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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 BASE_IOS_SCOPED_CRITICAL_ACTION_H_
#define BASE_IOS_SCOPED_CRITICAL_ACTION_H_
#include "base/memory/ref_counted.h"
#include "base/synchronization/lock.h"
namespace base {
namespace ios {
// This class attempts to allow the application to continue to run for a period
// of time after it transitions to the background. The construction of an
// instance of this class marks the beginning of a task that needs background
// running time when the application is moved to the background and the
// destruction marks the end of such a task.
//
// Note there is no guarantee that the task will continue to finish when the
// application is moved to the background.
//
// This class should be used at times where leaving a task unfinished might be
// detrimental to user experience. For example, it should be used to ensure that
// the application has enough time to save important data or at least attempt to
// save such data.
class ScopedCriticalAction {
public:
ScopedCriticalAction();
~ScopedCriticalAction();
private:
// Core logic; ScopedCriticalAction should not be reference counted so
// that it follows the normal pattern of stack-allocating ScopedFoo objects,
// but the expiration handler needs to have a reference counted object to
// refer to.
class Core : public base::RefCountedThreadSafe<Core> {
public:
Core();
// Informs the OS that the background task has completed.
void EndBackgroundTask();
private:
friend base::RefCountedThreadSafe<Core>;
~Core();
// |UIBackgroundTaskIdentifier| returned by
// |beginBackgroundTaskWithExpirationHandler:| when marking the beginning of
// a long-running background task. It is defined as an |unsigned int|
// instead of a |UIBackgroundTaskIdentifier| so this class can be used in
// .cc files.
unsigned int background_task_id_;
Lock background_task_id_lock_;
DISALLOW_COPY_AND_ASSIGN(Core);
};
// The instance of the core that drives the background task.
scoped_refptr<Core> core_;
DISALLOW_COPY_AND_ASSIGN(ScopedCriticalAction);
};
} // namespace ios
} // namespace base
#endif // BASE_IOS_SCOPED_CRITICAL_ACTION_H_
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