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Refactor check_stale_header() function

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The check_stale_header() function now updates header_prev directly
so it doesn't have to be handled in the outer loop; it's always
set to the correct value of the previous header in the chain.
This commit is contained in:
Ondřej Surý 2025-02-02 19:21:44 +01:00 committed by Evan Hunt
parent b24981ea02
commit 53d9ef5bd0
1 changed files with 103 additions and 113 deletions
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216
lib/dns/qpcache.c
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@ -1196,97 +1196,92 @@ static bool
check_stale_header(qpcnode_t *node, dns_slabheader_t *header, check_stale_header(qpcnode_t *node, dns_slabheader_t *header,
isc_rwlocktype_t *nlocktypep, isc_rwlock_t *nlock, isc_rwlocktype_t *nlocktypep, isc_rwlock_t *nlock,
qpc_search_t *search, dns_slabheader_t **header_prev) { qpc_search_t *search, dns_slabheader_t **header_prev) {
if (!ACTIVE(header, search->now)) { if (ACTIVE(header, search->now)) {
dns_ttl_t stale = header->expire + *header_prev = header;
STALE_TTL(header, search->qpdb); return false;
/*
* If this data is in the stale window keep it and if
* DNS_DBFIND_STALEOK is not set we tell the caller to
* skip this record. We skip the records with ZEROTTL
* (these records should not be cached anyway).
*/
DNS_SLABHEADER_CLRATTR(header, DNS_SLABHEADERATTR_STALE_WINDOW);
if (!ZEROTTL(header) && KEEPSTALE(search->qpdb) &&
stale > search->now)
{
mark(header, DNS_SLABHEADERATTR_STALE);
*header_prev = header;
/*
* If DNS_DBFIND_STALESTART is set then it means we
* failed to resolve the name during recursion, in
* this case we mark the time in which the refresh
* failed.
*/
if ((search->options & DNS_DBFIND_STALESTART) != 0) {
atomic_store_release(
&header->last_refresh_fail_ts,
search->now);
} else if ((search->options &
DNS_DBFIND_STALEENABLED) != 0 &&
search->now <
(atomic_load_acquire(
&header->last_refresh_fail_ts) +
search->qpdb->serve_stale_refresh))
{
/*
* If we are within interval between last
* refresh failure time + 'stale-refresh-time',
* then don't skip this stale entry but use it
* instead.
*/
DNS_SLABHEADER_SETATTR(
header,
DNS_SLABHEADERATTR_STALE_WINDOW);
return false;
} else if ((search->options &
DNS_DBFIND_STALETIMEOUT) != 0)
{
/*
* We want stale RRset due to timeout, so we
* don't skip it.
*/
return false;
}
return (search->options & DNS_DBFIND_STALEOK) == 0;
}
/*
* This rdataset is stale. If no one else is using the
* node, we can clean it up right now, otherwise we mark
* it as ancient, and the node as dirty, so it will get
* cleaned up later.
*/
if ((header->expire < search->now - QPDB_VIRTUAL) &&
(*nlocktypep == isc_rwlocktype_write ||
NODE_TRYUPGRADE(nlock, nlocktypep) == ISC_R_SUCCESS))
{
/*
* We update the node's status only when we can
* get write access; otherwise, we leave others
* to this work. Periodical cleaning will
* eventually take the job as the last resort.
* We won't downgrade the lock, since other
* rdatasets are probably stale, too.
*/
if (isc_refcount_current(&node->references) == 0) {
clean_stale_headers(header);
if (*header_prev != NULL) {
(*header_prev)->next = header->next;
} else {
node->data = header->next;
}
dns_slabheader_destroy(&header);
} else {
mark_ancient(header);
*header_prev = header;
}
} else {
*header_prev = header;
}
return true;
} }
return false;
isc_stdtime_t stale = header->expire + STALE_TTL(header, search->qpdb);
/*
* If this data is in the stale window keep it and if
* DNS_DBFIND_STALEOK is not set we tell the caller to
* skip this record. We skip the records with ZEROTTL
* (these records should not be cached anyway).
*/
DNS_SLABHEADER_CLRATTR(header, DNS_SLABHEADERATTR_STALE_WINDOW);
if (!ZEROTTL(header) && KEEPSTALE(search->qpdb) && stale > search->now)
{
mark(header, DNS_SLABHEADERATTR_STALE);
*header_prev = header;
/*
* If DNS_DBFIND_STALESTART is set then it means we
* failed to resolve the name during recursion, in
* this case we mark the time in which the refresh
* failed.
*/
if ((search->options & DNS_DBFIND_STALESTART) != 0) {
atomic_store_release(&header->last_refresh_fail_ts,
search->now);
} else if ((search->options & DNS_DBFIND_STALEENABLED) != 0 &&
search->now <
(atomic_load_acquire(
&header->last_refresh_fail_ts) +
search->qpdb->serve_stale_refresh))
{
/*
* If we are within interval between last
* refresh failure time + 'stale-refresh-time',
* then don't skip this stale entry but use it
* instead.
*/
DNS_SLABHEADER_SETATTR(header,
DNS_SLABHEADERATTR_STALE_WINDOW);
return false;
} else if ((search->options & DNS_DBFIND_STALETIMEOUT) != 0) {
/*
* We want stale RRset due to timeout, so we
* don't skip it.
