NetEq/ACM: Refactor how packet waiting times are calculated

webrtc/modules/audio_coding/neteq/statistics_calculator.h

Index: webrtc/modules/audio_coding/neteq/statistics_calculator.h
diff --git a/webrtc/modules/audio_coding/neteq/statistics_calculator.h b/webrtc/modules/audio_coding/neteq/statistics_calculator.h
index a2cd9be6edc9db2f2b52f78b6122e75527dd3a7a..3a1d40da4d48cedcab8dcf536efb9152bddeae48 100644
--- a/webrtc/modules/audio_coding/neteq/statistics_calculator.h
+++ b/webrtc/modules/audio_coding/neteq/statistics_calculator.h
@@ -11,7 +11,7 @@
 #ifndef WEBRTC_MODULES_AUDIO_CODING_NETEQ_STATISTICS_CALCULATOR_H_
 #define WEBRTC_MODULES_AUDIO_CODING_NETEQ_STATISTICS_CALCULATOR_H_
 
-#include <vector>
+#include <list>
 
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/modules/audio_coding/neteq/interface/neteq.h"
@@ -28,7 +28,7 @@ class StatisticsCalculator {
  public:
   StatisticsCalculator();
 
-  virtual ~StatisticsCalculator() {}
+  virtual ~StatisticsCalculator();
 
   // Resets most of the counters.
   void Reset();
@@ -36,9 +36,6 @@ class StatisticsCalculator {
   // Resets the counters that are not handled by Reset().
   void ResetMcu();
 
-  // Resets the waiting time statistics.
-  void ResetWaitingTimeStatistics();
-
   // Reports that |num_samples| samples were produced through expansion, and
   // that the expansion produced other than just noise samples.
   void ExpandedVoiceSamples(int num_samples);
@@ -84,11 +81,9 @@ class StatisticsCalculator {
                             const DecisionLogic& decision_logic,
                             NetEqNetworkStatistics *stats);
 
-  void WaitingTimes(std::vector<int>* waiting_times);
-
  private:
   static const int kMaxReportPeriod = 60;  // Seconds before auto-reset.
-  static const int kLenWaitingTimes = 100;
+  static const size_t kLenWaitingTimes = 100;
 
   // Calculates numerator / denominator, and returns the value in Q14.
   static uint16_t CalculateQ14Ratio(uint32_t numerator, uint32_t denominator);
@@ -101,9 +96,7 @@ class StatisticsCalculator {
   int discarded_packets_;
   uint32_t lost_timestamps_;
   uint32_t timestamps_since_last_report_;
-  int waiting_times_[kLenWaitingTimes];  // Used as a circular buffer.
-  int len_waiting_times_;
-  int next_waiting_time_index_;
+  std::list<int> waiting_times_;

[minyue-webrtc, 2015/08/18 12:55:34]

why to change from vector to list?

[hlundin-webrtc, 2015/08/19 08:28:39]

The reasoning behind my choice is that waiting_times_ might in many cases be
acting as a FIFO buffer. In particular, if the list is full
(waiting_times_.size() >= kLenWaitingTimes), every new value being pushed to the
end will result in the oldest value being popped from the beginning of the list.
That is not very efficient to do with vectors, which is why I went with
std:list. Your input on this is more than welcome.

[minyue-webrtc, 2015/08/19 11:21:52]

maybe use std::deque

[hlundin-webrtc, 2015/08/19 14:34:49]

Yes, much better. Thanks!

   uint32_t secondary_decoded_samples_;
 
   DISALLOW_COPY_AND_ASSIGN(StatisticsCalculator);