afb-evt: prepare futur afb_eventid

Change-Id: Ie4668c2dadbdfbe79bac2c27a1b188edecbcf847
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

7 files changed, 426 insertions, 185 deletions

diff --git a/src/afb-api-dbus.c b/src/afb-api-dbus.c
index d31eda00..69f63ae4 100644
--- a/src/afb-api-dbus.c
+++ b/src/afb-api-dbus.c
@@ -382,7 +382,7 @@ static struct dbus_event *api_dbus_client_event_search(struct api_dbus *api, int
 	struct dbus_event *ev;
 
 	ev = api->client.events;
-	while (ev != NULL && (ev->id != id || 0 != strcmp(afb_evt_event_name(ev->event), name)))
+	while (ev != NULL && (ev->id != id || 0 != strcmp(afb_evt_event_fullname(ev->event), name)))
 		ev = ev->next;
 
 	return ev;
@@ -850,7 +850,7 @@ static int dbus_req_subscribe(struct afb_xreq *xreq, struct afb_event event)
 
 	rc = afb_evt_add_watch(dreq->listener->listener, event);
 	sd_bus_message_get_cookie(dreq->message, &msgid);
-	afb_api_dbus_server_event_send(dreq->listener->origin, 'S', afb_evt_event_name(event), afb_evt_event_id(event), "", msgid);
+	afb_api_dbus_server_event_send(dreq->listener->origin, 'S', afb_evt_event_fullname(event), afb_evt_event_id(event), "", msgid);
 	return rc;
 }
 
@@ -861,7 +861,7 @@ static int dbus_req_unsubscribe(struct afb_xreq *xreq, struct afb_event event)
 	int rc;
 
 	sd_bus_message_get_cookie(dreq->message, &msgid);
-	afb_api_dbus_server_event_send(dreq->listener->origin, 'U', afb_evt_event_name(event), afb_evt_event_id(event), "", msgid);
+	afb_api_dbus_server_event_send(dreq->listener->origin, 'U', afb_evt_event_fullname(event), afb_evt_event_id(event), "", msgid);
 	rc = afb_evt_remove_watch(dreq->listener->listener, event);
 	return rc;
 }
diff --git a/src/afb-evt.c b/src/afb-evt.c
index 1c81fd53..2bac0837 100644
--- a/src/afb-evt.c
+++ b/src/afb-evt.c
@@ -60,10 +60,13 @@ struct afb_evt_listener {
 /*
  * Structure for describing events
  */
-struct afb_evt_event {
+struct afb_evtid {
+
+	/* interface */
+	struct afb_event_itf *itf;
 
 	/* next event */
-	struct afb_evt_event *next;
+	struct afb_evtid *next;
 
 	/* head of the list of listeners watching the event */
 	struct afb_evt_watch *watchs;
@@ -74,11 +77,14 @@ struct afb_evt_event {
 	/* hooking */
 	int hookflags;
 
+	/* refcount */
+	int refcount;
+
 	/* mutex of the event */
 	pthread_mutex_t mutex;
 
-	/* name of the event */
-	char name[1];
+	/* fullname of the event */
+	char fullname[1];
 };
 
 /*
@@ -86,16 +92,16 @@ struct afb_evt_event {
  */
 struct afb_evt_watch {
 
-	/* the event */
-	struct afb_evt_event *event;
+	/* the evtid */
+	struct afb_evtid *evtid;
 
-	/* link to the next listener for the same event */
-	struct afb_evt_watch *next_by_event;
+	/* link to the next watcher for the same evtid */
+	struct afb_evt_watch *next_by_evtid;
 
 	/* the listener */
 	struct afb_evt_listener *listener;
 
-	/* link to the next event for the same listener */
+	/* link to the next watcher for the same listener */
 	struct afb_evt_watch *next_by_listener;
 
 	/* activity */
@@ -103,17 +109,22 @@ struct afb_evt_watch {
 };
 
 /* declare functions */
-static int evt_broadcast(struct afb_evt_event *evt, struct json_object *obj);
-static int evt_push(struct afb_evt_event *evt, struct json_object *obj);
-static void evt_destroy(struct afb_evt_event *evt);
-static const char *evt_name(struct afb_evt_event *evt);
+static void evt_hooked_drop(struct afb_evtid *evtid);
 
 /* the interface for events */
 static struct afb_event_itf afb_evt_event_itf = {
-	.broadcast = (void*)evt_broadcast,
-	.push = (void*)evt_push,
-	.drop = (void*)evt_destroy,
-	.name = (void*)evt_name
+	.broadcast = (void*)afb_evt_evtid_broadcast,
+	.push = (void*)afb_evt_evtid_push,
+	.drop = (void*)afb_evt_evtid_unref,
+	.name = (void*)afb_evt_evtid_name
+};
+
+/* the interface for events */
+static struct afb_event_itf afb_evt_hooked_event_itf = {
+	.broadcast = (void*)afb_evt_evtid_hooked_broadcast,
+	.push = (void*)afb_evt_evtid_hooked_push,
+	.drop = (void*)evt_hooked_drop,
+	.name = (void*)afb_evt_evtid_hooked_name
 };
 
 /* head of the list of listeners */
@@ -122,23 +133,20 @@ static struct afb_evt_listener *listeners = NULL;
 
 /* handling id of events */
 static pthread_mutex_t events_mutex = PTHREAD_MUTEX_INITIALIZER;
-static struct afb_evt_event *events = NULL;
+static struct afb_evtid *evtids = NULL;
 static int event_id_counter = 0;
 static int event_id_wrapped = 0;
 
 /*
  * Broadcasts the 'event' of 'id' with its 'obj'
  * 'obj' is released (like json_object_put)
- * calls hooks if hookflags isn't 0
  * Returns the count of listener having receive the event.
  */
-static int broadcast(const char *event, struct json_object *obj, int id, int hookflags)
+static int broadcast(const char *event, struct json_object *obj, int id)
 {
 	int result;
 	struct afb_evt_listener *listener;
 
