Implemented reference counting to knot_zone_t.

refs #1976

src/knot/server/zones.c

@@ -122,7 +122,6 @@ static int zonedata_destroy(knot_zone_t *zone)
 	free(zd);
 	
 	/* Invalidate. */
-	zone->dtor = 0;
 	zone->data = 0;
 
 	return KNOTD_EOK;
@@ -181,7 +180,7 @@ static int zonedata_init(conf_zone_t *cfg, knot_zone_t *zone)
 
 	/* Set and install destructor. */
 	zone->data = zd;
-	zone->dtor = zonedata_destroy;
+	knot_zone_set_dtor(zone, zonedata_destroy);
 
 	/* Set zonefile SOA serial. */
 	const knot_rrset_t *soa_rrs = 0;

src/knot/server/zones.h

@@ -59,7 +59,7 @@ typedef struct zonedata_t
 
 	/*! \brief Zone data lock for exclusive access. */
 	pthread_mutex_t lock;
-
+	
 	/*! \brief Access control lists. */
 	acl_t *xfr_out;    /*!< ACL for xfr-out.*/
 	acl_t *notify_in;  /*!< ACL for notify-in.*/

src/libknot/zone/zone.c

@@ -33,6 +33,12 @@
 #include "hash/cuckoo-hash-table.h"
 #include "zone/zone-contents.h"
 
+/*! \brief Adaptor for knot_zone_deep_free() */
+static void knot_zone_dtor(struct ref_t *p) {
+	knot_zone_t *z = (knot_zone_t *)p;
+	knot_zone_deep_free(&z, 0);
+}
+
 /*----------------------------------------------------------------------------*/
 /* API functions                                                              */
 /*----------------------------------------------------------------------------*/
@@ -55,6 +61,13 @@ knot_zone_t *knot_zone_new_empty(knot_dname_t *name)
 	// save the zone name
 	dbg_zone("Setting zone name.\n");
 	zone->name = name;
+	
+	/* Initialize reference counting. */
+	ref_init(&zone->ref, knot_zone_dtor);
+	
+	/* Set reference counter to 1, caller should release it after use. */
+	knot_zone_retain(zone);
+	
 	return zone;
 }
 
@@ -242,3 +255,10 @@ dbg_zone_exec(
 	free(*zone);
 	*zone = NULL;
 }
+
+void knot_zone_set_dtor(knot_zone_t *zone, int (*dtor)(struct knot_zone *))
+{
+	if (zone != NULL) {
+		zone->dtor = dtor;
+	}
+}

src/libknot/zone/zone.h

@@ -34,6 +34,7 @@
 #include "nsec3.h"
 #include "zone/dname-table.h"
 #include "common/tree.h"
+#include "common/ref.h"
 #include "hash/cuckoo-hash-table.h"
 
 #include "zone-tree.h"
@@ -63,6 +64,7 @@ typedef enum knot_zone_retvals knot_zone_retvals_t;
  *          double-free errors when destroying the zone.
  */
 struct knot_zone {
+	ref_t ref;     /*!< Reference counting. */
 	knot_dname_t *name;
 
 	knot_zone_contents_t *contents;
@@ -147,6 +149,36 @@ void knot_zone_free(knot_zone_t **zone);
  */
 void knot_zone_deep_free(knot_zone_t **zone, int destroy_dname_table);
 
+/*!
+ * \brief Set destructor and initialize reference counter to 1.
+ *
+ * \param zone Related zone.
+ * \param dtor Destructor.
+ */
+void knot_zone_set_dtor(knot_zone_t *zone, int (*dtor)(struct knot_zone *));
+
+/*!
+ * \brief Increment reference counter for dname.
+ *
+ * \param zone Referenced zone.
+ */
+ static inline void knot_zone_retain(knot_zone_t *zone) {
+	if (zone != NULL) {
+		ref_retain(&zone->ref);
+	}
+}
+
+/*!
+ * \brief Decrement reference counter for dname.
+ *
+ * \param zone Referenced zone.
+ */
+ static inline void knot_zone_release(knot_zone_t *zone) {
+	if (zone != NULL) {
+		ref_release(&zone->ref);
+	}
+}
+
 #endif
 
 /*! @} */

src/libknot/zone/zonedb.c

@@ -280,7 +280,8 @@ static void delete_zone_from_db(void *node, void *data)
 	knot_zone_t *zone = (knot_zone_t *)node;
 	assert(zone);
 	synchronize_rcu();
-	knot_zone_deep_free(&zone, 0);
+	knot_zone_release(zone);
+	zone = NULL;
 }
 
 void knot_zonedb_deep_free(knot_zonedb_t **db)