Merge branch 'develop' into matthew/preview_urls

1 files changed, 16 insertions, 4 deletions

diff --git a/synapse/util/caches/expiringcache.py b/synapse/util/caches/expiringcache.py
index 494226f5ea..2b68c1ac93 100644
--- a/synapse/util/caches/expiringcache.py
+++ b/synapse/util/caches/expiringcache.py
@@ -13,6 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from synapse.util.caches import cache_counter, caches_by_name
+
 import logging
 
 
@@ -47,6 +49,8 @@ class ExpiringCache(object):
 
         self._cache = {}
 
+        caches_by_name[cache_name] = self._cache
+
     def start(self):
         if not self._expiry_ms:
             # Don't bother starting the loop if things never expire
@@ -55,7 +59,7 @@ class ExpiringCache(object):
         def f():
             self._prune_cache()
 
-        self._clock.looping_call(f, self._expiry_ms/2)
+        self._clock.looping_call(f, self._expiry_ms / 2)
 
     def __setitem__(self, key, value):
         now = self._clock.time_msec()
@@ -65,14 +69,19 @@ class ExpiringCache(object):
         if self._max_len and len(self._cache.keys()) > self._max_len:
             sorted_entries = sorted(
                 self._cache.items(),
-                key=lambda (k, v): v.time,
+                key=lambda item: item[1].time,
             )
 
             for k, _ in sorted_entries[self._max_len:]:
                 self._cache.pop(k)
 
     def __getitem__(self, key):
-        entry = self._cache[key]
+        try:
+            entry = self._cache[key]
+            cache_counter.inc_hits(self._cache_name)
+        except KeyError:
+            cache_counter.inc_misses(self._cache_name)
+            raise
 
         if self._reset_expiry_on_get:
             entry.time = self._clock.time_msec()
@@ -105,9 +114,12 @@ class ExpiringCache(object):
 
         logger.debug(
             "[%s] _prune_cache before: %d, after len: %d",
-            self._cache_name, begin_length, len(self._cache.keys())
+            self._cache_name, begin_length, len(self._cache)
         )
 
+    def __len__(self):
+        return len(self._cache)
+
 
 class _CacheEntry(object):
     def __init__(self, time, value):