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@@ -18,6 +18,7 @@ from functools import wraps
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from typing import Callable, Optional, Type, Union
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from synapse.config import cache as cache_config
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+from synapse.util.caches import CacheMetric, register_cache
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from synapse.util.caches.treecache import TreeCache
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@@ -43,27 +44,29 @@ class _Node:
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class LruCache:
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"""
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- Least-recently-used cache.
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+ Least-recently-used cache, supporting prometheus metrics and invalidation callbacks.
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+
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Supports del_multi only if cache_type=TreeCache
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If cache_type=TreeCache, all keys must be tuples.
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-
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- Can also set callbacks on objects when getting/setting which are fired
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- when that key gets invalidated/evicted.
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"""
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def __init__(
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self,
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max_size: int,
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+ cache_name: Optional[str] = None,
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keylen: int = 1,
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cache_type: Type[Union[dict, TreeCache]] = dict,
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size_callback: Optional[Callable] = None,
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- evicted_callback: Optional[Callable] = None,
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+ metrics_collection_callback: Optional[Callable[[], None]] = None,
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apply_cache_factor_from_config: bool = True,
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):
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"""
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Args:
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max_size: The maximum amount of entries the cache can hold
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+ cache_name: The name of this cache, for the prometheus metrics. If unset,
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+ no metrics will be reported on this cache.
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+
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keylen: The length of the tuple used as the cache key. Ignored unless
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cache_type is `TreeCache`.
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@@ -73,9 +76,13 @@ class LruCache:
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size_callback (func(V) -> int | None):
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- evicted_callback (func(int)|None):
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- if not None, called on eviction with the size of the evicted
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- entry
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+ metrics_collection_callback:
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+ metrics collection callback. This is called early in the metrics
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+ collection process, before any of the metrics registered with the
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+ prometheus Registry are collected, so can be used to update any dynamic
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+ metrics.
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+
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+ Ignored if cache_name is None.
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apply_cache_factor_from_config (bool): If true, `max_size` will be
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multiplied by a cache factor derived from the homeserver config
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@@ -94,6 +101,19 @@ class LruCache:
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else:
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self.max_size = int(max_size)
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+ if cache_name is not None:
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+ metrics = register_cache(
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+ "lru_cache",
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+ cache_name,
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+ self,
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+ collect_callback=metrics_collection_callback,
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+ ) # type: Optional[CacheMetric]
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+ else:
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+ metrics = None
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+
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+ # this is exposed for access from outside this class
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+ self.metrics = metrics
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+
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list_root = _Node(None, None, None, None)
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list_root.next_node = list_root
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list_root.prev_node = list_root
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@@ -105,8 +125,8 @@ class LruCache:
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todelete = list_root.prev_node
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evicted_len = delete_node(todelete)
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cache.pop(todelete.key, None)
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- if evicted_callback:
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- evicted_callback(evicted_len)
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+ if metrics:
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+ metrics.inc_evictions(evicted_len)
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def synchronized(f):
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@wraps(f)
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@@ -169,13 +189,17 @@ class LruCache:
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return deleted_len
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@synchronized
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- def cache_get(key, default=None, callbacks=[]):
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+ def cache_get(key, default=None, callbacks=[], update_metrics=True):
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node = cache.get(key, None)
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if node is not None:
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move_node_to_front(node)
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node.callbacks.update(callbacks)
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+ if update_metrics and metrics:
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+ metrics.inc_hits()
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return node.value
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else:
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+ if update_metrics and metrics:
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+ metrics.inc_misses()
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return default
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@synchronized
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