Split CongestionController into send- and receive-side classes.

webrtc/modules/congestion_controller/receive_side_congestion_controller.cc

+/*
+ *  Copyright (c) 2017 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.
+ */
+
+#include "webrtc/modules/congestion_controller/include/receive_side_congestion_controller.h"
+
+#include "webrtc/base/logging.h"
+#include "webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_abs_send_time.h"
+#include "webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_single_stream.h"
+
+namespace webrtc {
+
+namespace {
+static const uint32_t kTimeOffsetSwitchThreshold = 30;
+}  // namespace
+
+ReceiveSideCongestionController::WrappingBitrateEstimator::
+    WrappingBitrateEstimator(RemoteBitrateObserver* observer,
+                             const Clock* clock)
+    : observer_(observer),
+      clock_(clock),
+      rbe_(new RemoteBitrateEstimatorSingleStream(observer_, clock_)),
+      using_absolute_send_time_(false),
+      packets_since_absolute_send_time_(0),
+      min_bitrate_bps_(congestion_controller::GetMinBitrateBps()) {}
+
+void ReceiveSideCongestionController::WrappingBitrateEstimator::IncomingPacket(
+    int64_t arrival_time_ms,
+    size_t payload_size,
+    const RTPHeader& header) {
+  rtc::CritScope cs(&crit_sect_);
+  PickEstimatorFromHeader(header);
+  rbe_->IncomingPacket(arrival_time_ms, payload_size, header);
+}
+
+void ReceiveSideCongestionController::WrappingBitrateEstimator::Process() {
+  rtc::CritScope cs(&crit_sect_);
+  rbe_->Process();
+}
+
+int64_t ReceiveSideCongestionController::WrappingBitrateEstimator::
+    TimeUntilNextProcess() {
+  rtc::CritScope cs(&crit_sect_);
+  return rbe_->TimeUntilNextProcess();
+}
+
+void ReceiveSideCongestionController::WrappingBitrateEstimator::OnRttUpdate(
+    int64_t avg_rtt_ms,
+    int64_t max_rtt_ms) {
+  rtc::CritScope cs(&crit_sect_);
+  rbe_->OnRttUpdate(avg_rtt_ms, max_rtt_ms);
+}
+
+void ReceiveSideCongestionController::WrappingBitrateEstimator::RemoveStream(
+    unsigned int ssrc) {
+  rtc::CritScope cs(&crit_sect_);
+  rbe_->RemoveStream(ssrc);
+}
+
+bool ReceiveSideCongestionController::WrappingBitrateEstimator::LatestEstimate(
+    std::vector<unsigned int>* ssrcs,
+    unsigned int* bitrate_bps) const {
+  rtc::CritScope cs(&crit_sect_);
+  return rbe_->LatestEstimate(ssrcs, bitrate_bps);
+}
+
+void ReceiveSideCongestionController::WrappingBitrateEstimator::SetMinBitrate(
+    int min_bitrate_bps) {
+  rtc::CritScope cs(&crit_sect_);
+  rbe_->SetMinBitrate(min_bitrate_bps);
+  min_bitrate_bps_ = min_bitrate_bps;
+}
+
+void ReceiveSideCongestionController::WrappingBitrateEstimator::
+    PickEstimatorFromHeader(const RTPHeader& header) {
+  if (header.extension.hasAbsoluteSendTime) {
+    // If we see AST in header, switch RBE strategy immediately.
+    if (!using_absolute_send_time_) {
+      LOG(LS_INFO)
+          << "WrappingBitrateEstimator: Switching to absolute send time RBE.";
+      using_absolute_send_time_ = true;
+      PickEstimator();
+    }
+    packets_since_absolute_send_time_ = 0;
+  } else {
+    // When we don't see AST, wait for a few packets before going back to TOF.
+    if (using_absolute_send_time_) {
+      ++packets_since_absolute_send_time_;
+      if (packets_since_absolute_send_time_ >= kTimeOffsetSwitchThreshold) {
