Doc: Clean up threading examples
- Example 3 (Clock) is a collection of anti-patterns.
- It implements a slot in a QThread subclass and then forces the new
thread to use Qt::DirectConnection to invoke the slot in the
"wrong" thread.
- It talks about getting away with non-thread-safe usage
- It uses a thread as a timer and then admits that it's an over-
complicated approach.
- Example 4 (Permanent Thread) is over-complicated yet incomplete. A
better one exists in the QThread class ref.
- Example 1 (Thread Pool) is covered by the QThreadPool class ref.
- Example 2 (QtConcurrent::run()) is covered in the "Threading and
Concurrent Programming Examples" page and the "QtConcurrentRun" page.
- The undocumented "Hello Thread" example is covered in the QThread
class ref.
- These examples cannot be accessed from Qt Creator's Examples tool.
- These examples are neither widget-related nor tutorials, contrary to
their source paths.
Task-number: QTBUG-33360
Change-Id: Ic79cb764ee925ddbcbeafee8e1d01db7fe0f6cfe
Reviewed-by: Topi Reiniö <topi.reinio@digia.com>
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
This commit is contained in:
Sze Howe Koh
The Qt Project
parent
a8351096db
commit
6b8e866391
@ -1,10 +0,0 @@
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QT += widgets
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CONFIG += console
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TEMPLATE = app
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SOURCES += main.cpp \
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clockthread.cpp
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HEADERS += clockthread.h
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# install
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target.path = $$[QT_INSTALL_EXAMPLES]/widgets/tutorials/threads/clock
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INSTALLS += target
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@ -1,66 +0,0 @@
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/****************************************************************************
|
||||
**
|
||||
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
|
||||
** Contact: http://www.qt-project.org/legal
|
||||
**
|
||||
** This file is part of the examples of the Qt Toolkit.
|
||||
**
|
||||
** $QT_BEGIN_LICENSE:BSD$
|
||||
** You may use this file under the terms of the BSD license as follows:
|
||||
**
|
||||
** "Redistribution and use in source and binary forms, with or without
|
||||
** modification, are permitted provided that the following conditions are
|
||||
** met:
|
||||
** * Redistributions of source code must retain the above copyright
|
||||
** notice, this list of conditions and the following disclaimer.
|
||||
** * Redistributions in binary form must reproduce the above copyright
|
||||
** notice, this list of conditions and the following disclaimer in
|
||||
** the documentation and/or other materials provided with the
|
||||
** distribution.
|
||||
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
|
||||
** of its contributors may be used to endorse or promote products derived
|
||||
** from this software without specific prior written permission.
|
||||
**
|
||||
**
|
||||
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
|
||||
**
|
||||
** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include <QtWidgets>
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#include "clockthread.h"
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//This class starts another thread where it emits a signal for every new second.
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//! [1]
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// clock/clockthread.cpp
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void ClockThread::run()
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{
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QTimer timer;
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connect(&timer, SIGNAL(timeout()), this, SLOT(timerHit()), Qt::DirectConnection);
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timer.setInterval(10);
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timer.start(); // puts one event in the threads event queue
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exec();
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timer.stop();
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}
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void ClockThread::timerHit()
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{
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QString newTime= QDateTime::currentDateTime().toString("ddd MMMM d yy, hh:mm:ss");
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if(m_lastTime != newTime ){
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m_lastTime = newTime;
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emit sendTime(newTime) ;
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}
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}
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//! [1]
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@ -1,64 +0,0 @@
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/****************************************************************************
|
||||
**
|
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** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
