]> git.sesse.net Git - vlc/blobdiff - src/misc/objects.c
Use a doubly-linked list for objects instead of a flat table
[vlc] / src / misc / objects.c
index adda93139319dfa350950baf3b6941c217c671a7..06177dc240ad8867592e6721b8168507ad04d5bc 100644 (file)
 #endif
 #include <assert.h>
 
-/*****************************************************************************
- * Constants
- *****************************************************************************/
-
-const vlc_destructor_t kVLCDestructor = NULL;
-
 /*****************************************************************************
  * Local prototypes
  *****************************************************************************/
@@ -76,11 +70,8 @@ static int  DumpCommand( vlc_object_t *, char const *,
 
 static vlc_object_t * FindObject    ( vlc_object_t *, int, int );
 static vlc_object_t * FindObjectName( vlc_object_t *, const char *, int );
-static void           DetachObject  ( vlc_object_t * );
 static void           PrintObject   ( vlc_object_t *, const char * );
 static void           DumpStructure ( vlc_object_t *, int, char * );
-static int            FindIndex     ( vlc_object_t *, vlc_object_t **, int );
-static void           SetAttachment ( vlc_object_t *, bool );
 
 static vlc_list_t   * NewList       ( int );
 static void           ListReplace   ( vlc_list_t *, vlc_object_t *, int );
@@ -89,7 +80,7 @@ static int            CountChildren ( vlc_object_t *, int );
 static void           ListChildren  ( vlc_list_t *, vlc_object_t *, int );
 
 static void vlc_object_destroy( vlc_object_t *p_this );
-static void vlc_object_yield_locked( vlc_object_t *p_this );
+static void vlc_object_detach_unlocked (vlc_object_t *p_this);
 
 /*****************************************************************************
  * Local structure lock
@@ -125,7 +116,6 @@ void *vlc_custom_create( vlc_object_t *p_this, size_t i_size,
     p_new->b_die = false;
     p_new->b_error = false;
     p_new->b_dead = false;
-    p_priv->b_attached = false;
     p_new->b_force = false;
 
     p_new->psz_header = NULL;
@@ -143,57 +133,50 @@ void *vlc_custom_create( vlc_object_t *p_this, size_t i_size,
     }
 
     libvlc_global_data_t *p_libvlc_global;
-    if( i_type == VLC_OBJECT_GLOBAL )
+    if( p_this == NULL )
     {
-        /* If i_type is global, then p_new is actually p_libvlc_global */
+        /* Only the global root object is created out of the blue */
         p_libvlc_global = (libvlc_global_data_t *)p_new;
         p_new->p_libvlc = NULL;
 
         p_libvlc_global->i_counter = 0;
-        p_libvlc_global->i_objects = 0;
-        p_libvlc_global->pp_objects = NULL;
-        p_priv->b_attached = true;
-        vlc_mutex_init( p_new, &structure_lock );
+        p_priv->next = p_priv->prev = p_new;
+        vlc_mutex_init( &structure_lock );
     }
     else
     {
         p_libvlc_global = vlc_global();
         if( i_type == VLC_OBJECT_LIBVLC )
-        {
             p_new->p_libvlc = (libvlc_int_t*)p_new;
-            p_priv->b_attached = true;
-        }
         else
-        {
             p_new->p_libvlc = p_this->p_libvlc;
-        }
     }
 
-    vlc_mutex_lock( &structure_lock );
-    p_new->i_object_id = p_libvlc_global->i_counter++;
-
-    /* Wooohaa! If *this* fails, we're in serious trouble! Anyway it's
-     * useless to try and recover anything if pp_objects gets smashed. */
-    TAB_APPEND( p_libvlc_global->i_objects, p_libvlc_global->pp_objects,
-                p_new );
-    vlc_mutex_unlock( &structure_lock );
-
+    vlc_spin_init( &p_priv->ref_spin );
     p_priv->i_refcount = 1;
-    p_priv->pf_destructor = kVLCDestructor;
+    p_priv->pf_destructor = NULL;
     p_priv->b_thread = false;
     p_new->p_parent = NULL;
-    p_new->pp_children = NULL;
-    p_new->i_children = 0;
+    p_priv->pp_children = NULL;
+    p_priv->i_children = 0;
 
     p_new->p_private = NULL;
 
     /* Initialize mutexes and condvars */
-    vlc_mutex_init( p_new, &p_new->object_lock );
+    vlc_mutex_init( &p_new->object_lock );
     vlc_cond_init( p_new, &p_new->object_wait );
-    vlc_mutex_init( p_new, &p_priv->var_lock );
+    vlc_mutex_init( &p_priv->var_lock );
     vlc_spin_init( &p_priv->spin );
     p_priv->pipes[0] = p_priv->pipes[1] = -1;
 