+        LOG(LS_INFO) << "WrappingBitrateEstimator: Switching to transmission "
+                     << "time offset RBE.";
+        using_absolute_send_time_ = false;
+        PickEstimator();
+      }
+    }
+  }
+}
+
+// Instantiate RBE for Time Offset or Absolute Send Time extensions.
+void ReceiveSideCongestionController::WrappingBitrateEstimator::
+    PickEstimator() {
+  if (using_absolute_send_time_) {
+    rbe_.reset(new RemoteBitrateEstimatorAbsSendTime(observer_, clock_));
+  } else {
+    rbe_.reset(new RemoteBitrateEstimatorSingleStream(observer_, clock_));
+  }
+  rbe_->SetMinBitrate(min_bitrate_bps_);
+}
+
+ReceiveSideCongestionController::ReceiveSideCongestionController(
+    const Clock* clock,
+    RemoteBitrateObserver* remote_bitrate_observer,
+    PacketRouter* packet_router)
+    : remote_bitrate_estimator_(remote_bitrate_observer, clock),
+      remote_estimator_proxy_(clock, packet_router) {}
+
+void ReceiveSideCongestionController::OnReceivedPacket(
+    int64_t arrival_time_ms,
+    size_t payload_size,
+    const RTPHeader& header) {
+  // Send-side BWE.
+  if (header.extension.hasTransportSequenceNumber) {
+    remote_estimator_proxy_.IncomingPacket(arrival_time_ms, payload_size,
+                                           header);
+  } else {
+    // Receive-side BWE.
+    remote_bitrate_estimator_.IncomingPacket(arrival_time_ms, payload_size,
+                                             header);
+  }
+}
+
+RemoteBitrateEstimator*
+ReceiveSideCongestionController::GetRemoteBitrateEstimator(bool send_side_bwe) {
+  if (send_side_bwe) {
+    return &remote_estimator_proxy_;
+  } else {
+    return &remote_bitrate_estimator_;
+  }
+}
+
+const RemoteBitrateEstimator*
+ReceiveSideCongestionController::GetRemoteBitrateEstimator(
+    bool send_side_bwe) const {
+  if (send_side_bwe) {
+    return &remote_estimator_proxy_;
+  } else {
+    return &remote_bitrate_estimator_;
+  }
+}
+
+// TODO(nisse): When this code was part of CongestionController, the
+// method MaybeTriggerOnNetworkChanged called
+// remote_estimator_proxy_.OnBitrateChanged(bitrate_bps), and this was
+// called by both OnNetworkRouteChanged and Process. Do we need any
+// calls to OnBitRateChanged here?
+
+void ReceiveSideCongestionController::OnNetworkRouteChanged(
+    int min_bitrate_bps) {

[stefan-webrtc, 2017/03/17 08:03:32]

I doubt there's much value in this as I don't think anyone will be changing the
min bitrate if the network route changes. I would suggest we remove it.

[nisse-webrtc, 2017/03/17 10:49:23]

Sounds good to me. Deleted.

+  // TODO(nisse): Do we need to clamp using
+  // webrtc::congestion_controller::GetMinBitrateBps?
+  // TODO(honghaiz): Recreate this object once the remote bitrate estimator is
+  // no longer exposed outside CongestionController.
+  remote_bitrate_estimator_.SetMinBitrate(min_bitrate_bps);
+}
+
+void ReceiveSideCongestionController::OnRttUpdate(int64_t avg_rtt_ms,
+                                                  int64_t max_rtt_ms) {
+  remote_bitrate_estimator_.OnRttUpdate(avg_rtt_ms, max_rtt_ms);
+}
+
+int64_t ReceiveSideCongestionController::TimeUntilNextProcess() {
+  return remote_bitrate_estimator_.TimeUntilNextProcess();
+}
+
+void ReceiveSideCongestionController::Process() {
+  remote_bitrate_estimator_.Process();
+}
+
+}  // namespace webrtc