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Update HostDBContinuation timeout handling to clear pending queue. #8480

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Merged
SolidWallOfCode merged 1 commit into from
Nov 4, 2021
Merged

Update HostDBContinuation timeout handling to clear pending queue. #8480

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17 changes: 13 additions & 4 deletions iocore/hostdb/HostDB.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1109,11 +1109,20 @@ HostDBContinuation::dnsEvent(int event, HostEnt *e)
}
EThread *thread = mutex->thread_holding;
if (event != DNS_EVENT_LOOKUP) {
// This was an event_interval or an event_immediate
// Either we timed out, or remove_trigger_pending gave up on us
// Event should be immediate or interval.
if (!action.continuation) {
// give up on insert, it has been too long
hostDB.pending_dns_for_hash(hash.hash).remove(this);
// Nothing to do, give up.
if (event == EVENT_INTERVAL) {
// Timeout - clear all queries queued up for this FQDN because none of the other ones have sent an
// actual DNS query. If the request rate is high enough this can cause a persistent queue where the
// DNS query is never sent and all requests timeout, even if it was a transient error.
// See issue #8417.
remove_trigger_pending_dns();
} else {
// "local" signal to give up, usually due this being one of those "other" queries.
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@bneradt bneradt Nov 1, 2021

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nit: "usually due to this..."

// That generally means @a this has already been removed from the queue, but just in case...
hostDB.pending_dns_for_hash(hash.hash).remove(this);
}
hostdb_cont_free(this);
return EVENT_DONE;
}
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