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// Copyright (c) 2012 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 COMPONENTS_SYNC_ENGINE_UI_MODEL_WORKER_H_
#define COMPONENTS_SYNC_ENGINE_UI_MODEL_WORKER_H_
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/sequence_checker.h"
#include "base/single_thread_task_runner.h"
#include "base/synchronization/waitable_event.h"
#include "components/sync/engine/model_safe_worker.h"
namespace syncer {
// A ModelSafeWorker for UI models (e.g. bookmarks) that
// accepts work requests from the syncapi that need to be fulfilled
// from the MessageLoop home to the native model.
class UIModelWorker : public ModelSafeWorker {
public:
explicit UIModelWorker(scoped_refptr<base::SingleThreadTaskRunner> ui_thread);
// ModelSafeWorker implementation.
void RequestStop() override;
ModelSafeGroup GetModelSafeGroup() override;
bool IsOnModelThread() override;
protected:
SyncerError DoWorkAndWaitUntilDoneImpl(const WorkCallback& work) override;
private:
~UIModelWorker() override;
// A reference to the UI thread's task runner.
const scoped_refptr<base::SingleThreadTaskRunner> ui_thread_;
// Signaled when a task posted by DoWorkAndWaitUntilDoneImpl() is deleted,
// i.e. after it runs or when it is abandoned. Reset at the beginning of every
// DoWorkAndWaitUntilDoneImpl() call.
base::WaitableEvent work_done_or_abandoned_;
// Signaled from RequestStop(). When this is signaled,
// DoWorkAndWaitUntilDoneImpl() returns immediately. This is needed to prevent
// the UI thread from joining the sync thread while it is waiting for a
// WorkCallback to run on the UI thread. See crbug.com/663600.
base::WaitableEvent stop_requested_;
// Verifies that calls to DoWorkAndWaitUntilDoneImpl() are sequenced.
base::SequenceChecker sequence_checker_;
DISALLOW_COPY_AND_ASSIGN(UIModelWorker);
};
} // namespace syncer
#endif // COMPONENTS_SYNC_ENGINE_UI_MODEL_WORKER_H_
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