diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index af65bfe7b8..bf3a66eae4 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -75,6 +75,7 @@ class Cache(object):
self.cache = LruCache(
max_size=max_entries, keylen=keylen, cache_type=cache_type,
size_callback=(lambda d: len(d)) if iterable else None,
+ evicted_callback=self._on_evicted,
)
self.name = name
@@ -83,6 +84,9 @@ class Cache(object):
self.thread = None
self.metrics = register_cache(name, self.cache)
+ def _on_evicted(self, evicted_count):
+ self.metrics.inc_evictions(evicted_count)
+
def check_thread(self):
expected_thread = self.thread
if expected_thread is None:
diff --git a/synapse/util/caches/dictionary_cache.py b/synapse/util/caches/dictionary_cache.py
index d4105822b3..1709e8b429 100644
--- a/synapse/util/caches/dictionary_cache.py
+++ b/synapse/util/caches/dictionary_cache.py
@@ -132,9 +132,13 @@ class DictionaryCache(object):
self._update_or_insert(key, value, known_absent)
def _update_or_insert(self, key, value, known_absent):
- entry = self.cache.setdefault(key, DictionaryEntry(False, set(), {}))
+ # We pop and reinsert as we need to tell the cache the size may have
+ # changed
+
+ entry = self.cache.pop(key, DictionaryEntry(False, set(), {}))
entry.value.update(value)
entry.known_absent.update(known_absent)
+ self.cache[key] = entry
def _insert(self, key, value, known_absent):
self.cache[key] = DictionaryEntry(True, known_absent, value)
diff --git a/synapse/util/caches/expiringcache.py b/synapse/util/caches/expiringcache.py
index 6ad53a6390..0aa103eecb 100644
--- a/synapse/util/caches/expiringcache.py
+++ b/synapse/util/caches/expiringcache.py
@@ -79,7 +79,11 @@ class ExpiringCache(object):
while self._max_len and len(self) > self._max_len:
_key, value = self._cache.popitem(last=False)
if self.iterable:
- self._size_estimate -= len(value.value)
+ removed_len = len(value.value)
+ self.metrics.inc_evictions(removed_len)
+ self._size_estimate -= removed_len
+ else:
+ self.metrics.inc_evictions()
def __getitem__(self, key):
try:
diff --git a/synapse/util/caches/lrucache.py b/synapse/util/caches/lrucache.py
index cf5fbb679c..1c5a982094 100644
--- a/synapse/util/caches/lrucache.py
+++ b/synapse/util/caches/lrucache.py
@@ -49,7 +49,24 @@ class LruCache(object):
Can also set callbacks on objects when getting/setting which are fired
when that key gets invalidated/evicted.
"""
- def __init__(self, max_size, keylen=1, cache_type=dict, size_callback=None):
+ def __init__(self, max_size, keylen=1, cache_type=dict, size_callback=None,
+ evicted_callback=None):
+ """
+ Args:
+ max_size (int):
+
+ keylen (int):
+
+ cache_type (type):
+ type of underlying cache to be used. Typically one of dict
+ or TreeCache.
+
+ size_callback (func(V) -> int | None):
+
+ evicted_callback (func(int)|None):
+ if not None, called on eviction with the size of the evicted
+ entry
+ """
cache = cache_type()
self.cache = cache # Used for introspection.
list_root = _Node(None, None, None, None)
@@ -61,8 +78,10 @@ class LruCache(object):
def evict():
while cache_len() > max_size:
todelete = list_root.prev_node
- delete_node(todelete)
+ evicted_len = delete_node(todelete)
cache.pop(todelete.key, None)
+ if evicted_callback:
+ evicted_callback(evicted_len)
def synchronized(f):
@wraps(f)
@@ -111,12 +130,15 @@ class LruCache(object):
prev_node.next_node = next_node
next_node.prev_node = prev_node
+ deleted_len = 1
if size_callback:
- cached_cache_len[0] -= size_callback(node.value)
+ deleted_len = size_callback(node.value)
+ cached_cache_len[0] -= deleted_len
for cb in node.callbacks:
cb()
node.callbacks.clear()
+ return deleted_len
@synchronized
def cache_get(key, default=None, callbacks=[]):
@@ -132,14 +154,21 @@ class LruCache(object):
def cache_set(key, value, callbacks=[]):
node = cache.get(key, None)
if node is not None:
- if value != node.value:
+ # We sometimes store large objects, e.g. dicts, which cause
+ # the inequality check to take a long time. So let's only do
+ # the check if we have some callbacks to call.
+ if node.callbacks and value != node.value:
for cb in node.callbacks:
cb()
node.callbacks.clear()
- if size_callback:
- cached_cache_len[0] -= size_callback(node.value)
- cached_cache_len[0] += size_callback(value)
+ # We don't bother to protect this by value != node.value as
+ # generally size_callback will be cheap compared with equality
+ # checks. (For example, taking the size of two dicts is quicker
+ # than comparing them for equality.)
+ if size_callback:
+ cached_cache_len[0] -= size_callback(node.value)
+ cached_cache_len[0] += size_callback(value)
node.callbacks.update(callbacks)
|