|
||||
** Contact: http://www.qt-project.org/legal
|
||||
**
|
||||
** This file is part of the examples of the Qt Toolkit.
|
||||
**
|
||||
** $QT_BEGIN_LICENSE:BSD$
|
||||
** You may use this file under the terms of the BSD license as follows:
|
||||
**
|
||||
** "Redistribution and use in source and binary forms, with or without
|
||||
** modification, are permitted provided that the following conditions are
|
||||
** met:
|
||||
** * Redistributions of source code must retain the above copyright
|
||||
** notice, this list of conditions and the following disclaimer.
|
||||
** * Redistributions in binary form must reproduce the above copyright
|
||||
** notice, this list of conditions and the following disclaimer in
|
||||
** the documentation and/or other materials provided with the
|
||||
** distribution.
|
||||
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
|
||||
** of its contributors may be used to endorse or promote products derived
|
||||
** from this software without specific prior written permission.
|
||||
**
|
||||
**
|
||||
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
|
||||
**
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** $QT_END_LICENSE$
|
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**
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****************************************************************************/
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#ifndef CLOCKTHREAD_H
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#define CLOCKTHREAD_H
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#include <QString>
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#include <QThread>
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//! [1]
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// clock/clockthread.h
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class ClockThread : public QThread
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{
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Q_OBJECT
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signals:
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void sendTime(QString time);
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private:
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void run();
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QString m_lastTime;
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private slots:
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void timerHit();
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};
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//! [1]
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#endif // CLOCKTHREAD_H
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@ -1,67 +0,0 @@
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/****************************************************************************
|
||||
**
|
||||
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
|
||||
** Contact: http://www.qt-project.org/legal
|
||||
**
|
||||
** This file is part of the examples of the Qt Toolkit.
|
||||
**
|
||||
** $QT_BEGIN_LICENSE:BSD$
|
||||
** You may use this file under the terms of the BSD license as follows:
|
||||
**
|
||||
** "Redistribution and use in source and binary forms, with or without
|
||||
** modification, are permitted provided that the following conditions are
|
||||
** met:
|
||||
** * Redistributions of source code must retain the above copyright
|
||||
** notice, this list of conditions and the following disclaimer.
|
||||
** * Redistributions in binary form must reproduce the above copyright
|
||||
** notice, this list of conditions and the following disclaimer in
|
||||
** the documentation and/or other materials provided with the
|
||||
** distribution.
|
||||
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
|
||||
** of its contributors may be used to endorse or promote products derived
|
||||
** from this software without specific prior written permission.
|
||||
**
|
||||
**
|
||||
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
|
||||
**
|
||||
** $QT_END_LICENSE$
|
||||
**
|
||||
****************************************************************************/
|
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|
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#include <QtWidgets>
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#include "clockthread.h"
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//A clock that does time formatting in another thread
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//! [1]
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int main(int argc, char *argv[])
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{
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QApplication app(argc, argv);
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// build gui
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QWidget widget;
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QLabel *label = new QLabel;
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QHBoxLayout *layout = new QHBoxLayout(&widget);
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layout->addWidget(label);
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widget.setWindowTitle("clock");
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//instantiate thread object
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ClockThread clockThread;
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QObject::connect(&clockThread, SIGNAL(sendTime(QString)), label, SLOT(setText(QString)), Qt::QueuedConnection);
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clockThread.start();
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widget.show();
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app.exec();
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clockThread.quit();
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clockThread.wait();
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return 0;
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}
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//! [1]
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@ -1,63 +0,0 @@
|
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/****************************************************************************