+    p_priv->next = VLC_OBJECT (p_libvlc_global);
+    vlc_mutex_lock( &structure_lock );
+    p_priv->prev = vlc_internals (p_libvlc_global)->prev;
+    vlc_internals (p_libvlc_global)->prev = p_new;
+    vlc_internals (p_priv->prev)->next = p_new;
+    p_new->i_object_id = p_libvlc_global->i_counter++;
+    vlc_mutex_unlock( &structure_lock );
+
     if( i_type == VLC_OBJECT_LIBVLC )
     {
         var_Create( p_new, "list", VLC_VAR_STRING | VLC_VAR_ISCOMMAND );
@@ -307,10 +290,7 @@ void __vlc_object_set_destructor( vlc_object_t *p_this,
                                   vlc_destructor_t pf_destructor )
 {
     vlc_object_internals_t *p_priv = vlc_internals(p_this );
-
-    vlc_mutex_lock( &structure_lock );
     p_priv->pf_destructor = pf_destructor;
-    vlc_mutex_unlock( &structure_lock );
 }
 
 /**
@@ -325,9 +305,8 @@ static void vlc_object_destroy( vlc_object_t *p_this )
 {
     vlc_object_internals_t *p_priv = vlc_internals( p_this );
 
-    /* Automatically detach the object from its parents */
-    if( p_this->p_parent ) vlc_object_detach( p_this );
-
+    /* Objects are always detached beforehand */
+    assert( !p_this->p_parent );
 
     /* Send a kill to the object's thread if applicable */
     vlc_object_kill( p_this );
@@ -340,33 +319,6 @@ static void vlc_object_destroy( vlc_object_t *p_this )
     if( p_priv->pf_destructor )
         p_priv->pf_destructor( p_this );
 
-    /* Sanity checks */
-    if( p_this->i_children )
-    {
-        int i;
-
-        fprintf( stderr,
-                 "ERROR: cannot delete object (%i, %s) with %d children\n",
-                 p_this->i_object_id, p_this->psz_object_name,
-                 p_this->i_children );
-
-        for( i = 0; i < p_this->i_children; i++ )
-        {
-            fprintf( stderr,
-                     "ERROR: Remaining children object "
-                     "(id:%i, type:%s, name:%s)\n",
-                     p_this->pp_children[i]->i_object_id,
-                     p_this->pp_children[i]->psz_object_type,
-                     p_this->pp_children[i]->psz_object_name );
-        }
-        fflush(stderr);
-
-        /* Dump libvlc object to ease debugging */
-        vlc_object_dump( p_this->p_libvlc );
-
-        abort();
-    }
-
     /* Destroy the associated variables, starting from the end so that
      * no memmove calls have to be done. */
     while( p_priv->i_vars )
@@ -379,40 +331,37 @@ static void vlc_object_destroy( vlc_object_t *p_this )
 
     free( p_this->psz_header );
 
-    if( p_this->i_object_type == VLC_OBJECT_GLOBAL )
+    if( p_this->p_libvlc == NULL )
     {
         libvlc_global_data_t *p_global = (libvlc_global_data_t *)p_this;
 
+#ifndef NDEBUG
+        assert( p_global == vlc_global() );
         /* Test for leaks */
-        if( p_global->i_objects > 0 )
+        for( vlc_object_t *leaked = p_priv->next;
+             leaked != p_this;
+             leaked = vlc_internals (leaked)->next )
         {
-            int i;
-            for( i = 0; i < p_global->i_objects; i++ )
-            {
-                /* We are leaking this object */
-                fprintf( stderr,
-                         "ERROR: leaking object (id:%i, type:%s, name:%s)\n",
-                         p_global->pp_objects[i]->i_object_id,
-                         p_global->pp_objects[i]->psz_object_type,
-                         p_global->pp_objects[i]->psz_object_name );
-
-                /* Dump libvlc object to ease debugging */
-                vlc_object_dump( p_global->pp_objects[i] );
-
-                fflush(stderr);
-            }
+            /* We are leaking this object */
+            fprintf( stderr,
+                     "ERROR: leaking object (id:%i, type:%s, name:%s)\n",
+                     leaked->i_object_id, leaked->psz_object_type,
+                     leaked->psz_object_name );
+            /* Dump libvlc object to ease debugging */
+            vlc_object_dump( leaked );
+            fflush(stderr);
+        }
 
+        if( p_priv->next != p_this )
+        {
             /* Dump libvlc object to ease debugging */
             vlc_object_dump( p_this );
-
             /* Strongly abort, cause we want these to be fixed */
             abort();
         }
+#endif
 
         /* We are the global object ... no need to lock. */
-        free( p_global->pp_objects );
-        p_global->pp_objects = NULL;
-
         vlc_mutex_destroy( &structure_lock );
     }
 
@@ -420,10 +369,11 @@ static void vlc_object_destroy( vlc_object_t *p_this )
 
 #if defined(WIN32) || defined(UNDER_CE)
     /* if object has an associated thread, close it now */
-    if( p_priv->thread_id.hThread )
-       CloseHandle(p_priv->thread_id.hThread);
+    if( p_priv->thread_id )
+       CloseHandle(p_priv->thread_id);
 #endif
 
