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qfilesystemwatcher.cpp

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#include "qfilesystemwatcher.h"
#include "qfilesystemwatcher_p.h"

#ifndef QT_NO_FILESYSTEMWATCHER

#include <qdatetime.h>
#include <qdebug.h>
#include <qfileinfo.h>
#include <qmutex.h>
#include <qset.h>
#include <qtimer.h>

#if defined(Q_OS_WIN)
#  include "qfilesystemwatcher_win_p.h"
#elif defined(Q_OS_LINUX)
#  include "qfilesystemwatcher_inotify_p.h"
#elif defined(Q_OS_FREEBSD) || defined(Q_OS_MAC)
#  include "qfilesystemwatcher_kqueue_p.h"
#endif

enum { PollingInterval = 1000 };

class QPollingFileSystemWatcherEngine : public QFileSystemWatcherEngine
{
    Q_OBJECT

    class FileInfo
    {
        uint ownerId;
        uint groupId;
        QFile::Permissions permissions;
        QDateTime lastModified;

    public:
        FileInfo(const QFileInfo &fileInfo)
            : ownerId(fileInfo.ownerId()),
              groupId(fileInfo.groupId()),
              permissions(fileInfo.permissions()),
              lastModified(fileInfo.lastModified())
        { }
        FileInfo &operator=(const QFileInfo &fileInfo)
        {
            *this = FileInfo(fileInfo);
            return *this;
        }

        bool operator!=(const QFileInfo &fileInfo) const
        {
            return (ownerId != fileInfo.ownerId()
                    || groupId != fileInfo.groupId()
                    || permissions != fileInfo.permissions()
                    || lastModified != fileInfo.lastModified());
        }
    };

    mutable QMutex mutex;
    QHash<QString, FileInfo> files, directories;

public:
    QPollingFileSystemWatcherEngine();

    void run();

    QStringList addPaths(const QStringList &paths, QStringList *files, QStringList *directories);
    QStringList removePaths(const QStringList &paths, QStringList *files, QStringList *directories);

    void stop();

private slots:
    void timeout();
};

QPollingFileSystemWatcherEngine::QPollingFileSystemWatcherEngine()
{
    moveToThread(this);
}

void QPollingFileSystemWatcherEngine::run()
{
    QTimer timer;
    connect(&timer, SIGNAL(timeout()), SLOT(timeout()));
    timer.start(PollingInterval);
    (void) exec();
}

QStringList QPollingFileSystemWatcherEngine::addPaths(const QStringList &paths,
                                                      QStringList *files,
                                                      QStringList *directories)
{
    QMutexLocker locker(&mutex);
    QStringList p = paths;
    QMutableListIterator<QString> it(p);
    while (it.hasNext()) {
        QString path = it.next();
        QFileInfo fi(path);
        if (!fi.exists())
            continue;
        if (fi.isDir()) {
            if (!directories->contains(path))
                directories->append(path);
            this->directories.insert(path, fi);
        } else {
            if (!files->contains(path))
                files->append(path);
            this->files.insert(path, fi);
        }
        it.remove();
    }
    start();
    return p;
}

QStringList QPollingFileSystemWatcherEngine::removePaths(const QStringList &paths,
                                                         QStringList *files,
                                                         QStringList *directories)
{
    QMutexLocker locker(&mutex);
    QStringList p = paths;
    QMutableListIterator<QString> it(p);
    while (it.hasNext()) {
        QString path = it.next();
        if (this->directories.remove(path)) {
            directories->removeAll(path);
            it.remove();
        } else if (this->files.remove(path)) {
            files->removeAll(path);
            it.remove();
        }
    }
    if (this->files.isEmpty() && this->directories.isEmpty()) {
        locker.unlock();
        stop();
        wait();
    }
    return p;
}

void QPollingFileSystemWatcherEngine::stop()
{
    QMetaObject::invokeMethod(this, "quit");
}

void QPollingFileSystemWatcherEngine::timeout()
{
    QMutexLocker locker(&mutex);
    QMutableHashIterator<QString, FileInfo> fit(files);
    while (fit.hasNext()) {
        QHash<QString, FileInfo>::iterator x = fit.next();
        QString path = x.key();
        QFileInfo fi(path);
        if (!fi.exists()) {
            fit.remove();
            emit fileChanged(path, true);
        } else if (x.value() != fi) {
            x.value() = fi;
            emit fileChanged(path, false);
        }
    }
    QMutableHashIterator<QString, FileInfo> dit(directories);
    while (dit.hasNext()) {
        QHash<QString, FileInfo>::iterator x = dit.next();
        QString path = x.key();
        QFileInfo fi(path);
        if (!fi.exists()) {
            dit.remove();
            emit directoryChanged(path, true);
        } else if (x.value() != fi) {
            x.value() = fi;
            emit directoryChanged(path, false);
        }
    }
}