-	if (hookflags & afb_hook_flag_evt_broadcast_before)
-		afb_hook_evt_broadcast_before(event, id, obj);
 	result = 0;
 	pthread_mutex_lock(&listeners_mutex);
 	listener = listeners;
@@ -150,20 +158,53 @@ static int broadcast(const char *event, struct json_object *obj, int id, int hoo
 		listener = listener->next;
 	}
 	pthread_mutex_unlock(&listeners_mutex);
+	json_object_put(obj);
+	return result;
+}
+
+/*
+ * Broadcasts the 'event' of 'id' with its 'obj'
+ * 'obj' is released (like json_object_put)
+ * calls hooks if hookflags isn't 0
+ * Returns the count of listener having receive the event.
+ */
+static int hooked_broadcast(const char *event, struct json_object *obj, int id, int hookflags)
+{
+	int result;
+
+	json_object_get(obj);
+
+	if (hookflags & afb_hook_flag_evt_broadcast_before)
+		afb_hook_evt_broadcast_before(event, id, obj);
+
+	result = broadcast(event, obj, id);
+
 	if (hookflags & afb_hook_flag_evt_broadcast_after)
 		afb_hook_evt_broadcast_after(event, id, obj, result);
+
 	json_object_put(obj);
+
 	return result;
 }
 
 /*
- * Broadcasts the event 'evt' with its 'object'
+ * Broadcasts the event 'evtid' with its 'object'
+ * 'object' is released (like json_object_put)
+ * Returns the count of listener that received the event.
+ */
+int afb_evt_evtid_broadcast(struct afb_evtid *evtid, struct json_object *object)
+{
+	return broadcast(evtid->fullname, object, evtid->id);
+}
+
+/*
+ * Broadcasts the event 'evtid' with its 'object'
  * 'object' is released (like json_object_put)
  * Returns the count of listener that received the event.
  */
-static int evt_broadcast(struct afb_evt_event *evt, struct json_object *object)
+int afb_evt_evtid_hooked_broadcast(struct afb_evtid *evtid, struct json_object *object)
 {
-	return broadcast(evt->name, object, evt->id, evt->hookflags);
+	return hooked_broadcast(evtid->fullname, object, evtid->id, evtid->hookflags);
 }
 
 /*
@@ -173,62 +214,64 @@ static int evt_broadcast(struct afb_evt_event *evt, struct json_object *object)
  */
 int afb_evt_broadcast(const char *event, struct json_object *object)
 {
-	return broadcast(event, object, 0, -1);
+	return hooked_broadcast(event, object, 0, -1);
 }
 
 /*
- * Pushes the event 'evt' with 'obj' to its listeners
+ * Pushes the event 'evtid' with 'obj' to its listeners
  * 'obj' is released (like json_object_put)
- * calls hooks if hookflags isn't 0
- * Returns the count of listener taht received the event.
+ * Returns the count of listener that received the event.
  */
-static int push(struct afb_evt_event *evt, struct json_object *obj, int hookflags)
+int afb_evt_evtid_push(struct afb_evtid *evtid, struct json_object *obj)
 {
 	int result;
 	struct afb_evt_watch *watch;
 	struct afb_evt_listener *listener;
 
 	result = 0;
-	pthread_mutex_lock(&evt->mutex);
-	if (hookflags & afb_hook_flag_evt_push_before)
-		afb_hook_evt_push_before(evt->name, evt->id, obj);
-	watch = evt->watchs;
+	pthread_mutex_lock(&evtid->mutex);
+	watch = evtid->watchs;
 	while(watch) {
 		listener = watch->listener;
 		assert(listener->itf->push != NULL);
 		if (watch->activity != 0) {
-			listener->itf->push(listener->closure, evt->name, evt->id, json_object_get(obj));
+			listener->itf->push(listener->closure, evtid->fullname, evtid->id, json_object_get(obj));
 			result++;
 		}
-		watch = watch->next_by_event;
+		watch = watch->next_by_evtid;
 	}
-	if (hookflags & afb_hook_flag_evt_push_after)
-		afb_hook_evt_push_after(evt->name, evt->id, obj, result);
-	pthread_mutex_unlock(&evt->mutex);
+	pthread_mutex_unlock(&evtid->mutex);
 	json_object_put(obj);
 	return result;
 }
 
 /*
- * Pushes the event 'evt' with 'obj' to its listeners
+ * Pushes the event 'evtid' with 'obj' to its listeners
  * 'obj' is released (like json_object_put)
+ * Emits calls to hooks.
  * Returns the count of listener taht received the event.
  */
-static int evt_push(struct afb_evt_event *evt, struct json_object *obj)
+int afb_evt_evtid_hooked_push(struct afb_evtid *evtid, struct json_object *obj)
 {
-	return push(evt, obj, evt->hookflags);
-}
+	int result;
 
-/*
- * Returns the name associated to the event 'evt'.
- */
-static const char *evt_name(struct afb_evt_event *evt)
-{
-	const char *name = strchr(evt->name, '/');
-	name = name ? name + 1 : evt->name;
-	if (evt->hookflags & afb_hook_flag_evt_name)
-		afb_hook_evt_name(evt->name, evt->id);
-	return name;
+	/* lease the object */
+	json_object_get(obj);
+
+	/* hook before push */
+	if (evtid->hookflags & afb_hook_flag_evt_push_before)
+		afb_hook_evt_push_before(evtid->fullname, evtid->id, obj);
+
+	/* push */
+	result = afb_evt_evtid_push(evtid, obj);
+
+	/* hook after push */
+	if (evtid->hookflags & afb_hook_flag_evt_push_after)
+		afb_hook_evt_push_after(evtid->fullname, evtid->id, obj, result);
+
+	/* release the object */
+	json_object_put(obj);
+	return result;
 }
 
 /*
@@ -237,20 +280,20 @@ static const char *evt_name(struct afb_evt_event *evt)
 static void remove_watch(struct afb_evt_watch *watch)
 {
 	struct afb_evt_watch **prv;
-	struct afb_evt_event *evt;
+	struct afb_evtid *evtid;
 	struct afb_evt_listener *listener;
 
