1// Copyright 2013 The Chromium Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style license that can be 3// found in the LICENSE file. 4 5#ifndef CHROME_BROWSER_HISTORY_HISTORY_DB_TASK_H_ 6#define CHROME_BROWSER_HISTORY_HISTORY_DB_TASK_H_ 7 8namespace history { 9 10class HistoryBackend; 11class HistoryDatabase; 12 13// HistoryDBTask can be used to process arbitrary work on the history backend 14// thread. HistoryDBTask is scheduled using HistoryService::ScheduleDBTask. 15// When HistoryBackend processes the task it invokes RunOnDBThread. Once the 16// task completes and has not been canceled, DoneRunOnMainThread is invoked back 17// on the main thread, after which this object is destroyed, also on the 18// main thread. 19class HistoryDBTask { 20 public: 21 virtual ~HistoryDBTask() {} 22 23 // Invoked on the database thread. The return value indicates whether the 24 // task is done. A return value of true signals the task is done and 25 // RunOnDBThread should NOT be invoked again. A return value of false 26 // indicates the task is not done, and should be run again after other 27 // tasks are given a chance to be processed. 28 virtual bool RunOnDBThread(HistoryBackend* backend, HistoryDatabase* db) = 0; 29 30 // Invoked on the main thread once RunOnDBThread has returned true. This is 31 // only invoked if the request was not canceled and returned true from 32 // RunOnDBThread. 33 virtual void DoneRunOnMainThread() = 0; 34}; 35 36} // namespace history 37 38#endif // CHROME_BROWSER_HISTORY_HISTORY_DB_TASK_H_ 39