/**
* gst_mini_object_unlock:
* @object: the mini-object to unlock
* @flags: #GstLockFlags
*
* Unlock the mini-object with the specified access mode in @flags.
*/
void
gst_mini_object_unlock (GstMiniObject * object, GstLockFlags flags)
{
gint access_mode, state, newstate;
g_return_if_fail (object != NULL);
g_return_if_fail (GST_MINI_OBJECT_IS_LOCKABLE (object));
do {
access_mode = flags & FLAG_MASK;
newstate = state = g_atomic_int_get (&object->lockstate);
GST_CAT_TRACE (GST_CAT_LOCKING, "unlock %p: state %08x, access_mode %d",
object, state, access_mode);
if (access_mode & GST_LOCK_FLAG_EXCLUSIVE) {
/* shared counter */
g_return_if_fail (state >= SHARE_ONE);
newstate -= SHARE_ONE;
access_mode &= ~GST_LOCK_FLAG_EXCLUSIVE;
}
if (access_mode) {
g_return_if_fail ((state & access_mode) == access_mode);
/* decrease the refcount */
newstate -= LOCK_ONE;
/* last refcount, unset access_mode */
if ((newstate & LOCK_FLAG_MASK) == access_mode)
newstate &= ~LOCK_FLAG_MASK;
}
} while (!g_atomic_int_compare_and_exchange (&object->lockstate, state,
newstate));
}
/**
* gst_mini_object_lock:
* @object: the mini-object to lock
* @flags: #GstLockFlags
*
* Lock the mini-object with the specified access mode in @flags.
*
* Returns: %TRUE if @object could be locked.
*/
gboolean
gst_mini_object_lock (GstMiniObject * object, GstLockFlags flags)
{
gint access_mode, state, newstate;
g_return_val_if_fail (object != NULL, FALSE);
g_return_val_if_fail (GST_MINI_OBJECT_IS_LOCKABLE (object), FALSE);
if (G_UNLIKELY (object->flags & GST_MINI_OBJECT_FLAG_LOCK_READONLY &&
flags & GST_LOCK_FLAG_WRITE))
return FALSE;
do {
access_mode = flags & FLAG_MASK;
newstate = state = g_atomic_int_get (&object->lockstate);
GST_CAT_TRACE (GST_CAT_LOCKING, "lock %p: state %08x, access_mode %d",
object, state, access_mode);
if (access_mode & GST_LOCK_FLAG_EXCLUSIVE) {
/* shared ref */
newstate += SHARE_ONE;
access_mode &= ~GST_LOCK_FLAG_EXCLUSIVE;
}
/* shared counter > 1 and write access is not allowed */
if (((state & GST_LOCK_FLAG_WRITE) != 0
|| (access_mode & GST_LOCK_FLAG_WRITE) != 0)
&& IS_SHARED (newstate))
goto lock_failed;
if (access_mode) {
if ((state & LOCK_FLAG_MASK) == 0) {
/* nothing mapped, set access_mode */
newstate |= access_mode;
} else {
/* access_mode must match */
if ((state & access_mode) != access_mode)
goto lock_failed;
}
/* increase refcount */
newstate += LOCK_ONE;
}
} while (!g_atomic_int_compare_and_exchange (&object->lockstate, state,
newstate));
return TRUE;
lock_failed:
{
GST_CAT_DEBUG (GST_CAT_LOCKING,
"lock failed %p: state %08x, access_mode %d", object, state,
access_mode);
return FALSE;
}
}
/**
* gst_mini_object_is_writable:
* @mini_object: the mini-object to check
*
* If @mini_object has the LOCKABLE flag set, check if the current EXCLUSIVE
* lock on @object is the only one, this means that changes to the object will
* not be visible to any other object.
*
* If the LOCKABLE flag is not set, check if the refcount of @mini_object is
* exactly 1, meaning that no other reference exists to the object and that the
* object is therefore writable.
*
* Modification of a mini-object should only be done after verifying that it
* is writable.
*
* Returns: TRUE if the object is writable.
*/
gboolean
gst_mini_object_is_writable (const GstMiniObject * mini_object)
{
gboolean result;
g_return_val_if_fail (mini_object != NULL, FALSE);
if (GST_MINI_OBJECT_IS_LOCKABLE (mini_object)) {
result = !IS_SHARED (g_atomic_int_get (&mini_object->lockstate));
} else {
result = (GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) == 1);
}
return result;
}
