Use SNAPSHOT sync mode for LocalSync

chrome/browser/sync_file_system/local/local_file_sync_context.h

 // Copyright 2013 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 CHROME_BROWSER_SYNC_FILE_SYSTEM_LOCAL_LOCAL_FILE_SYNC_CONTEXT_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_LOCAL_LOCAL_FILE_SYNC_CONTEXT_H_
 
 #include <deque>
 #include <map>
 #include <set>
@@ skipping 15 matching lines @@
 
 namespace base {
 class SingleThreadTaskRunner;
 }
 
 namespace fileapi {
 class FileSystemContext;
 class FileSystemURL;
 }
 
+namespace webkit_blob {
+class ScopedFile;
+}
+
 namespace sync_file_system {
 
 class FileChange;
 class LocalFileChangeTracker;
 struct LocalFileSyncInfo;
 class LocalOriginChangeObserver;
 class SyncableFileOperationRunner;
 
 // This class works as a bridge between LocalFileSyncService (which is a
 // per-profile object) and FileSystemContext's (which is a per-storage-partition
 // object and may exist multiple in a profile).
 // An instance of this class is shared by FileSystemContexts and outlives
 // LocalFileSyncService.
 class LocalFileSyncContext
     : public base::RefCountedThreadSafe<LocalFileSyncContext>,
       public LocalFileSyncStatus::Observer {
  public:
   enum SyncMode {
     SYNC_EXCLUSIVE,
     SYNC_SNAPSHOT,
   };
 
   typedef base::Callback<void(
-      SyncStatusCode status, const LocalFileSyncInfo& sync_file_info)>
+      SyncStatusCode status,
+      const LocalFileSyncInfo& sync_file_info,
+      scoped_ptr<webkit_blob::ScopedFile> snapshot)>
           LocalFileSyncInfoCallback;
 
   typedef base::Callback<void(SyncStatusCode status,
                               bool has_pending_changes)>
       HasPendingLocalChangeCallback;
 
-  LocalFileSyncContext(base::SingleThreadTaskRunner* ui_task_runner,
+  LocalFileSyncContext(const base::FilePath& base_path,
+                       base::SingleThreadTaskRunner* ui_task_runner,
                        base::SingleThreadTaskRunner* io_task_runner);
 
   // Initializes |file_system_context| for syncable file operations
   // and registers the it into the internal map.
   // Calling this multiple times for the same file_system_context is valid.
   // This method must be called on UI thread.
   void MaybeInitializeFileSystemContext(
       const GURL& source_url,
       fileapi::FileSystemContext* file_system_context,
       const SyncStatusCallback& callback);
@@ skipping 153 matching lines @@
       std::deque<fileapi::FileSystemURL>* urls);
   void TryPrepareForLocalSync(
       fileapi::FileSystemContext* file_system_context,
       std::deque<fileapi::FileSystemURL>* urls,
       const LocalFileSyncInfoCallback& callback);
   void DidTryPrepareForLocalSync(
       fileapi::FileSystemContext* file_system_context,
       std::deque<fileapi::FileSystemURL>* remaining_urls,
       const LocalFileSyncInfoCallback& callback,
       SyncStatusCode status,
-      const LocalFileSyncInfo& sync_file_info);
+      const LocalFileSyncInfo& sync_file_info,
+      scoped_ptr<webkit_blob::ScopedFile> snapshot);
 
   // Callback routine for PrepareForSync and GetFileForLocalSync.
   void DidGetWritingStatusForSync(
       fileapi::FileSystemContext* file_system_context,
       SyncStatusCode status,
       const fileapi::FileSystemURL& url,
       SyncMode sync_mode,
       const LocalFileSyncInfoCallback& callback);
 
-  // Helper routine for ClearSyncFlagForURL.
-  void EnableWritingOnIOThread(const fileapi::FileSystemURL& url,
-                               bool may_have_updates);
+  // Helper routine for sync/writing flag handling, primarily for
+  // ClearSyncFlagForURL but is also called by other internal routines.
+  // If |keep_url_in_writing| is true this increments the writing counter
+  // for |url| (after clearing syncing flag), so that the caller can
+  // continue to hold a shared lock on the URL.
+  // (The counter must be manually decremented by EndWritingOnIOThread
+  // if that's the case)
+  void ClearSyncFlagOnIOThread(const fileapi::FileSystemURL& url,
+                               bool keep_url_in_writing);
+  void EndWritingOnIOThread(const fileapi::FileSystemURL& url);
 
   void DidRemoveExistingEntryForApplyRemoteChange(
       fileapi::FileSystemContext* file_system_context,
       const FileChange& change,
       const base::FilePath& local_path,
       const fileapi::FileSystemURL& url,
       const SyncStatusCallback& callback,
       base::PlatformFileError error);
 
   // Callback routine for ApplyRemoteChange.
   void DidApplyRemoteChange(
       const fileapi::FileSystemURL& url,
       const SyncStatusCallback& callback_on_ui,
       base::PlatformFileError file_error);
 
   void DidGetFileMetadata(
       const SyncFileMetadataCallback& callback,
       base::PlatformFileError file_error,
       const base::PlatformFileInfo& file_info);
 
   base::TimeDelta NotifyChangesDuration();
 
   void DidCreateDirectoryForCopyIn(
       fileapi::FileSystemContext* file_system_context,
       const base::FilePath& local_file_path,
       const fileapi::FileSystemURL& dest_url,
       const StatusCallback& callback,
       base::PlatformFileError error);
 
+  const base::FilePath local_base_path_;
+
   scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
 
   // Indicates if the sync service is shutdown on UI thread.
   bool shutdown_on_ui_;
 
   // OperationRunner. This must be accessed only on IO thread.
   scoped_ptr<SyncableFileOperationRunner> operation_runner_;
 
   // Keeps track of writing/syncing status.
@@ skipping 22 matching lines @@
   ObserverList<LocalOriginChangeObserver> origin_change_observers_;
 
   int mock_notify_changes_duration_in_sec_;
 
   DISALLOW_COPY_AND_ASSIGN(LocalFileSyncContext);
 };
 
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_LOCAL_LOCAL_FILE_SYNC_CONTEXT_H_