 	/* notify listener if needed */
-	evt = watch->event;
+	evtid = watch->evtid;
 	listener = watch->listener;
 	if (watch->activity != 0 && listener->itf->remove != NULL)
-		listener->itf->remove(listener->closure, evt->name, evt->id);
+		listener->itf->remove(listener->closure, evtid->fullname, evtid->id);
 
 	/* unlink the watch for its event */
-	prv = &evt->watchs;
+	prv = &evtid->watchs;
 	while(*prv != watch)
-		prv = &(*prv)->next_by_event;
-	*prv = watch->next_by_event;
+		prv = &(*prv)->next_by_evtid;
+	*prv = watch->next_by_evtid;
 
 	/* unlink the watch for its listener */
 	prv = &listener->watchs;
@@ -263,109 +306,169 @@ static void remove_watch(struct afb_evt_watch *watch)
 }
 
 /*
- * Destroys the event 'evt'
+ * Creates an event of name 'fullname' and returns it or NULL on error.
  */
-static void evt_destroy(struct afb_evt_event *evt)
+struct afb_evtid *afb_evt_evtid_create(const char *fullname)
+{
+	size_t len;
+	struct afb_evtid *evtid, *oevt;
+
+	/* allocates the event */
+	len = strlen(fullname);
+	evtid = malloc(len + sizeof * evtid);
+	if (evtid == NULL)
+		goto error;
+
+	/* allocates the id */
+	pthread_mutex_lock(&events_mutex);
+	do {
+		if (++event_id_counter < 0) {
+			event_id_wrapped = 1;
+			event_id_counter = 1024; /* heuristic: small numbers are not destroyed */
+		}
+		if (!event_id_wrapped)
+			break;
+		oevt = evtids;
+		while(oevt != NULL && oevt->id != event_id_counter)
+			oevt = oevt->next;
+	} while (oevt != NULL);
+
+	/* initialize the event */
+	memcpy(evtid->fullname, fullname, len + 1);
+	evtid->next = evtids;
+	evtid->watchs = NULL;
+	evtid->id = event_id_counter;
+	pthread_mutex_init(&evtid->mutex, NULL);
+	evtids = evtid;
+	evtid->hookflags = afb_hook_flags_evt(evtid->fullname);
+	evtid->itf = evtid->hookflags ? &afb_evt_hooked_event_itf : &afb_evt_event_itf;
+	if (evtid->hookflags & afb_hook_flag_evt_create)
+		afb_hook_evt_create(evtid->fullname, evtid->id);
+	pthread_mutex_unlock(&events_mutex);
+
+	/* returns the event */
+	return evtid;
+error:
+	return NULL;
+}
+
+/*
+ * increment the reference count of the event 'evtid'
+ */
+struct afb_evtid *afb_evt_evtid_addref(struct afb_evtid *evtid)
+{
+	__atomic_add_fetch(&evtid->refcount, 1, __ATOMIC_RELAXED);
+	return evtid;
+}
+
+/*
+ * increment the reference count of the event 'evtid'
+ */
+struct afb_evtid *afb_evt_evtid_hooked_addref(struct afb_evtid *evtid)
+{
+	if (evtid->hookflags & afb_hook_flag_evt_addref)
+		afb_hook_evt_addref(evtid->fullname, evtid->id);
+	return afb_evt_evtid_addref(evtid);
+}
+
+/*
+ * decrement the reference count of the event 'evtid'
+ * and destroy it when the count reachs zero
+ */
+void afb_evt_evtid_unref(struct afb_evtid *evtid)
 {
 	int found;
-	struct afb_evt_event **prv;
+	struct afb_evtid **prv;
 	struct afb_evt_listener *listener;
 
-	if (evt != NULL) {
+	if (!__atomic_sub_fetch(&evtid->refcount, 1, __ATOMIC_RELAXED)) {
 		/* unlinks the event if valid! */
 		pthread_mutex_lock(&events_mutex);
 		found = 0;
-		prv = &events;
-		while (*prv && !(found = (*prv == evt)))
+		prv = &evtids;
+		while (*prv && !(found = (*prv == evtid)))
 			prv = &(*prv)->next;
 		if (found)
-			*prv = evt->next;
+			*prv = evtid->next;
 		pthread_mutex_unlock(&events_mutex);
 
 		/* destroys the event */
-		if (found) {
+		if (!found)
+			ERROR("event not found");
+		else {
 			/* removes all watchers */
-			while(evt->watchs != NULL) {
-				listener = evt->watchs->listener;
+			while(evtid->watchs != NULL) {
+				listener = evtid->watchs->listener;
 				pthread_mutex_lock(&listener->mutex);
-				pthread_mutex_lock(&evt->mutex);
-				remove_watch(evt->watchs);
-				pthread_mutex_unlock(&evt->mutex);
+				pthread_mutex_lock(&evtid->mutex);
+				remove_watch(evtid->watchs);
+				pthread_mutex_unlock(&evtid->mutex);
 				pthread_mutex_unlock(&listener->mutex);
 			}
 
 			/* hook */
-			if (evt->hookflags & afb_hook_flag_evt_drop)
-				afb_hook_evt_drop(evt->name, evt->id);
+			if (evtid->hookflags & afb_hook_flag_evt_drop)
+				afb_hook_evt_drop(evtid->fullname, evtid->id);
 
 			/* free */
-			pthread_mutex_destroy(&evt->mutex);
-			free(evt);
+			pthread_mutex_destroy(&evtid->mutex);
+			free(evtid);
 		}
 	}
 }
 
 /*
- * Creates an event of 'name' and returns it.
- * Returns an event with closure==NULL in case of error.
+ * decrement the reference count of the event 'evtid'
+ * and destroy it when the count reachs zero
  */
-struct afb_event afb_evt_create_event(const char *name)
+void afb_evt_evtid_hooked_unref(struct afb_evtid *evtid)
 {
-	size_t len;
-	struct afb_evt_event *evt, *oevt;
-
-	/* allocates the event */
-	len = strlen(name);
-	evt = malloc(len + sizeof * evt);
-	if (evt == NULL)
-		goto error;
-
-	/* allocates the id */
-	pthread_mutex_lock(&events_mutex);
-	do {
-		if (++event_id_counter < 0) {
-			event_id_wrapped = 1;
-			event_id_counter = 1024; /* heuristic: small numbers are not destroyed */
-		}
-		if (!event_id_wrapped)
-			break;
-		oevt = events;
-		while(oevt != NULL && oevt->id != event_id_counter)
-			oevt = oevt->next;
-	} while (oevt != NULL);
+	if (evtid->hookflags & afb_hook_flag_evt_unref)
+		afb_hook_evt_unref(evtid->fullname, evtid->id);
+	afb_evt_evtid_unref(evtid);
+}
 
