/*****************************************************************************
* 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 );
vlc_object_t *parent = NULL;
bool b_should_destroy;
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 );
/* Slow path */
/* Remember that we cannot hold the spin while waiting on the mutex */
libvlc_lock (p_this->p_libvlc);
/* Take the spin again. Note that another thread may have held 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 )
{
/* Detach from parent to protect against FIND_CHILDREN */
parent = p_this->p_parent;
if (likely(parent))
{
/* Unlink */
if (internals->prev != NULL)
internals->prev->next = internals->next;
else
vlc_internals(parent)->first = internals->next;
if (internals->next != NULL)
internals->next->prev = internals->prev;
}
/* We have no children */
assert (internals->first == NULL);
}
libvlc_unlock (p_this->p_libvlc);
if( b_should_destroy )
{
int canc;
canc = vlc_savecancel ();
vlc_object_destroy( p_this );
vlc_restorecancel (canc);
if (parent)
vlc_object_release (parent);
}
}
/**
****************************************************************************
* detach object from its parent
*****************************************************************************
* This function removes all links between an object and its parent.
*****************************************************************************/
void vlc_object_detach( vlc_object_t *p_this )
{
vlc_object_t *p_parent;
if( !p_this ) return;
libvlc_lock (p_this->p_libvlc);
p_parent = p_this->p_parent;
if (p_parent)
vlc_object_detach_unlocked( p_this );
libvlc_unlock (p_this->p_libvlc);
if (p_parent)
vlc_object_release (p_parent);
}
/*****************************************************************************
* DumpCommand: print the current vlc structure
*****************************************************************************
* This function prints either an ASCII tree showing the connections between
* vlc objects, and additional information such as their refcount, thread ID,
* etc. (command "tree"), or the same data as a simple list (command "list").
*****************************************************************************/
static int DumpCommand( vlc_object_t *p_this, char const *psz_cmd,
vlc_value_t oldval, vlc_value_t newval, void *p_data )
{
(void)oldval; (void)p_data;
vlc_object_t *p_object = NULL;
if( *newval.psz_string )
{
/* try using the object's name to find it */
p_object = vlc_object_find_name( p_this, newval.psz_string,
FIND_ANYWHERE );
if( !p_object )
{
return VLC_ENOOBJ;
}
}
libvlc_lock (p_this->p_libvlc);
if( *psz_cmd == 't' )
{
char psz_foo[2 * MAX_DUMPSTRUCTURE_DEPTH + 1];
if( !p_object )
p_object = VLC_OBJECT(p_this->p_libvlc);
psz_foo[0] = '|';
DumpStructure( vlc_internals(p_object), 0, psz_foo );
}
else if( *psz_cmd == 'v' )
{
if( !p_object )
p_object = p_this->p_libvlc ? VLC_OBJECT(p_this->p_libvlc) : p_this;
PrintObject( vlc_internals(p_object), "" );
vlc_mutex_lock( &vlc_internals( p_object )->var_lock );
if( vlc_internals( p_object )->var_root == NULL )
puts( " `-o No variables" );
else
twalk( vlc_internals( p_object )->var_root, DumpVariable );
vlc_mutex_unlock( &vlc_internals( p_object )->var_lock );
}
libvlc_unlock (p_this->p_libvlc);
if( *newval.psz_string )
{
vlc_object_release( p_object );
}
return VLC_SUCCESS;
}
/*****************************************************************************
* find a typed object and increment its refcount
*****************************************************************************
* This function recursively looks for a given object type. i_mode can be one
* of FIND_PARENT, FIND_CHILD or FIND_ANYWHERE.
*****************************************************************************/
void * vlc_object_find( vlc_object_t *p_this, int i_type, int i_mode )
{
vlc_object_t *p_found;
/* If we are of the requested type ourselves, don't look further */
if( vlc_internals (p_this)->i_object_type == i_type )
{
vlc_object_hold( p_this );
return p_this;
}
/* Otherwise, recursively look for the object */
if (i_mode == FIND_ANYWHERE)
return vlc_object_find (VLC_OBJECT(p_this->p_libvlc), i_type, FIND_CHILD);
switch (i_type)
{
case VLC_OBJECT_VOUT:
case VLC_OBJECT_AOUT:
break;
case VLC_OBJECT_INPUT:
/* input can only be accessed like this from children,
* otherwise we could not promise that it is initialized */
if (i_mode != FIND_PARENT)
return NULL;
break;
default:
return NULL;
}
libvlc_lock (p_this->p_libvlc);
switch (i_mode)
{
case FIND_PARENT:
p_found = FindParent (p_this, i_type);
break;
case FIND_CHILD:
p_found = FindChild (vlc_internals (p_this), i_type);
break;
default:
assert (0);
}
libvlc_unlock (p_this->p_libvlc);
return p_found;
}
/**
****************************************************************************
* attach object to a parent object
*****************************************************************************
* This function sets p_this as a child of p_parent, and p_parent as a parent
* of p_this. This link can be undone using vlc_object_detach.
