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#include "qsocketnotifier.h"

#include "qplatformdefs.h"

#include "qabstracteventdispatcher.h"

#include "qcoreapplication.h"

#include "qobject_p.h"

#include <private/qthread_p.h>

QT_BEGIN_NAMESPACE

/*!

    \class QSocketNotifier

    \brief The QSocketNotifier class provides support for monitoring

    activity on a file descriptor.

    \ingroup network

    \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

    \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");

    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");

    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;

}

QT_END_NAMESPACE