-	/* initialize the event */
-	memcpy(evt->name, name, len + 1);
-	evt->next = events;
-	evt->watchs = NULL;
-	evt->id = event_id_counter;
-	pthread_mutex_init(&evt->mutex, NULL);
-	events = evt;
-	evt->hookflags = afb_hook_flags_evt(evt->name);
-	if (evt->hookflags & afb_hook_flag_evt_create)
-		afb_hook_evt_create(evt->name, evt->id);
-	pthread_mutex_unlock(&events_mutex);
+static void evt_hooked_drop(struct afb_evtid *evtid)
+{
+	if (evtid->hookflags & afb_hook_flag_evt_drop)
+		afb_hook_evt_drop(evtid->fullname, evtid->id);
+	afb_evt_evtid_unref(evtid);
+}
 
-	/* returns the event */
-	return (struct afb_event){ .itf = &afb_evt_event_itf, .closure = evt };
-error:
-	return (struct afb_event){ .itf = NULL, .closure = NULL };
+/*
+ * Returns the true name of the 'event'
+ */
+const char *afb_evt_evtid_fullname(struct afb_evtid *evtid)
+{
+	return evtid->fullname;
 }
 
 /*
  * Returns the name of the 'event'
  */
-const char *afb_evt_event_name(struct afb_event event)
+const char *afb_evt_evtid_name(struct afb_evtid *evtid)
 {
-	return (event.itf != &afb_evt_event_itf) ? NULL : ((struct afb_evt_event *)event.closure)->name;
+	const char *name = strchr(evtid->fullname, '/');
+	return name ? name + 1 : evtid->fullname;
+}
+
+/*
+ * Returns the name associated to the event 'evtid'.
+ */
+const char *afb_evt_evtid_hooked_name(struct afb_evtid *evtid)
+{
+	const char *result = afb_evt_evtid_name(evtid);
+	if (evtid->hookflags & afb_hook_flag_evt_name)
+		afb_hook_evt_name(evtid->fullname, evtid->id, result);
+	return result;
 }
 
 /*
  * Returns the id of the 'event'
  */
-int afb_evt_event_id(struct afb_event event)
+int afb_evt_evtid_id(struct afb_evtid *evtid)
 {
-	return (event.itf != &afb_evt_event_itf) ? 0 : ((struct afb_evt_event *)event.closure)->id;
+	return evtid->id;
 }
 
 /*
@@ -421,7 +524,7 @@ struct afb_evt_listener *afb_evt_listener_addref(struct afb_evt_listener *listen
 void afb_evt_listener_unref(struct afb_evt_listener *listener)
 {
 	struct afb_evt_listener **prv;
-	struct afb_evt_event *evt;
+	struct afb_evtid *evtid;
 
 	if (!__atomic_sub_fetch(&listener->refcount, 1, __ATOMIC_RELAXED)) {
 
@@ -436,10 +539,10 @@ void afb_evt_listener_unref(struct afb_evt_listener *listener)
 		/* remove the watchers */
 		pthread_mutex_lock(&listener->mutex);
 		while (listener->watchs != NULL) {
-			evt = listener->watchs->event;
-			pthread_mutex_lock(&evt->mutex);
+			evtid = listener->watchs->evtid;
+			pthread_mutex_lock(&evtid->mutex);
 			remove_watch(listener->watchs);
-			pthread_mutex_unlock(&evt->mutex);
+			pthread_mutex_unlock(&evtid->mutex);
 		}
 		pthread_mutex_unlock(&listener->mutex);
 
@@ -450,26 +553,24 @@ void afb_evt_listener_unref(struct afb_evt_listener *listener)
 }
 
 /*
- * Makes the 'listener' watching 'event'
+ * Makes the 'listener' watching 'evtid'
  * Returns 0 in case of success or else -1.
  */
-int afb_evt_add_watch(struct afb_evt_listener *listener, struct afb_event event)
+int afb_evt_watch_add_evtid(struct afb_evt_listener *listener, struct afb_evtid *evtid)
 {
 	struct afb_evt_watch *watch;
-	struct afb_evt_event *evt;
 
 	/* check parameter */
-	if (event.itf != &afb_evt_event_itf || listener->itf->push == NULL) {
+	if (listener->itf->push == NULL) {
 		errno = EINVAL;
 		return -1;
 	}
 
 	/* search the existing watch for the listener */
-	evt = event.closure;
 	pthread_mutex_lock(&listener->mutex);
 	watch = listener->watchs;
 	while(watch != NULL) {
-		if (watch->event == evt)
+		if (watch->evtid == evtid)
 			goto found;
 		watch = watch->next_by_listener;
 	}
@@ -483,19 +584,19 @@ int afb_evt_add_watch(struct afb_evt_listener *listener, struct afb_event event)
 	}
 
 	/* initialise and link */
-	watch->event = evt;
+	watch->evtid = evtid;
 	watch->activity = 0;
 	watch->listener = listener;
 	watch->next_by_listener = listener->watchs;
 	listener->watchs = watch;
-	pthread_mutex_lock(&evt->mutex);
-	watch->next_by_event = evt->watchs;
-	evt->watchs = watch;
-	pthread_mutex_unlock(&evt->mutex);
+	pthread_mutex_lock(&evtid->mutex);
+	watch->next_by_evtid = evtid->watchs;
+	evtid->watchs = watch;
+	pthread_mutex_unlock(&evtid->mutex);
 
 found:
 	if (watch->activity == 0 && listener->itf->add != NULL)
-		listener->itf->add(listener->closure, evt->name, evt->id);
+		listener->itf->add(listener->closure, evtid->fullname, evtid->id);
 	watch->activity++;
 	pthread_mutex_unlock(&listener->mutex);
 
