watch add/remove -> subscribe/unsubscribe:

rename the ADD_WATCH/REMOVE_WATCH messages to SUBSCRIBE/UNSUBSCRIBE and change
the message format and libubus API in preparation for adding object notifications

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

CMakeLists.txt

@@ -12,7 +12,7 @@ IF(APPLE)
   LINK_DIRECTORIES(/opt/local/lib)
 ENDIF()
 
-ADD_LIBRARY(ubus SHARED libubus.c libubus-io.c libubus-obj.c)
+ADD_LIBRARY(ubus SHARED libubus.c libubus-io.c libubus-obj.c libubus-sub.c)
 TARGET_LINK_LIBRARIES(ubus ubox)
 
 ADD_EXECUTABLE(ubusd ubusd.c ubusd_id.c ubusd_obj.c ubusd_proto.c ubusd_event.c)

examples/server.c

@@ -16,7 +16,7 @@
 #include "libubus.h"
 
 static struct ubus_context *ctx;
-static struct ubus_watch_object test_event;
+static struct ubus_subscriber test_event;
 static struct blob_buf b;
 
 enum {
@@ -79,7 +79,8 @@ static const struct blobmsg_policy watch_policy[__WATCH_MAX] = {
 	[WATCH_ID] = { .name = "id", .type = BLOBMSG_TYPE_INT32 },
 };
 
-static void test_handle_event(struct ubus_context *ctx, struct ubus_watch_object *w,
+static void
+test_handle_remove(struct ubus_context *ctx, struct ubus_subscriber *s,
                    uint32_t id)
 {
 	fprintf(stderr, "Object %08x went away\n", id);
@@ -96,8 +97,8 @@ static int test_watch(struct ubus_context *ctx, struct ubus_object *obj,
 	if (!tb[WATCH_ID])
 		return UBUS_STATUS_INVALID_ARGUMENT;
 
-	test_event.cb = test_handle_event;
-	ret = ubus_watch_object_add(ctx, &test_event, blobmsg_get_u32(tb[WATCH_ID]));
+	test_event.remove_cb = test_handle_remove;
+	ret = ubus_subscribe(ctx, &test_event, blobmsg_get_u32(tb[WATCH_ID]));
 	fprintf(stderr, "Watching object %08x: %s\n", blobmsg_get_u32(tb[WATCH_ID]), ubus_strerror(ret));
 	return ret;
 }
@@ -125,7 +126,7 @@ static void server_main(void)
 	if (ret)
 		fprintf(stderr, "Failed to add object: %s\n", ubus_strerror(ret));
 
-	ret = ubus_register_watch_object(ctx, &test_event);
+	ret = ubus_register_subscriber(ctx, &test_event);
 	if (ret)
 		fprintf(stderr, "Failed to add watch handler: %s\n", ubus_strerror(ret));
 

libubus-internal.h

@@ -26,5 +26,6 @@ void ubus_process_msg(struct ubus_context *ctx, struct ubus_msghdr *hdr);
 void ubus_process_invoke(struct ubus_context *ctx, struct ubus_msghdr *hdr);
 int __hidden ubus_start_request(struct ubus_context *ctx, struct ubus_request *req,
 				struct blob_attr *msg, int cmd, uint32_t peer);
+void ubus_process_unsubscribe(struct ubus_context *ctx, struct ubus_msghdr *hdr);
 