+    vlc_spin_destroy( &p_priv->ref_spin );
     vlc_mutex_destroy( &p_this->object_lock );
     vlc_cond_destroy( &p_this->object_wait );
     vlc_spin_destroy( &p_priv->spin );
@@ -667,8 +617,8 @@ void __vlc_object_kill( vlc_object_t *p_this )
     }
 
     if( p_this->i_object_type == VLC_OBJECT_LIBVLC )
-        for( int i = 0; i < p_this->i_children ; i++ )
-            vlc_object_kill( p_this->pp_children[i] );
+        for( int i = 0; i < internals->i_children ; i++ )
+            vlc_object_kill( internals->pp_children[i] );
 
     vlc_object_signal_unlocked( p_this );
     vlc_mutex_unlock( &p_this->object_lock );
@@ -676,67 +626,34 @@ void __vlc_object_kill( vlc_object_t *p_this )
 
 
 /**
- * find an object given its ID
+ * Find an object given its ID.
  *
- * This function looks for the object whose i_object_id field is i_id. We
- * use a dichotomy so that lookups are in log2(n).
- *****************************************************************************/
+ * This function looks for the object whose i_object_id field is i_id.
+ * This function is slow, and often used to hide bugs. Do not use it.
+ * If you need to retain reference to an object, yield the object pointer with
+ * vlc_object_yield(), use the pointer as your reference, and call
+ * vlc_object_release() when you're done.
+ */
 void * vlc_object_get( int i_id )
 {
-    int i_max, i_middle;
-    vlc_object_t **pp_objects;
     libvlc_global_data_t *p_libvlc_global = vlc_global();
+    vlc_object_t *obj = NULL;
 
     vlc_mutex_lock( &structure_lock );
 
-    pp_objects = p_libvlc_global->pp_objects;
-
-    /* Perform our dichotomy */
-    for( i_max = p_libvlc_global->i_objects - 1 ; ; )
+    for( obj = vlc_internals (p_libvlc_global)->next;
+         obj != VLC_OBJECT (p_libvlc_global);
+         obj = vlc_internals (obj)->next )
     {
-        i_middle = i_max / 2;
-
-        if( pp_objects[i_middle]->i_object_id > i_id )
-        {
-            i_max = i_middle;
-        }
-        else if( pp_objects[i_middle]->i_object_id < i_id )
+        if( obj->i_object_id == i_id )
         {
-            if( i_middle )
-            {
-                pp_objects += i_middle;
-                i_max -= i_middle;
-            }
-            else
-            {
-                /* This happens when there are only two remaining objects */
-                if( pp_objects[i_middle+1]->i_object_id == i_id
-                    && vlc_internals( pp_objects[i_middle+1] )->i_refcount > 0 )
-                {
-                    vlc_object_yield_locked( pp_objects[i_middle+1] );
-                    vlc_mutex_unlock( &structure_lock );
-                    return pp_objects[i_middle+1];
-                }
-                break;
-            }
-        }
-        else if( vlc_internals( pp_objects[i_middle] )->i_refcount > 0 )
-        {
-            vlc_object_yield_locked( pp_objects[i_middle] );
-            vlc_mutex_unlock( &structure_lock );
-            return pp_objects[i_middle];
-        }
-
-        if( i_max == 0 )
-        {
-            /* this means that i_max == i_middle, and since we have already
-             * tested pp_objects[i_middle]), p_found is properly set. */
-            break;
+            vlc_object_yield( obj );
+            return obj;
         }
     }
 
     vlc_mutex_unlock( &structure_lock );
-    return NULL;
+    return obj;
 }
 
 /**
@@ -750,43 +667,28 @@ void * __vlc_object_find( vlc_object_t *p_this, int i_type, int i_mode )
 {
     vlc_object_t *p_found;
 
-    vlc_mutex_lock( &structure_lock );
-
     /* If we are of the requested type ourselves, don't look further */
-    if( !(i_mode & FIND_STRICT) && p_this->i_object_type == i_type
-        && vlc_internals( p_this )->i_refcount > 0 )
+    if( !(i_mode & FIND_STRICT) && p_this->i_object_type == i_type )
     {
-        vlc_object_yield_locked( p_this );
-        vlc_mutex_unlock( &structure_lock );
+        vlc_object_yield( p_this );
         return p_this;
     }
 
     /* Otherwise, recursively look for the object */
-    if( (i_mode & 0x000f) == FIND_ANYWHERE )
-    {
-        vlc_object_t *p_root = p_this;
-
-        /* Find the root */
-        while( p_root->p_parent != NULL &&
-               p_root != VLC_OBJECT( p_this->p_libvlc ) )
-        {
-            p_root = p_root->p_parent;
-        }
-
-        p_found = FindObject( p_root, i_type, (i_mode & ~0x000f)|FIND_CHILD );
-        if( p_found == NULL && p_root != VLC_OBJECT( p_this->p_libvlc ) )
-        {
-            p_found = FindObject( VLC_OBJECT( p_this->p_libvlc ),
-                                  i_type, (i_mode & ~0x000f)|FIND_CHILD );
-        }
-    }
-    else
+    if ((i_mode & 0x000f) == FIND_ANYWHERE)
     {
-        p_found = FindObject( p_this, i_type, i_mode );
+#ifndef NDEBUG
+        if (i_type == VLC_OBJECT_PLAYLIST)
+           msg_Warn (p_this, "using vlc_object_find(VLC_OBJECT_PLAYLIST) "
+                      "instead of pl_Yield()");
+#endif
+        return vlc_object_find (p_this->p_libvlc, i_type,
+                                (i_mode & ~0x000f)|FIND_CHILD);
     }
 