QFileSystemWatcherEngine *QFileSystemWatcherPrivate::createNativeEngine()
{
#if defined(Q_OS_WIN)
    return new QWindowsFileSystemWatcherEngine;
#elif defined(Q_OS_LINUX)
    return QInotifyFileSystemWatcherEngine::create();
#elif defined(Q_OS_FREEBSD) || defined(Q_OS_MAC)
    return QKqueueFileSystemWatcherEngine::create();
#else
    return 0;
#endif
}

QFileSystemWatcherPrivate::QFileSystemWatcherPrivate()
    : native(0), poller(0)
{
}

void QFileSystemWatcherPrivate::init()
{
    Q_Q(QFileSystemWatcher);
    native = createNativeEngine();
    if (native) {
        QObject::connect(native,
                         SIGNAL(fileChanged(QString,bool)),
                         q,
                         SLOT(_q_fileChanged(QString,bool)));
        QObject::connect(native,
                         SIGNAL(directoryChanged(QString,bool)),
                         q,
                         SLOT(_q_directoryChanged(QString,bool)));
    }
}

void QFileSystemWatcherPrivate::_q_fileChanged(const QString &path, bool removed)
{
    Q_Q(QFileSystemWatcher);
    if (!files.contains(path)) {
        // the path was removed after a change was detected, but before we delivered the signal
        return;
    }
    if (removed)
        files.removeAll(path);
    emit q->fileChanged(path);
}

void QFileSystemWatcherPrivate::_q_directoryChanged(const QString &path, bool removed)
{
    Q_Q(QFileSystemWatcher);
    if (!directories.contains(path)) {
        // perhaps the path was removed after a change was detected, but before we delivered the signal
        return;
    }
    if (removed)
        directories.removeAll(path);
    emit q->directoryChanged(path);
}



/*!
    \class QFileSystemWatcher
    \brief The QFileSystemWatcher class provides an interface for monitoring files and directories for modifications.
    \ingroup io
    \since 4.2
    \reentrant

    QFileSystemWatcher monitors the file system for changes to files
    and directories by watching a list of specified paths.

    Call addPath() to watch a particular file or directory. Multiple
    paths can be added using the addPaths() function. Existing paths can
    be removed by using the removePath() and removePaths() functions.

    QFileSystemWatcher examines each path added to it. Files that have
    been added to the QFileSystemWatcher can be accessed using the
    files() function, and directories using the directories() function.

    The fileChanged() signal is emitted when a file has been modified
    or removed from disk. Similarly, the directoryChanged() signal
    is emitted when a directory or its contents is modified or removed.
    Note that QFileSystemWatcher stops monitoring files and directories
    once they have been removed from disk.

    \sa QFile, QDir
*/


/*!
    Constructs a new file system watcher object with the given \a parent.
*/
00311 QFileSystemWatcher::QFileSystemWatcher(QObject *parent)
    : QObject(*new QFileSystemWatcherPrivate, parent)
{
    d_func()->init();
}

/*!
    Constructs a new file system watcher object with the given \a parent
    which monitors the specified \a paths list.
*/
00321 QFileSystemWatcher::QFileSystemWatcher(const QStringList &paths, QObject *parent)
    : QObject(*new QFileSystemWatcherPrivate, parent)
{
    d_func()->init();
    addPaths(paths);
}

/*!
    Destroys the file system watcher.
*/
00331 QFileSystemWatcher::~QFileSystemWatcher()
{
    Q_D(QFileSystemWatcher);
    if (d->native) {
        d->native->stop();
        d->native->wait();
        delete d->native;
        d->native = 0;
    }
    if (d->poller) {
        d->poller->stop();
        d->poller->wait();
        delete d->poller;
        d->poller = 0;
    }
}

/*!
    Adds \a path to the file system watcher if \a path exists. The path is
    not added if it does not exist, or if it is already being monitored by
    the file system watcher.

    If \a path specifies a directory, the directoryChanged() signal
    will be emitted when \a path is modified or removed from disk;
    otherwise the fileChanged() signal is emitted when \a path is
    modified or removed.

