225 lines
8.1 KiB
Python
225 lines
8.1 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 Any, Callable, Dict, Optional
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import attr
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from synapse.types import JsonDict
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from synapse.util.check_dependencies import 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 whose 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 run 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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event_cache_size: int
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cache_factors: Dict[str, float]
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global_factor: float
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track_memory_usage: bool
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expiry_time_msec: Optional[int]
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sync_response_cache_duration: int
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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 read_config(self, config: JsonDict, **kwargs: Any) -> None:
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"""Populate this config object with values from `config`.
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This method does NOT resize existing or future caches: use `resize_all_caches`.
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We use two separate methods so that we can reject bad config before applying it.
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"""
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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 = {}
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cache_config = config.get("caches") or {}
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self.global_factor = cache_config.get("global_factor", _DEFAULT_FACTOR_SIZE)
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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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# 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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check_requirements("cache_memory")
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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 = 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.cache_autotuning = cache_config.get("cache_autotuning")
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if self.cache_autotuning:
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max_memory_usage = self.cache_autotuning.get("max_cache_memory_usage")
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self.cache_autotuning["max_cache_memory_usage"] = self.parse_size(
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max_memory_usage
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)
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target_mem_size = self.cache_autotuning.get("target_cache_memory_usage")
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self.cache_autotuning["target_cache_memory_usage"] = self.parse_size(
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target_mem_size
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)
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min_cache_ttl = self.cache_autotuning.get("min_cache_ttl")
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self.cache_autotuning["min_cache_ttl"] = self.parse_duration(min_cache_ttl)
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self.sync_response_cache_duration = self.parse_duration(
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cache_config.get("sync_response_cache_duration", "2m")
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)
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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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# Set the global factor size, so that new caches are appropriately sized.
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properties.default_factor_size = self.global_factor
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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 CacheConfig
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properties.resize_all_caches_func = self.resize_all_caches
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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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