ProbingEstimator: Erase history based on time threshold

webrtc/modules/congestion_controller/probe_bitrate_estimator.h

 /*
  *  Copyright (c) 2016 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_PROBE_BITRATE_ESTIMATOR_H_
 #define WEBRTC_MODULES_CONGESTION_CONTROLLER_PROBE_BITRATE_ESTIMATOR_H_
 
 #include <map>
 #include <limits>
 
 #include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
 
 namespace webrtc {
 
-struct ProbingResult {
-  static constexpr int kNoEstimate = -1;
-
-  ProbingResult();
-  ProbingResult(int bps, int64_t timestamp);
-  bool valid() const;
-
-  int bps;
-  int64_t timestamp;
-};
-
 class ProbeBitrateEstimator {
  public:
   ProbeBitrateEstimator();
 
-  // Should be called for every packet we receive feedback about. If the
-  // packet was used for probing it will validate/calculate the resulting
-  // bitrate and return the result.
-  ProbingResult PacketFeedback(const PacketInfo& packet_info);
+  // Should be called for every probe packet we receive feedback about.
+  // Estimates highest bitrate across all probe clusters received.
+  // |min_probe_clusters| specifies minimum number of probe clusters to
+  // have a valid BW value.
+  int HandleProbeAndEstimateBitrate(const PacketInfo& packet_info,

[danilchap, 2016/08/19 11:46:30]

this function returns -1 when bitrate doesn't change and
the bitrate when it may be changed (when it is recalculated, probably to the
same cluster).

May it would be cleaner if the funciton always return highest (cached) bitrate,
even if is obviously same as before.
Or return bool to indicate the bitrate may be changed and have an output
parameter or accessor to get highest bitrate so far.

[Irfan, 2016/08/22 18:11:17]

Given that I have removed the highest across clusters functionality now, I think
this is pretty clean now in that it returns bitrate for the cluster to which the
probe belongs to.

+                                    int min_probe_clusters);
 
  private:
   struct AggregatedCluster {
     int num_probes = 0;
     int64_t first_send_ms = std::numeric_limits<int64_t>::max();
     int64_t last_send_ms = 0;
     int64_t first_receive_ms = std::numeric_limits<int64_t>::max();
     int64_t last_receive_ms = 0;
     size_t size = 0;
+    int bps = 0;
   };
 
+  // Erases old cluster data that was seen before |timestamp_ms|.
+  void EraseOldClusters(int64_t timestamp_ms);
+
+  int HighestBitrateOnClusters();
+
   std::map<int, AggregatedCluster> clusters_;
-  int last_valid_cluster_id_;
+  int valid_clusters_ = 0;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_CONGESTION_CONTROLLER_PROBE_BITRATE_ESTIMATOR_H_