@@ -503,30 +604,22 @@ found:
 }
 
 /*
- * Avoids the 'listener' to watch 'event'
+ * Avoids the 'listener' to watch 'evtid'
  * Returns 0 in case of success or else -1.
  */
-int afb_evt_remove_watch(struct afb_evt_listener *listener, struct afb_event event)
+int afb_evt_watch_sub_evtid(struct afb_evt_listener *listener, struct afb_evtid *evtid)
 {
 	struct afb_evt_watch *watch;
-	struct afb_evt_event *evt;
-
-	/* check parameter */
-	if (event.itf != &afb_evt_event_itf) {
-		errno = EINVAL;
-		return -1;
-	}
 
 	/* search the existing watch */
-	evt = event.closure;
 	pthread_mutex_lock(&listener->mutex);
 	watch = listener->watchs;
 	while(watch != NULL) {
-		if (watch->event == evt) {
+		if (watch->evtid == evtid) {
 			if (watch->activity != 0) {
 				watch->activity--;
 				if (watch->activity == 0 && listener->itf->remove != NULL)
-					listener->itf->remove(listener->closure, evt->name, evt->id);
+					listener->itf->remove(listener->closure, evtid->fullname, evtid->id);
 			}
 			pthread_mutex_unlock(&listener->mutex);
 			return 0;
@@ -543,26 +636,103 @@ int afb_evt_remove_watch(struct afb_evt_listener *listener, struct afb_event eve
  */
 void afb_evt_update_hooks()
 {
-	struct afb_evt_event *evt;
+	struct afb_evtid *evtid;
 
 	pthread_mutex_lock(&events_mutex);
-	for (evt = events ; evt ; evt = evt->next)
-		evt->hookflags = afb_hook_flags_evt(evt->name);
+	for (evtid = evtids ; evtid ; evtid = evtid->next) {
+		evtid->hookflags = afb_hook_flags_evt(evtid->fullname);
+		evtid->itf = evtid->hookflags ? &afb_evt_hooked_event_itf : &afb_evt_event_itf;
+	}
 	pthread_mutex_unlock(&events_mutex);
 }
 
+struct afb_evtid *afb_evt_to_evtid(struct afb_event event)
+{
+	return (struct afb_evtid*)(event.itf == &afb_evt_hooked_event_itf ? event.closure : NULL);
+}
+
+struct afb_event afb_evt_from_evtid(struct afb_evtid *evtid)
+{
+	return (struct afb_event){ .itf = evtid ? &afb_evt_hooked_event_itf : NULL, .closure = evtid };
+}
+
+/*
+ * Creates an event of 'fullname' and returns it.
+ * Returns an event with closure==NULL in case of error.
+ */
+struct afb_event afb_evt_create_event(const char *fullname)
+{
+	return afb_evt_from_evtid(afb_evt_evtid_create(fullname));
+}
+
+/*
+ * Returns the fullname of the 'event'
+ */
+const char *afb_evt_event_fullname(struct afb_event event)
+{
+	struct afb_evtid *evtid = afb_evt_to_evtid(event);
+	return evtid ? evtid->fullname : NULL;
+}
+
+/*
+ * Returns the id of the 'event'
+ */
+int afb_evt_event_id(struct afb_event event)
+{
+	struct afb_evtid *evtid = afb_evt_to_evtid(event);
+	return evtid ? evtid->id : 0;
+}
+
+/*
+ * Makes the 'listener' watching 'event'
+ * Returns 0 in case of success or else -1.
+ */
+int afb_evt_add_watch(struct afb_evt_listener *listener, struct afb_event event)
+{
+	struct afb_evtid *evtid = afb_evt_to_evtid(event);
+
+	/* check parameter */
+	if (!evtid) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	/* search the existing watch for the listener */
+	return afb_evt_watch_add_evtid(listener, evtid);
+}
+
+/*
+ * Avoids the 'listener' to watch 'event'
+ * Returns 0 in case of success or else -1.
+ */
+int afb_evt_remove_watch(struct afb_evt_listener *listener, struct afb_event event)
+{
+	struct afb_evtid *evtid = afb_evt_to_evtid(event);
+
+	/* check parameter */
+	if (!evtid) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	/* search the existing watch */
+	return afb_evt_watch_sub_evtid(listener, evtid);
+}
+
 int afb_evt_push(struct afb_event event, struct json_object *object)
 {
-	if (event.itf == &afb_evt_event_itf)
-		return evt_push((struct afb_evt_event *)event.closure, object);
+	struct afb_evtid *evtid = afb_evt_to_evtid(event);
+	if (evtid)
+		return afb_evt_evtid_hooked_push(evtid, object);
 	json_object_put(object);
 	return 0;
 }
 
 int afb_evt_unhooked_push(struct afb_event event, struct json_object *object)
 {
-	if (event.itf == &afb_evt_event_itf)
-		return push((struct afb_evt_event *)event.closure, object, 0);
+	struct afb_evtid *evtid = afb_evt_to_evtid(event);
+	if (evtid)
+		return afb_evt_evtid_push(evtid, object);
 	json_object_put(object);
 	return 0;
 }
diff --git a/src/afb-evt.h b/src/afb-evt.h
index 9071b32a..823f8fd0 100644
--- a/src/afb-evt.h
+++ b/src/afb-evt.h
@@ -18,16 +18,17 @@
 #pragma once
 
 struct afb_event;
+struct afb_evtid;
 struct afb_session;
 struct json_object;
 struct afb_evt_listener;
 
 struct afb_evt_itf
 {
-	void (*push)(void *closure, const char *event, int eventid, struct json_object *object);
-	void (*broadcast)(void *closure, const char *event, int eventid, struct json_object *object);
-	void (*add)(void *closure, const char *event, int eventid);
-	void (*remove)(void *closure, const char *event, int eventid);
+	void (*push)(void *closure, const char *event, int evtid, struct json_object *object);
+	void (*broadcast)(void *closure, const char *event, int evtid, struct json_object *object);
+	void (*add)(void *closure, const char *event, int evtid);
+	void (*remove)(void *closure, const char *event, int evtid);
 };
 
 extern struct afb_evt_listener *afb_evt_listener_create(const struct afb_evt_itf *itf, void *closure);
@@ -37,8 +38,34 @@ extern int afb_evt_broadcast(const char *event, struct json_object *object);
 extern struct afb_evt_listener *afb_evt_listener_addref(struct afb_evt_listener *listener);
 extern void afb_evt_listener_unref(struct afb_evt_listener *listener);
 