|
||||
**
|
||||
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
|
||||
** Contact: http://www.qt-project.org/legal
|
||||
**
|
||||
** This file is part of the examples of the Qt Toolkit.
|
||||
**
|
||||
** $QT_BEGIN_LICENSE:BSD$
|
||||
** You may use this file under the terms of the BSD license as follows:
|
||||
**
|
||||
** "Redistribution and use in source and binary forms, with or without
|
||||
** modification, are permitted provided that the following conditions are
|
||||
** met:
|
||||
** * Redistributions of source code must retain the above copyright
|
||||
** notice, this list of conditions and the following disclaimer.
|
||||
** * Redistributions in binary form must reproduce the above copyright
|
||||
** notice, this list of conditions and the following disclaimer in
|
||||
** the documentation and/or other materials provided with the
|
||||
** distribution.
|
||||
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
|
||||
** of its contributors may be used to endorse or promote products derived
|
||||
** from this software without specific prior written permission.
|
||||
**
|
||||
**
|
||||
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
|
||||
**
|
||||
** $QT_END_LICENSE$
|
||||
**
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||||
****************************************************************************/
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||||
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#include <QtCore>
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#include <QtConcurrent>
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/*
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says hello from main thread and secondary thread using QtConcurrent
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*/
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//! [1]
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// helloconcurrent/main.cpp
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void hello()
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{
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qDebug() << "Hello from thread " << QThread::currentThread();
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}
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int main(int argc, char *argv[])
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{
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QCoreApplication app(argc, argv);
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QFuture<void> future = QtConcurrent::run(hello);
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qDebug() << "hello from GUI thread " << QThread::currentThread();
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future.waitForFinished();
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return 0;
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}
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//! [1]
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@ -1,14 +0,0 @@
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QT -= gui
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QT += concurrent
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CONFIG += console
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CONFIG -= app_bundle
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TEMPLATE = app
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SOURCES += helloconcurrent.cpp
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||||
|
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# install
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target.path = $$[QT_INSTALL_EXAMPLES]/widgets/tutorials/threads/helloconcurrent
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INSTALLS += target
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|
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@ -1,50 +0,0 @@
|
||||
/****************************************************************************
|
||||
**
|
||||
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
|
||||
** Contact: http://www.qt-project.org/legal
|
||||
**
|
||||
** This file is part of the examples of the Qt Toolkit.
|
||||
**
|
||||
** $QT_BEGIN_LICENSE:BSD$
|
||||
** You may use this file under the terms of the BSD license as follows:
|
||||
**
|
||||
** "Redistribution and use in source and binary forms, with or without
|
||||
** modification, are permitted provided that the following conditions are
|
||||
** met:
|
||||
** * Redistributions of source code must retain the above copyright
|
||||
** notice, this list of conditions and the following disclaimer.
|
||||
** * Redistributions in binary form must reproduce the above copyright
|
||||
** notice, this list of conditions and the following disclaimer in
|
||||
** the documentation and/or other materials provided with the
|
||||
** distribution.
|
||||
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
|
||||
** of its contributors may be used to endorse or promote products derived
|
||||
** from this software without specific prior written permission.
|
||||
**
|
||||
**
|
||||
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
|
||||
**
|
||||
** $QT_END_LICENSE$
|
||||
**
|
||||
****************************************************************************/
|
||||
|
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#include <QDebug>
|
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#include "hellothread.h"
|
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/*
|
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* demonstrates use of QThread, says hello in another thread and terminates
|
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*/
|
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|
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void HelloThread::run()
|
||||
{
|
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qDebug() << "hello from worker thread " << thread()->currentThreadId();
|
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}
|
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@ -1,53 +0,0 @@
|
||||
/****************************************************************************
|
||||
**
|
||||
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
|
||||
** Contact: http://www.qt-project.org/legal
|
||||
**
|
||||
** This file is part of the examples of the Qt Toolkit.
|
||||
**
|
||||
** $QT_BEGIN_LICENSE:BSD$
|
||||
** You may use this file under the terms of the BSD license as follows:
|
||||
**
|
||||
** "Redistribution and use in source and binary forms, with or without
|
||||
** modification, are permitted provided that the following conditions are
|
||||
** met:
|
||||
** * Redistributions of source code must retain the above copyright
|
||||
** notice, this list of conditions and the following disclaimer.
|
||||
** * Redistributions in binary form must reproduce the above copyright
|
||||
** notice, this list of conditions and the following disclaimer in
|
||||
** the documentation and/or other materials provided with the
|
||||
** distribution.
|
||||
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
|
||||
** of its contributors may be used to endorse or promote products derived
|
||||
** from this software without specific prior written permission.
|
||||
**
|
||||
**
|
||||
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
|
||||
**
|
||||
** $QT_END_LICENSE$
|
||||
**
|
||||
****************************************************************************/
|
||||
|
||||
#ifndef HELLOTHREAD_H
|
||||
#define HELLOTHREAD_H
|
||||
|
||||
#include <QThread>
|
||||
|
||||
class HelloThread : public QThread
|
||||
{
|
||||
Q_OBJECT
|
||||
private:
|
||||
void run();
|
||||
};
