Made MixerAudioSource a pure interface.

webrtc/modules/audio_mixer/audio_mixer_impl.h

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_MODULES_AUDIO_MIXER_AUDIO_MIXER_IMPL_H_
 #define WEBRTC_MODULES_AUDIO_MIXER_AUDIO_MIXER_IMPL_H_
 
 #include <map>
 #include <memory>
 #include <vector>
 
+#include "webrtc/base/gtest_prod_util.h"
 #include "webrtc/base/thread_annotations.h"
 #include "webrtc/base/thread_checker.h"
 #include "webrtc/engine_configurations.h"
 #include "webrtc/modules/audio_mixer/audio_mixer.h"
 #include "webrtc/modules/audio_mixer/audio_mixer_defines.h"
+#include "webrtc/modules/audio_mixer/audio_source_with_mix_status.h"
 #include "webrtc/modules/audio_processing/include/audio_processing.h"
 #include "webrtc/modules/include/module_common_types.h"
 #include "webrtc/system_wrappers/include/critical_section_wrapper.h"
 #include "webrtc/voice_engine/level_indicator.h"
 
 namespace webrtc {
 
 typedef std::vector<AudioFrame*> AudioFrameList;
-typedef std::vector<MixerAudioSource*> MixerAudioSourceList;
+typedef std::vector<AudioSourceWithMixStatus> MixerAudioSourceList;
 
 class AudioMixerImpl : public AudioMixer {
  public:
   // AudioProcessing only accepts 10 ms frames.
   static const int kFrameDurationInMs = 10;
 
-  static std::unique_ptr<AudioMixer> Create(int id);
+  static std::unique_ptr<AudioMixerImpl> Create(int id);

[ivoc, 2016/10/04 20:39:29]

Don't you need the old Create function as well?

[aleloi, 2016/10/05 15:18:19]

There are two Create functions defined in the impl.cc file: 
std::unique_ptr<AudioMixer> AudioMixer::Create
std::unique_ptr<AudioMixerImpl> AudioMixerImpl::Create

Both are currently needed, but the latest redesign plan will move the first one
somewhere else and rename it into something like 

std::unique_ptr<AudioMixer> Something::CreateTop3Mixer

 
   ~AudioMixerImpl() override;
 
   // AudioMixer functions
   int32_t SetMixabilityStatus(MixerAudioSource* audio_source,
                               bool mixable) override;
   bool MixabilityStatus(const MixerAudioSource& audio_source) const override;
   int32_t SetAnonymousMixabilityStatus(MixerAudioSource* audio_source,
                                        bool mixable) override;
   void Mix(int sample_rate,
            size_t number_of_channels,
            AudioFrame* audio_frame_for_mixing) override;
   bool AnonymousMixabilityStatus(
       const MixerAudioSource& audio_source) const override;
 
+  // Returns true if the participant was mixed last round. Returns
+  // false and logs an error if the participant was never added to the
+  // mixer.
+  bool GetAudioSourceMixabilityStatus(MixerAudioSource* participant);

[the sun, 2016/10/04 20:36:10]

Source or participant? Make thy mind up! :)

[aleloi, 2016/10/05 15:18:19]

Done.

+
  private:
   AudioMixerImpl(int id, std::unique_ptr<AudioProcessing> limiter);
 
   // Set/get mix frequency
   int32_t SetOutputFrequency(const Frequency& frequency);
   Frequency OutputFrequency() const;
 
   // Compute what audio sources to mix from audio_source_list_. Ramp
   // in and out. Update mixed status. Mixes up to
   // kMaximumAmountOfMixedAudioSources audio sources.
-  AudioFrameList GetNonAnonymousAudio() const EXCLUSIVE_LOCKS_REQUIRED(crit_);
+  AudioFrameList GetNonAnonymousAudio() EXCLUSIVE_LOCKS_REQUIRED(crit_);
 
   // Return the AudioFrames that should be mixed anonymously. Ramp in
   // and out. Update mixed status.
-  AudioFrameList GetAnonymousAudio() const EXCLUSIVE_LOCKS_REQUIRED(crit_);
+  AudioFrameList GetAnonymousAudio() EXCLUSIVE_LOCKS_REQUIRED(crit_);
 
   // This function returns true if it finds the MixerAudioSource in the
   // specified list of MixerAudioSources.
   bool IsAudioSourceInList(const MixerAudioSource& audio_source,
                            const MixerAudioSourceList& audio_source_list) const;
 
   // Add/remove the MixerAudioSource to the specified
   // MixerAudioSource list.
   bool AddAudioSourceToList(MixerAudioSource* audio_source,
                             MixerAudioSourceList* audio_source_list) const;
   bool RemoveAudioSourceFromList(MixerAudioSource* remove_audio_source,
                                  MixerAudioSourceList* audio_source_list) const;
 
   bool LimitMixedAudio(AudioFrame* mixed_audio) const;
 
   // Output level functions for VoEVolumeControl.
   int GetOutputAudioLevel() override;
 
   int GetOutputAudioLevelFullRange() override;
 
+  // Searches for the AudioSourceWithMixStatus object corresponding to
+  // an audio source. If the audio source was never added with
+  // Set*MixabilityStatus, this returns nullptr.
+  AudioSourceWithMixStatus* GetSourceWithStatus(MixerAudioSource* audio_source);
+
   rtc::CriticalSection crit_;
 
   const int32_t id_;
 
   // The current sample frequency and sample size when mixing.
   Frequency output_frequency_ ACCESS_ON(&thread_checker_);
   size_t sample_size_ ACCESS_ON(&thread_checker_);
 
   // List of all audio sources. Note all lists are disjunct
   MixerAudioSourceList audio_source_list_ GUARDED_BY(crit_);  // May be mixed.
@@ skipping 11 matching lines @@
   // Ensures that Mix is called from the same thread.
   rtc::ThreadChecker thread_checker_;
 
   // Used for inhibiting saturation in mixing.
   std::unique_ptr<AudioProcessing> limiter_ ACCESS_ON(&thread_checker_);
 
   // Measures audio level for the combined signal.
   voe::AudioLevel audio_level_ ACCESS_ON(&thread_checker_);
 
   RTC_DISALLOW_COPY_AND_ASSIGN(AudioMixerImpl);
+  FRIEND_TEST_ALL_PREFIXES(AudioMixerTest, Create);

[the sun, 2016/10/04 20:36:10]

Can we test without creating a circular relationship between the mixer impl and
the test cases? Please?

[aleloi, 2016/10/05 15:18:19]

MixerImpl::Create is public now. When we split the mixer build targets into API
+ implementation, we can make the tests depend on the implementation. Then it
should be possible to get a gn check warning if some other target includes
audio_mixer_impl.

[the sun, 2016/10/05 19:32:11]

I don't understand. Why can't we make the test depend on the impl already now?

Declaring a test as a friend of the class being tested tells me something is
wrong...

[aleloi, 2016/10/06 09:26:12]

That was confusing, sorry. We can depend only on the implementation now (which
we do in the patch that removes 'friend'). When we split the build target into
api + impl, that dependency can be done more explicit and the build system will
issue warnings when someone includes the impl.h  file.

 };
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_MIXER_AUDIO_MIXER_IMPL_H_