Events: refactoring

This new version allows to subscribe a client for
an event.

The event should first be created for the API
(the API's prefix is added) using 'afb_daemon_make_event'.

After that, plugins can subscribe or unsubscribe their
clients (identified through requests) to the events that
it generates. See 'afb_req_subscribe' and 'afb_req_unsubscribe'.

Events created by 'afb_daemon_make_event' can be widely
broadcasted using 'afb_event_broadcast' or pushed only to
suscribers using 'afb_event_push'.

Events can be destroyed using 'afb_event_drop'.

Change-Id: I7c0bed5e625c2052dcd81c6bfe960def1fa032f3
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

1 files changed, 84 insertions, 0 deletions

diff --git a/include/afb/afb-event-itf.h b/include/afb/afb-event-itf.h
new file mode 100644
index 00000000..47ffa387
--- /dev/null
+++ b/include/afb/afb-event-itf.h
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2016 "IoT.bzh"
+ * Author: José Bollo <jose.bollo@iot.bzh>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+/* avoid inclusion of <json-c/json.h> */
+struct json_object;
+
+/*
+ * Interface for handling requests.
+ * It records the functions to be called for the request.
+ * Don't use this structure directly.
+ * Use the helper functions documented below.
+ */ 
+struct afb_event_itf {
+	/* CAUTION: respect the order, add at the end */
+
+	int (*broadcast)(void *closure, struct json_object *obj);
+	int (*push)(void *closure, struct json_object *obj);
+	void (*drop)(void *closure);
+};
+
+/*
+ * Describes the request by plugins from afb-daemon
+ */
+struct afb_event {
+	const struct afb_event_itf *itf;	/* the interface to use */
+	void *closure;				/* the closure argument for functions of 'itf' */
+};
+
+/*
+ * Broadcasts widely the 'event' with the data 'object'.
+ * 'object' can be NULL.
+ *
+ * For conveniency, the function calls 'json_object_put' for 'object'.
+ * Thus, in the case where 'object' should remain available after
+ * the function returns, the function 'json_object_get' shall be used.
+ *
+ * Returns the count of clients that received the event.
+ */
+static inline int afb_event_broadcast(struct afb_event event, struct json_object *object)
+{
+	return event.itf->broadcast(event.closure, object);
+}
+
+/*
+ * Pushes the 'event' with the data 'object' to its obeservers.
+ * 'object' can be NULL.
+ *
+ * For conveniency, the function calls 'json_object_put' for 'object'.
+ * Thus, in the case where 'object' should remain available after
+ * the function returns, the function 'json_object_get' shall be used.
+ *
+ * Returns the count of clients that received the event.
+ */
+static inline int afb_event_push(struct afb_event event, struct json_object *object)
+{
+	return event.itf->push(event.closure, object);
+}
+
+/*
+ * Drops the data associated to the event
+ * After calling this function, the event
+ * MUST NOT BE USED ANYMORE.
+ */
+static inline void afb_event_drop(struct afb_event event)
+{
+	event.itf->drop(event.closure);
+}
+