1 | /****************************************************************************
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2 | **
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3 | ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
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4 | ** Contact: Qt Software Information ([email protected])
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5 | **
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6 | ** This file is part of the QtCore module of the Qt Toolkit.
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7 | **
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8 | ** $QT_BEGIN_LICENSE:LGPL$
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9 | ** Commercial Usage
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10 | ** Licensees holding valid Qt Commercial licenses may use this file in
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11 | ** accordance with the Qt Commercial License Agreement provided with the
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12 | ** Software or, alternatively, in accordance with the terms contained in
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13 | ** a written agreement between you and Nokia.
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14 | **
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15 | ** GNU Lesser General Public License Usage
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16 | ** Alternatively, this file may be used under the terms of the GNU Lesser
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17 | ** General Public License version 2.1 as published by the Free Software
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18 | ** Foundation and appearing in the file LICENSE.LGPL included in the
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19 | ** packaging of this file. Please review the following information to
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20 | ** ensure the GNU Lesser General Public License version 2.1 requirements
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21 | ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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22 | **
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23 | ** In addition, as a special exception, Nokia gives you certain
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24 | ** additional rights. These rights are described in the Nokia Qt LGPL
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25 | ** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
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26 | ** package.
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27 | **
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28 | ** GNU General Public License Usage
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29 | ** Alternatively, this file may be used under the terms of the GNU
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30 | ** General Public License version 3.0 as published by the Free Software
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31 | ** Foundation and appearing in the file LICENSE.GPL included in the
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32 | ** packaging of this file. Please review the following information to
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33 | ** ensure the GNU General Public License version 3.0 requirements will be
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34 | ** met: http://www.gnu.org/copyleft/gpl.html.
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35 | **
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36 | ** If you are unsure which license is appropriate for your use, please
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37 | ** contact the sales department at [email protected].
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38 | ** $QT_END_LICENSE$
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39 | **
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40 | ****************************************************************************/
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41 |
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42 | #include "qsocketnotifier.h"
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43 |
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44 | #include "qplatformdefs.h"
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45 |
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46 | #include "qabstracteventdispatcher.h"
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47 | #include "qcoreapplication.h"
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48 |
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49 | #include "qobject_p.h"
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50 | #include <private/qthread_p.h>
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51 |
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52 | QT_BEGIN_NAMESPACE
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53 |
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54 | /*!
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55 | \class QSocketNotifier
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56 | \brief The QSocketNotifier class provides support for monitoring
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57 | activity on a file descriptor.
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58 |
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59 | \ingroup io
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60 |
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61 | The QSocketNotifier makes it possible to integrate Qt's event
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62 | loop with other event loops based on file descriptors. For
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63 | example, the \l{CORBA Framework} uses it to process CORBA
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64 | events. File descriptor action is detected in Qt's main event
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65 | loop (QCoreApplication::exec()).
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66 |
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67 | \target write notifiers
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68 |
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69 | Once you have opened a device using a low-level (usually
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70 | platform-specific) API, you can create a socket notifier to
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71 | monitor the file descriptor. The socket notifier is enabled by
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72 | default, i.e. it emits the activated() signal whenever a socket
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73 | event corresponding to its type occurs. Connect the activated()
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74 | signal to the slot you want to be called when an event
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75 | corresponding to your socket notifier's type occurs.
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76 |
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77 | There are three types of socket notifiers: read, write, and
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78 | exception. The type is described by the \l Type enum, and must be
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79 | specified when constructing the socket notifier. After
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80 | construction it can be determined using the type() function. Note
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81 | that if you need to monitor both reads and writes for the same
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82 | file descriptor, you must create two socket notifiers. Note also
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83 | that it is not possible to install two socket notifiers of the
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84 | same type (\l Read, \l Write, \l Exception) on the same socket.
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85 |
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86 | The setEnabled() function allows you to disable as well as enable
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87 | the socket notifier. It is generally advisable to explicitly
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88 | enable or disable the socket notifier, especially for write
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89 | notifiers. A disabled notifier ignores socket events (the same
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90 | effect as not creating the socket notifier). Use the isEnabled()
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91 | function to determine the notifier's current status.
