# # This file is licensed under the Affero General Public License (AGPL) version 3. # # Copyright (C) 2023 New Vector, Ltd # # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU Affero General Public License as # published by the Free Software Foundation, either version 3 of the # License, or (at your option) any later version. # # See the GNU Affero General Public License for more details: # . # # Originally licensed under the Apache License, Version 2.0: # . # # [This file includes modifications made by New Vector Limited] # # import logging import os import re import threading from typing import Any, Callable, Dict, Mapping, Optional import attr from synapse.types import JsonDict from synapse.util.check_dependencies import check_requirements from ._base import Config, ConfigError logger = logging.getLogger(__name__) # The prefix for all cache factor-related environment variables _CACHE_PREFIX = "SYNAPSE_CACHE_FACTOR" # Map from canonicalised cache name to cache. _CACHES: Dict[str, Callable[[float], None]] = {} # a lock on the contents of _CACHES _CACHES_LOCK = threading.Lock() _DEFAULT_FACTOR_SIZE = 0.5 _DEFAULT_EVENT_CACHE_SIZE = "10K" @attr.s(slots=True, auto_attribs=True) class CacheProperties: # The default factor size for all caches default_factor_size: float = float( os.environ.get(_CACHE_PREFIX, _DEFAULT_FACTOR_SIZE) ) resize_all_caches_func: Optional[Callable[[], None]] = None properties = CacheProperties() def _canonicalise_cache_name(cache_name: str) -> str: """Gets the canonical form of the cache name. Since we specify cache names in config and environment variables we need to ignore case and special characters. For example, some caches have asterisks in their name to denote that they're not attached to a particular database function, and these asterisks need to be stripped out """ cache_name = re.sub(r"[^A-Za-z_1-9]", "", cache_name) return cache_name.lower() def add_resizable_cache( cache_name: str, cache_resize_callback: Callable[[float], None] ) -> None: """Register a cache whose size can dynamically change Args: cache_name: A reference to the cache cache_resize_callback: A callback function that will run whenever the cache needs to be resized """ # Some caches have '*' in them which we strip out. cache_name = _canonicalise_cache_name(cache_name) # sometimes caches are initialised from background threads, so we need to make # sure we don't conflict with another thread running a resize operation with _CACHES_LOCK: _CACHES[cache_name] = cache_resize_callback # Ensure all loaded caches are sized appropriately # # This method should only run once the config has been read, # as it uses values read from it if properties.resize_all_caches_func: properties.resize_all_caches_func() class CacheConfig(Config): section = "caches" _environ: Mapping[str, str] = os.environ event_cache_size: int cache_factors: Dict[str, float] global_factor: float track_memory_usage: bool expiry_time_msec: Optional[int] sync_response_cache_duration: int @staticmethod def reset() -> None: """Resets the caches to their defaults. Used for tests.""" properties.default_factor_size = float( os.environ.get(_CACHE_PREFIX, _DEFAULT_FACTOR_SIZE) ) properties.resize_all_caches_func = None with _CACHES_LOCK: _CACHES.clear() def read_config(self, config: JsonDict, **kwargs: Any) -> None: """Populate this config object with values from `config`. This method does NOT resize existing or future caches: use `resize_all_caches`. We use two separate methods so that we can reject bad config before applying it. """ self.event_cache_size = self.parse_size( config.get("event_cache_size", _DEFAULT_EVENT_CACHE_SIZE) ) self.cache_factors = {} cache_config = config.get("caches") or {} self.global_factor = cache_config.get("global_factor", _DEFAULT_FACTOR_SIZE) if type(self.global_factor) not in (int, float): raise ConfigError("caches.global_factor must be a number.") # Load cache factors from the config individual_factors = cache_config.get("per_cache_factors") or {} if not isinstance(individual_factors, dict): raise ConfigError("caches.per_cache_factors must be a dictionary") # Canonicalise the cache names *before* updating with the environment # variables. individual_factors = { _canonicalise_cache_name(key): val for key, val in individual_factors.items() } # Override factors from environment if necessary individual_factors.update( { _canonicalise_cache_name(key[len(_CACHE_PREFIX) + 1 :]): float(val) for key, val in self._environ.items() if key.startswith(_CACHE_PREFIX + "_") } ) for cache, factor in individual_factors.items(): if type(factor) not in (int, float): raise ConfigError( "caches.per_cache_factors.%s must be a number" % (cache,) ) self.cache_factors[cache] = factor self.track_memory_usage = cache_config.get("track_memory_usage", False) if self.track_memory_usage: check_requirements("cache-memory") expire_caches = cache_config.get("expire_caches", True) cache_entry_ttl = cache_config.get("cache_entry_ttl", "30m") if expire_caches: self.expiry_time_msec = self.parse_duration(cache_entry_ttl) else: self.expiry_time_msec = None # Backwards compatibility support for the now-removed "expiry_time" config flag. expiry_time = cache_config.get("expiry_time") if expiry_time and expire_caches: logger.warning( "You have set two incompatible options, expiry_time and expire_caches. Please only use the " "expire_caches and cache_entry_ttl options and delete the expiry_time option as it is " "deprecated." ) if expiry_time: logger.warning( "Expiry_time is a deprecated option, please use the expire_caches and cache_entry_ttl options " "instead." ) self.expiry_time_msec = self.parse_duration(expiry_time) self.cache_autotuning = cache_config.get("cache_autotuning") if self.cache_autotuning: max_memory_usage = self.cache_autotuning.get("max_cache_memory_usage") self.cache_autotuning["max_cache_memory_usage"] = self.parse_size( max_memory_usage ) target_mem_size = self.cache_autotuning.get("target_cache_memory_usage") self.cache_autotuning["target_cache_memory_usage"] = self.parse_size( target_mem_size ) min_cache_ttl = self.cache_autotuning.get("min_cache_ttl") self.cache_autotuning["min_cache_ttl"] = self.parse_duration(min_cache_ttl) self.sync_response_cache_duration = self.parse_duration( cache_config.get("sync_response_cache_duration", "2m") ) def resize_all_caches(self) -> None: """Ensure all cache sizes are up-to-date. For each cache, run the mapped callback function with either a specific cache factor or the default, global one. """ # Set the global factor size, so that new caches are appropriately sized. properties.default_factor_size = self.global_factor # Store this function so that it can be called from other classes without # needing an instance of CacheConfig properties.resize_all_caches_func = self.resize_all_caches # block other threads from modifying _CACHES while we iterate it. with _CACHES_LOCK: for cache_name, callback in _CACHES.items(): new_factor = self.cache_factors.get(cache_name, self.global_factor) callback(new_factor)