TrackMediaInfoMap added.

webrtc/api/trackmediainfomap.cc

Index: webrtc/api/trackmediainfomap.cc
diff --git a/webrtc/api/trackmediainfomap.cc b/webrtc/api/trackmediainfomap.cc
new file mode 100644
index 0000000000000000000000000000000000000000..d1acefe0958195df291d34c6b7cd91961fafeba8
--- /dev/null
+++ b/webrtc/api/trackmediainfomap.cc
@@ -0,0 +1,255 @@
+/*
+ *  Copyright 2016 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.
+ */
+
+#include "webrtc/api/trackmediainfomap.h"
+
+#include <utility>
+
+namespace webrtc {
+
+namespace {
+
+template<typename T>
+T* CheckedTrackCast(MediaStreamTrackInterface* track);
+
+template<>

[hta-webrtc, 2017/01/11 12:34:24]

C++ ignorance: Why is there value in having the template<> marking when it
templates nothing? Why can't these be just overloaded functions?

[hbos, 2017/01/11 15:55:32]

Without the DCHECK I could remove this function and simply to a static_cast, but
the DCHECK needs to either use MediaStreamTrackInterface::kAudioKind or
kVideoKind depending on the type T. There's no "T::kKind" so a different
function implementation is required depending on T, this is called function
template specialization.

You can't use normal function overloading because the argument has the same type
in both cases, it's the return value that is different depending on T.

You declare "CheckedTrackCast<T> is a thing", and then say "for calls to
CheckedTrackCast<AudioTrackInterface>, use this implementation" and "for calls
to CheckedTrackCast<VideoTrackInterface>, use this implementation".
(CheckedTrackCast<Other> is undefined and gives link error.)

+AudioTrackInterface* CheckedTrackCast(MediaStreamTrackInterface* track) {
+  RTC_DCHECK_EQ(track->kind(), MediaStreamTrackInterface::kAudioKind);
+  return static_cast<AudioTrackInterface*>(track);
+}
+
+template<>
+VideoTrackInterface* CheckedTrackCast(MediaStreamTrackInterface* track) {
+  RTC_DCHECK_EQ(track->kind(), MediaStreamTrackInterface::kVideoKind);
+  return static_cast<VideoTrackInterface*>(track);
+}
+
+// |T|: |AudioTrackInterface| or |VideoTrackInterface|, must match with
+//      |media_type|.
+template<typename T>
+std::map<uint32_t, T*> GetSsrcToTrack(
+    cricket::MediaType media_type,
+    const std::vector<rtc::scoped_refptr<RtpSenderInterface>>& rtp_senders,
+    const std::vector<rtc::scoped_refptr<RtpReceiverInterface>>&
+        rtp_receivers) {
+  std::map<uint32_t, T*> ssrc_to_track;
+  for (const rtc::scoped_refptr<RtpSenderInterface>& rtp_sender : rtp_senders) {
+    if (rtp_sender->media_type() != media_type || !rtp_sender->track()) {
+      continue;
+    }
+    // TODO(deadbeef): |ssrc| should be removed in favor of |GetParameters|.
+    if (rtp_sender->ssrc() != 0) {

[hta-webrtc, 2017/01/11 12:34:23]

Why isn't it correct to loop over all the ssrcs in rtp_sender->ssrcs() here,
mapping them all to the same track?

[hbos, 2017/01/11 15:55:32]

If I understand correctly, it's because the first is used as the identifier for
that set of SSRCs. Why it is so I don't know.

+      RTC_DCHECK(ssrc_to_track.find(rtp_sender->ssrc()) == ssrc_to_track.end());
+      ssrc_to_track[rtp_sender->ssrc()] = CheckedTrackCast<T>(
+          rtp_sender->track());
+    }
+    RtpParameters params = rtp_sender->GetParameters();

[Taylor Brandstetter, 2017/01/10 17:29:24]

Something I wanted to point out before I forget: this will invoke on the worker
thread currently.

[hbos, 2017/01/11 15:55:32]

Thanks, I didn't realize [1] occurred. Ugh, but I'm guessing the proxy[2] is
used, so even if we were on the worker thread we would do W -> S -> W and back.
I added a TODO.

[1]
https://cs.chromium.org/chromium/src/third_party/webrtc/pc/channel.cc?sq=pack...
[2]
https://cs.chromium.org/chromium/src/third_party/webrtc/api/rtpsenderinterfac...

[Taylor Brandstetter, 2017/01/11 22:12:05]

Yes, if you call GetSenders you'll get proxies. But a pointer to the inner
non-proxy interface is kept around, using this "ProxyWithInternal" thing I
added:
https://cs.chromium.org/chromium/src/third_party/webrtc/api/peerconnection.h?...

So when we fix this, we can just add a "GetInternalSenders()" method to
PeerConnection (and not PeerConnectionInterface).