+    vlc_mutex_lock( &structure_lock );
+    p_found = FindObject( p_this, i_type, i_mode );
     vlc_mutex_unlock( &structure_lock );
-
     return p_found;
 }
 
@@ -802,22 +704,17 @@ void * __vlc_object_find_name( vlc_object_t *p_this, const char *psz_name,
 {
     vlc_object_t *p_found;
 
-    vlc_mutex_lock( &structure_lock );
-
-    /* Avoid obvious freed object uses */
-    assert( vlc_internals( p_this )->i_refcount > 0 );
-
     /* If have the requested name ourselves, don't look further */
     if( !(i_mode & FIND_STRICT)
         && p_this->psz_object_name
-        && !strcmp( p_this->psz_object_name, psz_name )
-        && vlc_internals( p_this )->i_refcount > 0 )
+        && !strcmp( p_this->psz_object_name, psz_name ) )
     {
-        vlc_object_yield_locked( p_this );
-        vlc_mutex_unlock( &structure_lock );
+        vlc_object_yield( p_this );
         return p_this;
     }
 
+    vlc_mutex_lock( &structure_lock );
+
     /* Otherwise, recursively look for the object */
     if( (i_mode & 0x000f) == FIND_ANYWHERE )
     {
@@ -849,64 +746,74 @@ void * __vlc_object_find_name( vlc_object_t *p_this, const char *psz_name,
 }
 
 /**
- ****************************************************************************
- * increment an object refcount
- *****************************************************************************/
-
-/* When the structure_lock is locked */
-static void vlc_object_yield_locked( vlc_object_t *p_this )
+ * Increment an object reference counter.
+ */
+void __vlc_object_yield( vlc_object_t *p_this )
 {
-    vlc_assert_locked (&structure_lock);
+    vlc_object_internals_t *internals = vlc_internals( p_this );
 
+    vlc_spin_lock( &internals->ref_spin );
     /* Avoid obvious freed object uses */
-    assert( vlc_internals( p_this )->i_refcount > 0 );
-
+    assert( internals->i_refcount > 0 );
     /* Increment the counter */
-    vlc_internals( p_this )->i_refcount++;
-}
-
-/* Public function */
-void __vlc_object_yield( vlc_object_t *p_this )
-{
-    vlc_mutex_lock( &structure_lock );
-    vlc_object_yield_locked( p_this );
-    vlc_mutex_unlock( &structure_lock );
+    internals->i_refcount++;
+    vlc_spin_unlock( &internals->ref_spin );
 }
 
-
 /*****************************************************************************
  * decrement an object refcount
  * And destroy the object if its refcount reach zero.
  *****************************************************************************/
 void __vlc_object_release( vlc_object_t *p_this )
 {
+    vlc_object_internals_t *internals = vlc_internals( p_this );
     bool b_should_destroy;
 
-    vlc_mutex_lock( &structure_lock );
+    vlc_spin_lock( &internals->ref_spin );
+    assert( internals->i_refcount > 0 );
+
+    if( internals->i_refcount > 1 )
+    {
+        /* Fast path */
+        /* There are still other references to the object */
+        internals->i_refcount--;
+        vlc_spin_unlock( &internals->ref_spin );
+        return;
+    }
+    vlc_spin_unlock( &internals->ref_spin );
 
-    assert( vlc_internals( p_this )->i_refcount > 0 );
-    vlc_internals( p_this )->i_refcount--;
-    b_should_destroy = (vlc_internals( p_this )->i_refcount == 0);
+    /* Slow path */
+    /* Remember that we cannot hold the spin while waiting on the mutex */
+    vlc_mutex_lock( &structure_lock );
+    /* Take the spin again. Note that another thread may have yielded the
+     * object in the (very short) mean time. */
+    vlc_spin_lock( &internals->ref_spin );
+    b_should_destroy = --internals->i_refcount == 0;
+    vlc_spin_unlock( &internals->ref_spin );
 
