mirror of
https://git.wownero.com/wownero/wownero.git
synced 2024-12-23 19:18:53 +00:00
122 lines
3.5 KiB
C
122 lines
3.5 KiB
C
/*
|
|
* util/rtt.c - UDP round trip time estimator for resend timeouts.
|
|
*
|
|
* Copyright (c) 2007, NLnet Labs. All rights reserved.
|
|
*
|
|
* This software is open source.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* Redistributions of source code must retain the above copyright notice,
|
|
* this list of conditions and the following disclaimer.
|
|
*
|
|
* Redistributions in binary form must reproduce the above copyright notice,
|
|
* this list of conditions and the following disclaimer in the documentation
|
|
* and/or other materials provided with the distribution.
|
|
*
|
|
* Neither the name of the NLNET LABS nor the names of its contributors may
|
|
* be used to endorse or promote products derived from this software without
|
|
* specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
|
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
|
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
|
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
|
|
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
|
|
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
|
|
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
|
|
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
|
|
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
/**
|
|
* \file
|
|
*
|
|
* This file contains a data type and functions to help estimate good
|
|
* round trip times for UDP resend timeout values.
|
|
*/
|
|
#include "config.h"
|
|
#include "util/rtt.h"
|
|
|
|
/* overwritten by config: infra_cache_min_rtt: */
|
|
int RTT_MIN_TIMEOUT = 50;
|
|
/** calculate RTO from rtt information */
|
|
static int
|
|
calc_rto(const struct rtt_info* rtt)
|
|
{
|
|
/* From Stevens, Unix Network Programming, Vol1, 3rd ed., p.598 */
|
|
int rto = rtt->srtt + 4*rtt->rttvar;
|
|
if(rto < RTT_MIN_TIMEOUT)
|
|
rto = RTT_MIN_TIMEOUT;
|
|
if(rto > RTT_MAX_TIMEOUT)
|
|
rto = RTT_MAX_TIMEOUT;
|
|
return rto;
|
|
}
|
|
|
|
void
|
|
rtt_init(struct rtt_info* rtt)
|
|
{
|
|
rtt->srtt = 0;
|
|
rtt->rttvar = 94;
|
|
rtt->rto = calc_rto(rtt);
|
|
/* default value from the book is 0 + 4*0.75 = 3 seconds */
|
|
/* first RTO is 0 + 4*0.094 = 0.376 seconds */
|
|
}
|
|
|
|
int
|
|
rtt_timeout(const struct rtt_info* rtt)
|
|
{
|
|
return rtt->rto;
|
|
}
|
|
|
|
int
|
|
rtt_unclamped(const struct rtt_info* rtt)
|
|
{
|
|
if(calc_rto(rtt) != rtt->rto) {
|
|
/* timeout fallback has happened */
|
|
return rtt->rto;
|
|
}
|
|
/* return unclamped value */
|
|
return rtt->srtt + 4*rtt->rttvar;
|
|
}
|
|
|
|
void
|
|
rtt_update(struct rtt_info* rtt, int ms)
|
|
{
|
|
int delta = ms - rtt->srtt;
|
|
rtt->srtt += delta / 8; /* g = 1/8 */
|
|
if(delta < 0)
|
|
delta = -delta; /* |delta| */
|
|
rtt->rttvar += (delta - rtt->rttvar) / 4; /* h = 1/4 */
|
|
rtt->rto = calc_rto(rtt);
|
|
}
|
|
|
|
void
|
|
rtt_lost(struct rtt_info* rtt, int orig)
|
|
{
|
|
/* exponential backoff */
|
|
|
|
/* if a query succeeded and put down the rto meanwhile, ignore this */
|
|
if(rtt->rto < orig)
|
|
return;
|
|
|
|
/* the original rto is doubled, not the current one to make sure
|
|
* that the values in the cache are not increased by lots of
|
|
* queries simultaneously as they time out at the same time */
|
|
orig *= 2;
|
|
if(rtt->rto <= orig) {
|
|
rtt->rto = orig;
|
|
if(rtt->rto > RTT_MAX_TIMEOUT)
|
|
rtt->rto = RTT_MAX_TIMEOUT;
|
|
}
|
|
}
|
|
|
|
int rtt_notimeout(const struct rtt_info* rtt)
|
|
{
|
|
return calc_rto(rtt);
|
|
}
|