diff --git a/synapse/util/caches/lrucache.py b/synapse/util/caches/lrucache.py
index 33eae2b7c4..e4804f79e0 100644
--- a/synapse/util/caches/lrucache.py
+++ b/synapse/util/caches/lrucache.py
@@ -18,6 +18,7 @@ from functools import wraps
from typing import Callable, Optional, Type, Union
from synapse.config import cache as cache_config
+from synapse.util.caches import CacheMetric, register_cache
from synapse.util.caches.treecache import TreeCache
@@ -43,27 +44,29 @@ class _Node:
class LruCache:
"""
- 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
+ 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`.
@@ -73,9 +76,13 @@ 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
@@ -94,6 +101,19 @@ class LruCache:
else:
self.max_size = int(max_size)
+ 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
@@ -105,8 +125,8 @@ 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):
@wraps(f)
@@ -169,13 +189,17 @@ class LruCache:
return deleted_len
@synchronized
- def cache_get(key, default=None, callbacks=[]):
+ def cache_get(key, default=None, callbacks=[], update_metrics=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
|