 #endif

libubus-sub.c

@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2011-2012 Felix Fietkau <nbd@openwrt.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1
+ * as published by the Free Software Foundation
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include "libubus.h"
+#include "libubus-internal.h"
+
+static int ubus_subscriber_cb(struct ubus_context *ctx, struct ubus_object *obj,
+			 struct ubus_request_data *req,
+			 const char *method, struct blob_attr *msg)
+{
+	struct ubus_subscriber *s;
+
+	s = container_of(obj, struct ubus_subscriber, obj);
+	s->cb(ctx, obj, req, method, msg);
+	return 0;
+}
+
+static const struct ubus_method watch_method = {
+	.name = NULL,
+	.handler = ubus_subscriber_cb,
+};
+
+int ubus_register_subscriber(struct ubus_context *ctx, struct ubus_subscriber *s)
+{
+	struct ubus_object *obj = &s->obj;
+
+	obj->methods = &watch_method;
+	obj->n_methods = 1;
+
+	return ubus_add_object(ctx, obj);
+}
+
+static int
+__ubus_subscribe_request(struct ubus_context *ctx, struct ubus_object *obj, uint32_t id, const char *method, int type)
+{
+	struct ubus_request req;
+
+	blob_buf_init(&b, 0);
+	blob_put_int32(&b, UBUS_ATTR_OBJID, obj->id);
+	blob_put_int32(&b, UBUS_ATTR_TARGET, id);
+	if (method)
+		blob_put_string(&b, UBUS_ATTR_METHOD, method);
+
+	if (ubus_start_request(ctx, &req, b.head, type, 0) < 0)
+		return UBUS_STATUS_INVALID_ARGUMENT;
+
+	return ubus_complete_request(ctx, &req, 0);
+
+}
+
+int ubus_subscribe(struct ubus_context *ctx, struct ubus_subscriber *obj, uint32_t id)
+{
+	return __ubus_subscribe_request(ctx, &obj->obj, id, "event", UBUS_MSG_SUBSCRIBE);
+}
+
+int ubus_unsubscribe(struct ubus_context *ctx, struct ubus_subscriber *obj, uint32_t id)
+{
+	return __ubus_subscribe_request(ctx, &obj->obj, id, NULL, UBUS_MSG_UNSUBSCRIBE);
+}
+
+void __hidden ubus_process_unsubscribe(struct ubus_context *ctx, struct ubus_msghdr *hdr)
+{
+	struct ubus_subscriber *s;
+	struct blob_attr **attrbuf;
+	struct ubus_object *obj;
+	uint32_t objid;
+
+	attrbuf = ubus_parse_msg(hdr->data);
+	if (!attrbuf[UBUS_ATTR_OBJID] || !attrbuf[UBUS_ATTR_TARGET])
+		return;
+
+	objid = blob_get_u32(attrbuf[UBUS_ATTR_OBJID]);
+	obj = avl_find_element(&ctx->objects, &objid, obj, avl);
+	if (!obj)
+		return;
+
+	if (obj->methods != &watch_method)
+		return;
+
+	s = container_of(obj, struct ubus_subscriber, obj);
+	s->remove_cb(ctx, s, blob_get_u32(attrbuf[UBUS_ATTR_TARGET]));
+}
+
+

libubus.c

@@ -228,6 +228,10 @@ void __hidden ubus_process_msg(struct ubus_context *ctx, struct ubus_msghdr *hdr
 			ubus_process_invoke(ctx, hdr);
 		}
 		break;
+
+	case UBUS_MSG_UNSUBSCRIBE:
+		ubus_process_unsubscribe(ctx, hdr);
+		break;
 	}
 }
 
@@ -514,81 +518,6 @@ int ubus_register_event_handler(struct ubus_context *ctx,
 			  NULL, NULL, 0);
 }
 
-enum {
-	WATCH_ID,
-	WATCH_NOTIFY,
-	__WATCH_MAX
-};
-
-static const struct blobmsg_policy watch_policy[] = {
-	[WATCH_ID] = { .name = "id", .type = BLOBMSG_TYPE_INT32 },
-	[WATCH_NOTIFY] = { .name = "notify", .type = BLOBMSG_TYPE_STRING },
-};
-
-
-static int ubus_watch_cb(struct ubus_context *ctx, struct ubus_object *obj,
-			 struct ubus_request_data *req,
-			 const char *method, struct blob_attr *msg)
-{
-	struct ubus_watch_object *w;
-	struct blob_attr *tb[__WATCH_MAX];
-
-	blobmsg_parse(watch_policy, ARRAY_SIZE(watch_policy), tb, blob_data(msg), blob_len(msg));
-
-	if (!tb[WATCH_ID] || !tb[WATCH_NOTIFY])
-		return UBUS_STATUS_INVALID_ARGUMENT;
-
-	if (req->peer)
-		return UBUS_STATUS_INVALID_ARGUMENT;
-
-	w = container_of(obj, struct ubus_watch_object, obj);
-	w->cb(ctx, w, blobmsg_get_u32(tb[WATCH_ID]));
-	return 0;
-}
-
-static const struct ubus_method watch_method = {
-	.name = NULL,
-	.handler = ubus_watch_cb,
-};
-
-int ubus_register_watch_object(struct ubus_context *ctx, struct ubus_watch_object *w_obj)
-{
-	struct ubus_object *obj = &w_obj->obj;
-
-	obj->methods = &watch_method;
-	obj->n_methods = 1;
-
-	return ubus_add_object(ctx, obj);
-}
-
-static int
-__ubus_watch_request(struct ubus_context *ctx, struct ubus_object *obj, uint32_t id, const char *method, int type)
-{
-	struct ubus_request req;
-
-	blob_buf_init(&b, 0);
-	blob_put_int32(&b, UBUS_ATTR_OBJID, obj->id);
-	blob_put_int32(&b, UBUS_ATTR_TARGET, id);
-	if (method)
-		blob_put_string(&b, UBUS_ATTR_METHOD, method);
-
-	if (ubus_start_request(ctx, &req, b.head, type, 0) < 0)
-		return UBUS_STATUS_INVALID_ARGUMENT;
-
-	return ubus_complete_request(ctx, &req, 0);
-
-}
-
-int ubus_watch_object_add(struct ubus_context *ctx, struct ubus_watch_object *obj, uint32_t id)
-{
-	return __ubus_watch_request(ctx, &obj->obj, id, "event", UBUS_MSG_ADD_WATCH);
-}
-
-int ubus_watch_object_remove(struct ubus_context *ctx, struct ubus_watch_object *obj, uint32_t id)
-{
-	return __ubus_watch_request(ctx, &obj->obj, id, NULL, UBUS_MSG_REMOVE_WATCH);
-}
-
 int ubus_send_event(struct ubus_context *ctx, const char *id,
 		    struct blob_attr *data)
 {

