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Diffstat (limited to 'src/serialport/qt4support/src/qlockfile.cpp')
| -rw-r--r-- | src/serialport/qt4support/src/qlockfile.cpp | 344 |
1 files changed, 0 insertions, 344 deletions
diff --git a/src/serialport/qt4support/src/qlockfile.cpp b/src/serialport/qt4support/src/qlockfile.cpp deleted file mode 100644 index 1f406cf1..00000000 --- a/src/serialport/qt4support/src/qlockfile.cpp +++ /dev/null @@ -1,344 +0,0 @@ -/**************************************************************************** -** -** Copyright (C) 2013 David Faure <faure+bluesystems@kde.org> -** Contact: http://www.qt-project.org/legal -** -** This file is part of the QtCore module of the Qt Toolkit. -** -** $QT_BEGIN_LICENSE:LGPL21$ -** 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 Digia. For licensing terms and -** conditions see http://qt.digia.com/licensing. For further information -** use the contact form at http://qt.digia.com/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 2.1 or version 3 as published by the Free -** Software Foundation and appearing in the file LICENSE.LGPLv21 and -** LICENSE.LGPLv3 included in the packaging of this file. Please review the -** following information to ensure the GNU Lesser General Public License -** requirements will be met: https://www.gnu.org/licenses/lgpl.html and -** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. -** -** In addition, as a special exception, Digia gives you certain additional -** rights. These rights are described in the Digia Qt LGPL Exception -** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. -** -** $QT_END_LICENSE$ -** -****************************************************************************/ - -#include "qlockfile.h" -#include "qlockfile_p.h" - -#include <QtCore/qthread.h> -#include <QtCore/qelapsedtimer.h> -#include <QtCore/qdatetime.h> - -QT_BEGIN_NAMESPACE - -class QLockFileThread : public QThread -{ -public: - static void msleep(unsigned long msecs) { QThread::msleep(msecs); } -}; - -/*! - \class QLockFile - \inmodule QtCore - \brief The QLockFile class provides locking between processes using a file. - \since 5.1 - - A lock file can be used to prevent multiple processes from accessing concurrently - the same resource. For instance, a configuration file on disk, or a socket, a port, - a region of shared memory... - - Serialization is only guaranteed if all processes that access the shared resource - use QLockFile, with the same file path. - - QLockFile supports two use cases: - to protect a resource for a short-term operation (e.g. verifying if a configuration - file has changed before saving new settings), and for long-lived protection of a - resource (e.g. a document opened by a user in an editor) for an indefinite amount of time. - - 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 - warn the user that the resource is locked. - - If the process holding the lock crashes, the lock file stays on disk and can prevent - any other process from accessing the shared resource, ever. For this reason, QLockFile - tries to detect such a "stale" lock file, based on the process ID written into the file, - and (in case that process ID got reused meanwhile), on the last modification time of - the lock file (30s by default, for the use case of a short-lived operation). - If the lock file is found to be stale, it will be deleted. - - For the use case of protecting a resource over a long time, you should therefore call - setStaleLockTime(0), and when tryLock() returns LockFailedError, inform the user - that the document is locked, possibly using getLockInfo() for more details. -*/ - -/*! - \enum QLockFile::LockError - - This enum describes the result of the last call to lock() or tryLock(). - - \value NoError The lock was acquired successfully. - \value LockFailedError The lock could not be acquired because another process holds it. - \value PermissionError The lock file could not be created, for lack of permissions - in the parent directory. - \value UnknownError Another error happened, for instance a full partition - prevented writing out the lock file. -*/ - -/*! - Constructs a new lock file object. - The object is created in an unlocked state. - When calling lock() or tryLock(), a lock file named \a fileName will be created, - if it doesn't already exist. - - \sa lock(), unlock() -*/ -QLockFile::QLockFile(const QString &fileName) - : d_ptr(new QLockFilePrivate(fileName)) -{ -} - -/*! - Destroys the lock file object. - If the lock was acquired, this will release the lock, by deleting the lock file. -*/ -QLockFile::~QLockFile() -{ - unlock(); -} - -/*! - Sets \a staleLockTime to be the time in milliseconds after which - a lock file is considered stale. - The default value is 30000, i.e. 30 seconds. - 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(). - - The value of \a staleLockTime is used by lock() and tryLock() in order - to determine when an existing lock file is considered stale, i.e. left over - by a crashed process. This is useful for the case where the PID got reused - meanwhile, so the only way to detect a stale lock file is by the fact that - it has been around for a long time. - - \sa staleLockTime() -*/ -void QLockFile::setStaleLockTime(int staleLockTime) -{ - Q_D(QLockFile); - d->staleLockTime = staleLockTime; -} - -/*! - Returns the time in milliseconds after which - a lock file is considered stale. - - \sa setStaleLockTime() -*/ -int