Split CongestionController into send- and receive-side classes.

webrtc/modules/congestion_controller/include/receive_side_congestion_controller.h

+/*
+ *  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.
+ */
+
+#ifndef WEBRTC_MODULES_CONGESTION_CONTROLLER_INCLUDE_RECEIVE_SIDE_CONGESTION_CONTROLLER_H_
+#define WEBRTC_MODULES_CONGESTION_CONTROLLER_INCLUDE_RECEIVE_SIDE_CONGESTION_CONTROLLER_H_
+
+#include <memory>
+#include <vector>
+
+#include "webrtc/base/constructormagic.h"
+#include "webrtc/base/criticalsection.h"
+#include "webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.h"
+
+namespace webrtc {
+class RemoteBitrateEstimator;
+class RemoteBitrateObserver;
+
+// This class represents the congestion control state for receive
+// streams. For send side bandwidth estimation, this is simply
+// relaying for each received RTP packet back to the sender. While for
+// receive side bandwidth estimation, we do the estimation locally and
+// send our results back to the sender.
+class ReceiveSideCongestionController : public CallStatsObserver,
+                                        public Module {
+ public:
+  ReceiveSideCongestionController(
+      const Clock* clock,
+      RemoteBitrateObserver* remote_bitrate_observer,
+      PacketRouter* packet_router);
+
+  virtual ~ReceiveSideCongestionController() {}
+
+  virtual void OnReceivedPacket(int64_t arrival_time_ms,
+                                size_t payload_size,
+                                const RTPHeader& header);
+
+  // TODO(nisse): Delete these methods, design a more specific interface.
+  virtual RemoteBitrateEstimator* GetRemoteBitrateEstimator(bool send_side_bwe);
+  virtual const RemoteBitrateEstimator* GetRemoteBitrateEstimator(
+      bool send_side_bwe) const;
+
+  // TODO(nisse): Call this whereever
+  // CongestionController::OnNetworkRouteChanged is called. And rename it.
+  // Resets the bitrate estimator.
+  virtual void OnNetworkRouteChanged(int min_bitrate_bps);
+
+  // TODO(nisse): Called by CongestionController, but not otherwise wired up.
+  // Implements CallStatsObserver.
+  void OnRttUpdate(int64_t avg_rtt_ms, int64_t max_rtt_ms) override;
+
+  // Implements Module.
+  int64_t TimeUntilNextProcess() override;
+  void Process() override;
+
+ private:
+  class WrappingBitrateEstimator : public RemoteBitrateEstimator {
+   public:
+    WrappingBitrateEstimator(RemoteBitrateObserver* observer,
+                             const Clock* clock);
+
+    virtual ~WrappingBitrateEstimator() {}
+
+    void IncomingPacket(int64_t arrival_time_ms,
+                        size_t payload_size,
+                        const RTPHeader& header) override;
+
+    void Process() override;
+
+    int64_t TimeUntilNextProcess() override;
+
+    void OnRttUpdate(int64_t avg_rtt_ms, int64_t max_rtt_ms) override;
+
+    void RemoveStream(unsigned int ssrc) override;
+
+    bool LatestEstimate(std::vector<unsigned int>* ssrcs,
+                        unsigned int* bitrate_bps) const override;
+
+    void SetMinBitrate(int min_bitrate_bps) override;
+
+   private:
+    void PickEstimatorFromHeader(const RTPHeader& header)
+        EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
+    void PickEstimator() EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
+    RemoteBitrateObserver* observer_;
+    const Clock* const clock_;
+    rtc::CriticalSection crit_sect_;
+    std::unique_ptr<RemoteBitrateEstimator> rbe_;
+    bool using_absolute_send_time_;
+    uint32_t packets_since_absolute_send_time_;
+    int min_bitrate_bps_;
+
+    RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(WrappingBitrateEstimator);
+  };
+
+  WrappingBitrateEstimator remote_bitrate_estimator_;
+  RemoteEstimatorProxy remote_estimator_proxy_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_CONGESTION_CONTROLLER_INCLUDE_RECEIVE_SIDE_CONGESTION_CONTROLLER_H_