ppapi/shared_impl/media_stream_buffer_manager.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 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
  16 namespace ppapi {
  17
  18 union 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.
  37 class 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   // Dequeues all the buffers from |buffer_queue_|.
  66   std::vector<int32_t> DequeueBuffers();
  67
  68   // Puts a buffer into |buffer_queue_|.
  69   void EnqueueBuffer(int32_t index);
  70
  71   // Gets the buffer address for the given buffer index.
  72   MediaStreamBuffer* GetBufferPointer(int32_t index);
  73
  74  private:
  75   Delegate* delegate_;
  76
  77   // A queue of buffer indices.
  78   std::deque<int32_t> buffer_queue_;
  79
  80   // A vector of buffer pointers. It is used for index to pointer converting.
  81   std::vector<MediaStreamBuffer*> buffers_;
  82
  83   // The buffer size in bytes.
  84   int32_t buffer_size_;
  85
  86   // The number of buffers in the shared memory.
  87   int32_t number_of_buffers_;
  88
  89   // A memory block shared between renderer process and plugin process.
  90   scoped_ptr<base::SharedMemory> shm_;
  91
  92   DISALLOW_COPY_AND_ASSIGN(MediaStreamBufferManager);
  93 };
  94
  95 }  // namespace ppapi
  96
  97 #endif  // PPAPI_SHAERD_IMPL_MEDIA_STREAM_BUFFER_MANAGER_H_