libubus.h

@@ -29,7 +29,7 @@ struct ubus_request;
 struct ubus_request_data;
 struct ubus_object_data;
 struct ubus_event_handler;
-struct ubus_watch_object;
+struct ubus_subscriber;
 
 typedef void (*ubus_lookup_handler_t)(struct ubus_context *ctx,
 				      struct ubus_object_data *obj,
@@ -37,10 +37,10 @@ typedef void (*ubus_lookup_handler_t)(struct ubus_context *ctx,
 typedef int (*ubus_handler_t)(struct ubus_context *ctx, struct ubus_object *obj,
 			      struct ubus_request_data *req,
 			      const char *method, struct blob_attr *msg);
+typedef void (*ubus_remove_handler_t)(struct ubus_context *ctx,
+				      struct ubus_subscriber *obj, uint32_t id);
 typedef void (*ubus_event_handler_t)(struct ubus_context *ctx, struct ubus_event_handler *ev,
 				     const char *type, struct blob_attr *msg);
-typedef void (*ubus_watch_handler_t)(struct ubus_context *ctx, struct ubus_watch_object *w,
-				     uint32_t id);
 typedef void (*ubus_data_handler_t)(struct ubus_request *req,
 				    int type, struct blob_attr *msg);
 typedef void (*ubus_complete_handler_t)(struct ubus_request *req, int ret);
@@ -90,10 +90,11 @@ struct ubus_object {
 	int n_methods;
 };
 
-struct ubus_watch_object {
+struct ubus_subscriber {
 	struct ubus_object obj;
 
-	ubus_watch_handler_t cb;
+	ubus_handler_t cb;
+	ubus_remove_handler_t remove_cb;
 };
 
 struct ubus_event_handler {
@@ -199,12 +200,10 @@ int ubus_add_object(struct ubus_context *ctx, struct ubus_object *obj);
 /* remove the object from the ubus connection */
 int ubus_remove_object(struct ubus_context *ctx, struct ubus_object *obj);
 
-/* add an object for watching other object state changes */
-int ubus_register_watch_object(struct ubus_context *ctx, struct ubus_watch_object *obj);
-
-int ubus_watch_object_add(struct ubus_context *ctx, struct ubus_watch_object *obj, uint32_t id);
-
-int ubus_watch_object_remove(struct ubus_context *ctx, struct ubus_watch_object *obj, uint32_t id);
+/* add a subscriber notifications from another object */
+int ubus_register_subscriber(struct ubus_context *ctx, struct ubus_subscriber *obj);
+int ubus_subscribe(struct ubus_context *ctx, struct ubus_subscriber *obj, uint32_t id);
+int ubus_unsubscribe(struct ubus_context *ctx, struct ubus_subscriber *obj, uint32_t id);
 
