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// 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_HISTORY_HISTORY_DB_TASK_H_
#define CHROME_BROWSER_HISTORY_HISTORY_DB_TASK_H_
#include "base/memory/ref_counted.h"
namespace history {
class HistoryBackend;
class HistoryDatabase;
// HistoryDBTask can be used to process arbitrary work on the history backend
// thread. HistoryDBTask is scheduled using HistoryService::ScheduleDBTask.
// When HistoryBackend processes the task it invokes RunOnDBThread. Once the
// task completes and has not been canceled, DoneRunOnMainThread is invoked back
// on the main thread.
class HistoryDBTask : public base::RefCountedThreadSafe<HistoryDBTask> {
public:
// Invoked on the database thread. The return value indicates whether the
// task is done. A return value of true signals the task is done and
// RunOnDBThread should NOT be invoked again. A return value of false
// indicates the task is not done, and should be run again after other
// tasks are given a chance to be processed.
virtual bool RunOnDBThread(HistoryBackend* backend, HistoryDatabase* db) = 0;
// Invoked on the main thread once RunOnDBThread has returned true. This is
// only invoked if the request was not canceled and returned true from
// RunOnDBThread.
virtual void DoneRunOnMainThread() = 0;
protected:
friend class base::RefCountedThreadSafe<HistoryDBTask>;
virtual ~HistoryDBTask() {}
};
} // namespace history
#endif // CHROME_BROWSER_HISTORY_HISTORY_DB_TASK_H_
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