LogDog: Add Storage-layer data caching.

logdog/common/storage/memory/memory.go

Index: logdog/common/storage/memory/memory.go
diff --git a/logdog/common/storage/memory/memory.go b/logdog/common/storage/memory/memory.go
index f5826f46cd3e63bc8e71bea97ebc3f2f38c60216..8186971f32a24b00e8fc896a2c947c224706f32e 100644
--- a/logdog/common/storage/memory/memory.go
+++ b/logdog/common/storage/memory/memory.go
@@ -57,6 +57,15 @@ func (s *Storage) Close() {
 	})
 }
 
+// ResetClose resets the storage instance, allowing it to be used another time.
+// The data stored in this instance is not changed.
+func (s *Storage) ResetClose() {
+	s.stateMu.Lock()
+	defer s.stateMu.Unlock()
+
+	s.closed = false
+}
+
 // Config implements storage.Storage.
 func (s *Storage) Config(cfg storage.Config) error {
 	return s.run(func() error {