     if( b_should_destroy )
     {
-        /* Make sure this object can't be obtained via vlc_find_object now that
-         * it is freed */
-        libvlc_global_data_t *p_libvlc_global = vlc_global();
-        int i_index;
-
-        /* Wooohaa! If *this* fails, we're in serious trouble! Anyway it's
-         * useless to try and recover anything if pp_objects gets smashed. */
-        i_index = FindIndex( p_this, p_libvlc_global->pp_objects,
-                             p_libvlc_global->i_objects );
-        REMOVE_ELEM( p_libvlc_global->pp_objects,
-                     p_libvlc_global->i_objects, i_index );
+        /* Remove the object from object list
+         * so that it cannot be encountered by vlc_object_get() */
+        vlc_internals (internals->next)->prev = internals->prev;
+        vlc_internals (internals->prev)->next = internals->next;
+
+        /* Detach from parent to protect against FIND_CHILDREN */
+        vlc_object_detach_unlocked (p_this);
+        /* Detach from children to protect against FIND_PARENT */
+        for (int i = 0; i < internals->i_children; i++)
+            internals->pp_children[i]->p_parent = NULL;
     }
 
     vlc_mutex_unlock( &structure_lock );
 
     if( b_should_destroy )
+    {
+        free( internals->pp_children );
+        internals->pp_children = NULL;
+        internals->i_children = 0;
         vlc_object_destroy( p_this );
+    }
 }
 
 /**
@@ -922,25 +829,58 @@ void __vlc_object_attach( vlc_object_t *p_this, vlc_object_t *p_parent )
 
     vlc_mutex_lock( &structure_lock );
 
-    /* Avoid obvious freed object uses */
-    assert( vlc_internals( p_this )->i_refcount > 0 );
-
     /* Attach the parent to its child */
+    assert (!p_this->p_parent);
     p_this->p_parent = p_parent;
 
     /* Attach the child to its parent */
-    INSERT_ELEM( p_parent->pp_children, p_parent->i_children,
-                 p_parent->i_children, p_this );
+    vlc_object_internals_t *priv = vlc_internals( p_parent );
+    INSERT_ELEM( priv->pp_children, priv->i_children, priv->i_children,
+                 p_this );
+
+    vlc_mutex_unlock( &structure_lock );
+}
+
+
+static void vlc_object_detach_unlocked (vlc_object_t *p_this)
+{
+    vlc_assert_locked (&structure_lock);
+
+    if (p_this->p_parent == NULL)
+        return;
+
+    vlc_object_internals_t *priv = vlc_internals( p_this->p_parent );
+
+    int i_index, i;
 
-    /* Climb up the tree to see whether we are connected with the root */
-    if( vlc_internals( p_parent )->b_attached )
+    /* Remove p_this's parent */
+    p_this->p_parent = NULL;
+
+    /* Remove all of p_parent's children which are p_this */
+    for( i_index = priv->i_children ; i_index-- ; )
     {
-        SetAttachment( p_this, true );
+        if( priv->pp_children[i_index] == p_this )
+        {
+            priv->i_children--;
+            for( i = i_index ; i < priv->i_children ; i++ )
+                priv->pp_children[i] = priv->pp_children[i+1];
+        }
     }
 
-    vlc_mutex_unlock( &structure_lock );
+    if( priv->i_children )
+    {
+        priv->pp_children = (vlc_object_t **)realloc( priv->pp_children,
+                               priv->i_children * sizeof(vlc_object_t *) );
+    }
+    else
+    {
+        /* Special case - don't realloc() to zero to avoid leaking */
+        free( priv->pp_children );
+        priv->pp_children = NULL;
+    }
 }
 
+
 /**
  ****************************************************************************
  * detach object from its parent
@@ -952,25 +892,14 @@ void __vlc_object_detach( vlc_object_t *p_this )
     if( !p_this ) return;
 
     vlc_mutex_lock( &structure_lock );
-
     if( !p_this->p_parent )
-    {
         msg_Err( p_this, "object is not attached" );
-        vlc_mutex_unlock( &structure_lock );
-        return;
-    }
-
-    /* Climb up the tree to see whether we are connected with the root */
-    if( vlc_internals( p_this->p_parent )->b_attached )
-    {
-        SetAttachment( p_this, false );
-    }
-
-    DetachObject( p_this );
+    else
+        vlc_object_detach_unlocked( p_this );
     vlc_mutex_unlock( &structure_lock );
-    p_this = NULL;
 }
 
+
 /**
  ****************************************************************************
  * find a list typed objects and increment their refcount
@@ -981,43 +910,22 @@ void __vlc_object_detach( vlc_object_t *p_this )
 vlc_list_t * __vlc_list_find( vlc_object_t *p_this, int i_type, int i_mode )
 {
     vlc_list_t *p_list;
-    vlc_object_t **pp_current, **pp_end;
-    int i_count = 0, i_index = 0;
-    libvlc_global_data_t *p_libvlc_global = vlc_global();
-
-    vlc_mutex_lock( &structure_lock );
+    int i_count = 0;
 
