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// Copyright (c) 2011 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.
#ifndef NET_CURVECP_RTT_AND_SEND_RATE_CALCULATOR_H_
#define NET_CURVECP_RTT_AND_SEND_RATE_CALCULATOR_H_
#include "base/basictypes.h"
#include "base/time.h"
namespace net {
// Calculator for tracking the current RTT value.
// Measurements are in microseconds.
class RttAndSendRateCalculator {
public:
RttAndSendRateCalculator();
// Returns the current, average RTT, in microseconds.
int32 rtt_average() const { return rtt_average_; }
// Returns the current, RTT timeout, in microseconds.
int32 rtt_timeout() const { return rtt_timeout_; }
// The current send rate.
// Measurement is in microseconds between sends.
int32 send_rate() const { return send_rate_; }
int32 rtt_hi() const { return rtt_highwater_; }
int32 rtt_lo() const { return rtt_lowwater_; }
// Called when a new RTT sample is measured.
void OnMessage(int32 rtt_us);
// Adjusts the sendrate when a timeout condition has occurred.
void OnTimeout();
private:
// Updates RTT
void UpdateRTT(int32 rtt_us);
// Adjusts the send rate when a message is received.
void AdjustSendRate();
void AttemptToDoubleSendRate();
// returns a random number from 0 to val-1.
int32 randommod(int32 val);
int32 rtt_latest_; // The most recent RTT
int32 rtt_average_;
int32 rtt_deviation_;
int32 rtt_lowwater_;
int32 rtt_highwater_;
int32 rtt_timeout_;
int32 send_rate_;
base::TimeTicks last_sample_time_;
base::TimeTicks last_send_adjust_time_;
base::TimeTicks last_edge_time_;
base::TimeTicks last_doubling_time_;
base::TimeTicks last_loss_time_;
bool rtt_seenrecenthigh_;
bool rtt_seenrecentlow_;
bool rtt_seenolderhigh_;
bool rtt_seenolderlow_;
bool rtt_phase_;
};
} // namespace net
#endif // NET_CURVECP_RTT_AND_SEND_RATE_CALCULATOR_H_
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