QLockFile::staleLockTime() const -{ - Q_D(const QLockFile); - return d->staleLockTime; -} - -/*! - Returns \c true if the lock was acquired by this QLockFile instance, - otherwise returns \c false. - - \sa lock(), unlock(), tryLock() -*/ -bool QLockFile::isLocked() const -{ - Q_D(const QLockFile); - return d->isLocked; -} - -/*! - Creates the lock file. - - If another process (or another thread) has created the lock file already, - this function will block until that process (or thread) releases it. - - Calling this function multiple times on the same lock from the same - thread without unlocking first is not allowed. This function will - \e dead-lock when the file is locked recursively. - - Returns \c true if the lock was acquired, false if it could not be acquired - due to an unrecoverable error, such as no permissions in the parent directory. - - \sa unlock(), tryLock() -*/ -bool QLockFile::lock() -{ - return tryLock(-1); -} - -/*! - 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 milliseconds for the lock file to become - available. - - Note: Passing a negative number as the \a timeout is equivalent to - calling lock(), i.e. this function will wait forever until the lock - file can be locked if \a timeout is negative. - - 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(int timeout) -{ - Q_D(QLockFile); - QElapsedTimer timer; - if (timeout > 0) - timer.start(); - int sleepTime = 100; - forever { - d->lockError = d->tryLock_sys(); - switch (d->lockError) { - case NoError: - d->isLocked = true; - return true; - case PermissionError: - case UnknownError: - return false; - case LockFailedError: - if (!d->isLocked && d->isApparentlyStale()) { - // Stale lock from another thread/process - // Ensure two processes don't remove it at the same time - QLockFile rmlock(d->fileName + QLatin1String(".rmlock")); - if (rmlock.tryLock()) { - if (d->isApparentlyStale() && d->removeStaleLock()) - continue; - } - } - break; - } - if (timeout == 0 || (timeout > 0 && timer.hasExpired(timeout))) - return false; - QLockFileThread::msleep(sleepTime); - if (sleepTime < 5 * 1000) - sleepTime *= 2; - } - // not reached - return false; -} - -/*! - \fn void QLockFile::unlock() - Releases the lock, by deleting the lock file. - - Calling unlock() without locking the file first, does nothing. - - \sa lock(), tryLock() -*/ - -/*! - Retrieves information about the current owner of the lock file. - - If tryLock() returns \c false, and error() returns LockFailedError, - this function can be called to find out more information about the existing - lock file: - \list - \li the PID of the application (returned in \a pid) - \li the \a hostname it's running on (useful in case of networked filesystems), - \li the name of the application which created it (returned in \a appname), - \endlist - - Note that tryLock() automatically deleted the file if there is no - running application with this PID, so LockFailedError can only happen if there is - an application with this PID (it could be unrelated though). - - This can be used to inform users about the existing lock file and give them - the choice to delete it. After removing the file using removeStaleLockFile(), - the application can call tryLock() again. - - This function returns \c true if the information could be successfully retrieved, false - if the lock file doesn't exist or doesn't contain the expected data. - This can happen if the lock file was deleted between the time where tryLock() failed - and the call to this function. Simply call tryLock() again if this happens. -*/ -bool QLockFile::getLockInfo(qint64 *pid, QString *hostname, QString *appname) const -{ - Q_D(const QLockFile); - return d->getLockInfo(pid, hostname, appname); -} - -bool QLockFilePrivate::getLockInfo(qint64 *pid, QString *hostname, QString *appname) const -{ - QFile reader(fileName); - if (!reader.open(QIODevice::ReadOnly)) - return false; - - QByteArray pidLine = reader.readLine(); - pidLine.chop(1); - QByteArray appNameLine = reader.readLine(); - appNameLine.chop(1); - QByteArray hostNameLine = reader.readLine(); - hostNameLine.chop(1); - if (pidLine.isEmpty() || appNameLine.isEmpty()) - return false; - - qint64 thePid = pidLine.toLongLong(); - if (pid) - *pid = thePid; - if (appname) - *appname = QString::fromUtf8(appNameLine); - if (hostname) - *hostname = QString::fromUtf8(hostNameLine); - return thePid > 0; -} - -/*! - Attempts to forcefully remove an existing lock file. - - Calling this is not recommended when protecting a short-lived operation: QLockFile - already takes care of removing lock files after they are older than staleLockTime(). - - This method should only be called when protecting a resource for a long time, i.e. - with staleLockTime(0), and after tryLock() returned LockFailedError, and the user - agreed on removing the lock file. - - Returns \c true on success, false if the lock file couldn't be removed. This happens - on Windows, when the application owning the lock is still running. -*/ -bool QLockFile::removeStaleLockFile() -{ - Q_D(QLockFile); - if (d->isLocked) { - qWarning("removeStaleLockFile can only be called when not holding the lock"); - return false; - } - return d->removeStaleLock(); -} - -/*! - Returns the lock file error status. - - If tryLock() returns \c false, this function can be called to find out - the reason why the locking failed. -*/ -QLockFile::LockError QLockFile::error() const -{ - Q_D(const QLockFile); - return d->lockError; -} - -QT_END_NAMESPACE |