diff --git a/synapse/util/caches/expiringcache.py b/synapse/util/caches/expiringcache.py
index ce85b2ae11..f369780277 100644
--- a/synapse/util/caches/expiringcache.py
+++ b/synapse/util/caches/expiringcache.py
@@ -16,12 +16,17 @@
import logging
from collections import OrderedDict
+from six import iteritems, itervalues
+
from synapse.metrics.background_process_metrics import run_as_background_process
from synapse.util.caches import register_cache
logger = logging.getLogger(__name__)
+SENTINEL = object()
+
+
class ExpiringCache(object):
def __init__(self, cache_name, clock, max_len=0, expiry_ms=0,
reset_expiry_on_get=False, iterable=False):
@@ -54,11 +59,8 @@ class ExpiringCache(object):
self.iterable = iterable
- self._size_estimate = 0
-
self.metrics = register_cache("expiring", cache_name, self)
- def start(self):
if not self._expiry_ms:
# Don't bother starting the loop if things never expire
return
@@ -75,16 +77,11 @@ class ExpiringCache(object):
now = self._clock.time_msec()
self._cache[key] = _CacheEntry(now, value)
- if self.iterable:
- self._size_estimate += len(value)
-
# Evict if there are now too many items
while self._max_len and len(self) > self._max_len:
_key, value = self._cache.popitem(last=False)
if self.iterable:
- removed_len = len(value.value)
- self.metrics.inc_evictions(removed_len)
- self._size_estimate -= removed_len
+ self.metrics.inc_evictions(len(value.value))
else:
self.metrics.inc_evictions()
@@ -101,6 +98,21 @@ class ExpiringCache(object):
return entry.value
+ def pop(self, key, default=SENTINEL):
+ """Removes and returns the value with the given key from the cache.
+
+ If the key isn't in the cache then `default` will be returned if
+ specified, otherwise `KeyError` will get raised.
+
+ Identical functionality to `dict.pop(..)`.
+ """
+
+ value = self._cache.pop(key, default)
+ if value is SENTINEL:
+ raise KeyError(key)
+
+ return value
+
def __contains__(self, key):
return key in self._cache
@@ -128,14 +140,16 @@ class ExpiringCache(object):
keys_to_delete = set()
- for key, cache_entry in self._cache.items():
+ for key, cache_entry in iteritems(self._cache):
if now - cache_entry.time > self._expiry_ms:
keys_to_delete.add(key)
for k in keys_to_delete:
value = self._cache.pop(k)
if self.iterable:
- self._size_estimate -= len(value.value)
+ self.metrics.inc_evictions(len(value.value))
+ else:
+ self.metrics.inc_evictions()
logger.debug(
"[%s] _prune_cache before: %d, after len: %d",
@@ -144,12 +158,14 @@ class ExpiringCache(object):
def __len__(self):
if self.iterable:
- return self._size_estimate
+ return sum(len(entry.value) for entry in itervalues(self._cache))
else:
return len(self._cache)
class _CacheEntry(object):
+ __slots__ = ["time", "value"]
+
def __init__(self, time, value):
self.time = time
self.value = value
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