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in findnode, use a read transaction when possible

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when findnode() is called with the 'create' flag set, instead of
automatically opening a write transaction, we will now try to look up
the name with a read transaction, and only open a write transaction if
that failed.
This commit is contained in:
Evan Hunt
2024-06-07 17:24:45 -07:00
parent 0ea634a5db
commit a7e6c06ef7
1 changed files with 22 additions and 11 deletions
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lib/dns/qpcache.c
+22 -11
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@@ -2601,13 +2601,9 @@ findnode(dns_db_t *db, const dns_name_t *name, bool create,
isc_result_t result;
dbmod_t modctx;
modctx = (dbmod_t){ .writing = create };
if (create) {
dns_qpmulti_write(qpdb->tree, &modctx.tree);
} else {
dns_qpmulti_query(qpdb->tree, &modctx.qpr);
modctx.tree = (dns_qp_t *)&modctx.qpr;
}
modctx = (dbmod_t){ .writing = false };
dns_qpmulti_query(qpdb->tree, &modctx.qpr);
modctx.tree = (dns_qp_t *)&modctx.qpr;
result = dns_qp_getname(modctx.tree, name, (void **)&node, NULL);
if (result != ISC_R_SUCCESS) {
@@ -2615,11 +2611,26 @@ findnode(dns_db_t *db, const dns_name_t *name, bool create,
goto cleanup;
}
/* Switch to a write transaction */
modctx.writing = true;
modctx.tree = NULL;
dns_qpread_destroy(qpdb->tree, &modctx.qpr);
dns_qpmulti_write(qpdb->tree, &modctx.tree);
/* Insert a new node, if we still need to */
node = new_qpcnode(qpdb, name);
result = dns_qp_insert(modctx.tree, node, 0);
INSIST(result == ISC_R_SUCCESS);
qpcnode_unref(node);
modctx.compact = true;
if (result == ISC_R_SUCCESS) {
/* Insertion succeeded; compact the DB. */
qpcnode_unref(node);
modctx.compact = true;
} else {
/* Some other thread added the node already */
qpcnode_detach(&node);
result = dns_qp_getname(modctx.tree, name,
(void **)&node, NULL);
INSIST(result == ISC_R_SUCCESS);
}
}
reactivate_node(qpdb, node, &modctx DNS__DB_FLARG_PASS);
@@ -2627,7 +2638,7 @@ findnode(dns_db_t *db, const dns_name_t *name, bool create,
*nodep = (dns_dbnode_t *)node;
cleanup:
if (create) {
if (modctx.writing) {
if (modctx.compact) {
dns_qp_compact(modctx.tree, DNS_QPGC_MAYBE);
}