lib/dns/sdb.c: use isc_refcount_t

diff --git a/lib/dns/sdb.c b/lib/dns/sdb.c
index 6be15d87200209700e614a54f724163d9f08489a..4325819e98d84902d1cafd8274c41b1c5191abb6 100644 (file)
--- a/lib/dns/sdb.c
+++ b/lib/dns/sdb.c
@@ -22,6 +22,7 @@
 #include <isc/mem.h>
 #include <isc/once.h>
 #include <isc/print.h>
+#include <isc/refcount.h>
 #include <isc/region.h>
 #include <isc/util.h>
 
@@ -56,9 +57,9 @@ struct dns_sdb {
        char                            *zone;
        dns_sdbimplementation_t         *implementation;
        void                            *dbdata;
-       isc_mutex_t                     lock;
-       /* Locked */
-       unsigned int                    references;
+
+       /* Atomic */
+       isc_refcount_t                  references;
 };
 
 struct dns_sdblookup {
@@ -69,10 +70,10 @@ struct dns_sdblookup {
        ISC_LIST(isc_buffer_t)          buffers;
        dns_name_t                      *name;
        ISC_LINK(dns_sdblookup_t)       link;
-       isc_mutex_t                     lock;
        dns_rdatacallbacks_t            callbacks;
-       /* Locked */
-       unsigned int                    references;
+
+       /* Atomic */
+       isc_refcount_t                  references;
 };
 
 typedef struct dns_sdblookup dns_sdbnode_t;
@@ -529,10 +530,7 @@ attach(dns_db_t *source, dns_db_t **targetp) {
 
        REQUIRE(VALID_SDB(sdb));
 
-       LOCK(&sdb->lock);
-       REQUIRE(sdb->references > 0);
-       sdb->references++;
-       UNLOCK(&sdb->lock);
+       isc_refcount_increment(&sdb->references);
 
        *targetp = source;
 }
@@ -552,7 +550,6 @@ destroy(dns_sdb_t *sdb) {
        }
 
        isc_mem_free(mctx, sdb->zone);
-       isc_mutex_destroy(&sdb->lock);
 
        sdb->common.magic = 0;
        sdb->common.impmagic = 0;
@@ -566,20 +563,14 @@ destroy(dns_sdb_t *sdb) {
 static void
 detach(dns_db_t **dbp) {
        dns_sdb_t *sdb = (dns_sdb_t *)(*dbp);
-       bool need_destroy = false;
 
        REQUIRE(VALID_SDB(sdb));
-       LOCK(&sdb->lock);
-       REQUIRE(sdb->references > 0);
-       sdb->references--;
-       if (sdb->references == 0)
-               need_destroy = true;
-       UNLOCK(&sdb->lock);
-
-       if (need_destroy)
-               destroy(sdb);
 
        *dbp = NULL;
+
+       if (isc_refcount_decrement(&sdb->references) == 1) {
+               destroy(sdb);
+       }
 }
 
 static isc_result_t
@@ -661,9 +652,10 @@ createnode(dns_sdb_t *sdb, dns_sdbnode_t **nodep) {
        ISC_LIST_INIT(node->buffers);
        ISC_LINK_INIT(node, link);
        node->name = NULL;
-       isc_mutex_init(&node->lock);
        dns_rdatacallbacks_init(&node->callbacks);
-       node->references = 1;
+
+       isc_refcount_init(&node->references, 1);
+
        node->magic = SDBLOOKUP_MAGIC;
 
        *nodep = node;
@@ -702,7 +694,7 @@ destroynode(dns_sdbnode_t *node) {
                dns_name_free(node->name, mctx);
                isc_mem_put(mctx, node->name, sizeof(dns_name_t));
        }
-       isc_mutex_destroy(&node->lock);
+
        node->magic = 0;
        isc_mem_put(mctx, node, sizeof(dns_sdbnode_t));
        detach((dns_db_t **) (void *)&sdb);
@@ -1001,11 +993,7 @@ attachnode(dns_db_t *db, dns_dbnode_t *source, dns_dbnode_t **targetp) {
 
        UNUSED(sdb);
 
-       LOCK(&node->lock);
-       INSIST(node->references > 0);
-       node->references++;
-       INSIST(node->references != 0);          /* Catch overflow. */
-       UNLOCK(&node->lock);
+       isc_refcount_increment(&node->references);
 
        *targetp = source;
 }
@@ -1014,7 +1002,6 @@ static void
 detachnode(dns_db_t *db, dns_dbnode_t **targetp) {
        dns_sdb_t *sdb = (dns_sdb_t *)db;
        dns_sdbnode_t *node;
-       bool need_destroy = false;
 
        REQUIRE(VALID_SDB(sdb));
        REQUIRE(targetp != NULL && *targetp != NULL);
@@ -1023,17 +1010,11 @@ detachnode(dns_db_t *db, dns_dbnode_t **targetp) {
 
        node = (dns_sdbnode_t *)(*targetp);
 
-       LOCK(&node->lock);
-       INSIST(node->references > 0);
-       node->references--;
-       if (node->references == 0)
-               need_destroy = true;
-       UNLOCK(&node->lock);
+       *targetp = NULL;
 
-       if (need_destroy)
+       if (isc_refcount_decrement(&node->references) == 1) {
                destroynode(node);
-
-       *targetp = NULL;
+       }
 }
 
 static isc_result_t
@@ -1323,8 +1304,6 @@ dns_sdb_create(isc_mem_t *mctx, const dns_name_t *origin, dns_dbtype_t type,
 
        isc_mem_attach(mctx, &sdb->common.mctx);
 
-       isc_mutex_init(&sdb->lock);
-
        result = dns_name_dupwithoffsets(origin, mctx, &sdb->common.origin);
        if (result != ISC_R_SUCCESS)
                goto cleanup_lock;
@@ -1351,7 +1330,7 @@ dns_sdb_create(isc_mem_t *mctx, const dns_name_t *origin, dns_dbtype_t type,
                        goto cleanup_zonestr;
        }
 
-       sdb->references = 1;
+       isc_refcount_init(&sdb->references, 1);
 
        sdb->common.magic = DNS_DB_MAGIC;
        sdb->common.impmagic = SDB_MAGIC;
@@ -1365,7 +1344,6 @@ dns_sdb_create(isc_mem_t *mctx, const dns_name_t *origin, dns_dbtype_t type,
  cleanup_origin:
        dns_name_free(&sdb->common.origin, mctx);
  cleanup_lock:
-       isc_mutex_destroy(&sdb->lock);
        isc_mem_put(mctx, sdb, sizeof(dns_sdb_t));
        isc_mem_detach(&mctx);