274 lines
10 KiB
Python
274 lines
10 KiB
Python
# Copyright 2019-2021 Matrix.org Foundation C.I.C.
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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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import logging
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import os
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import re
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import threading
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from typing import Callable, Dict, Optional
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import attr
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from synapse.python_dependencies import DependencyException, check_requirements
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from ._base import Config, ConfigError
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logger = logging.getLogger(__name__)
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# The prefix for all cache factor-related environment variables
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_CACHE_PREFIX = "SYNAPSE_CACHE_FACTOR"
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# Map from canonicalised cache name to cache.
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_CACHES: Dict[str, Callable[[float], None]] = {}
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# a lock on the contents of _CACHES
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_CACHES_LOCK = threading.Lock()
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_DEFAULT_FACTOR_SIZE = 0.5
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_DEFAULT_EVENT_CACHE_SIZE = "10K"
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@attr.s(slots=True, auto_attribs=True)
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class CacheProperties:
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# The default factor size for all caches
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default_factor_size: float = float(
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os.environ.get(_CACHE_PREFIX, _DEFAULT_FACTOR_SIZE)
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)
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resize_all_caches_func: Optional[Callable[[], None]] = None
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properties = CacheProperties()
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def _canonicalise_cache_name(cache_name: str) -> str:
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"""Gets the canonical form of the cache name.
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Since we specify cache names in config and environment variables we need to
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ignore case and special characters. For example, some caches have asterisks
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in their name to denote that they're not attached to a particular database
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function, and these asterisks need to be stripped out
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"""
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cache_name = re.sub(r"[^A-Za-z_1-9]", "", cache_name)
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return cache_name.lower()
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def add_resizable_cache(
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cache_name: str, cache_resize_callback: Callable[[float], None]
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) -> None:
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"""Register a cache that's size can dynamically change
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Args:
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cache_name: A reference to the cache
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cache_resize_callback: A callback function that will be ran whenever
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the cache needs to be resized
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"""
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# Some caches have '*' in them which we strip out.
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cache_name = _canonicalise_cache_name(cache_name)
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# sometimes caches are initialised from background threads, so we need to make
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# sure we don't conflict with another thread running a resize operation
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with _CACHES_LOCK:
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_CACHES[cache_name] = cache_resize_callback
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# Ensure all loaded caches are sized appropriately
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#
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# This method should only run once the config has been read,
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# as it uses values read from it
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if properties.resize_all_caches_func:
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properties.resize_all_caches_func()
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class CacheConfig(Config):
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section = "caches"
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_environ = os.environ
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@staticmethod
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def reset() -> None:
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"""Resets the caches to their defaults. Used for tests."""
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properties.default_factor_size = float(
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os.environ.get(_CACHE_PREFIX, _DEFAULT_FACTOR_SIZE)
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)
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properties.resize_all_caches_func = None
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with _CACHES_LOCK:
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_CACHES.clear()
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def generate_config_section(self, **kwargs) -> str:
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return """\
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## Caching ##
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# Caching can be configured through the following options.
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#
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# A cache 'factor' is a multiplier that can be applied to each of
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# Synapse's caches in order to increase or decrease the maximum
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# number of entries that can be stored.
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# The number of events to cache in memory. Not affected by
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# caches.global_factor.
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#
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#event_cache_size: 10K
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caches:
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# Controls the global cache factor, which is the default cache factor
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# for all caches if a specific factor for that cache is not otherwise
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# set.
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#
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# This can also be set by the "SYNAPSE_CACHE_FACTOR" environment
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# variable. Setting by environment variable takes priority over
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# setting through the config file.
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#
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# Defaults to 0.5, which will half the size of all caches.
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#
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#global_factor: 1.0
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# A dictionary of cache name to cache factor for that individual
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# cache. Overrides the global cache factor for a given cache.
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#
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# These can also be set through environment variables comprised
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# of "SYNAPSE_CACHE_FACTOR_" + the name of the cache in capital
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# letters and underscores. Setting by environment variable
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# takes priority over setting through the config file.
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# Ex. SYNAPSE_CACHE_FACTOR_GET_USERS_WHO_SHARE_ROOM_WITH_USER=2.0
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#
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# Some caches have '*' and other characters that are not
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# alphanumeric or underscores. These caches can be named with or
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# without the special characters stripped. For example, to specify
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# the cache factor for `*stateGroupCache*` via an environment
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# variable would be `SYNAPSE_CACHE_FACTOR_STATEGROUPCACHE=2.0`.
