LogDog: Add Storage-layer data caching.

logdog/common/storage/memory/memory.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package memory
 
 import (
         "errors"
         "sync"
         "time"
@@ skipping 39 matching lines @@
 var _ storage.Storage = (*Storage)(nil)
 
 // Close implements storage.Storage.
 func (s *Storage) Close() {
         s.run(func() error {
                 s.closed = true
                 return nil
         })
 }
 
+// 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 {
                 s.MaxLogAge = cfg.MaxLogAge
                 return nil
         })
 }
 
 // Put implements storage.Storage.
 func (s *Storage) Put(req storage.PutRequest) error {
@@ skipping 139 matching lines @@
                 }
 
                 if s.streams == nil {
                         s.streams = map[streamKey]*logStream{}
                 }
                 s.streams[key] = ls
         }
 
         return ls
 }