*/
return false;
}
return (search->options & DNS_DBFIND_STALEOK) == 0;
}
/*
* This rdataset is stale. If no one else is using the
* node, we can clean it up right now, otherwise we mark
* it as ancient, and the node as dirty, so it will get
* cleaned up later.
*/
if ((header->expire < search->now - QPDB_VIRTUAL) &&
(*nlocktypep == isc_rwlocktype_write ||
NODE_TRYUPGRADE(nlock, nlocktypep) == ISC_R_SUCCESS))
{
/*
* We update the node's status only when we can
* get write access; otherwise, we leave others
* to this work. Periodical cleaning will
* eventually take the job as the last resort.
* We won't downgrade the lock, since other
* rdatasets are probably stale, too.
*/
if (isc_refcount_current(&node->references) == 0) {
clean_stale_headers(header);
if (*header_prev != NULL) {
(*header_prev)->next = header->next;
} else {
node->data = header->next;
}
dns_slabheader_destroy(&header);
} else {
mark_ancient(header);
*header_prev = header;
}
} else {
*header_prev = header;
}
return true;
} }
static isc_result_t static isc_result_t
@ -1312,19 +1307,17 @@ check_zonecut(qpcnode_t *node, void *arg DNS__DB_FLARG) {
if (check_stale_header(node, header, &nlocktype, nlock, search, if (check_stale_header(node, header, &nlocktype, nlock, search,
&header_prev)) &header_prev))
{ {
/* Do nothing. */ continue;
} else if (header->type == dns_rdatatype_dname && }
EXISTS(header) && !ANCIENT(header))
if (header->type == dns_rdatatype_dname && EXISTS(header) &&
!ANCIENT(header))
{ {
dname_header = header; dname_header = header;
header_prev = header;
} else if (header->type == DNS_SIGTYPE(dns_rdatatype_dname) && } else if (header->type == DNS_SIGTYPE(dns_rdatatype_dname) &&
EXISTS(header) && !ANCIENT(header)) EXISTS(header) && !ANCIENT(header))
{ {
sigdname_header = header; sigdname_header = header;
header_prev = header;
} else {
header_prev = header;
} }
} }
@ -1387,8 +1380,10 @@ find_deepest_zonecut(qpc_search_t *search, qpcnode_t *node,
if (check_stale_header(node, header, &nlocktype, nlock, if (check_stale_header(node, header, &nlocktype, nlock,
search, &header_prev)) search, &header_prev))
{ {
/* Do nothing. */ continue;
} else if (EXISTS(header) && !ANCIENT(header)) { }
if (EXISTS(header) && !ANCIENT(header)) {
/* /*
* We've found an extant rdataset. See if * We've found an extant rdataset. See if
* we're interested in it. * we're interested in it.
@ -1406,9 +1401,6 @@ find_deepest_zonecut(qpc_search_t *search, qpcnode_t *node,
break; break;
} }
} }
header_prev = header;
} else {
header_prev = header;
} }
} }
@ -1533,8 +1525,8 @@ find_coveringnsec(qpc_search_t *search, const dns_name_t *name,
{ {
continue; continue;
} }
if (!EXISTS(header) || DNS_TYPEPAIR_TYPE(header->type) == 0) { if (!EXISTS(header) || DNS_TYPEPAIR_TYPE(header->type) == 0) {
header_prev = header;
continue; continue;
} }
if (header->type == matchtype) { if (header->type == matchtype) {
@ -1548,7 +1540,6 @@ find_coveringnsec(qpc_search_t *search, const dns_name_t *name,
break; break;
} }
} }
header_prev = header;
} }
if (found != NULL) { if (found != NULL) {
bindrdataset(search->qpdb, node, found, search->now, nlocktype, bindrdataset(search->qpdb, node, found, search->now, nlocktype,
@ -1724,8 +1715,10 @@ qpcache_find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
if (check_stale_header(node, header, &nlocktype, nlock, &search, if (check_stale_header(node, header, &nlocktype, nlock, &search,
&header_prev)) &header_prev))
{ {
/* Do nothing. */ continue;
} else if (EXISTS(header) && !ANCIENT(header)) { }
if (EXISTS(header) && !ANCIENT(header)) {
/* /*
* We now know that there is at least one active * We now know that there is at least one active
* non-stale rdataset at this node. * non-stale rdataset at this node.
@ -1811,9 +1804,6 @@ qpcache_find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
*/ */
cnamesig = header; cnamesig = header;
} }
header_prev = header;
} else {
header_prev = header;
} }
} }
@ -2110,7 +2100,10 @@ qpcache_findzonecut(dns_db_t *db, const dns_name_t *name, unsigned int options,
*/ */
break; break;
} }
} else if (EXISTS(header) && !ANCIENT(header)) { continue;
}
if (EXISTS(header) && !ANCIENT(header)) {
if (header->type == dns_rdatatype_ns) { if (header->type == dns_rdatatype_ns) {
found = header; found = header;
if (foundsig != NULL) { if (foundsig != NULL) {
@ -2124,9 +2117,6 @@ qpcache_findzonecut(dns_db_t *db, const dns_name_t *name, unsigned int options,
break; break;
} }
} }
header_prev = header;
} else {
header_prev = header;
} }
} }