Adds delta-time logging for audio playout

webrtc/modules/audio_device/audio_device_buffer.h

 /*
  *  Copyright (c) 2012 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_AUDIO_DEVICE_AUDIO_DEVICE_BUFFER_H_
 #define WEBRTC_MODULES_AUDIO_DEVICE_AUDIO_DEVICE_BUFFER_H_
 
+#include <map>
+
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/base/task_queue.h"
 #include "webrtc/base/thread_checker.h"
 #include "webrtc/modules/audio_device/include/audio_device.h"
 #include "webrtc/system_wrappers/include/file_wrapper.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
 class CriticalSectionWrapper;
 
@@ skipping 136 matching lines @@
   uint64_t last_rec_samples_;
 
   // Total number of played audio samples.
   uint64_t play_samples_;
 
   // Total number of played samples stored at the previous timer task.
   uint64_t last_play_samples_;
 
   // Time stamp of last stat report.
   uint64_t last_log_stat_time_;
+
+  uint64_t last_playout_time_;
+
+  // A map where the key value corresponds to time differences (in milliseconds)
+  // between two successive playout callbacks, and the mapped element represents
+  // the number of times a given time difference was found.
+  // Writing to the map is done without a lock since it is only read once at
+  // destruction when no audio is running.
+  std::map<int, int> playout_diff_time_map_;

[magjed_webrtc, 2016/07/29 10:07:11]

You can consider using std::unordered_map instead of map, but I'm not sure it's
faster for few elements. Maybe ask tommi@.

[henrika_webrtc, 2016/07/29 11:11:00]

I think it only affects reading and not writing. And we only read it once at
destruction. Hence not essential. Agree?

[magjed_webrtc, 2016/07/29 12:16:07]

It affects both reading and writing, a map will use an ordered tree (typically
red-black tree), and an unordered_map will use a hash map. It also affects
memory usage.

[henrika_webrtc, 2016/07/29 12:50:24]

Acknowledged.

 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_DEVICE_AUDIO_DEVICE_BUFFER_H_