media/audio/audio_device_thread.cc

   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 #include "media/audio/audio_device_thread.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/bind.h"
  10 #include "base/logging.h"
  11 #include "base/memory/aligned_memory.h"
  12 #include "base/message_loop/message_loop.h"
  13 #include "base/threading/platform_thread.h"
  14 #include "base/threading/thread_restrictions.h"
  15 #include "media/base/audio_bus.h"
  16
  17 using base::PlatformThread;
  18
  19 namespace media {
  20
  21 // The actual worker thread implementation.  It's very bare bones and much
  22 // simpler than SimpleThread (no synchronization in Start, etc) and supports
  23 // joining the thread handle asynchronously via a provided message loop even
  24 // after the Thread object itself has been deleted.
  25 class AudioDeviceThread::Thread
  26     : public PlatformThread::Delegate,
  27       public base::RefCountedThreadSafe<AudioDeviceThread::Thread> {
  28  public:
  29   Thread(AudioDeviceThread::Callback* callback,
  30          base::SyncSocket::Handle socket,
  31          const char* thread_name,
  32          bool synchronized_buffers);
  33
  34   void Start();
  35
  36   // Stops the thread.  If |loop_for_join| is non-NULL, the function posts
  37   // a task to join (close) the thread handle later instead of waiting for
  38   // the thread.  If loop_for_join is NULL, then the function waits
  39   // synchronously for the thread to terminate.
  40   void Stop(base::MessageLoop* loop_for_join);
  41
  42  private:
  43   friend class base::RefCountedThreadSafe<AudioDeviceThread::Thread>;
  44   virtual ~Thread();
  45
  46   // Overrides from PlatformThread::Delegate.
  47   virtual void ThreadMain() OVERRIDE;
  48
  49   // Runs the loop that reads from the socket.
  50   void Run();
  51
  52  private:
  53   base::PlatformThreadHandle thread_;
  54   AudioDeviceThread::Callback* callback_;
  55   base::CancelableSyncSocket socket_;
  56   base::Lock callback_lock_;
  57   const char* thread_name_;
  58   const bool synchronized_buffers_;
  59
  60   DISALLOW_COPY_AND_ASSIGN(Thread);
  61 };
  62
  63 // AudioDeviceThread implementation
  64
  65 AudioDeviceThread::AudioDeviceThread() {
  66 }
  67
  68 AudioDeviceThread::~AudioDeviceThread() { DCHECK(!thread_.get()); }
  69
  70 void AudioDeviceThread::Start(AudioDeviceThread::Callback* callback,
  71                               base::SyncSocket::Handle socket,
  72                               const char* thread_name,
  73                               bool synchronized_buffers) {
  74   base::AutoLock auto_lock(thread_lock_);
  75   CHECK(!thread_);
  76   thread_ = new AudioDeviceThread::Thread(
  77       callback, socket, thread_name, synchronized_buffers);
  78   thread_->Start();
  79 }
  80
  81 void AudioDeviceThread::Stop(base::MessageLoop* loop_for_join) {
  82   base::AutoLock auto_lock(thread_lock_);
  83   if (thread_.get()) {
  84     thread_->Stop(loop_for_join);
  85     thread_ = NULL;
  86   }
  87 }
  88
  89 bool AudioDeviceThread::IsStopped() {
  90   base::AutoLock auto_lock(thread_lock_);
  91   return !thread_;
  92 }
  93
  94 // AudioDeviceThread::Thread implementation
  95 AudioDeviceThread::Thread::Thread(AudioDeviceThread::Callback* callback,
  96                                   base::SyncSocket::Handle socket,
  97                                   const char* thread_name,
  98                                   bool synchronized_buffers)
  99     : thread_(),
 100       callback_(callback),
 101       socket_(socket),
 102       thread_name_(thread_name),
 103       synchronized_buffers_(synchronized_buffers) {
 104 }
 105
 106 AudioDeviceThread::Thread::~Thread() {
 107   DCHECK(thread_.is_null());
 108 }
 109
 110 void AudioDeviceThread::Thread::Start() {
 111   base::AutoLock auto_lock(callback_lock_);
 112   DCHECK(thread_.is_null());
 113   // This reference will be released when the thread exists.
