RTCStatsReport::AddStats DCHECKs that the ID is unique.

webrtc/api/rtcstatscollector.cc

 /*
  *  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.
  */
 
@@ skipping 215 matching lines @@
   outbound_video->nack_count =
       static_cast<uint32_t>(video_sender_info.nacks_rcvd);
 }
 
 void ProduceCertificateStatsFromSSLCertificateStats(
     int64_t timestamp_us, const rtc::SSLCertificateStats& certificate_stats,
     RTCStatsReport* report) {
   RTCCertificateStats* prev_certificate_stats = nullptr;
   for (const rtc::SSLCertificateStats* s = &certificate_stats; s;
        s = s->issuer.get()) {
+    std::string certificate_stats_id =
+        RTCCertificateIDFromFingerprint(s->fingerprint);
+    // It is possible for the same certificate to show up multiple times, e.g.
+    // if local and remote side use the same certificate in a loopback call.
+    // If the report already contains stats for this certificate, skip it.
+    if (report->Get(certificate_stats_id)) {
+      RTC_DCHECK_EQ(s, &certificate_stats);
+      break;
+    }
     RTCCertificateStats* certificate_stats = new RTCCertificateStats(
-        RTCCertificateIDFromFingerprint(s->fingerprint), timestamp_us);
+        certificate_stats_id, timestamp_us);
     certificate_stats->fingerprint = s->fingerprint;
     certificate_stats->fingerprint_algorithm = s->fingerprint_algorithm;
     certificate_stats->base64_certificate = s->base64_certificate;
     if (prev_certificate_stats)
       prev_certificate_stats->issuer_certificate_id = certificate_stats->id();
     report->AddStats(std::unique_ptr<RTCCertificateStats>(certificate_stats));
     prev_certificate_stats = certificate_stats;
   }
 }
 
@@ skipping 33 matching lines @@
   // crbug.com/659137
   // TODO(hbos): Return stats of detached tracks. We have to perform stats
   // gathering at the time of detachment to get accurate stats and timestamps.
   // crbug.com/659137
   if (!streams)
     return;
   for (size_t i = 0; i < streams->count(); ++i) {
     MediaStreamInterface* stream = streams->at(i);
 
     std::unique_ptr<RTCMediaStreamStats> stream_stats(
-        new RTCMediaStreamStats("RTCMediaStream_" + stream->label(),
-                                timestamp_us));
+        new RTCMediaStreamStats(
+            (is_local ? "RTCMediaStream_local_" : "RTCMediaStream_remote_") +
+            stream->label(), timestamp_us));
     stream_stats->stream_identifier = stream->label();
     stream_stats->track_ids = std::vector<std::string>();
     // Audio Tracks
     for (const rtc::scoped_refptr<AudioTrackInterface>& audio_track :
          stream->GetAudioTracks()) {
       std::string id = RTCMediaStreamTrackStatsIDFromMediaStreamTrackInterface(
         *audio_track.get());
       if (report->Get(id)) {
         // Skip track, stats already exist for it.
         continue;
@@ skipping 652 matching lines @@
     const std::string& type) {
   return CandidateTypeToRTCIceCandidateType(type);
 }
 
 const char* DataStateToRTCDataChannelStateForTesting(
     DataChannelInterface::DataState state) {
   return DataStateToRTCDataChannelState(state);
 }
 
 }  // namespace webrtc