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/* Copyright 2009-2018 Pierre Ossman for Cendio AB
*
* This is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this software; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
* USA.
*/
#ifndef __RFB_CONGESTION_H__
#define __RFB_CONGESTION_H__
#include <list>
namespace rfb {
class Congestion {
public:
Congestion();
~Congestion();
// updatePosition() registers the current stream position and can
// and should be called often.
void updatePosition(unsigned pos);
// sentPing() must be called when a marker is placed on the
// outgoing stream. gotPong() must be called when the response for
// such a marker is received.
void sentPing();
void gotPong();
// isCongested() determines if the transport is currently congested
// or if more data can be sent.
bool isCongested();
// getUncongestedETA() returns the number of milliseconds until the
// transport is no longer congested. Returns 0 if there is no
// congestion, and -1 if it is unknown when the transport will no
// longer be congested.
int getUncongestedETA();
// getBandwidth() returns the current bandwidth estimation in bytes
// per second.
size_t getBandwidth();
// debugTrace() writes the current congestion window, as well as the
// congestion window of the underlying TCP layer, to the specified
// file
void debugTrace(const char* filename, int fd);
protected:
unsigned getExtraBuffer();
unsigned getInFlight();
void updateCongestion();
private:
unsigned lastPosition;
unsigned extraBuffer;
struct timeval lastUpdate;
struct timeval lastSent;
unsigned baseRTT;
unsigned congWindow;
bool inSlowStart;
unsigned safeBaseRTT;
struct RTTInfo {
struct timeval tv;
unsigned pos;
unsigned extra;
bool congested;
};
std::list<struct RTTInfo> pings;
struct RTTInfo lastPong;
struct timeval lastPongArrival;
int measurements;
struct timeval lastAdjustment;
unsigned minRTT, minCongestedRTT;
};
}
#endif
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