Handle inconsistency between DB and Files

webkit/fileapi/file_system_usage_cache.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WEBKIT_FILEAPI_FILE_SYSTEM_USAGE_CACHE_H_
 #define WEBKIT_FILEAPI_FILE_SYSTEM_USAGE_CACHE_H_
 
 #include "base/basictypes.h"
 #include "base/file_path.h"
 
 namespace fileapi {
 
 class FileSystemUsageCache {
  public:
-  // Gets the size described in the .usage file even if dirty > 0.
-  // Returns less than zero if the .usage file is not available.
+  // Gets the size described in the .usage file even if dirty > 0 or
+  // is_valid == false.  Returns less than zero if the .usage file is not
+  // available.
   static int64 GetUsage(const FilePath& usage_file_path);
 
   // Gets the dirty count in the .usage file.
   // Returns less than zero if the .usage file is not available.
   static int32 GetDirty(const FilePath& usage_file_path);
 
   // Increments or decrements the "dirty" entry in the .usage file.
   // Returns false if no .usage is available.
   static bool IncrementDirty(const FilePath& usage_file_path);
   static bool DecrementDirty(const FilePath& usage_file_path);
 
+  // Notifies quota system need to recalculate their usage cache of the origin.

[ericu, 2011/08/24 03:43:50]

s/need/that it needs/
s/their/the

Sorry, I know it won't fit on one line now ;'>.

[tzik, 2011/08/29 06:54:13]

Done.

+  // Returns false if no .usage is available.
+  static bool Invalidate(const FilePath& usage_file_path);
+  static bool IsValid(const FilePath& usage_file_path);
+
   // Updates the size described in the .usage file.
   static int UpdateUsage(const FilePath& usage_file_path, int64 fs_usage);
 
   // Updates the size described in the .usage file by delta with keeping dirty
   // even if dirty > 0.
   static int AtomicUpdateUsageByDelta(
       const FilePath& usage_file_path, int64 delta);
 
   static bool Exists(const FilePath& usage_file_path);
   static bool Delete(const FilePath& usage_file_path);
 
   static const char kUsageFileName[];
   static const char kUsageFileHeader[];
   static const int kUsageFileSize;
   static const int kUsageFileHeaderSize;
 
  private:
-  // Read the size and the "dirty" entry described in the .usage file.
+  // Read the size, validity and the "dirty" entry described in the .usage file.
   // Returns less than zero if no .usage file is available.
-  static int64 Read(const FilePath& usage_file_path, uint32* dirty);
+  static int64 Read(const FilePath& usage_file_path,
+                    bool* is_valid,
+                    uint32* dirty);
 
   static int Write(const FilePath& usage_file_path,
-                   uint32 dirty, int64 fs_usage);
+                   bool is_valid,
+                   uint32 dirty,
+                   int64 fs_usage);
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_FILE_SYSTEM_USAGE_CACHE_H_