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- Introduce leniency for target discovery when under load.

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This commit is contained in:
George Thessalonikefs 2022-10-04 10:26:33 +02:00
parent bf7a2884fb
commit 9e53506240
2 changed files with 38 additions and 7 deletions
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43
iterator/iterator.c
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@ -2264,6 +2264,7 @@ processQueryTargets(struct module_qstate* qstate, struct iter_qstate* iq,
size_t qout_orig_len = 0;
int sq_check_ratelimit = 1;
int sq_was_ratelimited = 0;
int can_do_promisc = 0;
/* NOTE: a request will encounter this state for each target it
* needs to send a query to. That is, at least one per referral,
@ -2591,12 +2592,12 @@ processQueryTargets(struct module_qstate* qstate, struct iter_qstate* iq,
if(iq->depth < ie->max_dependency_depth
&& iq->num_target_queries == 0
&& (!iq->target_count || iq->target_count[TARGET_COUNT_NX]==0)
&& iq->sent_count < TARGET_FETCH_STOP
/* if the mesh query list is full, then do not waste cpu
* and sockets to fetch promiscuous targets. They can be
* looked up when needed. */
&& !mesh_jostle_exceeded(qstate->env->mesh)
) {
&& iq->sent_count < TARGET_FETCH_STOP) {
can_do_promisc = 1;
}
/* if the mesh query list is full, then do not waste cpu and sockets to
* fetch promiscuous targets. They can be looked up when needed. */
if(can_do_promisc && !mesh_jostle_exceeded(qstate->env->mesh)) {
tf_policy = ie->target_fetch_policy[iq->depth];
}
@ -2768,6 +2769,36 @@ processQueryTargets(struct module_qstate* qstate, struct iter_qstate* iq,
return 0;
}
/* We have a target. We could have created promiscuous target
* queries but we are currently under pressure (mesh_jostle_exceeded).
* If we are configured to allow promiscuous target queries and haven't
* gone out to the network for a target query for this delegation, then
* it is possible to slip in a promiscuous one with a 1/10 chance. */
if(can_do_promisc && tf_policy == 0 && iq->depth == 0
&& ie->target_fetch_policy[iq->depth] != 0
&& iq->dp_target_count == 0
&& !ub_random_max(qstate->env->rnd, 10)) {
int extra = 0;
verbose(VERB_ALGO, "available target exists in cache but "
"attempt to get extra 1 target");
(void)query_for_targets(qstate, iq, ie, id, 1, &extra);
/* errors ignored, these targets are not strictly necessary for
* this result, we do not have to reply with SERVFAIL */
if(extra > 0) {
iq->num_target_queries += extra;
target_count_increase(iq, extra);
check_waiting_queries(iq, qstate, id);
/* undo qname minimise step because we'll get back here
* to do it again */
if(qout_orig && iq->minimise_count > 0) {
iq->minimise_count--;
iq->qinfo_out.qname = qout_orig;
iq->qinfo_out.qname_len = qout_orig_len;
}
return 0;
}
}
/* Do not check ratelimit for forwarding queries or if we already got a
* pass. */
sq_check_ratelimit = (!(iq->chase_flags & BIT_RD) && !iq->ratelimit_ok);

2
iterator/iterator.h
View file

@ -324,7 +324,7 @@ struct iter_qstate {
/** the number of times this query has been restarted. */
int query_restart_count;
/** the number of times this query as followed a referral. */
/** the number of times this query has followed a referral. */
int referral_count;
/** number of queries fired off */