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92 |
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93 | Finally, you can use the socket() function to retrieve the
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94 | socket identifier. Although the class is called QSocketNotifier,
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95 | it is normally used for other types of devices than sockets.
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96 | QTcpSocket and QUdpSocket provide notification through signals, so
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97 | there is normally no need to use a QSocketNotifier on them.
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98 |
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99 | \section1 Notes for Windows Users
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100 |
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101 | The socket passed to QSocketNotifier will become non-blocking, even if
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102 | it was created as a blocking socket.
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103 | The activated() signal is sometimes triggered by high general activity
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104 | on the host, even if there is nothing to read. A subsequent read from
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105 | the socket can then fail, the error indicating that there is no data
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106 | available (e.g., \c{WSAEWOULDBLOCK}). This is an operating system
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107 | limitation, and not a bug in QSocketNotifier.
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108 |
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109 | To ensure that the socket notifier handles read notifications correctly,
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110 | follow these steps when you receive a notification:
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111 |
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112 | \list 1
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113 | \o Disable the notifier.
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114 | \o Read data from the socket.
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115 | \o Re-enable the notifier if you are interested in more data (such as after
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116 | having written a new command to a remote server).
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117 | \endlist
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118 |
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119 | To ensure that the socket notifier handles write notifications correctly,
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120 | follow these steps when you receive a notification:
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121 |
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122 | \list 1
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123 | \o Disable the notifier.
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124 | \o Write as much data as you can (before \c EWOULDBLOCK is returned).
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125 | \o Re-enable notifier if you have more data to write.
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126 | \endlist
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127 |
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128 | \bold{Further information:}
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129 | On Windows, Qt always disables the notifier after getting a notification,
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130 | and only re-enables it if more data is expected. For example, if data is
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131 | read from the socket and it can be used to read more, or if reading or
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132 | writing is not possible because the socket would block, in which case
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133 | it is necessary to wait before attempting to read or write again.
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134 |
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135 | \sa QFile, QProcess, QTcpSocket, QUdpSocket
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136 | */
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137 |
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138 | /*!
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139 | \enum QSocketNotifier::Type
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140 |
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141 | This enum describes the various types of events that a socket
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142 | notifier can recognize. The type must be specified when
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143 | constructing the socket notifier.
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144 |
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145 | Note that if you need to monitor both reads and writes for the
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146 | same file descriptor, you must create two socket notifiers. Note
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147 | also that it is not possible to install two socket notifiers of
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148 | the same type (Read, Write, Exception) on the same socket.
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149 |
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150 | \value Read There is data to be read.
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151 | \value Write Data can be written.
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152 | \value Exception An exception has occurred. We recommend against using this.
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153 |
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154 | \sa QSocketNotifier(), type()
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155 | */
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156 |
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157 | /*!
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158 | Constructs a socket notifier with the given \a parent. It enables
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159 | the \a socket, and watches for events of the given \a type.
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160 |
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161 | It is generally advisable to explicitly enable or disable the
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162 | socket notifier, especially for write notifiers.
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163 |
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164 | \bold{Note for Windows users:} The socket passed to QSocketNotifier
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165 | will become non-blocking, even if it was created as a blocking socket.
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166 |
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167 | \sa setEnabled(), isEnabled()
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168 | */
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169 |
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170 | QSocketNotifier::QSocketNotifier(int socket, Type type, QObject *parent)
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171 | : QObject(parent)
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172 | {
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173 | if (socket < 0)
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174 | qWarning("QSocketNotifier: Invalid socket specified");
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175 | sockfd = socket;
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176 | sntype = type;
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177 | snenabled = true;
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178 |
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179 | Q_D(QObject);
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180 | if (!d->threadData->eventDispatcher) {
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181 | qWarning("QSocketNotifier: Can only be used with threads started with QThread");
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182 | } else {
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183 | d->threadData->eventDispatcher->registerSocketNotifier(this);
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184 | }
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185 | }
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186 |
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187 | #ifdef QT3_SUPPORT
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188 | /*!
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189 | \obsolete
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190 |
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191 | Use the QSocketNotifier() constructor combined with the
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192 | QObject::setObjectName() function instead.
