Implement refcounting for notifications

src/dbus.c

@@ -282,7 +282,7 @@ static void on_notify(GDBusConnection *connection,
         // The message got discarded
         if (id == 0) {
                 signal_notification_closed(n, 2);
-                notification_free(n);
+                notification_unref(n);
         }
 
         wake_up();

src/notification.c

@@ -42,6 +42,10 @@ const char *enum_to_string_fullscreen(enum behavior_fullscreen in)
         }
 }
 
+struct _notification_private {
+        gint refcount;
+};
+
 /* see notification.h */
 void notification_print(const struct notification *n)
 {
@@ -206,12 +210,28 @@ void rawimage_free(struct raw_image *i)
         g_free(i);
 }
 
+static void notification_private_free(NotificationPrivate *p)
+{
+        g_free(p);
+}
+
 /* see notification.h */
-void notification_free(struct notification *n)
+void notification_ref(struct notification *n)
+{
+        assert(n->priv->refcount > 0);
+        g_atomic_int_inc(&n->priv->refcount);
+}
+
+/* see notification.h */
+void notification_unref(struct notification *n)
 {
         if (!n)
                 return;
 
+        assert(n->priv->refcount > 0);
+        if (!g_atomic_int_dec_and_test(&n->priv->refcount))
+                return;
+
         g_free(n->appname);
         g_free(n->summary);
         g_free(n->body);
@@ -228,6 +248,8 @@ void notification_free(struct notification *n)
         actions_free(n->actions);
         rawimage_free(n->raw_icon);
 
+        notification_private_free(n->priv);
+
         g_free(n);
 }
 
@@ -255,11 +277,21 @@ void notification_replace_single_field(char **haystack,
         g_free(input);
 }
 
+static NotificationPrivate *notification_private_create(void)
+{
+        NotificationPrivate *priv = g_malloc0(sizeof(NotificationPrivate));
+        g_atomic_int_set(&priv->refcount, 1);
+
+        return priv;
+}
+
 /* see notification.h */
 struct notification *notification_create(void)
 {
         struct notification *n = g_malloc0(sizeof(struct notification));
 
+        n->priv = notification_private_create();
+
         /* Unparameterized default values */
         n->first_render = true;
         n->markup = settings.markup;

src/notification.h

@@ -42,7 +42,10 @@ struct actions {
         gsize count;
 };
 
+typedef struct _notification_private NotificationPrivate;
+
 struct notification {
+        NotificationPrivate *priv;
         int id;
         char *dbus_client;
 
@@ -90,11 +93,18 @@ struct notification {
  *  - the default (if it's not needed to be freed later)
  *  - its undefined representation (NULL, -1)
  *
+ * The reference counter is set to 1.
+ *
  * This function is guaranteed to return a valid pointer.
  * @returns The generated notification
  */
 struct notification *notification_create(void);
 
+/**
+ * Increase the reference counter of the notification.
+ */
+void notification_ref(struct notification *n);
+
 /**
  * Sanitize values of notification, apply all matching rules
  * and generate derived fields.
@@ -118,11 +128,11 @@ void actions_free(struct actions *a);
 void rawimage_free(struct raw_image *i);
 
 /**
- * Free the memory used by the given notification.
+ * Decrease the reference counter of the notification.
  *
- * @param n (nullable): pointer to #notification
+ * If the reference count drops to 0, the object gets freed.
  */
-void notification_free(struct notification *n);
+void notification_unref(struct notification *n);
 
 /**
  * Helper function to compare two given notifications.

src/queues.c

@@ -191,7 +191,7 @@ static bool queues_stack_duplicate(struct notification *n)
                                 if ( allqueues[i] == displayed )
                                         n->start = time_monotonic_now();
 
-                                notification_free(orig);
+                                notification_unref(orig);
                                 return true;
                         }
                 }
@@ -218,7 +218,7 @@ bool queues_notification_replace_id(struct notification *new)
                                         notification_run_script(new);
                                 }
 
-                                notification_free(old);
+                                notification_unref(old);
                                 return true;
                         }
                 }
@@ -278,12 +278,12 @@ void queues_history_push(struct notification *n)
         if (!n->history_ignore) {
                 if (settings.history_length > 0 && history->length >= settings.history_length) {
                         struct notification *to_free = g_queue_pop_head(history);
-                        notification_free(to_free);
+                        notification_unref(to_free);
                 }
 
                 g_queue_push_tail(history, n);
         } else {
-                notification_free(n);
+                notification_unref(n);
         }
 }
 
@@ -488,7 +488,7 @@ bool queues_pause_status(void)
 static void teardown_notification(gpointer data)
 {
         struct notification *n = data;
-        notification_free(n);
+        notification_unref(n);
 }
 
 /* see queues.h */

test/notification.c

@@ -121,8 +121,8 @@ SUITE(suite_notification)
         struct notification *n[2] = {a, b};
 
         RUN_TEST1(test_notification_is_duplicate, (void*) n);
-        notification_free(a);
+        notification_unref(a);
-        notification_free(b);
+        notification_unref(b);
 
         RUN_TEST(test_notification_replace_single_field);