unsigned int i;
isc_result_t result;
char buf[DNS_NAME_FORMATSIZE];
+ dns_rbtnode_t *node = NULL;
dns_rbt_t **treep = NULL;
isc_time_t start;
* the overhead of unlinking all nodes here should be negligible.
*/
for (i = 0; i < rbtdb->node_lock_count; i++) {
- dns_rbtnode_t *node = NULL;
-
node = ISC_LIST_HEAD(rbtdb->deadnodes[i]);
while (node != NULL) {
ISC_LIST_UNLINK(rbtdb->deadnodes[i], node, deadlink);
}
}
+ node = ISC_LIST_HEAD(rbtdb->prunenodes);
+ while (node != NULL) {
+ ISC_LIST_UNLINK(rbtdb->prunenodes, node, prunelink);
+ node = ISC_LIST_HEAD(rbtdb->prunenodes);
+ }
+
rbtdb->quantum = (rbtdb->loop != NULL) ? 100 : 0;
for (;;) {
node->left == NULL && node->right == NULL);
}
+/*%
+ * The tree lock must be held when this function is called as it reads and
+ * updates rbtdb->prunenodes.
+ */
static void
send_to_prune_tree(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
isc_rwlocktype_t locktype DNS__DB_FLARG) {
- prune_t *prune = isc_mem_get(rbtdb->common.mctx, sizeof(*prune));
- *prune = (prune_t){ .node = node };
+ bool pruning_queued = (ISC_LIST_HEAD(rbtdb->prunenodes) != NULL);
+
+ INSIST(locktype == isc_rwlocktype_write);
- dns_db_attach((dns_db_t *)rbtdb, &prune->db);
dns__rbtdb_newref(rbtdb, node, locktype DNS__DB_FLARG_PASS);
+ INSIST(!ISC_LINK_LINKED(node, prunelink));
+ ISC_LIST_APPEND(rbtdb->prunenodes, node, prunelink);
- isc_async_run(rbtdb->loop, prune_tree, prune);
+ if (!pruning_queued) {
+ dns_db_t *db = NULL;
+ dns_db_attach((dns_db_t *)rbtdb, &db);
+ isc_async_run(rbtdb->loop, prune_tree, db);
+ }
}
/*%
}
/*
- * Prune the tree by recursively cleaning-up single leaves. In the worst
- * case, the number of iteration is the number of tree levels, which is at
- * most the maximum number of domain name labels, i.e, 127. In practice, this
- * should be much smaller (only a few times), and even the worst case would be
- * acceptable for a single event.
+ * Prune the tree by recursively cleaning up single leaves. Go through all
+ * nodes stored in the rbtdb->prunenodes list; for each of them, in the worst
+ * case, it will be necessary to traverse a number of tree levels equal to the
+ * maximum legal number of domain name labels (127); in practice, the number of
+ * tree levels to traverse will virtually always be much smaller (a few levels
+ * at most). While holding the tree lock throughout this entire operation is
+ * less than ideal, so is splitting the latter up by queueing a separate
+ * prune_tree() run for each node to start pruning from (as queueing requires
+ * allocating memory and can therefore potentially be exploited to exhaust
+ * available memory). Also note that actually freeing up the memory used by
+ * RBTDB nodes (which is what this function does) is essential to keeping cache
+ * memory use in check, so since the tree lock needs to be acquired anyway,
+ * freeing as many nodes as possible before the tree lock gets released is
+ * prudent.
