete:
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value = self._cache.pop(k)
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if self.iterable:
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self._size_estimate -= len(value.value)
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logger.debug(
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"[%s] _prune_cache before: %d, after len: %d",
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self._cache_name, begin_length, len(self)
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)
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def __len__(self):
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if self.iterable:
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return self._size_estimate
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else:
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return len(self._cache)
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class _CacheEntry(object):
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def __init__(self, time, value):
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self.time = time
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self.value = value
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