rtt.h File Reference

This file contains a data type and functions to help estimate good round trip times for UDP resend timeout values. More...

Data Structures
struct	rtt_info
	RTT information. More...
Defines
#define	RTT_MIN_TIMEOUT   50
	min retransmit timeout value, in milliseconds
#define	RTT_MAX_TIMEOUT   120000
	max retransmit timeout value, in milliseconds
Functions
void	rtt_init (struct rtt_info *rtt)
	Initialize RTT estimators.
int	rtt_timeout (const struct rtt_info *rtt)
	Get timeout to use for sending a UDP packet.
int	rtt_unclamped (const struct rtt_info *rtt)
	Get unclamped timeout to use for server selection.
void	rtt_update (struct rtt_info *rtt, int ms)
	Update the statistics with a new roundtrip estimate observation.
void	rtt_lost (struct rtt_info *rtt, int orig)
	Update the statistics with a new timout expired observation.

---

Detailed Description

This file contains a data type and functions to help estimate good round trip times for UDP resend timeout values.

---

Function Documentation

void rtt_init

(

struct rtt_info *

rtt

)

Initialize RTT estimators.

Parameters:

rtt,:

The structure. Caller is responsible for allocation of it.

References calc_rto(), rtt_info::rto, rtt_info::rttvar, and rtt_info::srtt.

Referenced by infra_host(), new_host_entry(), and rtt_test().

int rtt_timeout

(

const struct rtt_info *

rtt

)

Get timeout to use for sending a UDP packet.

Parameters:

rtt,:

round trip statistics structure.

Returns:

: timeout to use in milliseconds. Relative time value.

References rtt_info::rto.

Referenced by infra_host(), and rtt_test().

int rtt_unclamped

(

const struct rtt_info *

rtt

)

Get unclamped timeout to use for server selection.

Recent timeouts are reflected in the returned value.

Parameters:

rtt,:

round trip statistics structure.

Returns:

: value to use in milliseconds.

References calc_rto(), rtt_info::rto, rtt_info::rttvar, and rtt_info::srtt.

Referenced by infra_get_lame_rtt().

void rtt_update	(	struct rtt_info *	rtt,
		int	ms
	)

Update the statistics with a new roundtrip estimate observation.

Parameters:

	rtt,:	round trip statistics structure.
	ms,:	estimate of roundtrip time in milliseconds.

References calc_rto(), rtt_info::rto, rtt_info::rttvar, and rtt_info::srtt.

Referenced by infra_rtt_update(), and rtt_test().

void rtt_lost	(	struct rtt_info *	rtt,
		int	orig
	)

Update the statistics with a new timout expired observation.

Parameters:

	rtt,:	round trip statistics structure.
	orig,:	original rtt time given for the query that timed out. Used to calculate the maximum responsible backed off time that can reasonably be applied.

References rtt_info::rto, and RTT_MAX_TIMEOUT.

Referenced by infra_rtt_update(), and rtt_test().