1 files changed, 19 insertions, 2 deletions
diff --git a/synapse/util/caches/expiringcache.py b/synapse/util/caches/expiringcache.py
index 9af4ec4aa8..8ac56d85ff 100644
--- a/synapse/util/caches/expiringcache.py
+++ b/synapse/util/caches/expiringcache.py
@@ -16,7 +16,7 @@
 import logging
 from collections import OrderedDict
 
-from six import itervalues
+from six import iteritems, itervalues
 
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.util.caches import register_cache
@@ -24,6 +24,9 @@ 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):
@@ -95,6 +98,18 @@ class ExpiringCache(object):
 
         return entry.value
 
+    def pop(self, key, default=None):
+        value = self._cache.pop(key, SENTINEL)
+        if value is SENTINEL:
+            return default
+
+        if self.iterable:
+            self.metrics.inc_evictions(len(value.value))
+        else:
+            self.metrics.inc_evictions()
+
+        return value
+
     def __contains__(self, key):
         return key in self._cache
 
@@ -122,7 +137,7 @@ 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)
 
@@ -146,6 +161,8 @@ class ExpiringCache(object):
 
 
 class _CacheEntry(object):
+    __slots__ = ["time", "value"]
+
     def __init__(self, time, value):
         self.time = time
         self.value = value