    \sa addPaths(), removePath()
*/
00360 void QFileSystemWatcher::addPath(const QString &path)
{
    if (path.isEmpty()) {
        qWarning("QFileSystemWatcher::addPath: path is empty");
        return;
    }
    addPaths(QStringList(path));
}

/*!
    Adds each path in \a paths to the file system watcher. Paths are not
    added if they not exist, or if they are already being monitored by the
    file system watcher.

    If a path specifies a directory, the directoryChanged() signal will
    be emitted when the path is modified or removed from disk; otherwise
    the fileChanged() signal is emitted when the path is modified or
    removed.

    \sa addPath(), removePaths()
*/
00381 void QFileSystemWatcher::addPaths(const QStringList &paths)
{
    Q_D(QFileSystemWatcher);
    if (paths.isEmpty()) {
        qWarning("QFileSystemWatcher::addPaths: list is empty");
        return;
    }
    QStringList p = paths;
    if (objectName() != QLatin1String("_qt_autotest_force_engine_poller")) {
        if (d->native)
            p = d->native->addPaths(p, &d->files, &d->directories);
        if (p.isEmpty())
            return;
    } else {
        qDebug() << "QFileSystemWatcher: skipping native engine, using only polling engine";
    }
    if (objectName() != QLatin1String("_qt_autotest_force_engine_native")) {
        // try polling instead
        if (!d->poller) {
            d->poller = new QPollingFileSystemWatcherEngine; // that was a mouthful
            QObject::connect(d->poller,
                             SIGNAL(fileChanged(QString,bool)),
                             this,
                             SLOT(_q_fileChanged(QString,bool)));
            QObject::connect(d->poller,
                             SIGNAL(directoryChanged(QString,bool)),
                             this,
                             SLOT(_q_directoryChanged(QString,bool)));
        }
        p = d->poller->addPaths(p, &d->files, &d->directories);
    } else{
        qDebug("QFileSystemWatcher: skipping polling engine, using only native engine");
    }
    if (!p.isEmpty())
        qWarning("QFileSystemWatcher: failed to add paths: %s",
                 qPrintable(p.join(QLatin1String(", "))));
}

/*!
    Removes the specified \a path from the file system watcher.

    \sa removePaths(), addPath()
*/
00424 void QFileSystemWatcher::removePath(const QString &path)
{
    if (path.isEmpty()) {
        qWarning("QFileSystemWatcher::removePath: path is empty");
        return;
    }
    removePaths(QStringList(path));
}

/*!
    Removes the specified \a paths from the file system watcher.

    \sa removePath(), addPaths()
*/
00438 void QFileSystemWatcher::removePaths(const QStringList &paths)
{
    if (paths.isEmpty()) {
        qWarning("QFileSystemWatcher::removePaths: list is empty");
        return;
    }
    Q_D(QFileSystemWatcher);
    QStringList p = paths;
    if (d->native)
        p = d->native->removePaths(p, &d->files, &d->directories);
    if (d->poller)
        (void) d->poller->removePaths(p, &d->files, &d->directories);
}

/*!
    \fn void QFileSystemWatcher::fileChanged(const QString &path)

    This signal is emitted when the file at the specified \a path is modified
    or removed from disk.

    \sa directoryChanged()
*/

/*!
    \fn void QFileSystemWatcher::directoryChanged(const QString &path)

    This signal is emitted when the directory at a specified \a path, is modified
    (e.g., when a file is added, modified or deleted) or removed from disk. Note
    that if there are several changes during a short period of time, some of the
    changes might not emit this signal. However, the last change in the sequence
    of changes will always generate this signal.

    \sa fileChanged()
*/

/*!
    \fn QStringList QFileSystemWatcher::directories() const

    Returns a list of paths to directories that are being watched.

    \sa files()
*/

/*!
    \fn QStringList QFileSystemWatcher::files() const

    Returns a list of paths to files that are being watched.

    \sa directories()
*/

00489 QStringList QFileSystemWatcher::directories() const
{
    Q_D(const QFileSystemWatcher);
    return d->directories;
}

00495 QStringList QFileSystemWatcher::files() const
{
    Q_D(const QFileSystemWatcher);
    return d->files;
}

#include "moc_qfilesystemwatcher.cpp"
#include "qfilesystemwatcher.moc"

#endif // QT_NO_FILESYSTEMWATCHER

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