1 /**************************************************************************** 2 ** 3 ** Copyright (C) 2016 The Qt Company Ltd. 4 ** Contact: https://www.qt.io/licensing/ 5 ** 6 ** This file is part of the QtCore module of the Qt Toolkit. 7 ** 8 ** $QT_BEGIN_LICENSE:LGPL$ 9 ** Commercial License Usage 10 ** Licensees holding valid commercial Qt licenses may use this file in 11 ** accordance with the commercial license agreement provided with the 12 ** Software or, alternatively, in accordance with the terms contained in 13 ** a written agreement between you and The Qt Company. For licensing terms 14 ** and conditions see https://www.qt.io/terms-conditions. For further 15 ** information use the contact form at https://www.qt.io/contact-us. 16 ** 17 ** GNU Lesser General Public License Usage 18 ** Alternatively, this file may be used under the terms of the GNU Lesser 19 ** General Public License version 3 as published by the Free Software 20 ** Foundation and appearing in the file LICENSE.LGPL3 included in the 21 ** packaging of this file. Please review the following information to 22 ** ensure the GNU Lesser General Public License version 3 requirements 23 ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. 24 ** 25 ** GNU General Public License Usage 26 ** Alternatively, this file may be used under the terms of the GNU 27 ** General Public License version 2.0 or (at your option) the GNU General 28 ** Public license version 3 or any later version approved by the KDE Free 29 ** Qt Foundation. The licenses are as published by the Free Software 30 ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 31 ** included in the packaging of this file. Please review the following 32 ** information to ensure the GNU General Public License requirements will 33 ** be met: https://www.gnu.org/licenses/gpl-2.0.html and 34 ** https://www.gnu.org/licenses/gpl-3.0.html. 35 ** 36 ** $QT_END_LICENSE$ 37 ** 38 ****************************************************************************/ 39 40 #ifndef QREFCOUNT_H 41 #define QREFCOUNT_H 42 43 #include <QtCore/qatomic.h> 44 45 QT_BEGIN_NAMESPACE 46 47 48 namespace QtPrivate 49 { 50 51 class RefCount 52 { 53 public: ref()54 inline bool ref() noexcept { 55 int count = atomic.loadRelaxed(); 56 #if !defined(QT_NO_UNSHARABLE_CONTAINERS) 57 if (count == 0) // !isSharable 58 return false; 59 #endif 60 if (count != -1) // !isStatic 61 atomic.ref(); 62 return true; 63 } 64 deref()65 inline bool deref() noexcept { 66 int count = atomic.loadRelaxed(); 67 #if !defined(QT_NO_UNSHARABLE_CONTAINERS) 68 if (count == 0) // !isSharable 69 return false; 70 #endif 71 if (count == -1) // isStatic 72 return true; 73 return atomic.deref(); 74 } 75 76 #if !defined(QT_NO_UNSHARABLE_CONTAINERS) setSharable(bool sharable)77 bool setSharable(bool sharable) noexcept 78 { 79 Q_ASSERT(!isShared()); 80 if (sharable) 81 return atomic.testAndSetRelaxed(0, 1); 82 else 83 return atomic.testAndSetRelaxed(1, 0); 84 } 85 isSharable()86 bool isSharable() const noexcept 87 { 88 // Sharable === Shared ownership. 89 return atomic.loadRelaxed() != 0; 90 } 91 #endif 92 isStatic()93 bool isStatic() const noexcept 94 { 95 // Persistent object, never deleted 96 return atomic.loadRelaxed() == -1; 97 } 98 isShared()99 bool isShared() const noexcept 100 { 101 int count = atomic.loadRelaxed(); 102 return (count != 1) && (count != 0); 103 } 104 initializeOwned()105 void initializeOwned() noexcept { atomic.storeRelaxed(1); } initializeUnsharable()106 void initializeUnsharable() noexcept { atomic.storeRelaxed(0); } 107 108 QBasicAtomicInt atomic; 109 }; 110 111 } 112 113 #define Q_REFCOUNT_INITIALIZE_STATIC { Q_BASIC_ATOMIC_INITIALIZER(-1) } 114 115 QT_END_NAMESPACE 116 117 #endif 118