/******************************************************************************** Copyright (C) 1992-2006 Trolltech ASA. All rights reserved.**** This file is part of the QtCore module of the Qt Toolkit.**** This file may be used under the terms of the GNU General Public** License version 2.0 as published by the Free Software Foundation** and appearing in the file LICENSE.GPL included in the packaging of** this file.  Please review the following information to ensure GNU** General Public Licensing requirements will be met:** http://www.trolltech.com/products/qt/opensource.html**** If you are unsure which license is appropriate for your use, please** review the following information:** http://www.trolltech.com/products/qt/licensing.html or contact the** sales department at sales@trolltech.com.**** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.******************************************************************************/#include "qsocketnotifier.h"#include "qplatformdefs.h"#include "qabstracteventdispatcher.h"#include "qcoreapplication.h"#include "qobject_p.h"#include <private/qthread_p.h>/*!    \class QSocketNotifier    \brief The QSocketNotifier class provides support for monitoring    activity on a file descriptor.    \ingroup io    The QSocketNotifier makes it possible to integrate Qt's event    loop with other event loops based on file descriptors. For    example, the \l{CORBA Framework} uses it to process CORBA    events.  File descriptor action is detected in Qt's main event    loop (QCoreApplication::exec()).    \target write notifiers    Once you have opened a device using a low-level (usually    platform-specific) API, you can create a socket notifier to    monitor the file descriptor. The socket notifier is enabled by    default, i.e. it emits the activated() signal whenever a socket    event corresponding to its type occurs. Connect the activated()    signal to the slot you want to be called when an event    corresponding to your socket notifier's type occurs.    There are three types of socket notifiers: read, write, and    exception. The type is described by the \l Type enum, and must be    specified when constructing the socket notifier. After    construction it can be determined using the type() function. Note    that if you need to monitor both reads and writes for the same    file descriptor, you must create two socket notifiers. Note also    that it is not possible to install two socket notifiers of the    same type (\l Read, \l Write, \l Exception) on the same socket.    The setEnabled() function allows you to disable as well as enable    the socket notifier. It is generally advisable to explicitly    enable or disable the socket notifier, especially for write    notifiers. A disabled notifier ignores socket events (the same    effect as not creating the socket notifier). Use the isEnabled()    function to determine the notifier's current status.    Finally, you can use the socket() function to retrieve the    socket identifier.  Although the class is called QSocketNotifier,    it is normally used for other types of devices than sockets.    QTcpSocket and QUdpSocket provide notification through signals, so    there is normally no need to use a QSocketNotifier on them.    \section1 Notes for Windows Users    The socket passed to QSocketNotifier will become non-blocking, even if    it was created as a blocking socket.    The activated() signal is sometimes triggered by high general activity    on the host, even if there is nothing to read. A subsequent read from    the socket can then fail, the error indicating that there is no data    available (e.g., \c{WSAEWOULDBLOCK}). This is an operating system    limitation, and not a bug in QSocketNotifier.    To ensure that the socket notifier handles read notifications correctly,    follow these steps when you receive a notification:    \list 1    \o Disable the notifier.    \o Read data from the socket.    \o Re-enable the notifier if you are interested in more data (such as after       having written a new command to a remote server).    \endlist    To ensure that the socket notifier handles write notifications correctly,    follow these steps when you receive a notification:    \list 1    \o Disable the notifier.    \o Write as much data as you can (before \c EWOULDBLOCK is returned).    \o Re-enable notifier if you have more data to write.    \endlist    \endomit    \bold{Further information:}    On Windows, Qt always disables the notifier after getting a notification,    and only re-enables it if more data is expected. For example, if data is    read from the socket and it can be used to read more, or if reading or    writing is not possible because the socket would block, in which case    it is necessary to wait before attempting to read or write again.    \sa QFile, QProcess, QTcpSocket, QUdpSocket*//*!    \enum QSocketNotifier::Type    This enum describes the various types of events that a socket    notifier can recognize. The type must be specified when    constructing the socket notifier.    Note that if you need to monitor both reads and writes for the    same file descriptor, you must create two socket notifiers. Note    also that it is not possible to install two socket notifiers of    the same type (Read, Write, Exception) on the same socket.    \value Read      There is data to be read.    \value Write      Data can be written.    \value Exception  An exception has occurred. We recommend against using this.    \sa QSocketNotifier(), type()*//*!    Constructs a socket notifier with the given \a parent. It enables    the \a socket, and watches for events of the given \a type.    It is generally advisable to explicitly enable or disable the    socket notifier, especially for write notifiers.    \bold{Note for Windows users:} The socket passed to QSocketNotifier    will become non-blocking, even if it was created as a blocking socket.    \sa setEnabled(), isEnabled()*/QSocketNotifier::QSocketNotifier(int socket, Type type, QObject *parent)    : QObject(parent){    if (socket < 0)        qWarning("QSocketNotifier: Invalid socket specified");#if defined(Q_OS_UNIX)    if (socket >= FD_SETSIZE)        qWarning("QSocketNotifier: Socket descriptor too large for select()");#endif    sockfd = socket;    sntype = type;    snenabled = true;    Q_D(QObject);    if (!d->threadData->eventDispatcher) {        qWarning("QSocketNotifier: Can only be used with threads started with QThread");    } else {        d->threadData->eventDispatcher->registerSocketNotifier(this);    }}#ifdef QT3_SUPPORT/*!    \obsolete    Use the QSocketNotifier() constructor combined with the    QObject::setObjectName() function instead.    \oldcode        QSocketNotifier *notifier = new QSocketNotifier(socket, type, parent, name);    \newcode        QSocketNotifier *notifier = new QSocketNotifier(socket, type, parent);        notifier->setObjectName(name);    \endcode*/QSocketNotifier::QSocketNotifier(int socket, Type type, QObject *parent,                                  const char *name)    : QObject(parent){    setObjectName(QString::fromAscii(name));    if (socket < 0)        qWarning("QSocketNotifier: Invalid socket specified");#if defined(Q_OS_UNIX)    if (socket >= FD_SETSIZE)        qWarning("QSocketNotifier: Socket descriptor too large for select()");#endif    sockfd = socket;    sntype = type;    snenabled = true;    Q_D(QObject);    if (!d->threadData->eventDispatcher) {        qWarning("QSocketNotifier: Can only be used with threads started with QThread");    } else {        d->threadData->eventDispatcher->registerSocketNotifier(this);    }}#endif/*!    Destroys this socket notifier.*/QSocketNotifier::~QSocketNotifier(){    setEnabled(false);}/*!    \fn void QSocketNotifier::activated(int socket)    This signal is emitted whenever the socket notifier is enabled and    a socket event corresponding to its \l {Type}{type} occurs.    The socket identifier is passed in the \a socket parameter.    \sa type(), socket()*//*!    \fn int QSocketNotifier::socket() const    Returns the socket identifier specified to the constructor.    \sa type()*//*!    \fn Type QSocketNotifier::type() const    Returns the socket event type specified to the constructor.    \sa socket()*//*!    \fn bool QSocketNotifier::isEnabled() const    Returns true if the notifier is enabled; otherwise returns false.    \sa setEnabled()*//*!    If \a enable is true, the notifier is enabled; otherwise the notifier    is disabled.    The notifier is enabled by default, i.e. it emits the activated()    signal whenever a socket event corresponding to its    \l{type()}{type} occurs. If it is disabled, it ignores socket    events (the same effect as not creating the socket notifier).    Write notifiers should normally be disabled immediately after the    activated() signal has been emitted    \sa isEnabled(), activated()*/void QSocketNotifier::setEnabled(bool enable){    if (sockfd < 0)        return;    if (snenabled == enable)                        // no change        return;    snenabled = enable;    Q_D(QObject);    if (!d->threadData->eventDispatcher) // perhaps application/thread is shutting down        return;    if (snenabled)        d->threadData->eventDispatcher->registerSocketNotifier(this);    else        d->threadData->eventDispatcher->unregisterSocketNotifier(this);}/*!\reimp*/bool QSocketNotifier::event(QEvent *e){    // Emits the activated() signal when a QEvent::SockAct is    // received.    if (e->type() == QEvent::ThreadChange) {        if (snenabled) {            QMetaObject::invokeMethod(this, "setEnabled", Qt::QueuedConnection,                                      Q_ARG(bool, snenabled));            setEnabled(false);        }    }    QObject::event(e);                        // will activate filters    if (e->type() == QEvent::SockAct) {        emit activated(sockfd);        return true;    }    return false;}