include/QtCore/qrefcount.h

0001 // Copyright (C) 2016 The Qt Company Ltd.
0002 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
0003
0004 #ifndef QREFCOUNT_H
0005 #define QREFCOUNT_H
0006
0007 #include <QtCore/qatomic.h>
0008
0009 QT_BEGIN_NAMESPACE
0010
0011
0012 namespace QtPrivate
0013 {
0014
0015 class RefCount
0016 {
0017 public:
0018     inline bool ref() noexcept {
0019         int count = atomic.loadRelaxed();
0020         if (count != -1) // !isStatic
0021             atomic.ref();
0022         return true;
0023     }
0024
0025     inline bool deref() noexcept {
0026         int count = atomic.loadRelaxed();
0027         if (count == -1) // isStatic
0028             return true;
0029         return atomic.deref();
0030     }
0031
0032     bool isStatic() const noexcept
0033     {
0034         // Persistent object, never deleted
0035         return atomic.loadRelaxed() == -1;
0036     }
0037
0038     bool isShared() const noexcept
0039     {
0040         int count = atomic.loadRelaxed();
0041         return (count != 1) && (count != 0);
0042     }
0043
0044     void initializeOwned() noexcept { atomic.storeRelaxed(1); }
0045     void initializeUnsharable() noexcept { atomic.storeRelaxed(0); }
0046
0047     QBasicAtomicInt atomic;
0048 };
0049
0050 }
0051
0052 #define Q_REFCOUNT_INITIALIZE_STATIC { Q_BASIC_ATOMIC_INITIALIZER(-1) }
0053
0054 QT_END_NAMESPACE
0055
0056 #endif