 /* ----------- rpc ----------- */
 

ubusd_obj.c

@@ -112,8 +112,8 @@ struct ubus_object *ubusd_create_object_internal(struct ubus_object_type *type,
 	obj->type = type;
 	INIT_LIST_HEAD(&obj->list);
 	INIT_LIST_HEAD(&obj->events);
-	INIT_LIST_HEAD(&obj->watchers);
-	INIT_LIST_HEAD(&obj->watched);
+	INIT_LIST_HEAD(&obj->subscribers);
+	INIT_LIST_HEAD(&obj->target_list);
 	if (type)
 		type->refcount++;
 
@@ -164,37 +164,37 @@ free:
 	return NULL;
 }
 
-void ubus_watch_new(struct ubus_object *obj, struct ubus_object *target, const char *method)
+void ubus_subscribe(struct ubus_object *obj, struct ubus_object *target, const char *method)
 {
-	struct ubus_watch *w;
+	struct ubus_subscription *s;
 
-	w = calloc(1, sizeof(*w) + strlen(method) + 1);
-	if (!w)
+	s = calloc(1, sizeof(*s) + strlen(method) + 1);
+	if (!s)
 		return;
 
-	w->watcher = obj;
-	w->watched = target;
-	list_add(&w->watcher_list, &target->watchers);
-	list_add(&w->watched_list, &obj->watched);
-	strcpy(w->method, method);
+	s->subscriber = obj;
+	s->target = target;
+	list_add(&s->list, &target->subscribers);
+	list_add(&s->target_list, &obj->target_list);
+	strcpy(s->method, method);
 }
 
-void ubus_watch_free(struct ubus_watch *w)
+void ubus_unsubscribe(struct ubus_subscription *s)
 {
-	list_del(&w->watcher_list);
-	list_del(&w->watched_list);
-	free(w);
+	list_del(&s->list);
+	list_del(&s->target_list);
+	free(s);
 }
 
 void ubusd_free_object(struct ubus_object *obj)
 {
-	struct ubus_watch *w, *tmp;
+	struct ubus_subscription *s, *tmp;
 
-	list_for_each_entry_safe(w, tmp, &obj->watched, watched_list) {
-		ubus_watch_free(w);
+	list_for_each_entry_safe(s, tmp, &obj->target_list, target_list) {
+		ubus_unsubscribe(s);
 	}
-	list_for_each_entry_safe(w, tmp, &obj->watchers, watcher_list) {
-		ubus_proto_notify_watch(w);
+	list_for_each_entry_safe(s, tmp, &obj->subscribers, list) {
+		ubus_notify_unsubscribe(s);
 	}
 
 	ubusd_event_cleanup_object(obj);

ubusd_obj.h

@@ -35,9 +35,9 @@ struct ubus_method {
 	struct blob_attr data[];
 };
 
-struct ubus_watch {
-	struct list_head watcher_list, watched_list;
-	struct ubus_object *watcher, *watched;
+struct ubus_subscription {
+	struct list_head list, target_list;
+	struct ubus_object *subscriber, *target;
 	char method[];
 };
 
@@ -47,7 +47,7 @@ struct ubus_object {
 
 	struct list_head events;
 
-	struct list_head watchers, watched;
+	struct list_head subscribers, target_list;
 
 	struct ubus_object_type *type;
 	struct avl_node path;
@@ -76,8 +76,8 @@ static inline struct ubus_object *ubusd_find_object(uint32_t objid)
 	return obj;
 }
 
-void ubus_watch_new(struct ubus_object *obj, struct ubus_object *target, const char *method);
-void ubus_watch_free(struct ubus_watch *w);
-void ubus_proto_notify_watch(struct ubus_watch *w);
+void ubus_subscribe(struct ubus_object *obj, struct ubus_object *target, const char *method);
+void ubus_unsubscribe(struct ubus_subscription *s);
+void ubus_notify_unsubscribe(struct ubus_subscription *s);
 
 #endif

ubusd_proto.c

@@ -308,14 +308,14 @@ static int ubusd_handle_add_watch(struct ubus_client *cl, struct ubus_msg_buf *u
 	if (cl == target->client)
 		return UBUS_STATUS_INVALID_ARGUMENT;
 
