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/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** 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 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#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
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