*****************************************************************************/
void vlc_object_attach( vlc_object_t *p_this, vlc_object_t *p_parent )
{
if( !p_this ) return;
vlc_object_internals_t *pap = vlc_internals (p_parent);
vlc_object_internals_t *priv = vlc_internals (p_this);
vlc_object_t *p_old_parent;
priv->prev = NULL;
vlc_object_hold (p_parent);
libvlc_lock (p_this->p_libvlc);
#ifndef NDEBUG
/* Reparenting an object carries a risk of invalid access to the parent,
* from another thread. This can happen when inheriting a variable, or
* through any direct access to vlc_object_t.p_parent. Also, reparenting
* brings a functional bug, whereby the reparented object uses incorrect
* old values for inherited variables (as the new parent may have different
* variable values, especially if it is an input).
* Note that the old parent may be already destroyed.
* So its pointer must not be dereferenced.
*/
if (priv->old_parent)
msg_Info (p_this, "Reparenting an object is dangerous (%p -> %p)!",
priv->old_parent, p_parent);
#endif
p_old_parent = p_this->p_parent;
if (p_old_parent)
vlc_object_detach_unlocked (p_this);
/* Attach the parent to its child */
p_this->p_parent = p_parent;
/* Attach the child to its parent */
priv->next = pap->first;
if (priv->next != NULL)
priv->next->prev = priv;
pap->first = priv;
libvlc_unlock (p_this->p_libvlc);
if (p_old_parent)
vlc_object_release (p_old_parent);
}
/**
* 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;
unsigned count = 0;
libvlc_lock (obj->p_libvlc);
for (priv = vlc_internals (obj)->first; priv; priv = priv->next)
count++;
l = NewList (count);
if (likely(l != NULL))
{
unsigned i = 0;
for (priv = vlc_internals (obj)->first; priv; priv = priv->next)
l->p_values[i++].p_object = vlc_object_hold (vlc_externals (priv));
}
libvlc_unlock (obj->p_libvlc);
return l;
}
/**
****************************************************************************
* attach object to a parent object
*****************************************************************************
* This function sets p_this as a child of p_parent, and p_parent as a parent
* of p_this.
*****************************************************************************/
void vlc_object_attach( vlc_object_t *p_this, vlc_object_t *p_parent )
{
if( !p_this ) return;
vlc_object_internals_t *pap = vlc_internals (p_parent);
vlc_object_internals_t *priv = vlc_internals (p_this);
priv->prev = NULL;
vlc_object_hold (p_parent);
libvlc_lock (p_this->p_libvlc);
/* Attach the parent to its child */
assert (p_this->p_parent == NULL);
p_this->p_parent = p_parent;
/* Attach the child to its parent */
priv->next = pap->first;
if (priv->next != NULL)
priv->next->prev = priv;
pap->first = priv;
libvlc_unlock (p_this->p_libvlc);
}
/**
* Finds a named object and increment its reference count.
* Beware that objects found in this manner can be "owned" by another thread,
* be of _any_ type, and be attached to any module (if any). With such an
* object reference, you can set or get object variables, emit log messages,
* and read write-once object parameters (psz_object_type, etc).
* You CANNOT cast the object to a more specific object type, and you
* definitely cannot invoke object type-specific callbacks with this.
*
* @param p_this object to search from
* @param psz_name name of the object to search for
* @param i_mode search direction: FIND_PARENT, FIND_CHILD or FIND_ANYWHERE.
*
* @return a matching object (must be released by the caller),
* or NULL on error.
*/
vlc_object_t *vlc_object_find_name( vlc_object_t *p_this,
const char *psz_name, int i_mode )
{
vlc_object_t *p_found;
/* Reading psz_object_name from a separate inhibits thread-safety.
* Use a libvlc address variable instead for that sort of things! */
msg_Warn( p_this, "%s(%s) is not safe!", __func__, psz_name );
/* If have the requested name ourselves, don't look further */
if( !objnamecmp(p_this, psz_name) )
{
vlc_object_hold( p_this );
return p_this;
}
/* Otherwise, recursively look for the object */
if (i_mode == FIND_ANYWHERE)
return vlc_object_find_name (VLC_OBJECT(p_this->p_libvlc), psz_name,
FIND_CHILD);
libvlc_lock (p_this->p_libvlc);
vlc_mutex_lock (&name_lock);
switch (i_mode)
{
case FIND_PARENT:
p_found = FindParentName (p_this, psz_name);
break;
case FIND_CHILD:
p_found = FindChildName (vlc_internals (p_this), psz_name);
break;
default:
assert (0);
}
vlc_mutex_unlock (&name_lock);
libvlc_unlock (p_this->p_libvlc);
return p_found;
}
