properties: return if property changed

make property_set functions return 1 if there was a change.
Only emit property change notifications when something actually
changed.
Try to only copy property value when needed.

src/pipewire/client.c

@@ -195,7 +195,7 @@ struct pw_client *pw_client_new(struct pw_core *core,
 
 	pw_core_add_listener(core, &impl->core_listener, &core_events, impl);
 
-	this->info.props = this->properties ? &this->properties->dict : NULL;
+	this->info.props = &this->properties->dict;
 
 	return this;
 }
@@ -321,7 +321,6 @@ void pw_client_destroy(struct pw_client *client)
 	pw_map_clear(&client->objects);
 	pw_array_clear(&impl->permissions);
 
-	if (client->properties)
 	pw_properties_free(client->properties);
 
 	free(impl);
@@ -354,20 +353,17 @@ const struct pw_client_info *pw_client_get_info(struct pw_client *client)
 int pw_client_update_properties(struct pw_client *client, const struct spa_dict *dict)
 {
 	struct pw_resource *resource;
-
+	uint32_t i, changed = 0;
-	if (client->properties == NULL) {
-		if (dict)
-			client->properties = pw_properties_new_dict(dict);
-	} else {
-		uint32_t i;
 
 	for (i = 0; i < dict->n_items; i++)
-			pw_properties_set(client->properties,
+		changed += pw_properties_set(client->properties,
 				  dict->items[i].key, dict->items[i].value);
-	}
+
+	if (!changed)
+		return 0;
 
 	client->info.change_mask |= PW_CLIENT_CHANGE_MASK_PROPS;
-	client->info.props = client->properties ? &client->properties->dict : NULL;
+	client->info.props = &client->properties->dict;
 
 	pw_client_events_info_changed(client, &client->info);
 
@@ -376,7 +372,7 @@ int pw_client_update_properties(struct pw_client *client, const struct spa_dict
 
 	client->info.change_mask = 0;
 
-	return 0;
+	return changed;
 }
 
 struct permissions_update {

src/pipewire/core.c

@@ -573,10 +573,13 @@ const struct pw_properties *pw_core_get_properties(struct pw_core *core)
 int pw_core_update_properties(struct pw_core *core, const struct spa_dict *dict)
 {
 	struct pw_resource *resource;
-	uint32_t i;
+	uint32_t i, changed = 0;
 
 	for (i = 0; i < dict->n_items; i++)
-		pw_properties_set(core->properties, dict->items[i].key, dict->items[i].value);
+		changed += pw_properties_set(core->properties, dict->items[i].key, dict->items[i].value);
+
+	if (!changed)
+		return 0;
 
 	core->info.change_mask = PW_CORE_CHANGE_MASK_PROPS;
 	core->info.props = &core->properties->dict;
@@ -588,7 +591,7 @@ int pw_core_update_properties(struct pw_core *core, const struct spa_dict *dict)
 
 	core->info.change_mask = 0;
 
-	return 0;
+	return changed;
 }
 
 int pw_core_for_each_global(struct pw_core *core,

src/pipewire/module.c

@@ -334,10 +334,13 @@ const struct pw_properties *pw_module_get_properties(struct pw_module *module)
 int pw_module_update_properties(struct pw_module *module, const struct spa_dict *dict)
 {
 	struct pw_resource *resource;
-	uint32_t i;
+	uint32_t i, changed = 0;
 
 	for (i = 0; i < dict->n_items; i++)
-		pw_properties_set(module->properties, dict->items[i].key, dict->items[i].value);
+		changed += pw_properties_set(module->properties, dict->items[i].key, dict->items[i].value);
+
+	if (!changed)
+		return 0;
 
 	module->info.props = &module->properties->dict;
 
@@ -346,7 +349,7 @@ int pw_module_update_properties(struct pw_module *module, const struct spa_dict
 		pw_module_resource_info(resource, &module->info);
 	module->info.change_mask = 0;
 
-	return 0;
+	return changed;
 }
 
 const struct pw_module_info *

src/pipewire/node.c

@@ -721,15 +721,19 @@ const struct pw_properties *pw_node_get_properties(struct pw_node *node)
 int pw_node_update_properties(struct pw_node *node, const struct spa_dict *dict)
 {
 	struct pw_resource *resource;
-	uint32_t i;
+	uint32_t i, changed = 0;
 
 	for (i = 0; i < dict->n_items; i++)
-		pw_properties_set(node->properties, dict->items[i].key, dict->items[i].value);
+		changed += pw_properties_set(node->properties, dict->items[i].key, dict->items[i].value);
+
+	pw_log_debug("node %p: updated %d properties", node, changed);
+
+	if (!changed)
+		return 0;
 
 	check_properties(node);
 
 	node->info.props = &node->properties->dict;
-
 	node->info.change_mask |= PW_NODE_CHANGE_MASK_PROPS;
 	pw_node_events_info_changed(node, &node->info);
 
@@ -738,7 +742,7 @@ int pw_node_update_properties(struct pw_node *node, const struct spa_dict *dict)
 
 	node->info.change_mask = 0;
 
