diff options
Diffstat (limited to 'synapse/util/caches/lrucache.py')
| -rw-r--r-- | synapse/util/caches/lrucache.py | 138 |
1 files changed, 114 insertions, 24 deletions
diff --git a/synapse/util/caches/lrucache.py b/synapse/util/caches/lrucache.py index 4bc1a67b58..60bb6ff642 100644 --- a/synapse/util/caches/lrucache.py +++ b/synapse/util/caches/lrucache.py @@ -15,11 +15,35 @@ import threading from functools import wraps -from typing import Callable, Optional, Type, Union +from typing import ( + Any, + Callable, + Generic, + Iterable, + Optional, + Type, + TypeVar, + Union, + cast, + overload, +) + +from typing_extensions import Literal from synapse.config import cache as cache_config +from synapse.util.caches import CacheMetric, register_cache from synapse.util.caches.treecache import TreeCache +# Function type: the type used for invalidation callbacks +FT = TypeVar("FT", bound=Callable[..., Any]) + +# Key and Value type for the cache +KT = TypeVar("KT") +VT = TypeVar("VT") + +# a general type var, distinct from either KT or VT +T = TypeVar("T") + def enumerate_leaves(node, depth): if depth == 0: @@ -41,30 +65,33 @@ class _Node: self.callbacks = callbacks -class LruCache: +class LruCache(Generic[KT, VT]): """ - Least-recently-used cache. + Least-recently-used cache, supporting prometheus metrics and invalidation callbacks. + Supports del_multi only if cache_type=TreeCache If cache_type=TreeCache, all keys must be tuples. - - Can also set callbacks on objects when getting/setting which are fired - when that key gets invalidated/evicted. """ def __init__( self, max_size: int, + cache_name: Optional[str] = None, keylen: int = 1, cache_type: Type[Union[dict, TreeCache]] = dict, size_callback: Optional[Callable] = None, - evicted_callback: Optional[Callable] = None, + metrics_collection_callback: Optional[Callable[[], None]] = None, apply_cache_factor_from_config: bool = True, ): """ Args: max_size: The maximum amount of entries the cache can hold - keylen: The length of the tuple used as the cache key + cache_name: The name of this cache, for the prometheus metrics. If unset, + no metrics will be reported on this cache. + + keylen: The length of the tuple used as the cache key. Ignored unless + cache_type is `TreeCache`. cache_type (type): type of underlying cache to be used. Typically one of dict @@ -72,9 +99,13 @@ class LruCache: size_callback (func(V) -> int | None): - evicted_callback (func(int)|None): - if not None, called on eviction with the size of the evicted - entry + metrics_collection_callback: + metrics collection callback. This is called early in the metrics + collection process, before any of the metrics registered with the + prometheus Registry are collected, so can be used to update any dynamic + metrics. + + Ignored if cache_name is None. apply_cache_factor_from_config (bool): If true, `max_size` will be multiplied by a cache factor derived from the homeserver config @@ -93,6 +124,23 @@ class LruCache: else: self.max_size = int(max_size) + # register_cache might call our "set_cache_factor" callback; there's nothing to + # do yet when we get resized. + self._on_resize = None # type: Optional[Callable[[],None]] + + if cache_name is not None: + metrics = register_cache( + "lru_cache", + cache_name, + self, + collect_callback=metrics_collection_callback, + ) # type: Optional[CacheMetric] + else: + metrics = None + + # this is exposed for access from outside this class + self.metrics = metrics + list_root = _Node(None, None, None, None) list_root.next_node = list_root list_root.prev_node = list_root @@ -104,16 +152,16 @@ class LruCache: todelete = list_root.prev_node evicted_len = delete_node(todelete) cache.pop(todelete.key, None) - if evicted_callback: - evicted_callback(evicted_len) + if metrics: + metrics.inc_evictions(evicted_len) - def synchronized(f): + def synchronized(f: FT) -> FT: @wraps(f) def inner(*args, **kwargs): with lock: return f(*args, **kwargs) - return inner + return cast(FT, inner) cached_cache_len = [0] if size_callback is not None: @@ -167,18 +215,45 @@ class LruCache: node.callbacks.clear() return deleted_len + @overload + def cache_get( + key: KT, + default: Literal[None] = None, + callbacks: Iterable[Callable[[], None]] = ..., + update_metrics: bool = ..., + ) -> Optional[VT]: + ... + + @overload + def cache_get( + key: KT, + default: T, + callbacks: Iterable[Callable[[], None]] = ..., + update_metrics: bool = ..., + ) -> Union[T, VT]: + ... + @synchronized - def cache_get(key, default=None, callbacks=[]): + def cache_get( + key: KT, + default: Optional[T] = None, + callbacks: Iterable[Callable[[], None]] = [], + update_metrics: bool = True, + ): node = cache.get(key, None) if node is not None: move_node_to_front(node) node.callbacks.update(callbacks) + if update_metrics and metrics: + metrics.inc_hits() return node.value else: + if update_metrics and metrics: + metrics.inc_misses() return default @synchronized - def cache_set(key, value, callbacks=[]): + def cache_set(key: KT, value: VT, callbacks: Iterable[Callable[[], None]] = []): node = cache.get(key, None) if node is not None: # We sometimes store large objects, e.g. dicts, which cause @@ -207,7 +282,7 @@ class LruCache: evict() @synchronized - def cache_set_default(key, value): + def cache_set_default(key: KT, value: VT) -> VT: node = cache.get(key, None) if node is not None: return node.value @@ -216,8 +291,16 @@ class LruCache: evict() return value + @overload + def cache_pop(key: KT, default: Literal[None] = None) -> Optional[VT]: + ... + + @overload + def cache_pop(key: KT, default: T) -> Union[T, VT]: + ... + @synchronized - def cache_pop(key, default=None): + def cache_pop(key: KT, default: Optional[T] = None): node = cache.get(key, None) if node: delete_node(node) @@ -227,18 +310,18 @@ class LruCache: return default @synchronized - def cache_del_multi(key): + def cache_del_multi(key: KT) -> None: """ This will only work if constructed with cache_type=TreeCache """ popped = cache.pop(key) if popped is None: return - for leaf in enumerate_leaves(popped, keylen - len(key)): + for leaf in enumerate_leaves(popped, keylen - len(cast(tuple, key))): delete_node(leaf) @synchronized - def cache_clear(): + def cache_clear() -> None: list_root.next_node = list_root list_root.prev_node = list_root for node in cache.values(): @@ -249,15 +332,21 @@ class LruCache: cached_cache_len[0] = 0 @synchronized - def cache_contains(key): + def cache_contains(key: KT) -> bool: return key in cache self.sentinel = object() + + # make sure that we clear out any excess entries after we get resized. self._on_resize = evict + self.get = cache_get self.set = cache_set self.setdefault = cache_set_default self.pop = cache_pop + # `invalidate` is exposed for consistency with DeferredCache, so that it can be + # invalidated by the cache invalidation replication stream. + self.invalidate = cache_pop if cache_type is TreeCache: self.del_multi = cache_del_multi self.len = synchronized(cache_len) @@ -301,6 +390,7 @@ class LruCache: new_size = int(self._original_max_size * factor) if new_size != self.max_size: self.max_size = new_size - self._on_resize() + if self._on_resize: + self._on_resize() return True return False |