Add ability to handle data from multiple streams in RateAccCounter.

webrtc/video/stats_counter.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_VIDEO_STATS_COUNTER_H_
 #define WEBRTC_VIDEO_STATS_COUNTER_H_
 
+#include <limits>
+#include <map>
 #include <memory>
 
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
 
 class AggregatedCounter;
 class Clock;
 
@@ skipping 43 matching lines @@
 // counter.Add(7);
 // counter.Add(3);   // process interval passed -> GetMetric() avg:5
 // counter.Add(10);
 // counter.Add(20);  // process interval passed -> GetMetric() avg:15
 // AggregatedStats stats = counter.GetStats();
 // stats: {min:4, max:15, avg:8}
 //
 
 // Note: StatsCounter takes ownership of |observer|.
 
 class StatsCounter {

[stefan-webrtc, 2016/08/19 14:36:56]

Would it be cleaner to have an StreamsStatsCounter which contains a map from
ssrc or stream_id to StatsCounter? That way you still have the simple
StatsCounter and don't have to use ssrc 0 for that.

[åsapersson, 2016/08/23 09:06:02]

Updated the code a bit, ptal. GetMetric is returning a metric from one or more
streams. 

  public:
   virtual ~StatsCounter();
 
   virtual bool GetMetric(int* metric) const = 0;
 
   AggregatedStats GetStats();
 
+  // Holds gathered samples within a process interval.
+  struct Samples {
+    void Add(int sample);
+    void Set(int sample);
+    void Reset();
+
+    int max_ = std::numeric_limits<int>::min();
+    int64_t num_ = 0;
+    int64_t sum_ = 0;
+    int64_t last_sum_ = 0;
+  };
+
  protected:
   StatsCounter(Clock* clock,
                bool include_empty_intervals,
                StatsCounterObserver* observer);
 
   void Add(int sample);
-  void Set(int sample);
+  void Set(int sample, uint32_t ssrc);
 
-  int max_;
-  int64_t sum_;
-  int64_t num_samples_;
-  int64_t last_sum_;
+  const bool include_empty_intervals_;
+  std::map<uint32_t, Samples> samples_;  // Gathered samples mapped by SSRC.
 
  private:
   bool TimeToProcess();
   void TryProcess();
 
   Clock* const clock_;
-  const bool include_empty_intervals_;
   const std::unique_ptr<StatsCounterObserver> observer_;
   const std::unique_ptr<AggregatedCounter> aggregated_counter_;
   int64_t last_process_time_ms_;
 };
 
 // AvgCounter: average of samples
 //
 //           | *      *      *      | *           *       | ...
 //           | Add(5) Add(1) Add(6) | Add(5)      Add(5)  |
 // GetMetric | (5 + 1 + 6) / 3      | (5 + 5) / 2         |
@@ skipping 97 matching lines @@
 //           |<------ 2 sec ------->|                     |
 // GetMetric | 8 / 2                | (13 - 8) / 2        |
 //
 class RateAccCounter : public StatsCounter {
  public:
   RateAccCounter(Clock* clock,
                  StatsCounterObserver* observer,
                  bool include_empty_intervals);
   ~RateAccCounter() override {}
 
-  void Set(int sample);
+  void Set(int sample, uint32_t ssrc);
 
  private:
   bool GetMetric(int* metric) const override;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(RateAccCounter);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_VIDEO_STATS_COUNTER_H_