actioncache/storage.py: Log cache update events

buildgrid/server/actioncache/storage.py

@@ -20,22 +20,39 @@ Action Cache
 Implements an in-memory action Cache
 """
 
+import logging
 
 from ..referencestorage.storage import ReferenceCache
 
 
 class ActionCache(ReferenceCache):
 
+    def __init__(self, storage, max_cached_refs, allow_updates=True):
+        super().__init__(storage, max_cached_refs, allow_updates)
+
+        self.__logger = logging.getLogger(__name__)
+
+    # --- Public API ---
+
     def register_instance_with_server(self, instance_name, server):
         server.add_action_cache_instance(self, instance_name)
 
     def get_action_result(self, action_digest):
+        """Retrieves the cached result for an action."""
         key = self._get_key(action_digest)
+
         return self.get_action_reference(key)
 
     def update_action_result(self, action_digest, action_result):
+        """Stores in cache a result for an action."""
         key = self._get_key(action_digest)
+
         self.update_reference(key, action_result)
 
+        self.__logger.info("Result cached for action [%s/%s]",
+                           action_digest.hash, action_digest.size_bytes)
+
+    # --- Private API ---
+
     def _get_key(self, action_digest):
         return (action_digest.hash, action_digest.size_bytes)