-	return 0;
+	return changed;
 }
 
 static void node_done(void *data, int seq, int res)

src/pipewire/port.c

@@ -283,13 +283,17 @@ const struct pw_properties *pw_port_get_properties(struct pw_port *port)
 int pw_port_update_properties(struct pw_port *port, const struct spa_dict *dict)
 {
 	struct pw_resource *resource;
-	uint32_t i;
+	uint32_t i, changed = 0;
 
 	for (i = 0; i < dict->n_items; i++)
-		pw_properties_set(port->properties, dict->items[i].key, dict->items[i].value);
+		changed += pw_properties_set(port->properties, dict->items[i].key, dict->items[i].value);
+
+	pw_log_debug("port %p: updated %d properties", port, changed);
+
+	if (!changed)
+		return 0;
 
 	port->info.props = &port->properties->dict;
-
 	port->info.change_mask |= PW_PORT_CHANGE_MASK_PROPS;
 	pw_port_events_info_changed(port, &port->info);
 
@@ -298,7 +302,7 @@ int pw_port_update_properties(struct pw_port *port, const struct spa_dict *dict)
 
 	port->info.change_mask = 0;
 
-	return 0;
+	return changed;
 }
 
 struct pw_node *pw_port_get_node(struct pw_port *port)

src/pipewire/properties.c

@@ -247,31 +247,39 @@ void pw_properties_free(struct pw_properties *properties)
 	free(impl);
 }
 
-static int do_replace(struct pw_properties *properties, const char *key, char *value)
+static int do_replace(struct pw_properties *properties, const char *key, char *value, bool copy)
 {
 	struct properties *impl = SPA_CONTAINER_OF(properties, struct properties, this);
 	int index = find_index(properties, key);
 
 	if (index == -1) {
-		add_func(properties, strdup(key), value);
+		if (value == NULL)
+			return 0;
+		add_func(properties, strdup(key), copy ? strdup(value) : value);
 	} else {
 		struct spa_dict_item *item =
 		    pw_array_get_unchecked(&impl->items, index, struct spa_dict_item);
 
-		clear_item(item);
+		if (value && strcmp(item->value, value) == 0) {
+			if (!copy)
+				free(value);
+			return 0;
+		}
+
 		if (value == NULL) {
 			struct spa_dict_item *other = pw_array_get_unchecked(&impl->items,
 						     pw_array_get_len(&impl->items, struct spa_dict_item) - 1,
 						     struct spa_dict_item);
+			clear_item(item);
 			item->key = other->key;
 			item->value = other->value;
 			impl->items.size -= sizeof(struct spa_dict_item);
 		} else {
-			item->key = strdup(key);
+			free((char *) item->value);
-			item->value = value;
+			item->value = copy ? strdup(value) : value;
 		}
 	}
-	return 0;
+	return 1;
 }
 
 /** Set a property value
@@ -279,6 +287,9 @@ static int do_replace(struct pw_properties *properties, const char *key, char *v
  * \param properties the properties to change
  * \param key a key
  * \param value a value or NULL to remove the key
+ * \return 1 if the properties were changed. 0 if nothing was changed because
+ *  the property already existed with the same value or because the key to remove
+ *  did not exist.
  *
  * Set the property in \a properties with \a key to \a value. Any previous value
  * of \a key will be overwritten. When \a value is NULL, the key will be
@@ -288,7 +299,7 @@ static int do_replace(struct pw_properties *properties, const char *key, char *v
  */
 int pw_properties_set(struct pw_properties *properties, const char *key, const char *value)
 {
-	return do_replace(properties, key, value ? strdup(value) : NULL);
+	return do_replace(properties, key, (char*)value, true);
 }
 
 int
@@ -297,7 +308,7 @@ pw_properties_setva(struct pw_properties *properties,
 {
 	char *value;
 	vasprintf(&value, format, args);
-	return do_replace(properties, key, value);
+	return do_replace(properties, key, value, false);
 }
 
 /** Set a property value by format

src/pipewire/remote.c

@@ -330,16 +330,20 @@ const struct pw_properties *pw_remote_get_properties(struct pw_remote *remote)
 
 int pw_remote_update_properties(struct pw_remote *remote, const struct spa_dict *dict)
 {
-	uint32_t i;
+	uint32_t i, changed = 0;
 
 	for (i = 0; i < dict->n_items; i++)
-		pw_properties_set(remote->properties, dict->items[i].key, dict->items[i].value);
+		changed += pw_properties_set(remote->properties, dict->items[i].key, dict->items[i].value);
+
+	if (!changed)
+		return 0;
 
 	if (remote->core_proxy)
 		pw_core_proxy_client_update(remote->core_proxy, &remote->properties->dict);
 
-	return 0;
+	return changed;
 }
+
 void *pw_remote_get_user_data(struct pw_remote *remote)
 {
 	return remote->user_data;

src/tools/pipewire-monitor.c

@@ -290,7 +290,7 @@ static void print_port(struct proxy_data *data)
 	if (print_all) {
 		int i;
 		printf(" \tdirection: \"%s\"\n", pw_direction_as_string(info->direction));
-		printf("%c\tparams:\n", MARK_CHANGE(1));
+		printf("%c\tparams:\n", MARK_CHANGE(2));
 		for (i = 0; i < data->n_params; i++) {
 			if (spa_pod_is_object_type(data->params[i], SPA_TYPE_OBJECT_Format))
 				spa_debug_format(12, NULL, data->params[i]);