Add AlrDetector

webrtc/modules/pacing/alr_detector.h

Index: webrtc/modules/pacing/alr_detector.h
diff --git a/webrtc/modules/pacing/alr_detector.h b/webrtc/modules/pacing/alr_detector.h
new file mode 100644
index 0000000000000000000000000000000000000000..acbd36b656c23338e029f85d97b0aee6fef2c254
--- /dev/null
+++ b/webrtc/modules/pacing/alr_detector.h
@@ -0,0 +1,50 @@
+/*
+ *  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_MODULES_PACING_ALR_DETECTOR_H_
+#define WEBRTC_MODULES_PACING_ALR_DETECTOR_H_
+
+#include "webrtc/common_types.h"
+#include "webrtc/typedefs.h"
+
+namespace webrtc {
+
+// Application limited region detector is a class that utilizes signals of
+// elapsed time and bytes sent to estimate whether network traffic is
+// currently limited by the application's ability to generate traffic.
+//
+// AlrDetector provides a signal that can be utilized to adjust
+// estimate bandwidth.
+// Note: This class is not thread-safe.
+class AlrDetector {
+ public:
+  AlrDetector();
+  ~AlrDetector();
+  // Reports time delta elapsed since the last call |ReportElapsedTime|.
+  void ReportElapsedTime(int64_t delta_time_ms);
+  // Reports bytes sent out since the last call |ReportBytesSent|.
+  void ReportBytesSent(size_t bytes);

[philipel, 2016/09/15 15:00:20]

Internally we try to keep everything in bits. I know that PacedSender use bytes
but we want to move away from that.

[Irfan, 2016/09/19 06:51:13]

I think we should keep that change outside this since that requires changing a
bunch of places.

(Orthogonal to this change, am not sure changing everything to bits makes it
more readable. IMHO, packet size is best measured in bytes to be able to compare
to MTU and such)

+  // Set current estimated bandwidth.
+  void SetEstimatedBitrate(int bitrate_bps);
+  // Returns true if currently in application-limited region.
+  bool InApplicationLimitedRegion();
+
+ private:
+  int total_bytes_sent_;
+  int64_t total_elapsed_time_ms_;
+  int estimated_bitrate_bps_;
+  // Number of consecutive periods over which we observe traffic is application
+  // limited.
+  int application_limited_count_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_PACING_ALR_DETECTOR_H_