6fae6ec2ee
This prepares for being able to inject network congestion controllers. And makes it easier to use the units in other parts of the code. Bug: webrtc:9155 Change-Id: Ib8f9c1c97b06d791a01c3376046933d576ae46f9 Reviewed-on: https://webrtc-review.googlesource.com/70201 Reviewed-by: Karl Wiberg <kwiberg@webrtc.org> Commit-Queue: Sebastian Jansson <srte@webrtc.org> Cr-Commit-Position: refs/heads/master@{#23168}
90 lines
3.0 KiB
C++
90 lines
3.0 KiB
C++
/*
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* Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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// A convenience class to store RTT samples and calculate smoothed RTT.
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// From the Quic BBR implementation in Chromium.
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#ifndef MODULES_CONGESTION_CONTROLLER_BBR_RTT_STATS_H_
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#define MODULES_CONGESTION_CONTROLLER_BBR_RTT_STATS_H_
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#include <algorithm>
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#include <cstdint>
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#include "api/units/time_delta.h"
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#include "api/units/timestamp.h"
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#include "rtc_base/constructormagic.h"
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#include "rtc_base/logging.h"
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namespace webrtc {
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namespace bbr {
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class RttStats {
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public:
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RttStats();
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// Updates the RTT from an incoming ack which is received |send_delta| after
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// the packet is sent and the peer reports the ack being delayed |ack_delay|.
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void UpdateRtt(TimeDelta send_delta, TimeDelta ack_delay, Timestamp now);
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// Causes the smoothed_rtt to be increased to the latest_rtt if the latest_rtt
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// is larger. The mean deviation is increased to the most recent deviation if
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// it's larger.
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void ExpireSmoothedMetrics();
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// Called when connection migrates and RTT measurement needs to be reset.
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void OnConnectionMigration();
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// Returns the EWMA smoothed RTT for the connection.
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// May return Zero if no valid updates have occurred.
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TimeDelta smoothed_rtt() const { return smoothed_rtt_; }
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// Returns the EWMA smoothed RTT prior to the most recent RTT sample.
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TimeDelta previous_srtt() const { return previous_srtt_; }
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int64_t initial_rtt_us() const { return initial_rtt_us_; }
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// Sets an initial RTT to be used for SmoothedRtt before any RTT updates.
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void set_initial_rtt_us(int64_t initial_rtt_us) {
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RTC_DCHECK_GE(initial_rtt_us, 0);
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if (initial_rtt_us <= 0) {
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RTC_LOG(LS_ERROR) << "Attempt to set initial rtt to <= 0.";
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return;
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}
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initial_rtt_us_ = initial_rtt_us;
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}
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// The most recent RTT measurement.
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// May return Zero if no valid updates have occurred.
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TimeDelta latest_rtt() const { return latest_rtt_; }
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// Returns the min_rtt for the entire connection.
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// May return Zero if no valid updates have occurred.
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TimeDelta min_rtt() const { return min_rtt_; }
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TimeDelta mean_deviation() const { return mean_deviation_; }
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private:
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TimeDelta latest_rtt_;
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TimeDelta min_rtt_;
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TimeDelta smoothed_rtt_;
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TimeDelta previous_srtt_;
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// Mean RTT deviation during this session.
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// Approximation of standard deviation, the error is roughly 1.25 times
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// larger than the standard deviation, for a normally distributed signal.
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TimeDelta mean_deviation_;
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int64_t initial_rtt_us_;
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RTC_DISALLOW_COPY_AND_ASSIGN(RttStats);
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};
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} // namespace bbr
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} // namespace webrtc
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#endif // MODULES_CONGESTION_CONTROLLER_BBR_RTT_STATS_H_
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