     /* Look for the objects */
     switch( i_mode & 0x000f )
     {
     case FIND_ANYWHERE:
-        pp_current = p_libvlc_global->pp_objects;
-        pp_end = pp_current + p_libvlc_global->i_objects;
-
-        for( ; pp_current < pp_end ; pp_current++ )
-        {
-            if( vlc_internals(*pp_current)->b_attached
-                 && (*pp_current)->i_object_type == i_type )
-            {
-                i_count++;
-            }
-        }
-
-        p_list = NewList( i_count );
-        pp_current = p_libvlc_global->pp_objects;
-
-        for( ; pp_current < pp_end ; pp_current++ )
-        {
-            if( vlc_internals(*pp_current)->b_attached
-                 && (*pp_current)->i_object_type == i_type )
-            {
-                ListReplace( p_list, *pp_current, i_index );
-                if( i_index < i_count ) i_index++;
-            }
-        }
-    break;
+        /* Modules should probably not be object, and the module should perhaps
+         * not be shared across LibVLC instances. In the mean time, this ugly
+         * hack is brought to you by Courmisch. */
+        if (i_type == VLC_OBJECT_MODULE)
+            return vlc_list_find ((vlc_object_t *)vlc_global ()->p_module_bank,
+                                  i_type, FIND_CHILD);
+        return vlc_list_find (p_this->p_libvlc, i_type, FIND_CHILD);
 
     case FIND_CHILD:
+        vlc_mutex_lock( &structure_lock );
         i_count = CountChildren( p_this, i_type );
         p_list = NewList( i_count );
 
@@ -1031,6 +939,7 @@ vlc_list_t * __vlc_list_find( vlc_object_t *p_this, int i_type, int i_mode )
 
         p_list->i_count = 0;
         ListChildren( p_list, p_this, i_type );
+        vlc_mutex_unlock( &structure_lock );
         break;
 
     default:
@@ -1039,11 +948,30 @@ vlc_list_t * __vlc_list_find( vlc_object_t *p_this, int i_type, int i_mode )
         break;
     }
 
-    vlc_mutex_unlock( &structure_lock );
-
     return p_list;
 }
 
+/**
+ * Gets the list of children of an objects, and increment their reference
+ * count.
+ * @return a list (possibly empty) or NULL in case of error.
+ */
+vlc_list_t *__vlc_list_children( vlc_object_t *obj )
+{
+    vlc_list_t *l;
+    vlc_object_internals_t *priv = vlc_internals( obj );
+
+    vlc_mutex_lock( &structure_lock );
+    l = NewList( priv->i_children );
+    for (int i = 0; i < l->i_count; i++)
+    {
+        vlc_object_yield( priv->pp_children[i] );
+        l->p_values[i].p_object = priv->pp_children[i];
+    }
+    vlc_mutex_unlock( &structure_lock );
+    return l;
+}
+
 /*****************************************************************************
  * DumpCommand: print the current vlc structure
  *****************************************************************************
@@ -1054,32 +982,18 @@ vlc_list_t * __vlc_list_find( vlc_object_t *p_this, int i_type, int i_mode )
 static int DumpCommand( vlc_object_t *p_this, char const *psz_cmd,
                         vlc_value_t oldval, vlc_value_t newval, void *p_data )
 {
-    libvlc_global_data_t *p_libvlc_global = vlc_global();
-
     (void)oldval; (void)p_data;
     if( *psz_cmd == 'l' )
     {
-        vlc_mutex_lock( &structure_lock );
+        vlc_object_t *root = VLC_OBJECT (vlc_global ()), *cur = root; 
 
-        vlc_object_t **pp_current, **pp_end;
-
-        pp_current = p_libvlc_global->pp_objects;
-        pp_end = pp_current + p_libvlc_global->i_objects;
-
-        for( ; pp_current < pp_end ; pp_current++ )
+        vlc_mutex_lock( &structure_lock );
+        do
         {
-            if( vlc_internals(*pp_current)->b_attached )
-            {
-                PrintObject( *pp_current, "" );
-            }
-            else
-            {
-                printf( " o %.8i %s (not attached)\n",
-                        (*pp_current)->i_object_id,
-                        (*pp_current)->psz_object_type );
-            }
+            PrintObject (cur, "");
+            cur = vlc_internals (cur)->next;
         }
-
+        while (cur != root);
         vlc_mutex_unlock( &structure_lock );
     }
     else
@@ -1254,46 +1168,6 @@ void __vlc_object_dump( vlc_object_t *p_this )
 