+    for (const RtpEncodingParameters& encoding : params.encodings) {
+      if (!encoding.ssrc || *encoding.ssrc == rtp_sender->ssrc()) {
+        continue;
+      }
+      RTC_DCHECK(ssrc_to_track.find(*encoding.ssrc) == ssrc_to_track.end());
+      ssrc_to_track[*encoding.ssrc] = CheckedTrackCast<T>(rtp_sender->track());
+    }
+  }
+  for (const rtc::scoped_refptr<RtpReceiverInterface>& rtp_receiver :
+       rtp_receivers) {
+    if (rtp_receiver->media_type() != media_type) {
+      continue;
+    }
+    RTC_DCHECK(rtp_receiver->track());
+    RtpParameters params = rtp_receiver->GetParameters();
+    for (const RtpEncodingParameters& encoding : params.encodings) {
+      if (!encoding.ssrc) {
+        continue;
+      }
+      RTC_DCHECK(ssrc_to_track.find(*encoding.ssrc) == ssrc_to_track.end());
+      ssrc_to_track[*encoding.ssrc] = CheckedTrackCast<T>(
+          rtp_receiver->track());
+    }
+  }
+  return ssrc_to_track;
+}
+
+// Template in order to support both the audio and video case.
+template<typename TrackType, typename InfoType>
+TrackType* GetAssociatedTrack(
+  const std::map<uint32_t, TrackType*>& ssrc_to_track,
+  const InfoType& info) {
+  typename std::map<uint32_t, TrackType*>::const_iterator it =
+      ssrc_to_track.find(info.ssrc());
+  if (it == ssrc_to_track.end()) {
+    return nullptr;
+  }
+  return it->second;
+}
+
+// Template in order to support both the audio and video case.
+template<typename TrackType,
+         typename MediaInfoType,
+         typename SenderInfoToTrackType,
+         typename LocalTrackToInfosType,
+         typename ReceiverInfoToTrackType,
+         typename RemoteTrackToInfosType>
+void MapTracksAndInfos(
+    const std::map<uint32_t, TrackType*>& ssrc_to_track,
+    MediaInfoType* media_info,
+    SenderInfoToTrackType* sender_info_to_track,
+    LocalTrackToInfosType* local_track_to_infos,
+    ReceiverInfoToTrackType* receiver_info_to_track,
+    RemoteTrackToInfosType* remote_track_to_info) {
+  for (auto& sender_info : media_info->senders) {
+    TrackType* associated_track = GetAssociatedTrack<TrackType>(
+        ssrc_to_track, sender_info);
+    if (associated_track) {
+      // One sender is associated with at most one track.
+      // One track may be associated with multiple senders.
+      (*sender_info_to_track)[&sender_info] = associated_track;
+      (*local_track_to_infos)[associated_track].push_back(&sender_info);
+    }
+  }
+  for (auto& receiver_info : media_info->receivers) {
+    TrackType* associated_track = GetAssociatedTrack<TrackType>(
+        ssrc_to_track, receiver_info);
+    if (associated_track) {
+      // One receiver is associated with at most one track, which is uniquely
+      // associated with that receiver.
+      (*receiver_info_to_track)[&receiver_info] = associated_track;
+      RTC_DCHECK(remote_track_to_info->find(associated_track) ==
+                 remote_track_to_info->end());
+      (*remote_track_to_info)[associated_track] = &receiver_info;
+    }
+  }
+}
+
+}  // namespace
+
+TrackMediaInfoMap::TrackMediaInfoMap(
+    std::unique_ptr<cricket::VoiceMediaInfo> voice_media_info,
+    std::unique_ptr<cricket::VideoMediaInfo> video_media_info,
+    const std::vector<rtc::scoped_refptr<RtpSenderInterface>>& rtp_senders,
+    const std::vector<rtc::scoped_refptr<RtpReceiverInterface>>& rtp_receivers)
+    : voice_media_info_(std::move(voice_media_info)),
+      video_media_info_(std::move(video_media_info)) {
+  if (voice_media_info_) {
+    std::map<uint32_t, AudioTrackInterface*> ssrc_to_audio_track =
+        GetSsrcToTrack<AudioTrackInterface>(
+            cricket::MEDIA_TYPE_AUDIO, rtp_senders, rtp_receivers);
+    MapTracksAndInfos<AudioTrackInterface>(ssrc_to_audio_track,
+                                           voice_media_info_.get(),
+                                           &voice_sender_info_to_track_,
+                                           &local_audio_track_to_infos_,
+                                           &voice_receiver_info_to_track_,
+                                           &remote_audio_track_to_info_);
+  }
+  if (video_media_info_) {
+    std::map<uint32_t, VideoTrackInterface*> ssrc_to_video_track =
+        GetSsrcToTrack<VideoTrackInterface>(
+            cricket::MEDIA_TYPE_VIDEO, rtp_senders, rtp_receivers);
+    MapTracksAndInfos<VideoTrackInterface>(ssrc_to_video_track,
+                                           video_media_info_.get(),
+                                           &video_sender_info_to_track_,
+                                           &local_video_track_to_infos_,
+                                           &video_receiver_info_to_track_,
+                                           &remote_video_track_to_info_);
+  }
+}
+
+const std::vector<cricket::VoiceSenderInfo*>*
+TrackMediaInfoMap::GetVoiceSenderInfos(
+    const AudioTrackInterface& local_audio_track) const {
+  std::map<const AudioTrackInterface*,
+           std::vector<cricket::VoiceSenderInfo*>>::const_iterator it =
+      local_audio_track_to_infos_.find(&local_audio_track);
+  if (it == local_audio_track_to_infos_.end()) {
+    return nullptr;
+  }
+  return &it->second;
+}
+
+const cricket::VoiceReceiverInfo* TrackMediaInfoMap::GetVoiceReceiverInfo(
+    const AudioTrackInterface& remote_audio_track) const {
+  std::map<const AudioTrackInterface*,
+           cricket::VoiceReceiverInfo*>::const_iterator it =

