upstream/bind9
1
0
Fork 0
mirror of https://github.com/isc-projects/bind9.git synced 2026-05-28 04:34:54 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

exponential backoff on retransmission

Browse source
This commit is contained in:
Bob Halley 1999-12-13 22:30:55 +00:00
parent 4bb1729d24
commit 525cdd36b3
1 changed files with 41 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

45
lib/dns/resolver.c
View file

@ -508,6 +508,39 @@ fctx_addopt(dns_message_t *message) {
return (dns_message_setopt(message, rdataset));
}
static inline void
fctx_setretryinterval(fetchctx_t *fctx, unsigned int rtt) {
unsigned int seconds;
/*
* We retry every 2 seconds the first two times through the address
* list, and then we do exponential back-off.
*/
if (fctx->restarts < 3)
seconds = 2;
else
seconds = (2 << (fctx->restarts - 1));
/*
* Double the round-trip time and convert to seconds.
*/
rtt /= 500000;
/*
* Always wait for at least the doubled round-trip time.
*/
if (seconds < rtt)
seconds = rtt;
/*
* But don't ever wait for more than 30 seconds.
*/
if (seconds > 30)
seconds = 30;
isc_interval_set(&fctx->interval, seconds, 0);
}
static isc_result_t
fctx_query(fetchctx_t *fctx, dns_adbaddrinfo_t *addrinfo,
unsigned int options)
@ -523,6 +556,7 @@ fctx_query(fetchctx_t *fctx, dns_adbaddrinfo_t *addrinfo,
res = fctx->res;
task = res->buckets[fctx->bucketnum].task;
fctx_setretryinterval(fctx, addrinfo->srtt);
result = fctx_starttimer(fctx);
if (result != ISC_R_SUCCESS)
return (result);
@ -1495,7 +1529,7 @@ fctx_create(dns_resolver_t *res, dns_name_t *name, dns_rdatatype_t type,
/*
* Compute an expiration time for the entire fetch.
*/
isc_interval_set(&interval, 30, 0); /* XXXRTH constant */
isc_interval_set(&interval, 90, 0); /* XXXRTH constant */
iresult = isc_time_nowplusinterval(&fctx->expires, &interval);
if (iresult != ISC_R_SUCCESS) {
UNEXPECTED_ERROR(__FILE__, __LINE__,
@ -1506,10 +1540,11 @@ fctx_create(dns_resolver_t *res, dns_name_t *name, dns_rdatatype_t type,
}
/*
* XXX Retry interval initialization. Should be setup by the
* transmission strategy routine (when we have one).
* Default retry interval initialization. We set the interval now
* mostly so it won't be uninitialized. It will be set to the
* correct value before a query is issued.
*/
isc_interval_set(&fctx->interval, 1, 500000000);
isc_interval_set(&fctx->interval, 2, 0);
/*
* Create an inactive timer. It will be made active when the fetch
@ -2937,6 +2972,8 @@ resquery_response(isc_task_t *task, isc_event_t *event) {
/*
* Cancel the query.
*
* XXXRTH Don't cancel the query if waiting for validation?
*/
fctx_cancelquery(&query, &devent, finish, ISC_FALSE);