 /* Following functions are local */
 
-/*****************************************************************************
- * FindIndex: find the index of an object in an array of objects
- *****************************************************************************
- * This function assumes that p_this can be found in pp_objects. It will not
- * crash if p_this cannot be found, but will return a wrong value. It is your
- * duty to check the return value if you are not certain that the object could
- * be found for sure.
- *****************************************************************************/
-static int FindIndex( vlc_object_t *p_this,
-                      vlc_object_t **pp_objects, int i_count )
-{
-    int i_middle = i_count / 2;
-
-    if( i_count == 0 )
-    {
-        return 0;
-    }
-
-    if( pp_objects[i_middle] == p_this )
-    {
-        return i_middle;
-    }
-
-    if( i_count == 1 )
-    {
-        return 0;
-    }
-
-    /* We take advantage of the sorted array */
-    if( pp_objects[i_middle]->i_object_id < p_this->i_object_id )
-    {
-        return i_middle + FindIndex( p_this, pp_objects + i_middle,
-                                             i_count - i_middle );
-    }
-    else
-    {
-        return FindIndex( p_this, pp_objects, i_middle );
-    }
-}
-
 static vlc_object_t * FindObject( vlc_object_t *p_this, int i_type, int i_mode )
 {
     int i;
@@ -1305,10 +1179,9 @@ static vlc_object_t * FindObject( vlc_object_t *p_this, int i_type, int i_mode )
         p_tmp = p_this->p_parent;
         if( p_tmp )
         {
-            if( p_tmp->i_object_type == i_type
-                && vlc_internals( p_tmp )->i_refcount > 0 )
+            if( p_tmp->i_object_type == i_type )
             {
-                vlc_object_yield_locked( p_tmp );
+                vlc_object_yield( p_tmp );
                 return p_tmp;
             }
             else
@@ -1319,16 +1192,15 @@ static vlc_object_t * FindObject( vlc_object_t *p_this, int i_type, int i_mode )
         break;
 
     case FIND_CHILD:
-        for( i = p_this->i_children; i--; )
+        for( i = vlc_internals( p_this )->i_children; i--; )
         {
-            p_tmp = p_this->pp_children[i];
-            if( p_tmp->i_object_type == i_type
-                && vlc_internals( p_tmp )->i_refcount > 0 )
+            p_tmp = vlc_internals( p_this )->pp_children[i];
+            if( p_tmp->i_object_type == i_type )
             {
-                vlc_object_yield_locked( p_tmp );
+                vlc_object_yield( p_tmp );
                 return p_tmp;
             }
-            else if( p_tmp->i_children )
+            else if( vlc_internals( p_tmp )->i_children )
             {
                 p_tmp = FindObject( p_tmp, i_type, i_mode );
                 if( p_tmp )
@@ -1361,10 +1233,9 @@ static vlc_object_t * FindObjectName( vlc_object_t *p_this,
         if( p_tmp )
         {
             if( p_tmp->psz_object_name
-                && !strcmp( p_tmp->psz_object_name, psz_name )
-                && vlc_internals( p_tmp )->i_refcount > 0 )
+                && !strcmp( p_tmp->psz_object_name, psz_name ) )
             {
-                vlc_object_yield_locked( p_tmp );
+                vlc_object_yield( p_tmp );
                 return p_tmp;
             }
             else
@@ -1375,17 +1246,16 @@ static vlc_object_t * FindObjectName( vlc_object_t *p_this,
         break;
 
     case FIND_CHILD:
-        for( i = p_this->i_children; i--; )
+        for( i = vlc_internals( p_this )->i_children; i--; )
         {
-            p_tmp = p_this->pp_children[i];
+            p_tmp = vlc_internals( p_this )->pp_children[i];
             if( p_tmp->psz_object_name
-                && !strcmp( p_tmp->psz_object_name, psz_name )
-                && vlc_internals( p_tmp )->i_refcount > 0 )
+                && !strcmp( p_tmp->psz_object_name, psz_name ) )
             {
-                vlc_object_yield_locked( p_tmp );
+                vlc_object_yield( p_tmp );
                 return p_tmp;
             }
-            else if( p_tmp->i_children )
+            else if( vlc_internals( p_tmp )->i_children )
             {
                 p_tmp = FindObjectName( p_tmp, psz_name, i_mode );
                 if( p_tmp )
@@ -1404,56 +1274,6 @@ static vlc_object_t * FindObjectName( vlc_object_t *p_this,
     return NULL;
 }
 
-static void DetachObject( vlc_object_t *p_this )
-{
-    vlc_object_t *p_parent = p_this->p_parent;
-    int i_index, i;
-
-    /* Remove p_this's parent */
-    p_this->p_parent = NULL;
-
-    /* Remove all of p_parent's children which are p_this */
-    for( i_index = p_parent->i_children ; i_index-- ; )
-    {
-        if( p_parent->pp_children[i_index] == p_this )
-        {
-            p_parent->i_children--;
-            for( i = i_index ; i < p_parent->i_children ; i++ )
-            {
-                p_parent->pp_children[i] = p_parent->pp_children[i+1];
-            }
-        }
-    }
-
-    if( p_parent->i_children )
-    {
-        p_parent->pp_children = (vlc_object_t **)realloc( p_parent->pp_children,
-                               p_parent->i_children * sizeof(vlc_object_t *) );
-    }
-    else
-    {
-        free( p_parent->pp_children );
-        p_parent->pp_children = NULL;
-    }
-}
-
-/*****************************************************************************
- * SetAttachment: recursively set the b_attached flag of a subtree.
- *****************************************************************************
- * This function is used by the attach and detach functions to propagate
- * the b_attached flag in a subtree.
- *****************************************************************************/
-static void SetAttachment( vlc_object_t *p_this, bool b_attached )
-{
-    int i_index;
-
-    for( i_index = p_this->i_children ; i_index-- ; )
-    {
-        SetAttachment( p_this->pp_children[i_index], b_attached );
-    }
-
-    vlc_internals( p_this )->b_attached = b_attached;
-}
 
