mirror of
https://github.com/clementine-player/Clementine
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214 lines
6.6 KiB
C++
214 lines
6.6 KiB
C++
/****************************************************************************
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**
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** Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).
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** All rights reserved.
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** Contact: Nokia Corporation (qt-info@nokia.com)
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**
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** This file is part of a Qt Solutions component.
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**
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** Commercial Usage
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** Licensees holding valid Qt Commercial licenses may use this file in
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** accordance with the Qt Solutions Commercial License Agreement provided
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** with the Software or, alternatively, in accordance with the terms
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** contained in a written agreement between you and Nokia.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 2.1 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 2.1 requirements
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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**
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** In addition, as a special exception, Nokia gives you certain
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** additional rights. These rights are described in the Nokia Qt LGPL
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** Exception version 1.1, included in the file LGPL_EXCEPTION.txt in this
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** package.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 3.0 as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU General Public License version 3.0 requirements will be
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** met: http://www.gnu.org/copyleft/gpl.html.
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**
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** Please note Third Party Software included with Qt Solutions may impose
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** additional restrictions and it is the user's responsibility to ensure
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** that they have met the licensing requirements of the GPL, LGPL, or Qt
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** Solutions Commercial license and the relevant license of the Third
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** Party Software they are using.
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**
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** If you are unsure which license is appropriate for your use, please
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** contact Nokia at qt-info@nokia.com.
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**
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****************************************************************************/
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#include "qtlockedfile.h"
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#include <qt_windows.h>
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#include <QtCore/QFileInfo>
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#define MUTEX_PREFIX "QtLockedFile mutex "
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// Maximum number of concurrent read locks. Must not be greater than MAXIMUM_WAIT_OBJECTS
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#define MAX_READERS MAXIMUM_WAIT_OBJECTS
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Qt::HANDLE QtLockedFile::getMutexHandle(int idx, bool doCreate)
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{
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if (mutexname.isEmpty()) {
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QFileInfo fi(*this);
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mutexname = QString::fromLatin1(MUTEX_PREFIX)
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+ fi.absoluteFilePath().toLower();
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}
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QString mname(mutexname);
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if (idx >= 0)
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mname += QString::number(idx);
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Qt::HANDLE mutex;
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if (doCreate) {
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QT_WA( { mutex = CreateMutexW(NULL, FALSE, (WCHAR*)mname.utf16()); },
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{ mutex = CreateMutexA(NULL, FALSE, mname.toLocal8Bit().constData()); } );
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if (!mutex) {
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qErrnoWarning("QtLockedFile::lock(): CreateMutex failed");
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return 0;
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}
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}
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else {
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QT_WA( { mutex = OpenMutexW(SYNCHRONIZE | MUTEX_MODIFY_STATE, FALSE, (WCHAR*)mname.utf16()); },
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{ mutex = OpenMutexA(SYNCHRONIZE | MUTEX_MODIFY_STATE, FALSE, mname.toLocal8Bit().constData()); } );
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if (!mutex) {
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if (GetLastError() != ERROR_FILE_NOT_FOUND)
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qErrnoWarning("QtLockedFile::lock(): OpenMutex failed");
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return 0;
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}
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}
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return mutex;
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}
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bool QtLockedFile::waitMutex(Qt::HANDLE mutex, bool doBlock)
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{
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Q_ASSERT(mutex);
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DWORD res = WaitForSingleObject(mutex, doBlock ? INFINITE : 0);
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switch (res) {
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case WAIT_OBJECT_0:
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case WAIT_ABANDONED:
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return true;
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break;
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case WAIT_TIMEOUT:
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break;
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default:
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qErrnoWarning("QtLockedFile::lock(): WaitForSingleObject failed");
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}
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return false;
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}
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bool QtLockedFile::lock(LockMode mode, bool block)
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{
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if (!isOpen()) {
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qWarning("QtLockedFile::lock(): file is not opened");
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return false;
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}
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if (mode == NoLock)
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return unlock();
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if (mode == m_lock_mode)
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return true;
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if (m_lock_mode != NoLock)
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unlock();
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if (!wmutex && !(wmutex = getMutexHandle(-1, true)))
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return false;
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if (!waitMutex(wmutex, block))
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return false;
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if (mode == ReadLock) {
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int idx = 0;
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for (; idx < MAX_READERS; idx++) {
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rmutex = getMutexHandle(idx, false);
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if (!rmutex || waitMutex(rmutex, false))
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break;
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CloseHandle(rmutex);
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}
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bool ok = true;
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if (idx >= MAX_READERS) {
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qWarning("QtLockedFile::lock(): too many readers");
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rmutex = 0;
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ok = false;
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}
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else if (!rmutex) {
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rmutex = getMutexHandle(idx, true);
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if (!rmutex || !waitMutex(rmutex, false))
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ok = false;
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}
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if (!ok && rmutex) {
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CloseHandle(rmutex);
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rmutex = 0;
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}
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ReleaseMutex(wmutex);
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if (!ok)
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return false;
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}
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else {
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Q_ASSERT(rmutexes.isEmpty());
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for (int i = 0; i < MAX_READERS; i++) {
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Qt::HANDLE mutex = getMutexHandle(i, false);
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if (mutex)
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rmutexes.append(mutex);
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}
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if (rmutexes.size()) {
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DWORD res = WaitForMultipleObjects(rmutexes.size(), rmutexes.constData(),
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TRUE, block ? INFINITE : 0);
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if (res != WAIT_OBJECT_0 && res != WAIT_ABANDONED) {
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if (res != WAIT_TIMEOUT)
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qErrnoWarning("QtLockedFile::lock(): WaitForMultipleObjects failed");
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m_lock_mode = WriteLock; // trick unlock() to clean up - semiyucky
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unlock();
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return false;
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}
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}
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}
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m_lock_mode = mode;
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return true;
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}
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bool QtLockedFile::unlock()
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{
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if (!isOpen()) {
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qWarning("QtLockedFile::unlock(): file is not opened");
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return false;
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}
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if (!isLocked())
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return true;
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if (m_lock_mode == ReadLock) {
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ReleaseMutex(rmutex);
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CloseHandle(rmutex);
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rmutex = 0;
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}
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else {
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foreach(Qt::HANDLE mutex, rmutexes) {
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ReleaseMutex(mutex);
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CloseHandle(mutex);
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}
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rmutexes.clear();
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ReleaseMutex(wmutex);
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}
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m_lock_mode = QtLockedFile::NoLock;
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return true;
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}
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QtLockedFile::~QtLockedFile()
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{
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if (isOpen())
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unlock();
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if (wmutex)
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CloseHandle(wmutex);
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}
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