Avoid busy looping in case of send failure when probing.

webrtc/modules/pacing/paced_sender.cc

 /*
  *  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.
  */
 
@@ skipping 237 matching lines @@
 
 PacedSender::PacedSender(Clock* clock, PacketSender* packet_sender)
     : clock_(clock),
       packet_sender_(packet_sender),
       alr_detector_(new AlrDetector()),
       critsect_(CriticalSectionWrapper::CreateCriticalSection()),
       paused_(false),
       media_budget_(new paced_sender::IntervalBudget(0)),
       padding_budget_(new paced_sender::IntervalBudget(0)),
       prober_(new BitrateProber()),
+      probing_send_failure_(false),
       estimated_bitrate_bps_(0),
       min_send_bitrate_kbps_(0u),
       max_padding_bitrate_kbps_(0u),
       pacing_bitrate_kbps_(0),
       time_last_update_us_(clock->TimeInMicroseconds()),
       packets_(new paced_sender::PacketQueue(clock)),
       packet_counter_(0) {
   UpdateBudgetWithElapsedTime(kMinPacketLimitMs);
 }
 
@@ skipping 99 matching lines @@
 int64_t PacedSender::AverageQueueTimeMs() {
   CriticalSectionScoped cs(critsect_.get());
   packets_->UpdateQueueTime(clock_->TimeInMilliseconds());
   return packets_->AverageQueueTimeMs();
 }
 
 int64_t PacedSender::TimeUntilNextProcess() {
   CriticalSectionScoped cs(critsect_.get());
   if (prober_->IsProbing()) {
     int64_t ret = prober_->TimeUntilNextProbe(clock_->TimeInMilliseconds());
-    if (ret >= 0)
+    if (ret > 0 || (ret == 0 && !probing_send_failure_))
       return ret;
   }
   int64_t elapsed_time_us = clock_->TimeInMicroseconds() - time_last_update_us_;
   int64_t elapsed_time_ms = (elapsed_time_us + 500) / 1000;
   return std::max<int64_t>(kMinPacketLimitMs - elapsed_time_ms, 0);
 }
 
 void PacedSender::Process() {
   int64_t now_us = clock_->TimeInMicroseconds();
   CriticalSectionScoped cs(critsect_.get());
@@ skipping 53 matching lines @@
     // do, timestamps get messed up.
     if (packet_counter_ > 0) {
       int padding_needed =
           static_cast<int>(is_probing ? (recommended_probe_size - bytes_sent)
                                       : padding_budget_->bytes_remaining());
 
       if (padding_needed > 0)
         bytes_sent += SendPadding(padding_needed, pacing_info);
     }
   }
-  if (is_probing && bytes_sent > 0)
-    prober_->ProbeSent(clock_->TimeInMilliseconds(), bytes_sent);
+  if (is_probing) {
+    probing_send_failure_ = bytes_sent == 0;

[stefan-webrtc, 2017/02/28 14:23:41]

Why do we fail to send?

+    if (!probing_send_failure_)
+      prober_->ProbeSent(clock_->TimeInMilliseconds(), bytes_sent);
+  }
   alr_detector_->OnBytesSent(bytes_sent, now_us / 1000);
 }
 
 bool PacedSender::SendPacket(const paced_sender::Packet& packet,
                              const PacedPacketInfo& pacing_info) {
   if (paused_)
     return false;
   if (media_budget_->bytes_remaining() == 0 &&
       pacing_info.probe_cluster_id == PacedPacketInfo::kNotAProbe) {
     return false;
@@ skipping 33 matching lines @@
 void PacedSender::UpdateBudgetWithElapsedTime(int64_t delta_time_ms) {
   media_budget_->IncreaseBudget(delta_time_ms);
   padding_budget_->IncreaseBudget(delta_time_ms);
 }
 
 void PacedSender::UpdateBudgetWithBytesSent(size_t bytes_sent) {
   media_budget_->UseBudget(bytes_sent);
   padding_budget_->UseBudget(bytes_sent);
 }
 }  // namespace webrtc