evt: improves comments

Change-Id: I6c3e855030af9064335028e51d10c41db85a3f3c
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

1 files changed, 88 insertions, 4 deletions

diff --git a/src/afb-evt.c b/src/afb-evt.c
index ad5695f1..a99dc894 100644
--- a/src/afb-evt.c
+++ b/src/afb-evt.c
@@ -28,46 +28,89 @@
 
 #include "afb-evt.h"
 
-
 struct afb_evt_watch;
 
+/*
+ * Structure for event listeners
+ */
 struct afb_evt_listener {
+
+	/* chaining listeners */
 	struct afb_evt_listener *next;
+
+	/* callback on event */
 	void (*send)(void *closure, const char *event, struct json_object *object);
+
+	/* closure for the callback */
 	void *closure;
+
+	/* head of the list of events listened */
 	struct afb_evt_watch *watchs;
+
+	/* count of reference to the listener */
 	int refcount;
 };
 
+/*
+ * Structure for describing events
+ */
 struct afb_evt_event {
+
+	/* head of the list of listeners watching the event */
 	struct afb_evt_watch *watchs;
+
+	/* name of the event */
 	char name[1];
 };
 
+/*
+ * Structure for associating events and listeners
+ */
 struct afb_evt_watch {
+
+	/* the event */
 	struct afb_evt_event *event;
+
+	/* link to the next listener for the same event */
 	struct afb_evt_watch *next_by_event;
+
+	/* the listener */
 	struct afb_evt_listener *listener;
+
+	/* link to the next event for the same listener */
 	struct afb_evt_watch *next_by_listener;
 };
 
+/* 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_drop(struct afb_evt_event *evt);
+static void evt_destroy(struct afb_evt_event *evt);
 
+/* the interface for events */
 static struct afb_event_itf afb_evt_event_itf = {
 	.broadcast = (void*)evt_broadcast,
 	.push = (void*)evt_push,
-	.drop = (void*)evt_drop
+	.drop = (void*)evt_destroy
 };
 
+/* head of the list of listeners */
 static struct afb_evt_listener *listeners = NULL;
 
+/*
+ * Broadcasts the event 'evt' 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)
 {
 	return afb_evt_broadcast(evt->name, object);
 }
 
+/*
+ * Broadcasts the 'event' with its 'object'
+ * 'object' is released (like json_object_put)
+ * Returns the count of listener having receive the event.
+ */
 int afb_evt_broadcast(const char *event, struct json_object *object)
 {
 	int result;
@@ -78,11 +121,17 @@ int afb_evt_broadcast(const char *event, struct json_object *object)
 	while(listener) {
 		listener->send(listener->closure, event, json_object_get(object));
 		listener = listener->next;
+		result++;
 	}
 	json_object_put(object);
 	return result;
 }
 
+/*
+ * Broadcasts the event 'evt' with its 'object'
+ * 'object' is released (like json_object_put)
+ * Returns the count of listener taht received the event.
+ */
 static int evt_push(struct afb_evt_event *evt, struct json_object *obj)
 {
 	int result;
@@ -95,37 +144,52 @@ static int evt_push(struct afb_evt_event *evt, struct json_object *obj)
 		listener = watch->listener;
 		listener->send(listener->closure, evt->name, json_object_get(obj));
 		watch = watch->next_by_event;
+		result++;
 	}
 	json_object_put(obj);
 	return result;
 }
 
+/*
+ * remove the 'watch'
+ */
 static void remove_watch(struct afb_evt_watch *watch)
 {
 	struct afb_evt_watch **prv;
 
+	/* unlink the watch for its event */
 	prv = &watch->event->watchs;
 	while(*prv != watch)
 		prv = &(*prv)->next_by_event;
 	*prv = watch->next_by_event;
 
+	/* unlink the watch for its listener */
 	prv = &watch->listener->watchs;
 	while(*prv != watch)
 		prv = &(*prv)->next_by_listener;
 	*prv = watch->next_by_listener;
 
+	/* recycle memory */
 	free(watch);
 }
 
-static void evt_drop(struct afb_evt_event *evt)
+/*
+ * Destroys the event 'evt'
+ */
+static void evt_destroy(struct afb_evt_event *evt)
 {
 	if (evt != NULL) {
+		/* removes all watchers */
 		while(evt->watchs != NULL)
 			remove_watch(evt->watchs);
 		free(evt);
 	}
 }
 
+/*
+ * Creates an event of 'name' and returns it.
+ * Returns an event with closure==NULL in case of error.
+ */
 struct afb_event afb_evt_create_event(const char *name)
 {
 	size_t len;
@@ -140,6 +204,11 @@ struct afb_event afb_evt_create_event(const char *name)
 	return (struct afb_event){ .itf = &afb_evt_event_itf, .closure = evt };
 }
 
+/*
+ * Returns an instance of the listener defined by the 'send' callback
+ * and the 'closure'.
+ * Returns NULL in case of memory depletion.
+ */
 struct afb_evt_listener *afb_evt_listener_create(void (*send)(void *closure, const char *event, struct json_object *object), void *closure)
 {
 	struct afb_evt_listener *listener;
@@ -166,12 +235,19 @@ struct afb_evt_listener *afb_evt_listener_create(void (*send)(void *closure, con
 	return listener;
 }
 
+/*
+ * Increases the reference count of 'listener' and returns it
+ */
 struct afb_evt_listener *afb_evt_listener_addref(struct afb_evt_listener *listener)
 {
 	listener->refcount++;
 	return listener;
 }
 
+/*
+ * Decreases the reference count of the 'listener' and destroys it
+ * when no more used.
+ */
 void afb_evt_listener_unref(struct afb_evt_listener *listener)
 {
 	if (0 == --listener->refcount) {
@@ -192,6 +268,10 @@ void afb_evt_listener_unref(struct afb_evt_listener *listener)
 	}
 }
 
+/*
+ * 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_evt_watch *watch;
@@ -230,6 +310,10 @@ int afb_evt_add_watch(struct afb_evt_listener *listener, struct afb_event event)
 	return 0;
 }
 
+/*
+ * 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_evt_watch *watch;