-	ubus_watch_new(obj, target, blob_data(attr[UBUS_ATTR_METHOD]));
+	ubus_subscribe(obj, target, blob_data(attr[UBUS_ATTR_METHOD]));
 	return 0;
 }
 
 static int ubusd_handle_remove_watch(struct ubus_client *cl, struct ubus_msg_buf *ub, struct blob_attr **attr)
 {
 	struct ubus_object *obj;
-	struct ubus_watch *w;
+	struct ubus_subscription *s;
 	uint32_t id;
 
 	if (!attr[UBUS_ATTR_OBJID] || !attr[UBUS_ATTR_TARGET])
@@ -329,11 +329,11 @@ static int ubusd_handle_remove_watch(struct ubus_client *cl, struct ubus_msg_buf
 		return UBUS_STATUS_INVALID_ARGUMENT;
 
 	id = blob_get_u32(attr[UBUS_ATTR_TARGET]);
-	list_for_each_entry(w, &obj->watched, watched_list) {
-		if (w->watched->id.id != id)
+	list_for_each_entry(s, &obj->target_list, target_list) {
+		if (s->target->id.id != id)
 			continue;
 
-		ubus_watch_free(w);
+		ubus_unsubscribe(s);
 		return 0;
 	}
 
@@ -348,8 +348,8 @@ static const ubus_cmd_cb handlers[__UBUS_MSG_LAST] = {
 	[UBUS_MSG_INVOKE] = ubusd_handle_invoke,
 	[UBUS_MSG_STATUS] = ubusd_handle_response,
 	[UBUS_MSG_DATA] = ubusd_handle_response,
-	[UBUS_MSG_ADD_WATCH] = ubusd_handle_add_watch,
-	[UBUS_MSG_REMOVE_WATCH] = ubusd_handle_remove_watch,
+	[UBUS_MSG_SUBSCRIBE] = ubusd_handle_add_watch,
+	[UBUS_MSG_UNSUBSCRIBE] = ubusd_handle_remove_watch,
 };
 
 void ubusd_proto_receive_message(struct ubus_client *cl, struct ubus_msg_buf *ub)
@@ -416,26 +416,19 @@ void ubusd_proto_free_client(struct ubus_client *cl)
 	ubus_free_id(&clients, &cl->id);
 }
 
-void ubus_proto_notify_watch(struct ubus_watch *w)
+void ubus_notify_unsubscribe(struct ubus_subscription *s)
 {
 	struct ubus_msg_buf *ub;
-	void *data;
 
 	blob_buf_init(&b, 0);
-	blob_put_int32(&b, UBUS_ATTR_OBJID, w->watcher->id.id);
-	blob_put_string(&b, UBUS_ATTR_METHOD, w->method);
-
-	data = blob_nest_start(&b, UBUS_ATTR_DATA);
-	blobmsg_add_string(&b, "notify", "remove");
-	blobmsg_add_u32(&b, "id", w->watched->id.id);
-	blobmsg_add_u32(&b, "peer", w->watched->client->id.id);
-	blob_nest_end(&b, data);
+	blob_put_int32(&b, UBUS_ATTR_OBJID, s->subscriber->id.id);
+	blob_put_int32(&b, UBUS_ATTR_TARGET, s->target->id.id);
 
 	ub = ubus_msg_from_blob(false);
-	ubus_msg_init(ub, UBUS_MSG_INVOKE, ++w->watcher->invoke_seq, 0);
-	ubus_msg_send(w->watcher->client, ub, true);
+	ubus_msg_init(ub, UBUS_MSG_UNSUBSCRIBE, ++s->subscriber->invoke_seq, 0);
+	ubus_msg_send(s->subscriber->client, ub, true);
 
-	ubus_watch_free(w);
+	ubus_unsubscribe(s);
 }
 
 static void __init ubusd_proto_init(void)

ubusmsg.h

@@ -54,9 +54,13 @@ enum ubus_msg_type {
 	UBUS_MSG_ADD_OBJECT,
 	UBUS_MSG_REMOVE_OBJECT,
 
-	/* watch an object, notify on remove */
-	UBUS_MSG_ADD_WATCH,
-	UBUS_MSG_REMOVE_WATCH,
+	/*
+	 * subscribe/unsubscribe to object notifications
+	 * The unsubscribe message is sent from ubusd when
+	 * the object disappears
+	 */
+	UBUS_MSG_SUBSCRIBE,
+	UBUS_MSG_UNSUBSCRIBE,
 
 	/* must be last */
 	__UBUS_MSG_LAST,