Implement AudioOutputProxy.

media/audio/audio_manager_base.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/audio/audio_manager_base.h"
+#include "media/audio/audio_output_proxy.h"
+#include "media/audio/audio_output_dispatcher.h"

[scherkus (not reviewing), 2010/11/22 06:43:15]

dispatcher should come before proxy

[Sergey Ulanov, 2010/11/23 19:51:46]

Done.

+
+// CompareAudioParams is needed for map to use AudioParameters as a key.
+bool AudioManagerBase::CompareAudioParams::operator()(
+    const AudioParameters& a,
+    const AudioParameters& b) const {
+  if (a.format < b.format)
+    return true;
+  if (a.format > b.format)
+    return false;
+  if (a.channels < b.channels)
+    return true;
+  if (a.channels > b.channels)
+    return false;
+  if (a.sample_rate < b.sample_rate)
+    return true;
+  if (a.sample_rate > b.sample_rate)
+    return false;
+  if (a.bits_per_sample < b.bits_per_sample)
+    return true;
+  if (a.bits_per_sample > b.bits_per_sample)
+    return false;
+  return a.samples_per_packet > b.samples_per_packet;
+}
 
 AudioManagerBase::AudioManagerBase()
     : audio_thread_("AudioThread"),
       initialized_(false) {
 }
 
+AudioManagerBase::~AudioManagerBase() {
+}
+
 void AudioManagerBase::Init() {
   initialized_ = audio_thread_.Start();
 }
 
 MessageLoop* AudioManagerBase::GetMessageLoop() {
   DCHECK(initialized_);
   return audio_thread_.message_loop();
 }
+
+AudioOutputStream* AudioManagerBase::MakeAudioOutputStreamProxy(
+    AudioParameters params) {
+  if (!initialized_)
+    return NULL;
+
+  scoped_refptr<AudioOutputDispatcher>& dispatcher =
+      output_dispatchers_[params];

[scherkus (not reviewing), 2010/11/22 06:43:15]

I tend to avoid using operator[] with map since it'll create an element in the
map even if the key isn't found

also you don't seem to be inserting anything into output_dispatchers_ after
checking... are we supposed to be?

in any case, find() is your friend

[Sergey Ulanov, 2010/11/23 19:51:46]

Yes, and it is desired behavior here.
dispatcher is a reference to the map element. So the line below actually stores
new dispatcher in the map. Here is how this code would look like with
find()/insert()

  AudioOutputDispatcher* dispatcher;
  AudioOutputDispatchersMap::iterator it = output_dispatchers_.find(params);
  if (it == output_dispatchers_.end()) {
    dispatcher = new AudioOutputDispatcher(this, params);
    output_dispatchers_.insert(
        AudioOutputDispatchersMap::value_type(params, dispatcher));
  } else {
    dispatcher = it->second;
  }

It's almost twice as many lines, and it is less efficient :). Let me know if you
like this version better.

[scherkus (not reviewing), 2010/11/24 02:01:59]

Thanks for explaining -- SGTM!

+  if (!dispatcher)
+    dispatcher = new AudioOutputDispatcher(this, params);
+
+  return new AudioOutputProxy(dispatcher);
+}