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Fix pending HostDB DNS queue removal race #13294

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Fix pending HostDB DNS queue removal race #13294

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5 changes: 3 additions & 2 deletions src/iocore/hostdb/HostDB.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -837,6 +837,7 @@ HostDBContinuation::dnsEvent(int event, HostEnt *e)
// Event should be immediate or interval.
if (!action.continuation) {
// Nothing to do, give up.
bool cleanup_self = false;
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
Expand All @@ -846,9 +847,9 @@ HostDBContinuation::dnsEvent(int event, HostEnt *e)
} else {
// "local" signal to give up, usually due this being one of those "other" queries.
// 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);
cleanup_self = hostDB.remove_from_pending_dns_for_hash(hash.hash, this);
}
if (hostDB.remove_from_pending_dns_for_hash(hash.hash, this)) {
if (cleanup_self) {
hostdb_cont_free(this);
}
return EVENT_DONE;
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