 114   AddRef();
 115
 116   PlatformThread::CreateWithPriority(0, this, &thread_,
 117                                      base::kThreadPriority_RealtimeAudio);
 118   CHECK(!thread_.is_null());
 119 }
 120
 121 void AudioDeviceThread::Thread::Stop(base::MessageLoop* loop_for_join) {
 122   socket_.Shutdown();
 123
 124   base::PlatformThreadHandle thread = base::PlatformThreadHandle();
 125
 126   {  // NOLINT
 127     base::AutoLock auto_lock(callback_lock_);
 128     callback_ = NULL;
 129     std::swap(thread, thread_);
 130   }
 131
 132   if (!thread.is_null()) {
 133     if (loop_for_join) {
 134       loop_for_join->PostTask(FROM_HERE,
 135           base::Bind(&base::PlatformThread::Join, thread));
 136     } else {
 137       base::PlatformThread::Join(thread);
 138     }
 139   }
 140 }
 141
 142 void AudioDeviceThread::Thread::ThreadMain() {
 143   PlatformThread::SetName(thread_name_);
 144
 145   // Singleton access is safe from this thread as long as callback is non-NULL.
 146   // The callback is the only point where the thread calls out to 'unknown' code
 147   // that might touch singletons and the lifetime of the callback is controlled
 148   // by another thread on which singleton access is OK as well.
 149   base::ThreadRestrictions::SetSingletonAllowed(true);
 150
 151   {  // NOLINT
 152     base::AutoLock auto_lock(callback_lock_);
 153     if (callback_)
 154       callback_->InitializeOnAudioThread();
 155   }
 156
 157   Run();
 158
 159   // Release the reference for the thread. Note that after this, the Thread
 160   // instance will most likely be deleted.
 161   Release();
 162 }
 163
 164 void AudioDeviceThread::Thread::Run() {
 165   uint32 buffer_index = 0;
 166   while (true) {
 167     int pending_data = 0;
 168     size_t bytes_read = socket_.Receive(&pending_data, sizeof(pending_data));
 169     if (bytes_read != sizeof(pending_data)) {
 170       DCHECK_EQ(bytes_read, 0U);
 171       break;
 172     }
 173
 174     {
 175       base::AutoLock auto_lock(callback_lock_);
 176       if (callback_)
 177         callback_->Process(pending_data);
 178     }
 179
 180     // Let the other end know which buffer we just filled.  The buffer index is
 181     // used to ensure the other end is getting the buffer it expects.  For more
 182     // details on how this works see AudioSyncReader::WaitUntilDataIsReady().
 183     if (synchronized_buffers_) {
 184       ++buffer_index;
 185       size_t bytes_sent = socket_.Send(&buffer_index, sizeof(buffer_index));
 186       if (bytes_sent != sizeof(buffer_index))
 187         break;
 188     }
 189   }
 190 }
 191
 192 // AudioDeviceThread::Callback implementation
 193
 194 AudioDeviceThread::Callback::Callback(
 195     const AudioParameters& audio_parameters,
 196     base::SharedMemoryHandle memory,
 197     int memory_length,
 198     int total_segments)
 199     : audio_parameters_(audio_parameters),
 200       samples_per_ms_(audio_parameters.sample_rate() / 1000),
 201       bytes_per_ms_(audio_parameters.channels() *
 202                     (audio_parameters_.bits_per_sample() / 8) *
 203                     samples_per_ms_),
 204       shared_memory_(memory, false),
 205       memory_length_(memory_length),
 206       total_segments_(total_segments) {
 207   CHECK_NE(bytes_per_ms_, 0);  // Catch division by zero early.
 208   CHECK_NE(samples_per_ms_, 0);
 209   CHECK_GT(total_segments_, 0);
 210   CHECK_EQ(memory_length_ % total_segments_, 0);
 211   segment_length_ = memory_length_ / total_segments_;
 212 }
 213
 214 AudioDeviceThread::Callback::~Callback() {}
 215
 216 void AudioDeviceThread::Callback::InitializeOnAudioThread() {
 217   MapSharedMemory();
 218   CHECK(shared_memory_.memory());
 219 }
 220
 221 }  // namespace media.