-extern struct afb_event afb_evt_create_event(const char *name);
-extern const char *afb_evt_event_name(struct afb_event event);
+extern struct afb_evtid *afb_evt_evtid_create(const char *fullname);
+
+extern struct afb_evtid *afb_evt_evtid_addref(struct afb_evtid *evtid);
+extern struct afb_evtid *afb_evt_evtid_hooked_addref(struct afb_evtid *evtid);
+
+extern void afb_evt_evtid_unref(struct afb_evtid *evtid);
+extern void afb_evt_evtid_hooked_unref(struct afb_evtid *evtid);
+
+extern const char *afb_evt_evtid_fullname(struct afb_evtid *evtid);
+extern int afb_evt_evtid_id(struct afb_evtid *evtid);
+
+extern const char *afb_evt_evtid_name(struct afb_evtid *evtid);
+extern const char *afb_evt_evtid_hooked_name(struct afb_evtid *evtid);
+
+extern int afb_evt_evtid_push(struct afb_evtid *evtid, struct json_object *obj);
+extern int afb_evt_evtid_hooked_push(struct afb_evtid *evtid, struct json_object *obj);
+
+extern int afb_evt_evtid_broadcast(struct afb_evtid *evtid, struct json_object *object);
+extern int afb_evt_evtid_hooked_broadcast(struct afb_evtid *evtid, struct json_object *object);
+
+extern int afb_evt_watch_add_evtid(struct afb_evt_listener *listener, struct afb_evtid *evtid);
+extern int afb_evt_watch_sub_evtid(struct afb_evt_listener *listener, struct afb_evtid *evtid);
+
+extern void afb_evt_update_hooks();
+
+
+extern struct afb_event afb_evt_create_event(const char *fullname);
+extern const char *afb_evt_event_fullname(struct afb_event event);
 extern int afb_evt_event_id(struct afb_event event);
 
 extern int afb_evt_push(struct afb_event event, struct json_object *object);
@@ -47,4 +74,5 @@ extern int afb_evt_unhooked_push(struct afb_event event, struct json_object *obj
 extern int afb_evt_add_watch(struct afb_evt_listener *listener, struct afb_event event);
 extern int afb_evt_remove_watch(struct afb_evt_listener *listener, struct afb_event event);
 
-extern void afb_evt_update_hooks();
+extern struct afb_evtid *afb_evt_to_evtid(struct afb_event event);
+extern struct afb_event afb_evt_from_evtid(struct afb_evtid *evtid);
diff --git a/src/afb-hook.c b/src/afb-hook.c
index b3a13a7e..09e6062a 100644
--- a/src/afb-hook.c
+++ b/src/afb-hook.c
@@ -283,12 +283,12 @@ static void hook_xreq_session_set_LOA_default_cb(void *closure, const struct afb
 
 static void hook_xreq_subscribe_default_cb(void *closure, const struct afb_hookid *hookid, const struct afb_xreq *xreq, struct afb_event event, int result)
 {
-	_hook_xreq_(xreq, "subscribe(%s:%d) -> %d", afb_evt_event_name(event), afb_evt_event_id(event), result);
+	_hook_xreq_(xreq, "subscribe(%s:%d) -> %d", afb_evt_event_fullname(event), afb_evt_event_id(event), result);
 }
 
 static void hook_xreq_unsubscribe_default_cb(void *closure, const struct afb_hookid *hookid, const struct afb_xreq *xreq, struct afb_event event, int result)
 {
-	_hook_xreq_(xreq, "unsubscribe(%s:%d) -> %d", afb_evt_event_name(event), afb_evt_event_id(event), result);
+	_hook_xreq_(xreq, "unsubscribe(%s:%d) -> %d", afb_evt_event_fullname(event), afb_evt_event_id(event), result);
 }
 
 static void hook_xreq_subcall_default_cb(void *closure, const struct afb_hookid *hookid, const struct afb_xreq *xreq, const char *api, const char *verb, struct json_object *args)
@@ -726,7 +726,7 @@ static void hook_ditf_vverbose_cb(void *closure, const struct afb_hookid *hookid
 
 static void hook_ditf_event_make_cb(void *closure, const struct afb_hookid *hookid, const struct afb_export *export, const char *name, struct afb_event result)
 {
-	_hook_ditf_(export, "event_make(%s) -> %s:%d", name, afb_evt_event_name(result), afb_evt_event_id(result));
+	_hook_ditf_(export, "event_make(%s) -> %s:%d", name, afb_evt_event_fullname(result), afb_evt_event_id(result));
 }
 
 static void hook_ditf_rootdir_get_fd_cb(void *closure, const struct afb_hookid *hookid, const struct afb_export *export, int result)
@@ -1234,9 +1234,9 @@ static void hook_evt_broadcast_after_default_cb(void *closure, const struct afb_
 	_hook_evt_(evt, id, "broadcast.after(%s) -> %d", json_object_to_json_string(obj), result);
 }
 
-static void hook_evt_name_default_cb(void *closure, const struct afb_hookid *hookid, const char *evt, int id)
+static void hook_evt_name_default_cb(void *closure, const struct afb_hookid *hookid, const char *evt, int id, const char *result)
 {
-	_hook_evt_(evt, id, "name");
+	_hook_evt_(evt, id, "name -> %s", result);
 }
 
 static void hook_evt_drop_default_cb(void *closure, const struct afb_hookid *hookid, const char *evt, int id)
@@ -1244,6 +1244,16 @@ static void hook_evt_drop_default_cb(void *closure, const struct afb_hookid *hoo
 	_hook_evt_(evt, id, "drop");
 }
 
