Only create |remote_rate| when needed in RemoteBitrateEstimatorSingleStream.

webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_single_stream.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 115 matching lines @@
                                 estimator->detector.State(), now_ms);
     estimator->detector.Detect(estimator->estimator.offset(),
                                timestamp_delta_ms,
                                estimator->estimator.num_of_deltas(), now_ms);
   }
   if (estimator->detector.State() == kBwOverusing) {
     rtc::Optional<uint32_t> incoming_bitrate_bps =
         incoming_bitrate_.Rate(now_ms);
     if (incoming_bitrate_bps &&
         (prior_state != kBwOverusing ||
-         remote_rate_->TimeToReduceFurther(now_ms, *incoming_bitrate_bps))) {
+         GetRemoteRate()->TimeToReduceFurther(now_ms, *incoming_bitrate_bps))) {

[brandtr, 2016/11/28 13:17:18]

This change (and the one at the end) do not seem to be strictly necessary. Let
me know if you want me to remove them. I guess they do add a little bit of
overhead.

       // The first overuse should immediately trigger a new estimate.
       // We also have to update the estimate immediately if we are overusing
       // and the target bitrate is too high compared to what we are receiving.
       UpdateEstimate(now_ms);
     }
   }
 }
 
 void RemoteBitrateEstimatorSingleStream::Process() {
   if (TimeUntilNextProcess() > 0) {
@@ skipping 35 matching lines @@
       // Make sure that we trigger an over-use if any of the over-use detectors
       // is detecting over-use.
       if (it->second->detector.State() > bw_state) {
         bw_state = it->second->detector.State();
       }
       ++it;
     }
   }
   // We can't update the estimate if we don't have any active streams.
   if (overuse_detectors_.empty()) {
-    remote_rate_.reset(new AimdRateControl());
     return;
   }
+  AimdRateControl* remote_rate = GetRemoteRate();
 
   double mean_noise_var = sum_var_noise /
       static_cast<double>(overuse_detectors_.size());
   const RateControlInput input(bw_state,
                                incoming_bitrate_.Rate(now_ms),
                                mean_noise_var);
-  remote_rate_->Update(&input, now_ms);
-  uint32_t target_bitrate = remote_rate_->UpdateBandwidthEstimate(now_ms);
-  if (remote_rate_->ValidEstimate()) {
-    process_interval_ms_ = remote_rate_->GetFeedbackInterval();
+  remote_rate->Update(&input, now_ms);
+  uint32_t target_bitrate = remote_rate->UpdateBandwidthEstimate(now_ms);
+  if (remote_rate->ValidEstimate()) {
+    process_interval_ms_ = remote_rate->GetFeedbackInterval();
     std::vector<uint32_t> ssrcs;
     GetSsrcs(&ssrcs);
     observer_->OnReceiveBitrateChanged(ssrcs, target_bitrate);
   }
 }
 
 void RemoteBitrateEstimatorSingleStream::OnRttUpdate(int64_t avg_rtt_ms,
                                                      int64_t max_rtt_ms) {
   CriticalSectionScoped cs(crit_sect_.get());
-  remote_rate_->SetRtt(avg_rtt_ms);
+  GetRemoteRate()->SetRtt(avg_rtt_ms);
 }
 
 void RemoteBitrateEstimatorSingleStream::RemoveStream(unsigned int ssrc) {
   CriticalSectionScoped cs(crit_sect_.get());
   SsrcOveruseEstimatorMap::iterator it = overuse_detectors_.find(ssrc);
   if (it != overuse_detectors_.end()) {
     delete it->second;
     overuse_detectors_.erase(it);
   }
 }
@@ skipping 18 matching lines @@
     std::vector<uint32_t>* ssrcs) const {
   assert(ssrcs);
   ssrcs->resize(overuse_detectors_.size());
   int i = 0;
   for (SsrcOveruseEstimatorMap::const_iterator it = overuse_detectors_.begin();
       it != overuse_detectors_.end(); ++it, ++i) {
     (*ssrcs)[i] = it->first;
   }
 }
 
+AimdRateControl* RemoteBitrateEstimatorSingleStream::GetRemoteRate() {
+  if (!remote_rate_)
+    remote_rate_.reset(new AimdRateControl());
+  return remote_rate_.get();
+}
+
 void RemoteBitrateEstimatorSingleStream::SetMinBitrate(int min_bitrate_bps) {
   CriticalSectionScoped cs(crit_sect_.get());
   remote_rate_->SetMinBitrate(min_bitrate_bps);
 }
 
 }  // namespace webrtc