Adds delta-time logging for audio playout

webrtc/modules/audio_device/audio_device_buffer.h

Index: webrtc/modules/audio_device/audio_device_buffer.h
diff --git a/webrtc/modules/audio_device/audio_device_buffer.h b/webrtc/modules/audio_device/audio_device_buffer.h
index ee6b2297c77e8e3a981615e52d3c0ccf0db7c767..ba1b43c4c10b9e0a08ef02a55f3b6e7c34675162 100644
--- a/webrtc/modules/audio_device/audio_device_buffer.h
+++ b/webrtc/modules/audio_device/audio_device_buffer.h
@@ -11,6 +11,8 @@
 #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"
@@ -167,6 +169,15 @@ class AudioDeviceBuffer {
 
   // 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