diff options
Diffstat (limited to 'src/corelib/kernel/qapplicationstatic.h')
| -rw-r--r-- | src/corelib/kernel/qapplicationstatic.h | 154 |
1 files changed, 69 insertions, 85 deletions
diff --git a/src/corelib/kernel/qapplicationstatic.h b/src/corelib/kernel/qapplicationstatic.h index 33567596e6..bf5e79b8bf 100644 --- a/src/corelib/kernel/qapplicationstatic.h +++ b/src/corelib/kernel/qapplicationstatic.h @@ -1,101 +1,85 @@ -/**************************************************************************** -** -** Copyright (C) 2021 The Qt Company Ltd. -** Contact: https://www.qt.io/licensing/ -** -** This file is part of the QtCore module of the Qt Toolkit. -** -** $QT_BEGIN_LICENSE:LGPL$ -** Commercial License Usage -** Licensees holding valid commercial Qt licenses may use this file in -** accordance with the commercial license agreement provided with the -** Software or, alternatively, in accordance with the terms contained in -** a written agreement between you and The Qt Company. For licensing terms -** and conditions see https://www.qt.io/terms-conditions. For further -** information use the contact form at https://www.qt.io/contact-us. -** -** GNU Lesser General Public License Usage -** Alternatively, this file may be used under the terms of the GNU Lesser -** General Public License version 3 as published by the Free Software -** Foundation and appearing in the file LICENSE.LGPL3 included in the -** packaging of this file. Please review the following information to -** ensure the GNU Lesser General Public License version 3 requirements -** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. -** -** GNU General Public License Usage -** Alternatively, this file may be used under the terms of the GNU -** General Public License version 2.0 or (at your option) the GNU General -** Public license version 3 or any later version approved by the KDE Free -** Qt Foundation. The licenses are as published by the Free Software -** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 -** included in the packaging of this file. Please review the following -** information to ensure the GNU General Public License requirements will -** be met: https://www.gnu.org/licenses/gpl-2.0.html and -** https://www.gnu.org/licenses/gpl-3.0.html. -** -** $QT_END_LICENSE$ -** -****************************************************************************/ +// Copyright (C) 2021 The Qt Company Ltd. +// Copyright (C) 2021 Intel Corporation. +// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only #ifndef QAPPLICATIONSTATIC_H #define QAPPLICATIONSTATIC_H #include <QtCore/QMutex> +#include <QtCore/qcoreapplication.h> #include <QtCore/qglobalstatic.h> +#include <new> + QT_BEGIN_NAMESPACE -#define Q_APPLICATION_STATIC_INTERNAL_HOLDER(ARGS) \ - Q_GLOBAL_STATIC_INTERNAL_HOLDER(ARGS) \ - struct LifecycleHolder : public Holder \ - { \ - LifecycleHolder() { connectLifecycle(); } \ - BaseType *get() \ - { \ - const QMutexLocker locker(&theMutex); \ - if (value.get() == nullptr \ - && guard.loadRelaxed() == QtGlobalStatic::Initialized) { \ - value.reset(ARGS); \ - connectLifecycle(); \ - } \ - return value.get(); \ - } \ - void connectLifecycle() \ - { \ - Q_ASSERT(QCoreApplication::instance()); \ - QObject::connect(QCoreApplication::instance(), \ - &QCoreApplication::destroyed, [this] { \ - const QMutexLocker locker(&theMutex); \ - value.reset(nullptr); \ - }); \ - } \ - }; +namespace QtGlobalStatic { +template <typename QAS> struct ApplicationHolder +{ + using Type = typename QAS::QAS_Type; + using PlainType = std::remove_cv_t<Type>; + + Q_CONSTINIT static inline struct { alignas(Type) unsigned char data[sizeof(Type)]; } storage = {}; + Q_CONSTINIT static inline QBasicAtomicInteger<qint8> guard = { QtGlobalStatic::Uninitialized }; + Q_CONSTINIT static inline QBasicMutex mutex {}; + + static constexpr bool MutexLockIsNoexcept = noexcept(mutex.lock()); + static constexpr bool ConstructionIsNoexcept = noexcept(QAS::innerFunction(nullptr)); -#define Q_APPLICATION_STATIC_INTERNAL(ARGS) \ - Q_GLOBAL_STATIC_INTERNAL_DECORATION BaseType *innerFunction() \ - { \ - Q_APPLICATION_STATIC_INTERNAL_HOLDER(ARGS) \ - static LifecycleHolder holder; \ - return holder.get(); \ + ApplicationHolder() = default; + Q_DISABLE_COPY_MOVE(ApplicationHolder) + ~ApplicationHolder() + { + if (guard.loadAcquire() == QtGlobalStatic::Initialized) { + // No mutex! Up to external code to ensure no race happens. + guard.storeRelease(QtGlobalStatic::Destroyed); + realPointer()->~PlainType(); + } } -#define Q_APPLICATION_STATIC_WITH_ARGS(TYPE, NAME, ARGS) \ - QT_WARNING_PUSH \ - QT_WARNING_DISABLE_CLANG("-Wunevaluated-expression") \ - namespace { namespace Q_QAS_ ## NAME { \ - typedef TYPE BaseType; \ - typedef std::unique_ptr<BaseType> Type; \ - QBasicAtomicInt guard = Q_BASIC_ATOMIC_INITIALIZER(QtGlobalStatic::Uninitialized); \ - QBasicMutex theMutex; \ - Q_APPLICATION_STATIC_INTERNAL((new BaseType ARGS)) \ - } } \ - static QGlobalStatic<TYPE, \ - Q_QAS_ ## NAME::innerFunction, \ - Q_QAS_ ## NAME::guard> NAME; \ - QT_WARNING_POP + static PlainType *realPointer() + { + return std::launder(reinterpret_cast<PlainType *>(&storage)); + } + + // called from QGlobalStatic::instance() + PlainType *pointer() noexcept(MutexLockIsNoexcept && ConstructionIsNoexcept) + { + if (guard.loadAcquire() == QtGlobalStatic::Initialized) + return realPointer(); + QMutexLocker locker(&mutex); + if (guard.loadRelaxed() == QtGlobalStatic::Uninitialized) { + QAS::innerFunction(&storage); + const auto *app = QCoreApplication::instance(); + Q_ASSERT_X(app, Q_FUNC_INFO, + "The application static was used without a QCoreApplication instance"); + QObject::connect(app, &QObject::destroyed, app, reset, Qt::DirectConnection); + guard.storeRelease(QtGlobalStatic::Initialized); + } + return realPointer(); + } -#define Q_APPLICATION_STATIC(TYPE, NAME) \ - Q_APPLICATION_STATIC_WITH_ARGS(TYPE, NAME, ()) + static void reset() + { + // we only synchronize using the mutex here, not the guard + QMutexLocker locker(&mutex); + realPointer()->~PlainType(); + guard.storeRelaxed(QtGlobalStatic::Uninitialized); + } +}; +} // namespace QtGlobalStatic + +#define Q_APPLICATION_STATIC(TYPE, NAME, ...) \ + namespace { struct Q_QAS_ ## NAME { \ + typedef TYPE QAS_Type; \ + static void innerFunction(void *pointer) \ + noexcept(noexcept(std::remove_cv_t<QAS_Type>(__VA_ARGS__))) \ + { \ + new (pointer) QAS_Type(__VA_ARGS__); \ + } \ + }; } \ + static QGlobalStatic<QtGlobalStatic::ApplicationHolder<Q_QAS_ ## NAME>> NAME;\ + /**/ QT_END_NAMESPACE |