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#
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per_cache_factors:
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#get_users_who_share_room_with_user: 2.0
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# Controls whether cache entries are evicted after a specified time
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# period. Defaults to true. Uncomment to disable this feature.
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#
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#expire_caches: false
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# If expire_caches is enabled, this flag controls how long an entry can
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# be in a cache without having been accessed before being evicted.
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# Defaults to 30m. Uncomment to set a different time to live for cache entries.
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#
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#cache_entry_ttl: 30m
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# Controls how long the results of a /sync request are cached for after
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# a successful response is returned. A higher duration can help clients with
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# intermittent connections, at the cost of higher memory usage.
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#
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# By default, this is zero, which means that sync responses are not cached
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# at all.
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#
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#sync_response_cache_duration: 2m
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"""
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def read_config(self, config, **kwargs) -> None:
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self.event_cache_size = self.parse_size(
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config.get("event_cache_size", _DEFAULT_EVENT_CACHE_SIZE)
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)
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self.cache_factors: Dict[str, float] = {}
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cache_config = config.get("caches") or {}
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self.global_factor = cache_config.get(
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"global_factor", properties.default_factor_size
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)
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if not isinstance(self.global_factor, (int, float)):
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raise ConfigError("caches.global_factor must be a number.")
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# Set the global one so that it's reflected in new caches
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properties.default_factor_size = self.global_factor
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# Load cache factors from the config
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individual_factors = cache_config.get("per_cache_factors") or {}
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if not isinstance(individual_factors, dict):
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raise ConfigError("caches.per_cache_factors must be a dictionary")
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# Canonicalise the cache names *before* updating with the environment
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# variables.
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individual_factors = {
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_canonicalise_cache_name(key): val
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for key, val in individual_factors.items()
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}
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# Override factors from environment if necessary
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individual_factors.update(
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{
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_canonicalise_cache_name(key[len(_CACHE_PREFIX) + 1 :]): float(val)
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for key, val in self._environ.items()
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if key.startswith(_CACHE_PREFIX + "_")
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}
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)
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for cache, factor in individual_factors.items():
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if not isinstance(factor, (int, float)):
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raise ConfigError(
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"caches.per_cache_factors.%s must be a number" % (cache,)
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)
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self.cache_factors[cache] = factor
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self.track_memory_usage = cache_config.get("track_memory_usage", False)
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if self.track_memory_usage:
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try:
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check_requirements("cache_memory")
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except DependencyException as e:
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raise ConfigError(
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e.message # noqa: B306, DependencyException.message is a property
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)
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expire_caches = cache_config.get("expire_caches", True)
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cache_entry_ttl = cache_config.get("cache_entry_ttl", "30m")
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if expire_caches:
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self.expiry_time_msec: Optional[int] = self.parse_duration(cache_entry_ttl)
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else:
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self.expiry_time_msec = None
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# Backwards compatibility support for the now-removed "expiry_time" config flag.
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expiry_time = cache_config.get("expiry_time")
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if expiry_time and expire_caches:
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logger.warning(
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"You have set two incompatible options, expiry_time and expire_caches. Please only use the "
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"expire_caches and cache_entry_ttl options and delete the expiry_time option as it is "
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"deprecated."
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)
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if expiry_time:
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logger.warning(
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"Expiry_time is a deprecated option, please use the expire_caches and cache_entry_ttl options "
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"instead."
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)
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self.expiry_time_msec = self.parse_duration(expiry_time)
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self.sync_response_cache_duration = self.parse_duration(
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cache_config.get("sync_response_cache_duration", 0)
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)
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# Resize all caches (if necessary) with the new factors we've loaded
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self.resize_all_caches()
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# Store this function so that it can be called from other classes without
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# needing an instance of Config
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properties.resize_all_caches_func = self.resize_all_caches
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def resize_all_caches(self) -> None:
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"""Ensure all cache sizes are up to date
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For each cache, run the mapped callback function with either
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a specific cache factor or the default, global one.
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"""
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# block other threads from modifying _CACHES while we iterate it.
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with _CACHES_LOCK:
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for cache_name, callback in _CACHES.items():
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new_factor = self.cache_factors.get(cache_name, self.global_factor)
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callback(new_factor)
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