lib: remove event listener groups

In real use, there are few (typically only zero or one) listeners per
event type. In this case, the linear search through the listener groups
was actually slower than the linear search through the whole list of
listeners: it required one iteration per event type, even for event
types with no listeners.

(Note: using a hash table over the event type would make a lot more
 sense as an optimization.)

lib/event.c

@@ -83,16 +83,10 @@ typedef struct libvlc_event_listener_t
 typedef struct libvlc_event_manager_t
 {
     void * p_obj;
-    vlc_array_t listeners_groups;
+    vlc_array_t listeners;
     vlc_mutex_t lock;
 } libvlc_event_sender_t;
 
-typedef struct libvlc_event_listeners_group_t
-{
-    libvlc_event_type_t event_type;
-    vlc_array_t listeners;
-} libvlc_event_listeners_group_t;
-
 /*
  * Internal libvlc functions
  */
@@ -115,8 +109,7 @@ libvlc_event_manager_new( void * p_obj )
     }
 
     p_em->p_obj = p_obj;
-
-    vlc_array_init( &p_em->listeners_groups );
+    vlc_array_init(&p_em->listeners);
     vlc_mutex_init_recursive(&p_em->lock);
     return p_em;
 }
@@ -128,22 +121,12 @@ libvlc_event_manager_new( void * p_obj )
  **************************************************************************/
 void libvlc_event_manager_release( libvlc_event_manager_t * p_em )
 {
-    libvlc_event_listeners_group_t * p_lg;
-    int i,j ;
-
     vlc_mutex_destroy(&p_em->lock);
 
-    for( i = 0; i < vlc_array_count(&p_em->listeners_groups); i++)
-    {
-        p_lg = vlc_array_item_at_index( &p_em->listeners_groups, i );
-
-        for( j = 0; j < vlc_array_count(&p_lg->listeners); j++)
-            free( vlc_array_item_at_index( &p_lg->listeners, j ) );
+    for (int i = 0; i < vlc_array_count(&p_em->listeners); i++)
+        free(vlc_array_item_at_index(&p_em->listeners, i));
 
-        vlc_array_clear( &p_lg->listeners );
-        free( p_lg );
-    }
-    vlc_array_clear( &p_em->listeners_groups );
+    vlc_array_clear(&p_em->listeners);
     free( p_em );
 }
 
@@ -156,14 +139,7 @@ void libvlc_event_manager_register_event_type(
         libvlc_event_manager_t * p_em,
         libvlc_event_type_t event_type )
 {
-    libvlc_event_listeners_group_t * listeners_group;
-    listeners_group = xmalloc(sizeof(libvlc_event_listeners_group_t));
-    listeners_group->event_type = event_type;
-    vlc_array_init( &listeners_group->listeners );
-
-    vlc_mutex_lock(&p_em->lock);
-    vlc_array_append( &p_em->listeners_groups, listeners_group );
-    vlc_mutex_unlock(&p_em->lock);
+    (void) p_em; (void) event_type;
 }
 
 /**************************************************************************
@@ -174,28 +150,17 @@ void libvlc_event_manager_register_event_type(
 void libvlc_event_send( libvlc_event_manager_t * p_em,
                         libvlc_event_t * p_event )
 {
-    int i;
-
     /* Fill event with the sending object now */
     p_event->p_obj = p_em->p_obj;
 
     vlc_mutex_lock(&p_em->lock);
-    for( i = 0; i < vlc_array_count(&p_em->listeners_groups); i++)
+    for (int i = 0; i < vlc_array_count(&p_em->listeners); i++)
     {
-        libvlc_event_listeners_group_t *listeners_group;
-
-        listeners_group = vlc_array_item_at_index(&p_em->listeners_groups, i);
-        if (listeners_group->event_type != p_event->type)
-            continue;
-
-        for (int j = 0; j < vlc_array_count(&listeners_group->listeners); j++)
-        {
-            libvlc_event_listener_t *listener;
+        libvlc_event_listener_t *listener;
 
-            listener = vlc_array_item_at_index(&listeners_group->listeners, j);
+        listener = vlc_array_item_at_index(&p_em->listeners, i);
+        if (listener->event_type == p_event->type)
             listener->pf_callback(p_event, listener->p_user_data);
-        }
-        break;
     }
     vlc_mutex_unlock(&p_em->lock);
 }
@@ -300,58 +265,25 @@ const char * libvlc_event_type_name( int event_type )
 }
 
