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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <cstdint>
#include "quiche/quic/core/quic_bandwidth.h"
#include "quiche/quic/core/quic_time.h"
#include "quiche/quic/platform/api/quic_export.h"
#include "quiche/quic/platform/api/quic_logging.h"
namespace quic {
namespace test {
class QuicSustainedBandwidthRecorderPeer;
} // namespace test
// This class keeps track of a sustained bandwidth estimate to ultimately send
// to the client in a server config update message. A sustained bandwidth
// estimate is only marked as valid if the QuicSustainedBandwidthRecorder has
// been given uninterrupted reliable estimates over a certain period of time.
class QUICHE_EXPORT QuicSustainedBandwidthRecorder {
QuicSustainedBandwidthRecorder(const QuicSustainedBandwidthRecorder&) =
QuicSustainedBandwidthRecorder& operator=(
const QuicSustainedBandwidthRecorder&) = delete;
// As long as |in_recovery| is consistently false, multiple calls to this
// method over a 3 * srtt period results in storage of a valid sustained
// bandwidth estimate.
// |time_now| is used as a max bandwidth timestamp if needed.
void RecordEstimate(bool in_recovery, bool in_slow_start,
QuicBandwidth bandwidth, QuicTime estimate_time,
QuicWallTime wall_time, QuicTime::Delta srtt);
bool HasEstimate() const { return has_estimate_; }
QuicBandwidth BandwidthEstimate() const {
return bandwidth_estimate_;
QuicBandwidth MaxBandwidthEstimate() const {
return max_bandwidth_estimate_;
int64_t MaxBandwidthTimestamp() const {
return max_bandwidth_timestamp_;
bool EstimateRecordedDuringSlowStart() const {
return bandwidth_estimate_recorded_during_slow_start_;
friend class test::QuicSustainedBandwidthRecorderPeer;
// True if we have been able to calculate sustained bandwidth, over at least
// one recording period (3 * rtt).
bool has_estimate_;
// True if the last call to RecordEstimate had a reliable estimate.
bool is_recording_;
// True if the current sustained bandwidth estimate was generated while in
// slow start.
bool bandwidth_estimate_recorded_during_slow_start_;
// The latest sustained bandwidth estimate.
QuicBandwidth bandwidth_estimate_;
// The maximum sustained bandwidth seen over the lifetime of the connection.
QuicBandwidth max_bandwidth_estimate_;
// Timestamp indicating when the max_bandwidth_estimate_ was seen.
int64_t max_bandwidth_timestamp_;
// Timestamp marking the beginning of the latest recording period.
QuicTime start_time_;
} // namespace quic