 static void PrintObject( vlc_object_t *p_this, const char *psz_prefix )
 {
@@ -1469,7 +1289,7 @@ static void PrintObject( vlc_object_t *p_this, const char *psz_prefix )
     }
 
     psz_children[0] = '\0';
-    switch( p_this->i_children )
+    switch( vlc_internals( p_this )->i_children )
     {
         case 0:
             break;
@@ -1477,7 +1297,8 @@ static void PrintObject( vlc_object_t *p_this, const char *psz_prefix )
             strcpy( psz_children, ", 1 child" );
             break;
         default:
-            snprintf( psz_children, 19, ", %i children", p_this->i_children );
+            snprintf( psz_children, 19, ", %i children",
+                      vlc_internals( p_this )->i_children );
             break;
     }
 
@@ -1488,12 +1309,8 @@ static void PrintObject( vlc_object_t *p_this, const char *psz_prefix )
 
     psz_thread[0] = '\0';
     if( vlc_internals( p_this )->b_thread )
-        snprintf( psz_thread, 29, " (thread %u)",
-#if defined(WIN32) || defined(UNDER_CE)
-                  (unsigned)vlc_internals( p_this )->thread_id.id );
-#else
-                  (unsigned)vlc_internals( p_this )->thread_id );
-#endif
+        snprintf( psz_thread, 29, " (thread %lu)",
+                  (unsigned long)vlc_internals( p_this )->thread_id );
 
     psz_parent[0] = '\0';
     if( p_this->p_parent )
@@ -1521,7 +1338,7 @@ static void DumpStructure( vlc_object_t *p_this, int i_level, char *psz_foo )
         return;
     }
 
-    for( i = 0 ; i < p_this->i_children ; i++ )
+    for( i = 0 ; i < vlc_internals( p_this )->i_children ; i++ )
     {
         if( i_level )
         {
@@ -1533,7 +1350,7 @@ static void DumpStructure( vlc_object_t *p_this, int i_level, char *psz_foo )
             }
         }
 
-        if( i == p_this->i_children - 1 )
+        if( i == vlc_internals( p_this )->i_children - 1 )
         {
             psz_foo[i_level] = '`';
         }
@@ -1545,7 +1362,8 @@ static void DumpStructure( vlc_object_t *p_this, int i_level, char *psz_foo )
         psz_foo[i_level+1] = '-';
         psz_foo[i_level+2] = '\0';
 
-        DumpStructure( p_this->pp_children[i], i_level + 2, psz_foo );
+        DumpStructure( vlc_internals( p_this )->pp_children[i], i_level + 2,
+                       psz_foo );
     }
 }
 
@@ -1583,7 +1401,7 @@ static void ListReplace( vlc_list_t *p_list, vlc_object_t *p_object,
         return;
     }
 
-    vlc_object_yield_locked( p_object );
+    vlc_object_yield( p_object );
 
     p_list->p_values[i_index].p_object = p_object;
 
@@ -1605,7 +1423,7 @@ static void ListReplace( vlc_list_t *p_list, vlc_object_t *p_object,
         return;
     }
 
-    vlc_object_yield_locked( p_object );
+    vlc_object_yield( p_object );
 
     p_list->p_values[p_list->i_count].p_object = p_object;
     p_list->i_count++;
@@ -1618,19 +1436,15 @@ static int CountChildren( vlc_object_t *p_this, int i_type )
     vlc_object_t *p_tmp;
     int i, i_count = 0;
 
-    for( i = 0; i < p_this->i_children; i++ )
+    for( i = 0; i < vlc_internals( p_this )->i_children; i++ )
     {
-        p_tmp = p_this->pp_children[i];
+        p_tmp = vlc_internals( p_this )->pp_children[i];
 
         if( p_tmp->i_object_type == i_type )
         {
             i_count++;
         }
-
-        if( p_tmp->i_children )
-        {
-            i_count += CountChildren( p_tmp, i_type );
-        }
+        i_count += CountChildren( p_tmp, i_type );
     }
 
     return i_count;
@@ -1641,18 +1455,13 @@ static void ListChildren( vlc_list_t *p_list, vlc_object_t *p_this, int i_type )
     vlc_object_t *p_tmp;
     int i;
 
-    for( i = 0; i < p_this->i_children; i++ )
+    for( i = 0; i < vlc_internals( p_this )->i_children; i++ )
     {
-        p_tmp = p_this->pp_children[i];
+        p_tmp = vlc_internals( p_this )->pp_children[i];
 
         if( p_tmp->i_object_type == i_type )
-        {
             ListReplace( p_list, p_tmp, p_list->i_count++ );
-        }
 
-        if( p_tmp->i_children )
-        {
-            ListChildren( p_list, p_tmp, i_type );
-        }
+        ListChildren( p_list, p_tmp, i_type );
     }
 }