[hta-webrtc, 2017/01/11 12:34:23]

Would "auto" be usable here? Seems that C++ already has all the type
information.

[hbos, 2017/01/11 15:55:33]

Done.

+      remote_audio_track_to_info_.find(&remote_audio_track);
+  if (it == remote_audio_track_to_info_.end()) {
+    return nullptr;
+  }
+  return it->second;
+}
+
+const std::vector<cricket::VideoSenderInfo*>*
+TrackMediaInfoMap::GetVideoSenderInfos(
+    const VideoTrackInterface& local_video_track) const {
+  std::map<const VideoTrackInterface*,
+           std::vector<cricket::VideoSenderInfo*>>::const_iterator it =
+      local_video_track_to_infos_.find(&local_video_track);
+  if (it == local_video_track_to_infos_.end()) {
+    return nullptr;
+  }
+  return &it->second;
+}
+
+const cricket::VideoReceiverInfo* TrackMediaInfoMap::GetVideoReceiverInfo(
+    const VideoTrackInterface& remote_video_track) const {
+  std::map<const VideoTrackInterface*,
+           cricket::VideoReceiverInfo*>::const_iterator it =
+      remote_video_track_to_info_.find(&remote_video_track);
+  if (it == remote_video_track_to_info_.end()) {
+    return nullptr;
+  }
+  return it->second;
+}
+
+rtc::scoped_refptr<AudioTrackInterface> TrackMediaInfoMap::GetAudioTrack(
+    const cricket::VoiceSenderInfo& voice_sender_info) const {
+  std::map<const cricket::VoiceSenderInfo*,
+           rtc::scoped_refptr<AudioTrackInterface>>::const_iterator it =
+      voice_sender_info_to_track_.find(&voice_sender_info);
+  if (it == voice_sender_info_to_track_.end()) {
+    return nullptr;
+  }
+  return it->second;
+}
+
+rtc::scoped_refptr<AudioTrackInterface> TrackMediaInfoMap::GetAudioTrack(
+    const cricket::VoiceReceiverInfo& voice_receiver_info) const {
+  std::map<const cricket::VoiceReceiverInfo*,
+           rtc::scoped_refptr<AudioTrackInterface>>::const_iterator it =
+      voice_receiver_info_to_track_.find(&voice_receiver_info);
+  if (it == voice_receiver_info_to_track_.end()) {
+    return nullptr;
+  }
+  return it->second;
+}
+
+rtc::scoped_refptr<VideoTrackInterface> TrackMediaInfoMap::GetVideoTrack(
+    const cricket::VideoSenderInfo& video_sender_info) const {
+  std::map<const cricket::VideoSenderInfo*,
+           rtc::scoped_refptr<VideoTrackInterface>>::const_iterator it =
+      video_sender_info_to_track_.find(&video_sender_info);
+  if (it == video_sender_info_to_track_.end()) {
+    return nullptr;
+  }
+  return it->second;
+}
+
+rtc::scoped_refptr<VideoTrackInterface> TrackMediaInfoMap::GetVideoTrack(
+    const cricket::VideoReceiverInfo& video_receiver_info) const {
+  std::map<const cricket::VideoReceiverInfo*,
+           rtc::scoped_refptr<VideoTrackInterface>>::const_iterator it =
+      video_receiver_info_to_track_.find(&video_receiver_info);
+  if (it == video_receiver_info_to_track_.end()) {
+    return nullptr;
+  }
+  return it->second;
+}
+
+}  // namespace webrtc