media_stream_buffer_manager.h revision 5d1f7b1de12d16ceb2c938c56701a3e8bfa558f7 
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 PPAPI_SHARED_IMPL_MEDIA_STREAM_BUFFER_MANAGER_H_
6#define PPAPI_SHARED_IMPL_MEDIA_STREAM_BUFFER_MANAGER_H_
7
8#include <deque>
9#include <vector>
10
11#include "base/compiler_specific.h"
12#include "base/memory/scoped_ptr.h"
13#include "base/memory/shared_memory.h"
14#include "ppapi/shared_impl/ppapi_shared_export.h"
15
16namespace ppapi {
17
18union MediaStreamBuffer;
19
20// This class is used by both read side and write side of a MediaStreamTrack to
21// maintain a queue of buffers for reading or writing.
22//
23// An example:
24//  1. The writer calls the writer's |buffer_manager_.Dequeue()| to get a free
25//     buffer.
26//  2. The writer fills data into the buffer.
27//  3. The writer sends the buffer index to the reader via an IPC message.
28//  4. The reader receives the buffer index and calls the reader's
29//     |buffer_buffer.Enqueue()| to put the buffer into the read's queue.
30//  5. The reader calls reader's |buffer_buffer_.Dequeue()| to get a received
31//     buffer.
32//  6. When the buffer from the step 5 is consumed, the reader sends the buffer
33//     index back to writer via an IPC message.
34//  7. The writer receives the buffer index and puts it back to the writer's
35//     free buffer queue by calling the writer's |buffer_manager_.Enqueue()|.
36//  8. Go back to step 1.
37class PPAPI_SHARED_EXPORT MediaStreamBufferManager {
38 public:
39  class PPAPI_SHARED_EXPORT Delegate {
40   public:
41    virtual ~Delegate();
42    // It is called when a new buffer is enqueued.
43    virtual void OnNewBufferEnqueued();
44  };
45
46  // MediaStreamBufferManager doesn't own |delegate|, the caller should keep
47  // it alive during the MediaStreamBufferManager's lifecycle.
48  explicit MediaStreamBufferManager(Delegate* delegate);
49
50  ~MediaStreamBufferManager();
51
52  int32_t number_of_buffers() const { return number_of_buffers_; }
53
54  int32_t buffer_size() const { return buffer_size_; }
55
56  // Initializes shared memory for buffers transmission.
57  bool SetBuffers(int32_t number_of_buffers,
58                 int32_t buffer_size,
59                 scoped_ptr<base::SharedMemory> shm,
60                 bool enqueue_all_buffers);
61
62  // Dequeues a buffer from |buffer_queue_|.
63  int32_t DequeueBuffer();
64
65  // Puts a buffer into |buffer_queue_|.
66  void EnqueueBuffer(int32_t index);
67
68  // Gets the buffer address for the given buffer index.
69  MediaStreamBuffer* GetBufferPointer(int32_t index);
70
71 private:
72  Delegate* delegate_;
73
74  // A queue of buffer indices.
75  std::deque<int32_t> buffer_queue_;
76
77  // A vector of buffer pointers. It is used for index to pointer converting.
78  std::vector<MediaStreamBuffer*> buffers_;
79
80  // The buffer size in bytes.
81  int32_t buffer_size_;
82
83  // The number of buffers in the shared memory.
84  int32_t number_of_buffers_;
85
86  // A memory block shared between renderer process and plugin process.
87  scoped_ptr<base::SharedMemory> shm_;
88
89  DISALLOW_COPY_AND_ASSIGN(MediaStreamBufferManager);
90};
91
92}  // namespace ppapi
93
94#endif  // PPAPI_SHAERD_IMPL_MEDIA_STREAM_BUFFER_MANAGER_H_
95