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/*
* Copyright (c) 2016 Intel Corporation.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef _TCP_TIMER_H_
#define _TCP_TIMER_H_
#include <tle_timer.h>
#ifdef __cplusplus
extern "C" {
#endif
/*
* internal defines.
* all RTO values are in ms.
*/
#define TCP_RTO_MAX 60000U /* RFC 6298 (2.5) */
#define TCP_RTO_MIN 1000U /* RFC 6298 (2.4) */
#define TCP_RTO_2MSL (2 * TCP_RTO_MAX)
#define TCP_RTO_DEFAULT TCP_RTO_MIN /* RFC 6298 (2.1)*/
#define TCP_RTO_GRANULARITY 100U
static inline void
timer_stop(struct tle_tcp_stream *s)
{
struct tle_timer_wheel *tw;
if (s->timer.handle != NULL) {
tw = CTX_TCP_TMWHL(s->s.ctx);
tle_timer_stop(tw, s->timer.handle);
s->timer.handle = NULL;
}
}
static inline void
timer_start(struct tle_tcp_stream *s)
{
struct tle_timer_wheel *tw;
if (s->timer.handle == NULL) {
tw = CTX_TCP_TMWHL(s->s.ctx);
s->timer.handle = tle_timer_start(tw, s, s->tcb.snd.rto);
s->tcb.snd.nb_retx = 0;
}
}
static inline void
timer_restart(struct tle_tcp_stream *s)
{
struct tle_timer_wheel *tw;
tw = CTX_TCP_TMWHL(s->s.ctx);
s->timer.handle = tle_timer_start(tw, s, s->tcb.snd.rto);
}
/*
* reset number of retransmissions and restart RTO timer.
*/
static inline void
timer_reset(struct tle_tcp_stream *s)
{
timer_stop(s);
timer_start(s);
}
static inline uint32_t
rto_roundup(uint32_t rto)
{
rto = RTE_MAX(rto, TCP_RTO_MIN);
rto = RTE_MIN(rto, TCP_RTO_MAX);
return rto;
}
/*
* RFC6298: Computing TCP's Retransmission Timer
* RTTVAR <- (1 - beta) * RTTVAR + beta * |SRTT - R'|
* SRTT <- (1 - alpha) * SRTT + alpha * R'
* RTO <- SRTT + max (G, K*RTTVAR)
* the following computation is based on Jacobson'88 paper referenced
* in the RFC6298
*/
static inline void
rto_estimate(struct tcb *tcb, int32_t rtt)
{
uint32_t rto;
if (!rtt)
rtt = 1;
if (tcb->rcv.srtt) {
rtt -= (tcb->rcv.srtt >> 3); /* alpha = 1/8 */
tcb->rcv.srtt += rtt;
if (rtt < 0)
rtt = -rtt;
rtt -= (tcb->rcv.rttvar >> 2); /* beta = 1/4 */
tcb->rcv.rttvar += rtt;
} else {
tcb->rcv.srtt = rtt << 3;
tcb->rcv.rttvar = rtt << 1;
}
rto = (tcb->rcv.srtt >> 3) +
RTE_MAX(TCP_RTO_GRANULARITY, tcb->rcv.rttvar);
tcb->snd.rto = rto_roundup(rto);
}
#ifdef __cplusplus
}
#endif
#endif /* _TCP_TIMER_H_ */
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