Measure packet loss so we can use it to select ICE candidate pairs.

webrtc/p2p/base/port.cc

 /*
  *  Copyright 2004 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 59 matching lines @@
 inline int ConservativeRTTEstimate(int rtt) {
   return std::max(MINIMUM_RTT, std::min(MAXIMUM_RTT, 2 * rtt));
 }
 
 // Weighting of the old rtt value to new data.
 const int RTT_RATIO = 3;  // 3 : 1
 
 // The delay before we begin checking if this port is useless. We set
 // it to a little higher than a total STUN timeout.
 const int kPortTimeoutDelay = cricket::STUN_TOTAL_TIMEOUT + 5000;
+
+// For packet loss estimation.
+const int64_t kConsiderPacketLostAfter = 3000;  // 3 seconds
+
+// For packet loss estimation.
+const int64_t kForgetPacketAfter = 30000;  // 30 seconds
+
 }  // namespace
 
 namespace cricket {
 
 // TODO(ronghuawu): Use "host", "srflx", "prflx" and "relay". But this requires
 // the signaling part be updated correspondingly as well.
 const char LOCAL_PORT_TYPE[] = "local";
 const char STUN_PORT_TYPE[] = "stun";
 const char PRFLX_PORT_TYPE[] = "prflx";
 const char RELAY_PORT_TYPE[] = "relay";
@@ skipping 788 matching lines @@
       connected_(true),
       pruned_(false),
       use_candidate_attr_(false),
       remote_ice_mode_(ICEMODE_FULL),
       requests_(port->thread()),
       rtt_(DEFAULT_RTT),
       last_ping_sent_(0),
       last_ping_received_(0),
       last_data_received_(0),
       last_ping_response_received_(0),
+      packet_loss_estimator_(kConsiderPacketLostAfter, kForgetPacketAfter),
       reported_(false),
       state_(IceCandidatePairState::WAITING),
       receiving_timeout_(WEAK_CONNECTION_RECEIVE_TIMEOUT),
       time_created_ms_(rtc::TimeMillis()) {
   // All of our connections start in WAITING state.
   // TODO(mallinath) - Start connections from STATE_FROZEN.
   // Wire up to send stun packets
   requests_.SignalSendPacket.connect(this, &Connection::OnSendStunPacket);
   LOG_J(LS_INFO, this) << "Connection created";
 }
@@ skipping 332 matching lines @@
   UpdateReceiving(now);
   if (dead(now)) {
     Destroy();
   }
 }
 
 void Connection::Ping(int64_t now) {
   last_ping_sent_ = now;
   ConnectionRequest *req = new ConnectionRequest(this);
   pings_since_last_response_.push_back(SentPing(req->id(), now, nomination_));
+  packet_loss_estimator_.ExpectResponse(req->id(), now);
   LOG_J(LS_VERBOSE, this) << "Sending STUN ping "
                           << ", id=" << rtc::hex_encode(req->id())
                           << ", nomination=" << nomination_;
   requests_.Send(req);
   state_ = IceCandidatePairState::IN_PROGRESS;
   num_pings_sent_++;
 }
 
 void Connection::ReceivedPing() {
   last_ping_received_ = rtc::TimeMillis();
@@ skipping 134 matching lines @@
     std::string pings;
     PrintPingsSinceLastResponse(&pings, 5);
     LOG_JV(sev, this) << "Received STUN ping response"
                       << ", id=" << rtc::hex_encode(request->id())
                       << ", code=0"  // Makes logging easier to parse.
                       << ", rtt=" << rtt
                       << ", pings_since_last_response=" << pings;
   }
   ReceivedPingResponse(rtt, request->id());
 
+  int64_t time_received = rtc::TimeMillis();
+  packet_loss_estimator_.ReceivedResponse(request->id(), time_received);
+
   stats_.recv_ping_responses++;
 
   MaybeUpdateLocalCandidate(request, response);
 }
 
 void Connection::OnConnectionRequestErrorResponse(ConnectionRequest* request,
                                                   StunMessage* response) {
   const StunErrorCodeAttribute* error_attr = response->GetErrorCode();
   int error_code = STUN_ERROR_GLOBAL_FAILURE;
   if (error_attr) {
@@ skipping 208 matching lines @@
     RTC_DCHECK(sent < 0);
     error_ = port_->GetError();
     stats_.sent_discarded_packets++;
   } else {
     send_rate_tracker_.AddSamples(sent);
   }
   return sent;
 }
 
 }  // namespace cricket