RTCRtpReceiver.getContributingSources() added.

third_party/WebKit/Source/modules/peerconnection/RTCRtpReceiver.cpp

 // Copyright 2017 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 "modules/peerconnection/RTCRtpReceiver.h"
 
+#include "bindings/core/v8/Microtask.h"
+#include "public/platform/WebRTCRtpContributingSource.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 RTCRtpReceiver::RTCRtpReceiver(std::unique_ptr<WebRTCRtpReceiver> receiver,
                                MediaStreamTrack* track)
     : m_receiver(std::move(receiver)), m_track(track) {
   DCHECK(m_receiver);
   DCHECK(m_track);
   DCHECK_EQ(static_cast<String>(m_receiver->track().id()), m_track->id());
 }
 
 MediaStreamTrack* RTCRtpReceiver::track() const {
   return m_track;
 }
 
+const HeapVector<Member<RTCRtpContributingSource>>&
+RTCRtpReceiver::getContributingSources() {
+  updateSourcesIfNeeded();
+  return m_contributingSources;
+}
+
+void RTCRtpReceiver::updateSourcesIfNeeded() {
+  if (!m_contributingSourcesNeedsUpdating)
+    return;
+  m_contributingSources.clear();
+  for (const std::unique_ptr<WebRTCRtpContributingSource>&
+           webContributingSource : m_receiver->getSources()) {
+    if (webContributingSource->sourceType() ==
+        WebRTCRtpContributingSourceType::SSRC) {
+      // TODO(hbos): When |getSynchronizationSources| is added to get SSRC
+      // sources don't ignore SSRCs here.
+      continue;
+    }
+    DCHECK_EQ(webContributingSource->sourceType(),
+              WebRTCRtpContributingSourceType::CSRC);
+    auto it =
+        m_contributingSourcesBySourceId.find(webContributingSource->source());
+    if (it == m_contributingSourcesBySourceId.end()) {
+      RTCRtpContributingSource* contributingSource =
+          new RTCRtpContributingSource(this, *webContributingSource);
+      m_contributingSourcesBySourceId.insert(contributingSource->source(),
+                                             contributingSource);
+      m_contributingSources.push_back(contributingSource);
+    } else {
+      *it->value = *webContributingSource;
+      m_contributingSources.push_back(it->value);
+    }
+  }
+  // Clear the flag and schedule a microtask to reset it to true. This makes
+  // the cache valid until the next microtask checkpoint. As such, sources
+  // represent a snapshot and can be compared reliably in .js code, no risk of
+  // being updated due to an RTP packet arriving. E.g.
+  // "source.timestamp == source.timestamp" will always be true.
+  m_contributingSourcesNeedsUpdating = false;
+  Microtask::enqueueMicrotask(
+      WTF::bind(&RTCRtpReceiver::setContributingSourcesNeedsUpdating,
+                wrapWeakPersistent(this)));
+}
+
+void RTCRtpReceiver::setContributingSourcesNeedsUpdating() {
+  m_contributingSourcesNeedsUpdating = true;
+}
+
 DEFINE_TRACE(RTCRtpReceiver) {
   visitor->trace(m_track);
+  visitor->trace(m_contributingSourcesBySourceId);
+  visitor->trace(m_contributingSources);
 }
 
 }  // namespace blink