Almost full implementation of BBR's core.

webrtc/modules/remote_bitrate_estimator/test/estimators/min_rtt_filter.h

 /*
  *  Copyright (c) 2017 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_REMOTE_BITRATE_ESTIMATOR_TEST_ESTIMATORS_MIN_RTT_FILTER_H_
 #define WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_TEST_ESTIMATORS_MIN_RTT_FILTER_H_
 
 #include <cstdint>
 #include <limits>
 
 #include "webrtc/rtc_base/optional.h"
 
 namespace webrtc {
 namespace testing {
 namespace bwe {
+
+// Expiration time for min_rtt sample, which is set to 10 seconds according to
+// BBR design doc.
+const int64_t kMinRttFilterSizeMs = 10000;
+
 class MinRttFilter {
  public:
   MinRttFilter() {}
   ~MinRttFilter() {}
 
   rtc::Optional<int64_t> min_rtt_ms() { return min_rtt_ms_; }
-  void add_rtt_sample(int64_t rtt_ms, int64_t now_ms) {
-    if (!min_rtt_ms_ || rtt_ms <= *min_rtt_ms_) {
+  void AddRttSample(int64_t rtt_ms, int64_t now_ms) {
+    if (!min_rtt_ms_ || rtt_ms <= *min_rtt_ms_ || MinRttExpired(now_ms)) {
       min_rtt_ms_.emplace(rtt_ms);
       discovery_time_ms_ = now_ms;
     }
   }
   int64_t discovery_time() { return discovery_time_ms_; }
 
   // Checks whether or not last discovered min_rtt value is older than x
   // milliseconds.
-  bool min_rtt_expired(int64_t now_ms, int64_t min_rtt_filter_window_size_ms) {
-    return now_ms - discovery_time_ms_ >= min_rtt_filter_window_size_ms;
+  bool MinRttExpired(int64_t now_ms) {
+    return now_ms - discovery_time_ms_ >= kMinRttFilterSizeMs;
   }
 
  private:
   rtc::Optional<int64_t> min_rtt_ms_;
   int64_t discovery_time_ms_ = 0;
 };
 }  // namespace bwe
 }  // namespace testing
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_TEST_ESTIMATORS_MIN_RTT_FILTER_H_