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Refactor node reference counting in rbtdb.c

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Refactor the pattern in the newref() and decref() functions in rbtdb.c
following the pattern, so it follows the similar pattern we already have
for QPDB.
This commit is contained in:
Ondřej Surý
2025-01-30 17:48:34 +01:00
parent 5300eebc9e
commit 9c45de9473
1 changed files with 57 additions and 62 deletions
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119
lib/dns/rbtdb.c
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@@ -1115,14 +1115,39 @@ delete_node(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node) {
}
}
static void
rbtnode_newref(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node DNS__DB_FLARG) {
uint_fast32_t refs = isc_refcount_increment0(&node->references);
#if DNS_DB_NODETRACE
fprintf(stderr, "incr:node:%s:%s:%u:%p->references = %" PRIuFAST32 "\n",
func, file, line, node, refs + 1);
#endif
if (refs > 0) {
return;
}
/* this is the first reference to the node */
refs = isc_refcount_increment0(
&rbtdb->node_locks[node->locknum].references);
#if DNS_DB_NODETRACE
fprintf(stderr,
"incr:nodelock:%s:%s:%u:%p:%p->references = "
"%" PRIuFAST32 "\n",
func, file, line, node, &rbtdb->node_locks[node->locknum],
refs + 1);
#else
UNUSED(refs);
#endif
}
/*
* Caller must be holding the node lock.
*/
void
dns__rbtdb_newref(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
isc_rwlocktype_t nlocktype DNS__DB_FLARG) {
uint_fast32_t refs;
if (nlocktype == isc_rwlocktype_write &&
ISC_LINK_LINKED(node, deadlink))
{
@@ -1130,28 +1155,7 @@ dns__rbtdb_newref(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
deadlink);
}
refs = isc_refcount_increment0(&node->references);
#if DNS_DB_NODETRACE
fprintf(stderr, "incr:node:%s:%s:%u:%p->references = %" PRIuFAST32 "\n",
func, file, line, node, refs + 1);
#else
UNUSED(refs);
#endif
if (refs == 0) {
/* this is the first reference to the node */
refs = isc_refcount_increment0(
&rbtdb->node_locks[node->locknum].references);
#if DNS_DB_NODETRACE
fprintf(stderr,
"incr:nodelock:%s:%s:%u:%p:%p->references = "
"%" PRIuFAST32 "\n",
func, file, line, node,
&rbtdb->node_locks[node->locknum], refs + 1);
#else
UNUSED(refs);
#endif
}
rbtnode_newref(rbtdb, node);
}
/*%
@@ -1280,6 +1284,29 @@ reactivate_node(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
NODE_UNLOCK(nodelock, &nlocktype);
}
static bool
rbtnode_decref(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node DNS__DB_FLARG) {
db_nodelock_t *nodelock = &rbtdb->node_locks[node->locknum];
uint_fast32_t refs = isc_refcount_decrement(&node->references);
#if DNS_DB_NODETRACE
fprintf(stderr, "decr:node:%s:%s:%u:%p->references = %" PRIuFAST32 "\n",
func, file, line, node, refs - 1);
#endif
if (refs > 1) {
return false;
}
refs = isc_refcount_decrement(&nodelock->references);
#if DNS_DB_NODETRACE
fprintf(stderr,
"decr:nodelock:%s:%s:%u:%p:%p->references = "
"%" PRIuFAST32 "\n",
func, file, line, node, nodelock, refs - 1);
#else
UNUSED(refs);
#endif
return true;
}
/*
* Caller must be holding the node lock; either the read or write lock.
* Note that the lock must be held even when node references are
@@ -1302,10 +1329,8 @@ dns__rbtdb_decref(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
isc_result_t result;
bool locked = *tlocktypep != isc_rwlocktype_none;
bool write_locked = false;
int bucket = node->locknum;
db_nodelock_t *nodelock = &rbtdb->node_locks[bucket];
db_nodelock_t *nodelock = &rbtdb->node_locks[node->locknum];
bool no_reference = true;
uint_fast32_t refs;
REQUIRE(*nlocktypep != isc_rwlocktype_none);
@@ -1313,24 +1338,10 @@ dns__rbtdb_decref(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
((n)->data != NULL || ((l) && (n)->down != NULL) || \
(n) == (r)->origin_node || (n) == (r)->nsec3_origin_node)
/* Handle easy and/or typical case first. */
refs = isc_refcount_decrement(&node->references);
#if DNS_DB_NODETRACE
fprintf(stderr, "decr:node:%s:%s:%u:%p->references = %" PRIuFAST32 "\n",
func, file, line, node, refs - 1);
#endif
if (refs > 1) {
if (!rbtnode_decref(rbtdb, node DNS__DB_FLARG_PASS)) {
return false;
}
refs = isc_refcount_decrement(&nodelock->references);
#if DNS_DB_NODETRACE
fprintf(stderr,
"decr:nodelock:%s:%s:%u:%p:%p->references = "
"%" PRIuFAST32 "\n",
func, file, line, node, nodelock, refs - 1);
#else
UNUSED(refs);
#endif
if (!node->dirty && KEEP_NODE(node, rbtdb, locked)) {
return true;
}
@@ -1340,21 +1351,14 @@ dns__rbtdb_decref(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
* node. To clean it up, the node ref needs to decrement to 0 under the
* node write lock, so we regain the ref and try again.
*/
dns__rbtdb_newref(rbtdb, node, *nlocktypep DNS__DB_FLARG_PASS);
rbtnode_newref(rbtdb, node DNS__DB_FLARG_PASS);
/* Upgrade the lock? */
if (*nlocktypep == isc_rwlocktype_read) {
NODE_FORCEUPGRADE(&nodelock->lock, nlocktypep);
}
refs = isc_refcount_decrement(&node->references);
#if DNS_DB_NODETRACE
fprintf(stderr, "decr:node:%s:%s:%u:%p->references = %" PRIuFAST32 "\n",
func, file, line, node, refs - 1);
#else
UNUSED(refs);
#endif
if (refs > 1) {
if (!rbtnode_decref(rbtdb, node DNS__DB_FLARG_PASS)) {
return false;
}
@@ -1407,15 +1411,6 @@ dns__rbtdb_decref(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
write_locked = true;
}
refs = isc_refcount_decrement(&nodelock->references);
#if DNS_DB_NODETRACE
fprintf(stderr,
"decr:nodelock:%s:%s:%u:%p:%p->references = %" PRIuFAST32 "\n",
func, file, line, node, nodelock, refs - 1);
#else
UNUSED(refs);
#endif
if (KEEP_NODE(node, rbtdb, locked || write_locked)) {
goto restore_locks;
}
@@ -1455,7 +1450,7 @@ dns__rbtdb_decref(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
} else {
INSIST(node->data == NULL);
if (!ISC_LINK_LINKED(node, deadlink)) {
ISC_LIST_APPEND(rbtdb->deadnodes[bucket], node,
ISC_LIST_APPEND(rbtdb->deadnodes[node->locknum], node,
deadlink);
}
}