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_BUFFERING_CONTROLLER_H
6#define CHROMECAST_MEDIA_CMA_BASE_BUFFERING_CONTROLLER_H
7
8#include <list>
9
10#include "base/callback.h"
11#include "base/macros.h"
12#include "base/memory/ref_counted.h"
13#include "base/memory/weak_ptr.h"
14#include "base/threading/thread_checker.h"
15#include "base/time/time.h"
16
17namespace chromecast {
18namespace media {
19class BufferingConfig;
20class BufferingState;
21
22class BufferingController {
23 public:
24  typedef base::Callback<void(bool)> BufferingNotificationCB;
25
26  // Creates a buffering controller where the conditions to trigger rebuffering
27  // are given by |config|. The whole point of the buffering controller is to
28  // derive a single buffering state from the buffering state of various
29  // streams.
30  // |buffering_notification_cb| is a callback invoked to inform about possible
31  // changes of the buffering state.
32  BufferingController(
33      const scoped_refptr<BufferingConfig>& config,
34      const BufferingNotificationCB& buffering_notification_cb);
35  ~BufferingController();
36
37  // Creates a buffering state for one stream. This state is added to the list
38  // of streams monitored by the buffering controller.
39  scoped_refptr<BufferingState> AddStream();
40
41  // Sets the playback time.
42  void SetMediaTime(base::TimeDelta time);
43
44  // Returns the maximum media time available for rendering.
45  // Return kNoTimestamp() if unknown.
46  base::TimeDelta GetMaxRenderingTime() const;
47
48  // Returns whether there is an active buffering phase.
49  bool IsBuffering() const { return is_buffering_; }
50
51  // Resets the buffering controller. This includes removing all the streams
52  // that were previously added.
53  void Reset();
54
55 private:
56  // Invoked each time the buffering state of one of the streams has changed.
57  // If |force_notification| is set, |buffering_notification_cb_| is invoked
58  // regardless whether the buffering state has changed or not.
59  // If |buffering_timeout| is set, then the condition to leave the buffering
60  // state is relaxed (we don't want to wait more).
61  void OnBufferingStateChanged(bool force_notification,
62                               bool buffering_timeout);
63
64  // Updates the high buffer level threshold to |high_level_threshold|
65  // if needed.
66  // This condition is triggered when one of the stream reached its maximum
67  // capacity. In that case, to avoid possible race condition (the buffering
68  // controller waits for more data to come but the buffer is to small to
69  // accomodate additional data), the thresholds in |config_| are adjusted
70  // accordingly.
71  void UpdateHighLevelThreshold(base::TimeDelta high_level_threshold);
72
73  // Determines the overall buffer level based on the buffer level of each
74  // stream.
75  bool IsHighBufferLevel();
76  bool IsLowBufferLevel();
77
78  // Logs the state of the buffering controller.
79  void DumpState() const;
80
81  base::ThreadChecker thread_checker_;
82
83  // Settings used to determine when to start/stop buffering.
84  scoped_refptr<BufferingConfig> config_;
85
86  // Callback invoked each time there is a change of the buffering state.
87  BufferingNotificationCB buffering_notification_cb_;
88
89  // State of the buffering controller.
90  bool is_buffering_;
91
92  // Start time of a re-buffering phase.
93  base::Time begin_buffering_time_;
94
95  // Buffering level for each individual stream.
96  typedef std::list<scoped_refptr<BufferingState> > StreamList;
97  StreamList stream_list_;
98
99  base::WeakPtrFactory<BufferingController> weak_factory_;
100  base::WeakPtr<BufferingController> weak_this_;
101
102  DISALLOW_COPY_AND_ASSIGN(BufferingController);
103};
104
105}  // namespace media
106}  // namespace chromecast
107
108#endif  // CHROMECAST_MEDIA_CMA_BASE_BUFFERING_CONTROLLER_H
109