diff options
Diffstat (limited to 'synapse/util/caches/lrucache.py')
| -rw-r--r-- | synapse/util/caches/lrucache.py | 90 |
1 files changed, 88 insertions, 2 deletions
diff --git a/synapse/util/caches/lrucache.py b/synapse/util/caches/lrucache.py index 31f41fec82..b3bdedb04c 100644 --- a/synapse/util/caches/lrucache.py +++ b/synapse/util/caches/lrucache.py @@ -25,8 +25,10 @@ from typing import ( Collection, Dict, Generic, + Iterable, List, Optional, + Tuple, Type, TypeVar, Union, @@ -44,7 +46,11 @@ from synapse.metrics.background_process_metrics import wrap_as_background_proces from synapse.metrics.jemalloc import get_jemalloc_stats from synapse.util import Clock, caches from synapse.util.caches import CacheMetric, EvictionReason, register_cache -from synapse.util.caches.treecache import TreeCache, iterate_tree_cache_entry +from synapse.util.caches.treecache import ( + TreeCache, + iterate_tree_cache_entry, + iterate_tree_cache_items, +) from synapse.util.linked_list import ListNode if TYPE_CHECKING: @@ -537,6 +543,7 @@ class LruCache(Generic[KT, VT]): default: Literal[None] = None, callbacks: Collection[Callable[[], None]] = ..., update_metrics: bool = ..., + update_last_access: bool = ..., ) -> Optional[VT]: ... @@ -546,6 +553,7 @@ class LruCache(Generic[KT, VT]): default: T, callbacks: Collection[Callable[[], None]] = ..., update_metrics: bool = ..., + update_last_access: bool = ..., ) -> Union[T, VT]: ... @@ -555,10 +563,27 @@ class LruCache(Generic[KT, VT]): default: Optional[T] = None, callbacks: Collection[Callable[[], None]] = (), update_metrics: bool = True, + update_last_access: bool = True, ) -> Union[None, T, VT]: + """Look up a key in the cache + + Args: + key + default + callbacks: A collection of callbacks that will fire when the + node is removed from the cache (either due to invalidation + or expiry). + update_metrics: Whether to update the hit rate metrics + update_last_access: Whether to update the last access metrics + on a node if successfully fetched. These metrics are used + to determine when to remove the node from the cache. Set + to False if this fetch should *not* prevent a node from + being expired. + """ node = cache.get(key, None) if node is not None: - move_node_to_front(node) + if update_last_access: + move_node_to_front(node) node.add_callbacks(callbacks) if update_metrics and metrics: metrics.inc_hits() @@ -568,6 +593,65 @@ class LruCache(Generic[KT, VT]): metrics.inc_misses() return default + @overload + def cache_get_multi( + key: tuple, + default: Literal[None] = None, + update_metrics: bool = True, + ) -> Union[None, Iterable[Tuple[KT, VT]]]: + ... + + @overload + def cache_get_multi( + key: tuple, + default: T, + update_metrics: bool = True, + ) -> Union[T, Iterable[Tuple[KT, VT]]]: + ... + + @synchronized + def cache_get_multi( + key: tuple, + default: Optional[T] = None, + update_metrics: bool = True, + ) -> Union[None, T, Iterable[Tuple[KT, VT]]]: + """Returns a generator yielding all entries under the given key. + + Can only be used if backed by a tree cache. + + Example: + + cache = LruCache(10, cache_type=TreeCache) + cache[(1, 1)] = "a" + cache[(1, 2)] = "b" + cache[(2, 1)] = "c" + + items = cache.get_multi((1,)) + assert list(items) == [((1, 1), "a"), ((1, 2), "b")] + + Returns: + Either default if the key doesn't exist, or a generator of the + key/value pairs. + """ + + assert isinstance(cache, TreeCache) + + node = cache.get(key, None) + if node is not None: + if update_metrics and metrics: + metrics.inc_hits() + + # We store entries in the `TreeCache` with values of type `_Node`, + # which we need to unwrap. + return ( + (full_key, lru_node.value) + for full_key, lru_node in iterate_tree_cache_items(key, node) + ) + else: + if update_metrics and metrics: + metrics.inc_misses() + return default + @synchronized def cache_set( key: KT, value: VT, callbacks: Collection[Callable[[], None]] = () @@ -674,6 +758,8 @@ class LruCache(Generic[KT, VT]): self.setdefault = cache_set_default self.pop = cache_pop self.del_multi = cache_del_multi + if cache_type is TreeCache: + self.get_multi = cache_get_multi # `invalidate` is exposed for consistency with DeferredCache, so that it can be # invalidated by the cache invalidation replication stream. self.invalidate = cache_del_multi |