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/audio/audio_util.h"
  16 #include "media/base/audio_bus.h"
  17
  18 using base::PlatformThread;
  19
  20 namespace media {
  21
  22 // The actual worker thread implementation.  It's very bare bones and much
  23 // simpler than SimpleThread (no synchronization in Start, etc) and supports
  24 // joining the thread handle asynchronously via a provided message loop even
  25 // after the Thread object itself has been deleted.
  26 class AudioDeviceThread::Thread
  27     : public PlatformThread::Delegate,
  28       public base::RefCountedThreadSafe<AudioDeviceThread::Thread> {
  29  public:
  30   Thread(AudioDeviceThread::Callback* callback,
  31          base::SyncSocket::Handle socket,
  32          const char* thread_name);
  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
  59   DISALLOW_COPY_AND_ASSIGN(Thread);
  60 };
  61
  62 // AudioDeviceThread implementation
  63
  64 AudioDeviceThread::AudioDeviceThread() {
  65 }
  66
  67 AudioDeviceThread::~AudioDeviceThread() { DCHECK(!thread_.get()); }
  68
  69 void AudioDeviceThread::Start(AudioDeviceThread::Callback* callback,
  70                               base::SyncSocket::Handle socket,
  71                               const char* thread_name) {
  72   base::AutoLock auto_lock(thread_lock_);
  73   CHECK(thread_.get() == NULL);
  74   thread_ = new AudioDeviceThread::Thread(callback, socket, thread_name);
  75   thread_->Start();
  76 }
  77
  78 void AudioDeviceThread::Stop(base::MessageLoop* loop_for_join) {
  79   base::AutoLock auto_lock(thread_lock_);
  80   if (thread_.get()) {
  81     thread_->Stop(loop_for_join);
  82     thread_ = NULL;
  83   }
  84 }
  85
  86 bool AudioDeviceThread::IsStopped() {
  87   base::AutoLock auto_lock(thread_lock_);
  88   return thread_.get() == NULL;
  89 }
  90
  91 // AudioDeviceThread::Thread implementation
  92 AudioDeviceThread::Thread::Thread(AudioDeviceThread::Callback* callback,
  93                                   base::SyncSocket::Handle socket,
  94                                   const char* thread_name)
  95     : thread_(),
  96       callback_(callback),
  97       socket_(socket),
  98       thread_name_(thread_name) {
  99 }
 100
 101 AudioDeviceThread::Thread::~Thread() {
 102   DCHECK(thread_.is_null());
 103 }
 104
 105 void AudioDeviceThread::Thread::Start() {
 106   base::AutoLock auto_lock(callback_lock_);
 107   DCHECK(thread_.is_null());
 108   // This reference will be released when the thread exists.
 109   AddRef();
 110
 111   PlatformThread::CreateWithPriority(0, this, &thread_,
 112                                      base::kThreadPriority_RealtimeAudio);
 113   CHECK(!thread_.is_null());
 114 }
 115
 116 void AudioDeviceThread::Thread::Stop(base::MessageLoop* loop_for_join) {
 117   socket_.Shutdown();
 118
 119   base::PlatformThreadHandle thread = base::PlatformThreadHandle();
 120
 121   {  // NOLINT
 122     base::AutoLock auto_lock(callback_lock_);
 123     callback_ = NULL;
 124     std::swap(thread, thread_);
 125   }
 126
 127   if (!thread.is_null()) {
 128     if (loop_for_join) {
 129       loop_for_join->PostTask(FROM_HERE,
 130           base::Bind(&base::PlatformThread::Join, thread));
 131     } else {
 132       base::PlatformThread::Join(thread);
 133     }
 134   }
 135 }
 136
 137 void AudioDeviceThread::Thread::ThreadMain() {
 138   PlatformThread::SetName(thread_name_);
 139
 140   // Singleton access is safe from this thread as long as callback is non-NULL.
 141   // The callback is the only point where the thread calls out to 'unknown' code
 142   // that might touch singletons and the lifetime of the callback is controlled
 143   // by another thread on which singleton access is OK as well.
 144   base::ThreadRestrictions::SetSingletonAllowed(true);
 145
 146   {  // NOLINT
 147     base::AutoLock auto_lock(callback_lock_);
 148     if (callback_)
 149       callback_->InitializeOnAudioThread();
 150   }
 151
 152   Run();
 153
 154   // Release the reference for the thread. Note that after this, the Thread
 155   // instance will most likely be deleted.
 156   Release();
 157 }
 158
 159 void AudioDeviceThread::Thread::Run() {
 160   while (true) {
 161     int pending_data = 0;
 162     size_t bytes_read = socket_.Receive(&pending_data, sizeof(pending_data));
 163     if (bytes_read != sizeof(pending_data)) {
 164       DCHECK_EQ(bytes_read, 0U);
 165       break;
 166     }
 167
 168     base::AutoLock auto_lock(callback_lock_);
 169     if (callback_)
 170       callback_->Process(pending_data);
 171   }
 172 }
 173
 174 // AudioDeviceThread::Callback implementation
 175
 176 AudioDeviceThread::Callback::Callback(
 177     const AudioParameters& audio_parameters,
 178     base::SharedMemoryHandle memory,
 179     int memory_length,
 180     int total_segments)
 181     : audio_parameters_(audio_parameters),
 182       samples_per_ms_(audio_parameters.sample_rate() / 1000),
 183       bytes_per_ms_(audio_parameters.channels() *
 184                     (audio_parameters_.bits_per_sample() / 8) *
 185                     samples_per_ms_),
 186       shared_memory_(memory, false),
 187       memory_length_(memory_length),
 188       total_segments_(total_segments) {
 189   CHECK_NE(bytes_per_ms_, 0);  // Catch division by zero early.
 190   CHECK_NE(samples_per_ms_, 0);
 191   CHECK_GT(total_segments_, 0);
 192   CHECK_EQ(memory_length_ % total_segments_, 0);
 193   segment_length_ = memory_length_ / total_segments_;
 194 }
 195
 196 AudioDeviceThread::Callback::~Callback() {}
 197
 198 void AudioDeviceThread::Callback::InitializeOnAudioThread() {
 199   MapSharedMemory();
 200   CHECK(shared_memory_.memory());
 201 }
 202
 203 }  // namespace media.