+static void hook_evt_addref_default_cb(void *closure, const struct afb_hookid *hookid, const char *evt, int id)
+{
+	_hook_evt_(evt, id, "addref");
+}
+
+static void hook_evt_unref_default_cb(void *closure, const struct afb_hookid *hookid, const char *evt, int id)
+{
+	_hook_evt_(evt, id, "unref");
+}
+
 static struct afb_hook_evt_itf hook_evt_default_itf = {
 	.hook_evt_create = hook_evt_create_default_cb,
 	.hook_evt_push_before = hook_evt_push_before_default_cb,
@@ -1251,7 +1261,9 @@ static struct afb_hook_evt_itf hook_evt_default_itf = {
 	.hook_evt_broadcast_before = hook_evt_broadcast_before_default_cb,
 	.hook_evt_broadcast_after = hook_evt_broadcast_after_default_cb,
 	.hook_evt_name = hook_evt_name_default_cb,
-	.hook_evt_drop = hook_evt_drop_default_cb
+	.hook_evt_drop = hook_evt_drop_default_cb,
+	.hook_evt_addref = hook_evt_addref_default_cb,
+	.hook_evt_unref = hook_evt_unref_default_cb
 };
 
 /******************************************************************************
@@ -1301,9 +1313,9 @@ int afb_hook_evt_broadcast_after(const char *evt, int id, struct json_object *ob
 	return result;
 }
 
-void afb_hook_evt_name(const char *evt, int id)
+void afb_hook_evt_name(const char *evt, int id, const char *result)
 {
-	_HOOK_EVT_(name, evt, id);
+	_HOOK_EVT_(name, evt, id, result);
 }
 
 void afb_hook_evt_drop(const char *evt, int id)
@@ -1311,6 +1323,16 @@ void afb_hook_evt_drop(const char *evt, int id)
 	_HOOK_EVT_(drop, evt, id);
 }
 
+void afb_hook_evt_addref(const char *evt, int id)
+{
+	_HOOK_EVT_(addref, evt, id);
+}
+
+void afb_hook_evt_unref(const char *evt, int id)
+{
+	_HOOK_EVT_(unref, evt, id);
+}
+
 /******************************************************************************
  * section: hooking services (evt)
  *****************************************************************************/
diff --git a/src/afb-hook.h b/src/afb-hook.h
index be4ba54a..9cdca9c7 100644
--- a/src/afb-hook.h
+++ b/src/afb-hook.h
@@ -293,11 +293,14 @@ extern void afb_hook_unref_svc(struct afb_hook_svc *hook);
 #define afb_hook_flag_evt_broadcast_after		0x000010
 #define afb_hook_flag_evt_name				0x000020
 #define afb_hook_flag_evt_drop				0x000040
+#define afb_hook_flag_evt_addref			0x000080
+#define afb_hook_flag_evt_unref				0x000100
 
 #define afb_hook_flags_evt_common	(afb_hook_flag_evt_push_before|afb_hook_flag_evt_broadcast_before)
 #define afb_hook_flags_evt_extra	(afb_hook_flags_evt_common\
 					|afb_hook_flag_evt_push_after|afb_hook_flag_evt_broadcast_after\
-					|afb_hook_flag_evt_create|afb_hook_flag_evt_drop)
+					|afb_hook_flag_evt_create|afb_hook_flag_evt_drop\
+					|afb_hook_flag_evt_addref|afb_hook_flag_evt_unref)
 #define afb_hook_flags_evt_all		(afb_hook_flags_evt_extra|afb_hook_flag_evt_name)
 
 struct afb_hook_evt_itf {
@@ -306,8 +309,10 @@ struct afb_hook_evt_itf {
 	void (*hook_evt_push_after)(void *closure, const struct afb_hookid *hookid, const char *evt, int id, struct json_object *obj, int result);
 	void (*hook_evt_broadcast_before)(void *closure, const struct afb_hookid *hookid, const char *evt, int id, struct json_object *obj);
 	void (*hook_evt_broadcast_after)(void *closure, const struct afb_hookid *hookid, const char *evt, int id, struct json_object *obj, int result);
-	void (*hook_evt_name)(void *closure, const struct afb_hookid *hookid, const char *evt, int id);
+	void (*hook_evt_name)(void *closure, const struct afb_hookid *hookid, const char *evt, int id, const char *result);
 	void (*hook_evt_drop)(void *closure, const struct afb_hookid *hookid, const char *evt, int id);
+	void (*hook_evt_addref)(void *closure, const struct afb_hookid *hookid, const char *evt, int id);
+	void (*hook_evt_unref)(void *closure, const struct afb_hookid *hookid, const char *evt, int id);
 };
 
 extern void afb_hook_evt_create(const char *evt, int id);
@@ -315,8 +320,10 @@ extern void afb_hook_evt_push_before(const char *evt, int id, struct json_object
 extern int afb_hook_evt_push_after(const char *evt, int id, struct json_object *obj, int result);
 extern void afb_hook_evt_broadcast_before(const char *evt, int id, struct json_object *obj);
 extern int afb_hook_evt_broadcast_after(const char *evt, int id, struct json_object *obj, int result);
-extern void afb_hook_evt_name(const char *evt, int id);
+extern void afb_hook_evt_name(const char *evt, int id, const char *result);
 extern void afb_hook_evt_drop(const char *evt, int id);
+extern void afb_hook_evt_addref(const char *evt, int id);
+extern void afb_hook_evt_unref(const char *evt, int id);
 
 extern int afb_hook_flags_evt(const char *name);
 extern struct afb_hook_evt *afb_hook_create_evt(const char *pattern, int flags, struct afb_hook_evt_itf *itf, void *closure);
diff --git a/src/afb-stub-ws.c b/src/afb-stub-ws.c
index bdc2c144..9c903247 100644
--- a/src/afb-stub-ws.c
+++ b/src/afb-stub-ws.c
@@ -211,7 +211,7 @@ static int server_req_subscribe_cb(struct afb_xreq *xreq, struct afb_event event
 
 	rc = afb_evt_add_watch(wreq->stubws->listener, event);
 	if (rc >= 0)
-		rc = afb_proto_ws_call_subscribe(wreq->call,  afb_evt_event_name(event), afb_evt_event_id(event));
+		rc = afb_proto_ws_call_subscribe(wreq->call,  afb_evt_event_fullname(event), afb_evt_event_id(event));
 	if (rc < 0)
 		ERROR("error while subscribing event");
 	return rc;
@@ -222,7 +222,7 @@ static int server_req_unsubscribe_cb(struct afb_xreq *xreq, struct afb_event eve
 	int rc, rc2;
 	struct server_req *wreq = CONTAINER_OF_XREQ(struct server_req, xreq);
 
