/*
* Created on Jul 26, 2004
* Created by Alon Rohter
* Copyright (C) 2004, 2005, 2006 Aelitis, All Rights Reserved.
*
* This program 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 program 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 program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* AELITIS, SAS au capital de 46,603.30 euros
* 8 Allee Lenotre, La Grille Royale, 78600 Le Mesnil le Roi, France.
*
*/
package com.aelitis.azureus.core.networkmanager.impl;
import org.gudy.azureus2.core3.util.Debug;
import org.gudy.azureus2.core3.util.SystemTime;
import com.aelitis.azureus.core.networkmanager.NetworkManager;
/**
* Byte-bucket implementation based on the token bucket algorithm.
* Buckets can be configured with a guaranteed normal rate, along with
* a burst rate.
*/
public class ByteBucket {
private int rate;
private int burst_rate;
private long avail_bytes;
private long prev_update_time;
/**
* Create a new byte-bucket with the given byte fill (guaranteed) rate.
* Burst rate is set to default 1.2X of given fill rate.
* @param rate_bytes_per_sec fill rate
*/
public ByteBucket( int rate_bytes_per_sec ) {
this( rate_bytes_per_sec, rate_bytes_per_sec + (rate_bytes_per_sec/5) );
}
/**
* Create a new byte-bucket with the given byte fill (guaranteed) rate
* and the given burst rate.
* @param rate_bytes_per_sec fill rate
* @param burst_rate max rate
*/
public ByteBucket( int rate_bytes_per_sec, int burst_rate ) {
this.rate = rate_bytes_per_sec;
this.burst_rate = burst_rate;
avail_bytes = 0; //start bucket empty
prev_update_time = SystemTime.getCurrentTime();
ensureByteBucketMinBurstRate();
}
/**
* Get the number of bytes currently available for use.
* @return number of free bytes
*/
public int getAvailableByteCount() {
update_avail_byte_count();
return (int)avail_bytes;
}
/**
* Update the bucket with the number of bytes just used.
* @param bytes_used
*/
public void setBytesUsed( int bytes_used ) {
avail_bytes -= bytes_used;
if( avail_bytes < 0 ) Debug.out( "avail_bytes < 0: " + avail_bytes);
}
/**
* Get the configured fill rate.
* @return guaranteed rate in bytes per sec
*/
public int getRate() { return rate; }
/**
* Get the configured burst rate.
* @return burst rate in bytes per sec
*/
public int getBurstRate() { return burst_rate; }
/**
* Set the current fill/guaranteed rate, with a burst rate of 1.2X the given rate.
* @param rate_bytes_per_sec
*/
public void setRate( int rate_bytes_per_sec ) {
setRate( rate_bytes_per_sec, rate_bytes_per_sec + (rate_bytes_per_sec/5));
}
/**
* Set the current fill/guaranteed rate, along with the burst rate.
* @param rate_bytes_per_sec
* @param burst_rate
*/
public void setRate( int rate_bytes_per_sec, int burst_rate ) {
if( rate_bytes_per_sec < 0 ) {
Debug.out("rate_bytes_per_sec [" +rate_bytes_per_sec+ "] < 0");
rate_bytes_per_sec = 0;
}
if( burst_rate < rate_bytes_per_sec ) {
Debug.out("burst_rate [" +burst_rate+ "] < rate_bytes_per_sec [" +rate_bytes_per_sec+ "]");
burst_rate = rate_bytes_per_sec;
}
this.rate = rate_bytes_per_sec;
this.burst_rate = burst_rate;
ensureByteBucketMinBurstRate();
}
private void update_avail_byte_count() {
final long now =SystemTime.getCurrentTime();
if (prev_update_time <now) {
avail_bytes +=((now -prev_update_time) * rate) / 1000;
prev_update_time =now;
if( avail_bytes > burst_rate ) avail_bytes = burst_rate;
else if( avail_bytes < 0 ) Debug.out("ERROR: avail_bytes < 0: " + avail_bytes);
}
else if (prev_update_time >now) { //oops, time went backwards
avail_bytes =burst_rate;
prev_update_time =now;
}
}
/**
* Make sure the bucket's burst rate is at least MSS-sized,
* otherwise it will never allow a full packet's worth of data.
*/
private void ensureByteBucketMinBurstRate() {
int mss = NetworkManager.getMinMssSize();
if( burst_rate < mss ) { //oops, this won't ever allow a full packet
burst_rate = mss; //so increase the max byte size
}
}
}
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