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193 |
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194 | \oldcode
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195 | QSocketNotifier *notifier = new QSocketNotifier(socket, type, parent, name);
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196 | \newcode
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197 | QSocketNotifier *notifier = new QSocketNotifier(socket, type, parent);
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198 | notifier->setObjectName(name);
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199 | \endcode
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200 | */
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201 |
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202 | QSocketNotifier::QSocketNotifier(int socket, Type type, QObject *parent,
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203 | const char *name)
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204 | : QObject(parent)
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205 | {
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206 | setObjectName(QString::fromAscii(name));
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207 | if (socket < 0)
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208 | qWarning("QSocketNotifier: Invalid socket specified");
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209 | sockfd = socket;
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210 | sntype = type;
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211 | snenabled = true;
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212 |
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213 | Q_D(QObject);
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214 | if (!d->threadData->eventDispatcher) {
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215 | qWarning("QSocketNotifier: Can only be used with threads started with QThread");
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216 | } else {
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217 | d->threadData->eventDispatcher->registerSocketNotifier(this);
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218 | }
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219 | }
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220 | #endif
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221 | /*!
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222 | Destroys this socket notifier.
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223 | */
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224 |
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225 | QSocketNotifier::~QSocketNotifier()
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226 | {
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227 | setEnabled(false);
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228 | }
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229 |
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230 |
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231 | /*!
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232 | \fn void QSocketNotifier::activated(int socket)
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233 |
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234 | This signal is emitted whenever the socket notifier is enabled and
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235 | a socket event corresponding to its \l {Type}{type} occurs.
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236 |
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237 | The socket identifier is passed in the \a socket parameter.
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238 |
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239 | \sa type(), socket()
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240 | */
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241 |
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242 |
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243 | /*!
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244 | \fn int QSocketNotifier::socket() const
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245 |
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246 | Returns the socket identifier specified to the constructor.
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247 |
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248 | \sa type()
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249 | */
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250 |
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251 | /*!
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252 | \fn Type QSocketNotifier::type() const
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253 |
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254 | Returns the socket event type specified to the constructor.
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255 |
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256 | \sa socket()
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257 | */
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258 |
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259 |
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260 | /*!
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261 | \fn bool QSocketNotifier::isEnabled() const
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262 |
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263 | Returns true if the notifier is enabled; otherwise returns false.
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264 |
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265 | \sa setEnabled()
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266 | */
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267 |
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268 | /*!
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269 | If \a enable is true, the notifier is enabled; otherwise the notifier
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270 | is disabled.
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271 |
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272 | The notifier is enabled by default, i.e. it emits the activated()
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273 | signal whenever a socket event corresponding to its
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274 | \l{type()}{type} occurs. If it is disabled, it ignores socket
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275 | events (the same effect as not creating the socket notifier).
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276 |
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277 | Write notifiers should normally be disabled immediately after the
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278 | activated() signal has been emitted
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279 |
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280 | \sa isEnabled(), activated()
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281 | */
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282 |
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283 | void QSocketNotifier::setEnabled(bool enable)
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284 | {
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285 | if (sockfd < 0)
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286 | return;
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287 | if (snenabled == enable) // no change
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288 | return;
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289 | snenabled = enable;
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290 |
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291 | Q_D(QObject);
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292 | if (!d->threadData->eventDispatcher) // perhaps application/thread is shutting down
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293 | return;
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294 | if (snenabled)
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295 | d->threadData->eventDispatcher->registerSocketNotifier(this);
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296 | else
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297 | d->threadData->eventDispatcher->unregisterSocketNotifier(this);
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298 | }
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299 |
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300 |
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301 | /*!\reimp
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302 | */
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303 | bool QSocketNotifier::event(QEvent *e)
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304 | {
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305 | // Emits the activated() signal when a QEvent::SockAct is
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306 | // received.
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307 | if (e->type() == QEvent::ThreadChange) {
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308 | if (snenabled) {
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309 | QMetaObject::invokeMethod(this, "setEnabled", Qt::QueuedConnection,
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310 | Q_ARG(bool, snenabled));
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311 | setEnabled(false);
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312 | }
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313 | }
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314 | QObject::event(e); // will activate filters
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315 | if (e->type() == QEvent::SockAct) {
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316 | emit activated(sockfd);
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317 | return true;
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318 | }
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319 | return false;
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320 | }
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321 |
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322 | QT_END_NAMESPACE
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