degesch: extend weak pointers

1 files changed, 43 insertions, 10 deletions

diff --git a/degesch.c b/degesch.c
index 74da23d..ce7563b 100644
--- a/degesch.c
+++ b/degesch.c
@@ -732,16 +732,29 @@ input_on_readable (struct input *self)
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
-// We need a few reference countable objects with support
-// for both strong and weak references
+// We need a few reference countable objects with support for both strong
+// and weak references (mainly used for scripted plugins).
+//
+// Beware that if you don't own the object, you will most probably want
+// to keep the weak reference link so that you can get rid of it later.
+// Also note that you have to make sure the user_data don't leak resources.
+//
+// Having a callback is more versatile than just nulling out a pointer.
 
 /// Callback just before a reference counted object is destroyed
 typedef void (*destroy_cb_fn) (void *object, void *user_data);
 
+struct weak_ref_link
+{
+	LIST_HEADER (struct weak_ref_link)
+
+	destroy_cb_fn on_destroy;           ///< Called when object is destroyed
+	void *user_data;                    ///< User data
+};
+
 #define REF_COUNTABLE_HEADER                                                   \
 	size_t ref_count;                   /**< Reference count                */ \
-	destroy_cb_fn on_destroy;           /**< To remove any weak references  */ \
-	void *user_data;                    /**< User data for callbacks        */
+	struct weak_ref_link *weak_refs;    /**< To remove any weak references  */
 
 #define REF_COUNTABLE_METHODS(name)                                            \
 	static struct name *                                                       \
@@ -756,9 +769,31 @@ typedef void (*destroy_cb_fn) (void *object, void *user_data);
 	{                                                                          \
 		if (--self->ref_count)                                                 \
 			return;                                                            \
-		if (self->on_destroy)                                                  \
-			self->on_destroy (self, self->user_data);                          \
+		LIST_FOR_EACH (struct weak_ref_link, iter, self->weak_refs)            \
+		{                                                                      \
+			iter->on_destroy (self, iter->user_data);                          \
+			free (iter);                                                       \
+		}                                                                      \
 		name ## _destroy (self);                                               \
+	}                                                                          \
+																			   \
+	static struct weak_ref_link *                                              \
+	name ## _weak_ref (struct name *self, destroy_cb_fn cb, void *user_data)   \
+	{                                                                          \
+		struct weak_ref_link *link = xcalloc (1, sizeof *link);                \
+		link->on_destroy = cb;                                                 \
+		link->user_data = user_data;                                           \
+		LIST_PREPEND (self->weak_refs, link);                                  \
+		return link;                                                           \
+	}                                                                          \
+																			   \
+	static void                                                                \
+	name ## _weak_unref (struct name *self, struct weak_ref_link **link)       \
+	{                                                                          \
+		if (*link)                                                             \
+			LIST_UNLINK (self->weak_refs, *link);                              \
+		free (*link);                                                          \
+		*link = NULL;                                                          \
 	}
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -3378,8 +3413,7 @@ irc_make_user (struct server *s, char *nickname)
 	hard_assert (!str_map_find (&s->irc_users, nickname));
 
 	struct user *user = user_new ();
-	user->on_destroy = irc_user_on_destroy;
-	user->user_data = s;
+	(void) user_weak_ref (user, irc_user_on_destroy, s);
 	user->nickname = nickname;
 	str_map_set (&s->irc_users, user->nickname, user);
 	return user;
@@ -3482,8 +3516,7 @@ irc_make_channel (struct server *s, char *name)
 	hard_assert (!str_map_find (&s->irc_channels, name));
 
 	struct channel *channel = channel_new ();
-	channel->on_destroy = irc_channel_on_destroy;
-	channel->user_data = s;
+	(void) channel_weak_ref (channel, irc_channel_on_destroy, s);
 	channel->name = name;
 	channel->topic = NULL;
 	str_map_set (&s->irc_channels, channel->name, channel);