Docserver: Persist stat cache for versioned file systems

chrome/common/extensions/docs/server2/memcache_object_store.py

Index: chrome/common/extensions/docs/server2/memcache_object_store.py
diff --git a/chrome/common/extensions/docs/server2/memcache_object_store.py b/chrome/common/extensions/docs/server2/memcache_object_store.py
index 78d924166b3ff3da33d6632d81886b23d109e3a9..0099896f0da080d1156c49dcaeacb9ab56a04dbf 100644
--- a/chrome/common/extensions/docs/server2/memcache_object_store.py
+++ b/chrome/common/extensions/docs/server2/memcache_object_store.py
@@ -5,6 +5,7 @@
 import logging
 
 from appengine_wrappers import memcache
+from future import Future
 from object_store import ObjectStore
 
 class _AsyncMemcacheGetFuture(object):
@@ -22,9 +23,11 @@ class MemcacheObjectStore(ObjectStore):
     # talking_alarm_clock always fails because the zip is too big.
     # TODO(kalman): store example zips in blobstore.
     if any(key.find('talking_alarm_clock') != -1 for key in mapping.iterkeys()):
-      return
+      return Future(callback=lambda: None)
     try:
-      memcache.Client().set_multi_async(mapping, namespace=self._namespace)
+      rpc = memcache.Client().set_multi_async(mapping,
+          namespace=self._namespace)
+      return _AsyncMemcacheGetFuture(rpc)
     except ValueError as e:
       logging.error('Caught "ValueError: %s" when mapping keys %s' % (
           e, mapping.keys()))