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/*
* Copyright (c) 2020 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 MODULES_CONGESTION_CONTROLLER_GOOG_CC_INTER_ARRIVAL_DELTA_H_
#define MODULES_CONGESTION_CONTROLLER_GOOG_CC_INTER_ARRIVAL_DELTA_H_
#include <cstddef>
#include "api/units/time_delta.h"
#include "api/units/timestamp.h"
namespace webrtc {
// Helper class to compute the inter-arrival time delta and the size delta
// between two send bursts. This code is branched from
// modules/remote_bitrate_estimator/inter_arrival.
class InterArrivalDelta {
public:
// After this many packet groups received out of order InterArrival will
// reset, assuming that clocks have made a jump.
static constexpr int kReorderedResetThreshold = 3;
static constexpr TimeDelta kArrivalTimeOffsetThreshold =
TimeDelta::Seconds(3);
// A send time group is defined as all packets with a send time which are at
// most send_time_group_length older than the first timestamp in that
// group.
explicit InterArrivalDelta(TimeDelta send_time_group_length);
InterArrivalDelta() = delete;
InterArrivalDelta(const InterArrivalDelta&) = delete;
InterArrivalDelta& operator=(const InterArrivalDelta&) = delete;
// This function returns true if a delta was computed, or false if the current
// group is still incomplete or if only one group has been completed.
// `send_time` is the send time.
// `arrival_time` is the time at which the packet arrived.
// `packet_size` is the size of the packet.
// `timestamp_delta` (output) is the computed send time delta.
// `arrival_time_delta` (output) is the computed arrival-time delta.
// `packet_size_delta` (output) is the computed size delta.
bool ComputeDeltas(Timestamp send_time,
Timestamp arrival_time,
Timestamp system_time,
size_t packet_size,
TimeDelta* send_time_delta,
TimeDelta* arrival_time_delta,
int* packet_size_delta);
private:
struct SendTimeGroup {
SendTimeGroup()
: size(0),
first_send_time(Timestamp::MinusInfinity()),
send_time(Timestamp::MinusInfinity()),
first_arrival(Timestamp::MinusInfinity()),
complete_time(Timestamp::MinusInfinity()),
last_system_time(Timestamp::MinusInfinity()) {}
bool IsFirstPacket() const { return complete_time.IsInfinite(); }
size_t size;
Timestamp first_send_time;
Timestamp send_time;
Timestamp first_arrival;
Timestamp complete_time;
Timestamp last_system_time;
};
// Returns true if the last packet was the end of the current batch and the
// packet with `send_time` is the first of a new batch.
bool NewTimestampGroup(Timestamp arrival_time, Timestamp send_time) const;
bool BelongsToBurst(Timestamp arrival_time, Timestamp send_time) const;
void Reset();
const TimeDelta send_time_group_length_;
SendTimeGroup current_timestamp_group_;
SendTimeGroup prev_timestamp_group_;
int num_consecutive_reordered_packets_;
};
} // namespace webrtc
#endif // MODULES_CONGESTION_CONTROLLER_GOOG_CC_INTER_ARRIVAL_DELTA_H_
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