File indexing completed on 2024-05-12 15:56:58

 /*
  *  SPDX-FileCopyrightText: 2006 Cyrille Berger <cberger@cberger.net>
  *
  *  SPDX-License-Identifier: GPL-2.0-or-later
  */
 
 #include "kis_shared.h"
 #include "kis_debug.h"
 
 
 /**
  * NOTE: The description of how Weak shared pointers system works:
  *
  * Every KisShared object has his own _sharedWeakReference pointer.
  * This pointer holds QAtomicInt counter. When KisShared constructs
  * itself, it increments _sharedWeakReference by one. When it dies -
  * it decrements it. This is the only way how the number in the
  * counter can become odd. Obviously, when the number falls to zero,
  * the counter object is deleted.
  *
  * When a weak shared pointer is created, it gets the pointer and
  * increments the counter by 2, so the parity of the number is kept
  * unchanged. Now the counter is shared between the KisShared and
  * KisWeakSharedPtr and the latter one can check the correctness
  * of the pointer by checking parity!
  */
 
 KisShared::KisShared()
 {
     /**
      * We can defer creation of a weak reference until
      * better days... It gives us 41% better performance. ;)
      */
     _sharedWeakReference = 0;
 }
 
 KisShared::~KisShared()
 {
     /**
      * Check no-one references us
      */
     Q_ASSERT(_ref == 0);
 
     if(_sharedWeakReference && !_sharedWeakReference->deref())
         delete _sharedWeakReference;
 }