 /**************************************************************************
- *       event_attach (internal) :
+ *       libvlc_event_attach (public) :
  *
  * Add a callback for an event.
  **************************************************************************/
-static
-int event_attach( libvlc_event_manager_t * p_event_manager,
-                  libvlc_event_type_t event_type,
-                  libvlc_callback_t pf_callback, void *p_user_data )
+int libvlc_event_attach(libvlc_event_manager_t *em, libvlc_event_type_t type,
+                        libvlc_callback_t callback, void *opaque)
 {
-    libvlc_event_listeners_group_t * listeners_group;
-    libvlc_event_listener_t * listener;
-    int i;
-
-    listener = malloc(sizeof(libvlc_event_listener_t));
-    if( unlikely(listener == NULL) )
+    libvlc_event_listener_t *listener = malloc(sizeof (*listener));
+    if (unlikely(listener == NULL))
         return ENOMEM;
 
-    listener->event_type = event_type;
-    listener->p_user_data = p_user_data;
-    listener->pf_callback = pf_callback;
-
-    vlc_mutex_lock(&p_event_manager->lock);
-    for( i = 0; i < vlc_array_count(&p_event_manager->listeners_groups); i++ )
-    {
-        listeners_group = vlc_array_item_at_index(&p_event_manager->listeners_groups, i);
-        if( listeners_group->event_type == listener->event_type )
-        {
-            vlc_array_append( &listeners_group->listeners, listener );
-            vlc_mutex_unlock(&p_event_manager->lock);
-            return 0;
-        }
-    }
-    vlc_mutex_unlock(&p_event_manager->lock);
+    listener->event_type = type;
+    listener->p_user_data = opaque;
+    listener->pf_callback = callback;
 
-    free(listener);
-    fprintf( stderr, "This object event manager doesn't know about '%s' events",
-             libvlc_event_type_name(event_type) );
-    vlc_assert_unreachable();
-    return -1;
-}
-
-/**************************************************************************
- *       libvlc_event_attach (public) :
- *
- * Add a callback for an event.
- **************************************************************************/
-int libvlc_event_attach( libvlc_event_manager_t * p_event_manager,
-                         libvlc_event_type_t event_type,
-                         libvlc_callback_t pf_callback,
-                         void *p_user_data )
-{
-    return event_attach(p_event_manager, event_type, pf_callback, p_user_data);
+    vlc_mutex_lock(&em->lock);
+    vlc_array_append(&em->listeners, listener);
+    vlc_mutex_unlock(&em->lock);
+    return 0;
 }
 
 /**************************************************************************
@@ -359,39 +291,25 @@ int libvlc_event_attach( libvlc_event_manager_t * p_event_manager,
  *
  * Remove a callback for an event.
  **************************************************************************/
-void libvlc_event_detach( libvlc_event_manager_t *p_event_manager,
-                                     libvlc_event_type_t event_type,
-                                     libvlc_callback_t pf_callback,
-                                     void *p_user_data )
+void libvlc_event_detach(libvlc_event_manager_t *em, libvlc_event_type_t type,
+                         libvlc_callback_t callback, void *opaque)
 {
-    libvlc_event_listeners_group_t * listeners_group;
-    libvlc_event_listener_t * listener;
-    int i, j;
-    bool found = false;
-
-    vlc_mutex_lock(&p_event_manager->lock);
-    for( i = 0; i < vlc_array_count(&p_event_manager->listeners_groups); i++)
+    vlc_mutex_lock(&em->lock);
+    for (int i = 0; i < vlc_array_count(&em->listeners); i++)
     {
-        listeners_group = vlc_array_item_at_index(&p_event_manager->listeners_groups, i);
-        if( listeners_group->event_type == event_type )
-        {
-            for( j = 0; j < vlc_array_count(&listeners_group->listeners); j++)
-            {
-                listener = vlc_array_item_at_index(&listeners_group->listeners, j);
-                if( listener->event_type == event_type &&
-                    listener->pf_callback == pf_callback &&
-                    listener->p_user_data == p_user_data )
-                {
-                    /* that's our listener */
-                    free( listener );
-                    vlc_array_remove( &listeners_group->listeners, j );
-                    found = true;
-                    break;
-                }
-            }
-        }
+         libvlc_event_listener_t *listener;
+
+         listener = vlc_array_item_at_index(&em->listeners, i);
+
+         if (listener->event_type == type
+          && listener->pf_callback == callback
+          && listener->p_user_data == opaque)
+         {   /* that's our listener */
+             vlc_array_remove(&em->listeners, i);
+             vlc_mutex_unlock(&em->lock);
+             free(listener);
+             return;
+         }
     }
-    vlc_mutex_unlock(&p_event_manager->lock);
-
-    assert(found);
+    abort();
 }