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..547501fda51ca54280a78546c7e6276c37d8b6b7
--- /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/base/criticalsection.h"
+#include "webrtc/common_types.h"
+#include "webrtc/modules/pacing/paced_sender.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();
+  void OnBytesSent(size_t bytes_sent, int64_t elapsed_time_ms);
+  // Set current estimated bandwidth.
+  void SetEstimatedBitrate(int bitrate_bps);
+  // Returns true if currently in application-limited region.
+  bool InApplicationLimitedRegion();
+
+ private:
+  rtc::CriticalSection critsect_;
+  int measurement_interval_bytes_sent_ GUARDED_BY(critsect_);
+  int64_t measurement_interval_elapsed_time_ms_ GUARDED_BY(critsect_);
+  int estimated_bitrate_bps_ GUARDED_BY(critsect_);
+  // Number of consecutive periods over which we observe traffic is application
+  // limited.
+  int application_limited_count_ GUARDED_BY(critsect_);
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_PACING_ALR_DETECTOR_H_