chromecast/media/cma/base/balanced_media_task_runner_factory.h

   1 // Copyright 2014 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 CHROMECAST_MEDIA_CMA_BASE_BALANCED_TASK_RUNNER_FACTORY_H_
   6 #define CHROMECAST_MEDIA_CMA_BASE_BALANCED_TASK_RUNNER_FACTORY_H_
   7
   8 #include <set>
   9
  10 #include "base/macros.h"
  11 #include "base/memory/ref_counted.h"
  12 #include "base/synchronization/lock.h"
  13 #include "base/time/time.h"
  14
  15 namespace base {
  16 class SingleThreadTaskRunner;
  17 }
  18
  19 namespace chromecast {
  20 namespace media {
  21 class BalancedMediaTaskRunner;
  22 class MediaTaskRunner;
  23
  24 // BalancedMediaTaskRunnerFactory -
  25 // Create media tasks runners that are loosely synchronized between each other.
  26 // For two tasks T1 and T2 with timestamps ts1 and ts2, the scheduler ensures
  27 // T2 is not scheduled before T1 if ts2 > ts1 + |max_delta|.
  28 class BalancedMediaTaskRunnerFactory
  29     : public base::RefCountedThreadSafe<BalancedMediaTaskRunnerFactory> {
  30  public:
  31   explicit BalancedMediaTaskRunnerFactory(base::TimeDelta max_delta);
  32
  33   // Creates a media task runner using |task_runner| as the underlying
  34   // regular task runner.
  35   // Restriction on the returned media task runner:
  36   // - can only schedule only one media task at a time.
  37   // - timestamps of tasks posted on that task runner must be increasing.
  38   scoped_refptr<MediaTaskRunner> CreateMediaTaskRunner(
  39       const scoped_refptr<base::SingleThreadTaskRunner>& task_runner);
  40
  41  private:
  42   typedef std::set<scoped_refptr<BalancedMediaTaskRunner> > MediaTaskRunnerSet;
  43
  44   friend class base::RefCountedThreadSafe<BalancedMediaTaskRunnerFactory>;
  45   virtual ~BalancedMediaTaskRunnerFactory();
  46
  47   // Invoked when one of the registered media task runners received a new media
  48   // task.
  49   void OnNewTask();
  50
  51   // Unregister a media task runner.
  52   void UnregisterMediaTaskRunner(
  53       const scoped_refptr<BalancedMediaTaskRunner>& media_task_runner);
  54
  55   // Maximum timestamp deviation between tasks from the registered task runners.
  56   const base::TimeDelta max_delta_;
  57
  58   // Task runners created by the factory that have not been unregistered yet.
  59   base::Lock lock_;
  60   MediaTaskRunnerSet task_runners_;
  61
  62   DISALLOW_COPY_AND_ASSIGN(BalancedMediaTaskRunnerFactory);
  63 };
  64
  65 }  // namespace media
  66 }  // namespace chromecast
  67
  68 #endif  // CHROMECAST_MEDIA_CMA_BASE_BALANCED_TASK_RUNNER_FACTORY_H_