*/
static void
prune_tree(void *arg) {
- prune_t *prune = (prune_t *)arg;
- dns_rbtdb_t *rbtdb = (dns_rbtdb_t *)prune->db;
- dns_rbtnode_t *node = prune->node;
+ dns_rbtdb_t *rbtdb = (dns_rbtdb_t *)arg;
+ dns_rbtnode_t *node = NULL;
dns_rbtnode_t *parent = NULL;
unsigned int locknum;
isc_rwlocktype_t tlocktype = isc_rwlocktype_none;
isc_rwlocktype_t nlocktype = isc_rwlocktype_none;
- isc_mem_put(rbtdb->common.mctx, prune, sizeof(*prune));
-
TREE_WRLOCK(&rbtdb->tree_lock, &tlocktype);
- locknum = node->locknum;
- NODE_WRLOCK(&rbtdb->node_locks[locknum].lock, &nlocktype);
- do {
- parent = node->parent;
- dns__rbtdb_decref(rbtdb, node, 0, &nlocktype, &tlocktype, true,
- true DNS__DB_FILELINE);
- if (parent != NULL && parent->down == NULL) {
- /*
- * node was the only down child of the parent and has
- * just been removed. We'll then need to examine the
- * parent. Keep the lock if possible; otherwise,
- * release the old lock and acquire one for the parent.
- */
- if (parent->locknum != locknum) {
- NODE_UNLOCK(&rbtdb->node_locks[locknum].lock,
- &nlocktype);
- locknum = parent->locknum;
- NODE_WRLOCK(&rbtdb->node_locks[locknum].lock,
- &nlocktype);
+ while ((node = ISC_LIST_HEAD(rbtdb->prunenodes)) != NULL) {
+ locknum = node->locknum;
+ NODE_WRLOCK(&rbtdb->node_locks[locknum].lock, &nlocktype);
+ do {
+ if (ISC_LINK_LINKED(node, prunelink)) {
+ ISC_LIST_UNLINK(rbtdb->prunenodes, node,
+ prunelink);
}
- /*
- * We need to gain a reference to the node before
- * decrementing it in the next iteration.
- */
- if (ISC_LINK_LINKED(parent, deadlink)) {
- ISC_LIST_UNLINK(rbtdb->deadnodes[locknum],
+ parent = node->parent;
+ dns__rbtdb_decref(rbtdb, node, 0, &nlocktype,
+ &tlocktype, true,
+ true DNS__DB_FILELINE);
+
+ if (parent != NULL && parent->down == NULL) {
+ /*
+ * node was the only down child of the parent
+ * and has just been removed. We'll then need
+ * to examine the parent. Keep the lock if
+ * possible; otherwise, release the old lock and
+ * acquire one for the parent.
+ */
+ if (parent->locknum != locknum) {
+ NODE_UNLOCK(
+ &rbtdb->node_locks[locknum].lock,
+ &nlocktype);
+ locknum = parent->locknum;
+ NODE_WRLOCK(
+ &rbtdb->node_locks[locknum].lock,
+ &nlocktype);
+ }
+
+ /*
+ * We need to gain a reference to the node
+ * before decrementing it in the next iteration.
+ */
+ if (ISC_LINK_LINKED(parent, deadlink)) {
+ ISC_LIST_UNLINK(
+ rbtdb->deadnodes[locknum],
parent, deadlink);
+ }
+ dns__rbtdb_newref(rbtdb, parent,
+ nlocktype DNS__DB_FILELINE);
+ } else {
+ parent = NULL;
}
- dns__rbtdb_newref(rbtdb, parent,
- nlocktype DNS__DB_FILELINE);
- } else {
- parent = NULL;
- }
- node = parent;
- } while (node != NULL);
- NODE_UNLOCK(&rbtdb->node_locks[locknum].lock, &nlocktype);
+ node = parent;
+ } while (node != NULL);
+ NODE_UNLOCK(&rbtdb->node_locks[locknum].lock, &nlocktype);
+ }
TREE_UNLOCK(&rbtdb->tree_lock, &tlocktype);
dns_db_detach((dns_db_t **)&rbtdb);
ISC_LIST_INIT(rbtdb->deadnodes[i]);
}
+ ISC_LIST_INIT(rbtdb->prunenodes);
+
rbtdb->active = rbtdb->node_lock_count;
for (i = 0; i < (int)(rbtdb->node_lock_count); i++) {
projects / thirdparty / bind9.git / commitdiff
