base/ios/scoped_critical_action.h

   1 // Copyright (c) 2012 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 BASE_IOS_SCOPED_CRITICAL_ACTION_H_
   6 #define BASE_IOS_SCOPED_CRITICAL_ACTION_H_
   7
   8 #include "base/synchronization/lock.h"
   9
  10 namespace base {
  11 namespace ios {
  12
  13 // This class attempts to allow the application to continue to run for a period
  14 // of time after it transitions to the background. The construction of an
  15 // instance of this class marks the beginning of a task that needs background
  16 // running time when the application is moved to the background and the
  17 // destruction marks the end of such a task.
  18 //
  19 // Note there is no guarantee that the task will continue to finish when the
  20 // application is moved to the background.
  21 //
  22 // This class should be used at times where leaving a task unfinished might be
  23 // detrimental to user experience. For example, it should be used to ensure that
  24 // the application has enough time to save important data or at least attempt to
  25 // save such data.
  26 class ScopedCriticalAction {
  27  public:
  28   ScopedCriticalAction();
  29   ~ScopedCriticalAction();
  30
  31  private:
  32   // Informs the OS that the background task has completed.
  33   void EndBackgroundTask();
  34
  35   // |UIBackgroundTaskIdentifier| returned by
  36   // |beginBackgroundTaskWithExpirationHandler:| when marking the beginning of
  37   // a long-running background task. It is defined as an |unsigned int| instead
  38   // of a |UIBackgroundTaskIdentifier| so this class can be used in .cc files.
  39   unsigned int background_task_id_;
  40   Lock background_task_id_lock_;
  41
  42   DISALLOW_COPY_AND_ASSIGN(ScopedCriticalAction);
  43 };
  44
  45 }  // namespace ios
  46 }  // namespace base
  47
  48 #endif  // BASE_IOS_SCOPED_CRITICAL_ACTION_H_