diff options
Diffstat (limited to 'src/corelib/io/qlockfile.cpp')
| -rw-r--r-- | src/corelib/io/qlockfile.cpp | 153 |
1 files changed, 72 insertions, 81 deletions
diff --git a/src/corelib/io/qlockfile.cpp b/src/corelib/io/qlockfile.cpp index e6812cedde..0eb6acb694 100644 --- a/src/corelib/io/qlockfile.cpp +++ b/src/corelib/io/qlockfile.cpp @@ -1,43 +1,7 @@ -/**************************************************************************** -** -** Copyright (C) 2013 David Faure <faure+bluesystems@kde.org> -** Copyright (C) 2016 The Qt Company Ltd. -** Copyright (C) 2017 Intel Corporation. -** 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) 2013 David Faure <faure+bluesystems@kde.org> +// Copyright (C) 2016 The Qt Company Ltd. +// Copyright (C) 2017 Intel Corporation. +// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only #include "qlockfile.h" #include "qlockfile_p.h" @@ -50,6 +14,8 @@ QT_BEGIN_NAMESPACE +using namespace Qt::StringLiterals; + namespace { struct LockFileInfo { @@ -94,7 +60,7 @@ static QString machineName() When protecting for a short-term operation, it is acceptable to call lock() and wait until any running operation finishes. When protecting a resource over a long time, however, the application should always - call setStaleLockTime(0) and then tryLock() with a short timeout, in order to + call setStaleLockTime(0ms) and then tryLock() with a short timeout, in order to warn the user that the resource is locked. If the process holding the lock crashes, the lock file stays on disk and can prevent @@ -172,20 +138,24 @@ QString QLockFile::fileName() const meanwhile, so one way to detect a stale lock file is by the fact that it has been around for a long time. + This is an overloaded function, equivalent to calling: + \code + setStaleLockTime(std::chrono::milliseconds{staleLockTime}); + \endcode + \sa staleLockTime() */ void QLockFile::setStaleLockTime(int staleLockTime) { - Q_D(QLockFile); - d->staleLockTime = staleLockTime; + setStaleLockTime(std::chrono::milliseconds{staleLockTime}); } -/*! \fn void QLockFile::setStaleLockTime(std::chrono::milliseconds value) - \overload +/*! \since 6.2 - Sets the interval after which a lock file is considered stale to \a value. - The default value is 30 seconds. + Sets the interval after which a lock file is considered stale to \a staleLockTime. + The default value is 30s. + If your application typically keeps the file locked for more than 30 seconds (for instance while saving megabytes of data for 2 minutes), you should set a bigger value using setStaleLockTime(). @@ -198,6 +168,11 @@ void QLockFile::setStaleLockTime(int staleLockTime) \sa staleLockTime() */ +void QLockFile::setStaleLockTime(std::chrono::milliseconds staleLockTime) +{ + Q_D(QLockFile); + d->staleLockTime = staleLockTime; +} /*! Returns the time in milliseconds after which @@ -207,8 +182,7 @@ void QLockFile::setStaleLockTime(int staleLockTime) */ int QLockFile::staleLockTime() const { - Q_D(const QLockFile); - return d->staleLockTime; + return int(staleLockTimeAsDuration().count()); } /*! \fn std::chrono::milliseconds QLockFile::staleLockTimeAsDuration() const @@ -220,6 +194,11 @@ int QLockFile::staleLockTime() const \sa setStaleLockTime() */ +std::chrono::milliseconds QLockFile::staleLockTimeAsDuration() const +{ + Q_D(const QLockFile); + return d->staleLockTime; +} /*! Returns \c true if the lock was acquired by this QLockFile instance, @@ -250,7 +229,7 @@ bool QLockFile::isLocked() const */ bool QLockFile::lock() { - return tryLock(-1); + return tryLock(std::chrono::milliseconds::max()); } /*! @@ -275,10 +254,38 @@ bool QLockFile::lock() */ bool QLockFile::tryLock(int timeout) { + return tryLock(std::chrono::milliseconds{ timeout }); +} + +/*! + \overload + \since 6.2 + + Attempts to create the lock file. This function returns \c true if the + lock was obtained; otherwise it returns \c false. If another process (or + another thread) has created the lock file already, this function will + wait for at most \a timeout for the lock file to become available. + + If the lock was obtained, it must be released with unlock() + before another process (or thread) can successfully lock it. + + Calling this function multiple times on the same lock from the same + thread without unlocking first is not allowed, this function will + \e always return false when attempting to lock the file recursively. + + \sa lock(), unlock() +*/ +bool QLockFile::tryLock(std::chrono::milliseconds timeout) +{ + using namespace std::chrono_literals; + using Msec = std::chrono::milliseconds; + Q_D(QLockFile); - QDeadlineTimer timer(qMax(timeout, -1)); // QDT only takes -1 as "forever" - int sleepTime = 100; - forever { + + QDeadlineTimer timer(timeout < 0ms ? Msec::max() : timeout); + + Msec sleepTime = 100ms; + while (true) { d->lockError = d->tryLock_sys(); switch (d->lockError) { case NoError: @@ -289,11 +296,11 @@ bool QLockFile::tryLock(int timeout) return false; case LockFailedError: if (!d->isLocked && d->isApparentlyStale()) { - if (Q_UNLIKELY(QFileInfo(d->fileName).lastModified() > QDateTime::currentDateTimeUtc())) + if (Q_UNLIKELY(QFileInfo(d->fileName).lastModified(QTimeZone::UTC) > QDateTime::currentDateTimeUtc())) qInfo("QLockFile: Lock file '%ls' has a modification time in the future", qUtf16Printable(d->fileName)); // Stale lock from another thread/process // Ensure two processes don't remove it at the same time - QLockFile rmlock(d->fileName + QLatin1String(".rmlock")); + QLockFile rmlock(d->fileName + ".rmlock"_L1); if (rmlock.tryLock()) { if (d->isApparentlyStale() && d->removeStaleLock()) continue; @@ -302,39 +309,21 @@ bool QLockFile::tryLock(int timeout) break; } - int remainingTime = timer.remainingTime(); - if (remainingTime == 0) + auto remainingTime = std::chrono::duration_cast<Msec>(timer.remainingTimeAsDuration()); + if (remainingTime == 0ms) return false; - else if (uint(sleepTime) > uint(remainingTime)) + + if (sleepTime > remainingTime) sleepTime = remainingTime; - QThread::msleep(sleepTime); - if (sleepTime < 5 * 1000) + QThread::sleep(sleepTime); + if (sleepTime < 5s) sleepTime *= 2; } // not reached return false; } -/*! \fn bool QLockFile::tryLock(std::chrono::milliseconds timeout) - \overload - \since 6.2 - - Attempts to create the lock file. This function returns \c true if the - lock was obtained; otherwise it returns \c false. If another process (or - another thread) has created the lock file already, this function will - wait for at most \a timeout for the lock file to become available. - - If the lock was obtained, it must be released with unlock() - before another process (or thread) can successfully lock it. - - Calling this function multiple times on the same lock from the same - thread without unlocking first is not allowed, this function will - \e always return false when attempting to lock the file recursively. - - \sa lock(), unlock() -*/ - /*! \fn void QLockFile::unlock() Releases the lock, by deleting the lock file. @@ -447,8 +436,10 @@ bool QLockFilePrivate::isApparentlyStale() const } } - const qint64 age = QFileInfo(fileName).lastModified().msecsTo(QDateTime::currentDateTimeUtc()); - return staleLockTime > 0 && qAbs(age) > staleLockTime; + const QDateTime lastMod = QFileInfo(fileName).lastModified(QTimeZone::UTC); + using namespace std::chrono; + const milliseconds age{lastMod.msecsTo(QDateTime::currentDateTimeUtc())}; + return staleLockTime > 0ms && abs(age) > staleLockTime; } /*! |