sync: add CleanupDisabledTypesCommand to purge data pertaining to previously...

chrome/browser/sync/engine/cleanup_disabled_types_command.h

Index: chrome/browser/sync/engine/cleanup_disabled_types_command.h
===================================================================
--- chrome/browser/sync/engine/cleanup_disabled_types_command.h	(revision 0)
+++ chrome/browser/sync/engine/cleanup_disabled_types_command.h	(revision 0)
@@ -0,0 +1,44 @@
+// Copyright (c) 2010 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_ENGINE_CLEANUP_DISABLED_TYPES_COMMAND_H_
+#define CHROME_BROWSER_SYNC_ENGINE_CLEANUP_DISABLED_TYPES_COMMAND_H_
+
+#include "chrome/browser/sync/engine/syncer_command.h"
+
+namespace browser_sync {
+
+// A syncer command that purges (from memory and disk) entries belonging to
+// a ModelType or ServerModelType that the user has not elected to sync.
+//
+// This is done as part of a session to 1) ensure it does not block the UI,
+// and 2) avoid complicated races that could arise between a) deleting
+// things b) a sync session trying to use these things c) and the potential
+// re-enabling of the data type by the user before some scheduled deletion
+// took place.  Here, we are safe to perform I/O synchronously and we know it
+// is a safe time to delete as we are in the only active session.
+//
+// The removal from memory is done synchronously, while the disk purge is left
+// to an asynchronous SaveChanges operation.  However, all the updates for
+// meta data fields (such as initial_sync_ended) as well as the actual entry
+// deletions will be committed in a single sqlite transaction.  Thus it is
+// possible that disabled types re-appear (in the sync db) after a reboot,
+// but things will remain in a consistent state.  This kind of error case is
+// cared for in this command by retrying; see ExecuteImpl.
+class CleanupDisabledTypesCommand : public SyncerCommand {
+ public:
+  CleanupDisabledTypesCommand();
+  virtual ~CleanupDisabledTypesCommand();
+
+  // SyncerCommand implementation.
+  virtual void ExecuteImpl(sessions::SyncSession* session);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CleanupDisabledTypesCommand);
+};
+
+}  // namespace browser_sync
+
+#endif  // CHROME_BROWSER_SYNC_ENGINE_CLEANUP_DISABLED_TYPES_COMMAND_H_
+
Property changes on: chrome\browser\sync\engine\cleanup_disabled_types_command.h
___________________________________________________________________
Added: svn:eol-style
   + LF