-	rc = afb_proto_ws_call_unsubscribe(wreq->call,  afb_evt_event_name(event), afb_evt_event_id(event));
+	rc = afb_proto_ws_call_unsubscribe(wreq->call,  afb_evt_event_fullname(event), afb_evt_event_id(event));
 	rc2 = afb_evt_remove_watch(wreq->stubws->listener, event);
 	if (rc >= 0 && rc2 < 0)
 		rc = rc2;
@@ -248,7 +248,7 @@ static struct client_event *client_event_search(struct afb_stub_ws *stubws, uint
 	struct client_event *ev;
 
 	ev = stubws->events;
-	while (ev != NULL && (ev->eventid != eventid || 0 != strcmp(afb_evt_event_name(ev->event), name)))
+	while (ev != NULL && (ev->eventid != eventid || 0 != strcmp(afb_evt_event_fullname(ev->event), name)))
 		ev = ev->next;
 
 	return ev;
diff --git a/src/afb-trace.c b/src/afb-trace.c
index 5e82274a..0de501a9 100644
--- a/src/afb-trace.c
+++ b/src/afb-trace.c
@@ -365,7 +365,7 @@ static void hook_xreq_subscribe(void *closure, const struct afb_hookid *hookid,
 {
 	hook_xreq(closure, hookid, xreq, "subscribe", "{s{ss si} si}",
 					"event",
-						"name", afb_evt_event_name(event),
+						"name", afb_evt_event_fullname(event),
 						"id", afb_evt_event_id(event),
 					"result", result);
 }
@@ -374,7 +374,7 @@ static void hook_xreq_unsubscribe(void *closure, const struct afb_hookid *hookid
 {
 	hook_xreq(closure, hookid, xreq, "unsubscribe", "{s{ss? si} si}",
 					"event",
-						"name", afb_evt_event_name(event),
+						"name", afb_evt_event_fullname(event),
 						"id", afb_evt_event_id(event),
 					"result", result);
 }
@@ -614,7 +614,7 @@ static void hook_ditf_vverbose(void *closure, const struct afb_hookid *hookid, c
 static void hook_ditf_event_make(void *closure, const struct afb_hookid *hookid, const struct afb_export *export, const char *name, struct afb_event result)
 {
 	hook_ditf(closure, hookid, export, "event_make", "{ss ss si}",
-			"name", name, "event", afb_evt_event_name(result), "id", afb_evt_event_id(result));
+			"name", name, "event", afb_evt_event_fullname(result), "id", afb_evt_event_id(result));
 }
 
 static void hook_ditf_rootdir_get_fd(void *closure, const struct afb_hookid *hookid, const struct afb_export *export, int result)
@@ -779,6 +779,7 @@ static struct afb_hook_svc_itf hook_svc_itf = {
 /*******************************************************************************/
 
 static struct flag evt_flags[] = { /* must be sorted by names */
+		{ "addref",		afb_hook_flag_evt_addref },
 		{ "all",		afb_hook_flags_evt_all },
 		{ "broadcast_after",	afb_hook_flag_evt_broadcast_after },
 		{ "broadcast_before",	afb_hook_flag_evt_broadcast_before },
@@ -789,6 +790,7 @@ static struct flag evt_flags[] = { /* must be sorted by names */
 		{ "name",		afb_hook_flag_evt_name },
 		{ "push_after",		afb_hook_flag_evt_push_after },
 		{ "push_before",	afb_hook_flag_evt_push_before },
+		{ "unref",		afb_hook_flag_evt_unref },
 };
 
 /* get the evt value for flag of 'name' */
@@ -835,9 +837,9 @@ static void hook_evt_broadcast_after(void *closure, const struct afb_hookid *hoo
 	hook_evt(closure, hookid, evt, id, "broadcast_after", "{sO* si}", "data", obj, "result", result);
 }
 
-static void hook_evt_name(void *closure, const struct afb_hookid *hookid, const char *evt, int id)
+static void hook_evt_name(void *closure, const struct afb_hookid *hookid, const char *evt, int id, const char *result)
 {
-	hook_evt(closure, hookid, evt, id, "name", NULL);
+	hook_evt(closure, hookid, evt, id, "name", "{ss}", "result", result);
 }
 
 static void hook_evt_drop(void *closure, const struct afb_hookid *hookid, const char *evt, int id)
@@ -845,6 +847,16 @@ static void hook_evt_drop(void *closure, const struct afb_hookid *hookid, const
 	hook_evt(closure, hookid, evt, id, "drop", NULL);
 }
 
+static void hook_evt_addref(void *closure, const struct afb_hookid *hookid, const char *evt, int id)
+{
+	hook_evt(closure, hookid, evt, id, "addref", NULL);
+}
+
+static void hook_evt_unref(void *closure, const struct afb_hookid *hookid, const char *evt, int id)
+{
+	hook_evt(closure, hookid, evt, id, "unref", NULL);
+}
+
 static struct afb_hook_evt_itf hook_evt_itf = {
 	.hook_evt_create = hook_evt_create,
 	.hook_evt_push_before = hook_evt_push_before,
@@ -852,7 +864,9 @@ static struct afb_hook_evt_itf hook_evt_itf = {
 	.hook_evt_broadcast_before = hook_evt_broadcast_before,
 	.hook_evt_broadcast_after = hook_evt_broadcast_after,
 	.hook_evt_name = hook_evt_name,
-	.hook_evt_drop = hook_evt_drop
+	.hook_evt_drop = hook_evt_drop,
+	.hook_evt_addref = hook_evt_addref,
+	.hook_evt_unref = hook_evt_unref
 };
 
 /*******************************************************************************/