Refactor NACK bitrate allocation

webrtc/base/rate_statistics.cc

 /*
  *  Copyright (c) 2013 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.
  */
 
@@ skipping 59 matching lines @@
   if (num_samples_ == 0 || active_window_size <= 1 ||
       (num_samples_ <= 1 && active_window_size < current_window_size_ms_)) {
     return rtc::Optional<uint32_t>();
   }
 
   float scale = scale_ / active_window_size;
   return rtc::Optional<uint32_t>(
       static_cast<uint32_t>(accumulated_count_ * scale + 0.5f));
 }
 
+rtc::Optional<uint32_t> RateStatistics::Rate(int64_t now_ms) const {

[danilchap, 2016/06/28 14:26:17]

May be it would be slightly cleaner if only one Rate function would remain
(const version) and const_cast would be used to call EraseOld.

[sprang_webrtc, 2016/07/04 09:33:03]

Done.

+  // Yes, this is ugly, but it's preferable to declaring all internal state
+  // mutable...
+  return const_cast<RateStatistics*>(this)->Rate(now_ms);
+}
+
 void RateStatistics::EraseOld(int64_t now_ms) {
   if (!IsInitialized())
     return;
 
   // New oldest time that is included in data set.
   int64_t new_oldest_time = now_ms - current_window_size_ms_ + 1;
 
   // New oldest time is older than the current one, no need to cull data.
   if (new_oldest_time <= oldest_time_)
     return;
@@ skipping 20 matching lines @@
   current_window_size_ms_ = window_size_ms;
   EraseOld(now_ms);
   return true;
 }
 
 bool RateStatistics::IsInitialized() {
   return oldest_time_ != -max_window_size_ms_;
 }
 
 }  // namespace webrtc