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/**************************************************************************
**
** Copyright (C) 2022 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Installer Framework.
**
** $QT_BEGIN_LICENSE:GPL-EXCEPT$
** 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 General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 as published by the Free Software
** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
** 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-3.0.html.
**
** $QT_END_LICENSE$
**
**************************************************************************/
#include "fileguard.h"
#include <QTimer>
using namespace QInstaller;
/*!
\inmodule QtInstallerFramework
\class QInstaller::FileGuard
\brief The \c FileGuard class provides basic access serialization for file paths.
This class keeps a list of file paths that are locked from mutual
access. Attempting to lock them from another thread will fail until the
the locked path name is released.
*/
Q_GLOBAL_STATIC(FileGuard, globalFileGuard)
/*!
Attempts to lock \a path. Returns \c true if the lock could be
acquired, \c false if another thread has already locked the path.
*/
bool FileGuard::tryLock(const QString &path)
{
QMutexLocker _(&m_mutex);
if (path.isEmpty())
return false;
if (m_paths.contains(path))
return false;
m_paths.append(path);
return true;
}
/*!
Unlocks \a path.
*/
void FileGuard::release(const QString &path)
{
QMutexLocker _(&m_mutex);
m_paths.removeOne(path);
}
/*!
Returns the application global instance.
*/
FileGuard *FileGuard::globalObject()
{
return globalFileGuard;
}
/*!
\inmodule QtInstallerFramework
\class QInstaller::FileGuardLocker
\brief The \c FileGuardLocker class locks a file path and releases it on destruction.
A convenience class for locking a file path using the resource acquisition
is initialization (RAII) programming idiom.
*/
/*!
Constructs the object and attempts to lock \a path with \a guard. If the lock is already
held by another thread, this method will wait for it to become available.
*/
FileGuardLocker::FileGuardLocker(const QString &path, FileGuard *guard)
: m_path(path)
, m_guard(guard)
{
if (!m_guard->tryLock(m_path)) {
QTimer timer;
QEventLoop loop;
QObject::connect(&timer, &QTimer::timeout, [&]() {
if (m_guard->tryLock(m_path))
loop.quit();
});
timer.start(100);
loop.exec();
}
}
/*!
Destructs the object and unlocks the locked file path.
*/
FileGuardLocker::~FileGuardLocker()
{
m_guard->release(m_path);
}
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