|
||||
|
||||
#endif // HELLOTHREAD_H
|
||||
@ -1,14 +0,0 @@
|
||||
QT -= gui
|
||||
|
||||
CONFIG += console
|
||||
CONFIG -= app_bundle
|
||||
TEMPLATE = app
|
||||
SOURCES += main.cpp \
|
||||
hellothread.cpp
|
||||
HEADERS += hellothread.h
|
||||
|
||||
# install
|
||||
target.path = $$[QT_INSTALL_EXAMPLES]/widgets/tutorials/threads/hellothread
|
||||
INSTALLS += target
|
||||
|
||||
|
||||
@ -1,52 +0,0 @@
|
||||
/****************************************************************************
|
||||
**
|
||||
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
|
||||
** Contact: http://www.qt-project.org/legal
|
||||
**
|
||||
** This file is part of the examples of the Qt Toolkit.
|
||||
**
|
||||
** $QT_BEGIN_LICENSE:BSD$
|
||||
** You may use this file under the terms of the BSD license as follows:
|
||||
**
|
||||
** "Redistribution and use in source and binary forms, with or without
|
||||
** modification, are permitted provided that the following conditions are
|
||||
** met:
|
||||
** * Redistributions of source code must retain the above copyright
|
||||
** notice, this list of conditions and the following disclaimer.
|
||||
** * Redistributions in binary form must reproduce the above copyright
|
||||
** notice, this list of conditions and the following disclaimer in
|
||||
** the documentation and/or other materials provided with the
|
||||
** distribution.
|
||||
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
|
||||
** of its contributors may be used to endorse or promote products derived
|
||||
** from this software without specific prior written permission.
|
||||
**
|
||||
**
|
||||
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
|
||||
**
|
||||
** $QT_END_LICENSE$
|
||||
**
|
||||
****************************************************************************/
|
||||
|
||||
#include <QtCore>
|
||||
#include "hellothread.h"
|
||||
|
||||
int main(int argc, char *argv[])
|
||||
{
|
||||
QCoreApplication app(argc, argv);
|
||||
HelloThread thread;
|
||||
thread.start();
|
||||
qDebug() << "hello from GUI thread " << app.thread()->currentThreadId();
|
||||
thread.wait(); // do not exit before the thread is completed!
|
||||
return 0;
|
||||
}
|
||||
@ -1,65 +0,0 @@
|
||||
/****************************************************************************
|
||||
**
|
||||
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
|
||||
** Contact: http://www.qt-project.org/legal
|
||||
**
|
||||
** This file is part of the examples of the Qt Toolkit.
|
||||
**
|
||||
** $QT_BEGIN_LICENSE:BSD$
|
||||
** You may use this file under the terms of the BSD license as follows:
|
||||
**
|
||||
** "Redistribution and use in source and binary forms, with or without
|
||||
** modification, are permitted provided that the following conditions are
|
||||
** met:
|
||||
** * Redistributions of source code must retain the above copyright
|
||||
** notice, this list of conditions and the following disclaimer.
|
||||
** * Redistributions in binary form must reproduce the above copyright
|
||||
** notice, this list of conditions and the following disclaimer in
|
||||
** the documentation and/or other materials provided with the
|
||||
** distribution.
|
||||
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
|
||||
** of its contributors may be used to endorse or promote products derived
|
||||
** from this software without specific prior written permission.
|
||||
**
|
||||
**
|
||||
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
|
||||
**
|
||||
** $QT_END_LICENSE$
|
||||
**
|
||||
****************************************************************************/
|
||||
#include <QtCore>
|
||||
// A hello world program to demonstrate the use of the global thread pool
|
||||
|
||||
//! [1]
|
||||
// hellothreadpool/main.cpp
|
||||
class Work : public QRunnable
|
||||
{
|
||||
public:
|
||||
void run()
|
||||
{
|
||||
qDebug() << "Hello from thread " << QThread::currentThread();
|
||||
}
|
||||
};
|
||||
|
||||
int main(int argc, char *argv[])
|
||||
{
|
||||
QCoreApplication app(argc, argv);
|
||||
Work work;
|
||||
work.setAutoDelete(false);
|
||||
QThreadPool *threadPool = QThreadPool::globalInstance();
|
||||
threadPool->start(&work);
|
||||
qDebug() << "hello from GUI thread " << QThread::currentThread();
|
||||
threadPool->waitForDone();
|
||||
return 0;
|
||||
}
|
||||
//! [1]
|
||||
@ -1,14 +0,0 @@
|
||||
QT -= gui
|
||||
|
||||
CONFIG += console
|
||||
CONFIG -= app_bundle
|
||||
TEMPLATE = app
|
||||
SOURCES += hellothreadpool.cpp
|
||||
|
||||
# install
|
||||
target.path = $$[QT_INSTALL_EXAMPLES]/widgets/tutorials/threads/hellothreadpool
|
||||
INSTALLS += target
|
||||
|
||||
|
||||
|
||||
|
||||
@ -1,69 +0,0 @@
|
||||
/****************************************************************************
|
||||
**
|
||||
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
|
||||
** Contact: http://www.qt-project.org/legal
|
||||
**
|
||||
** This file is part of the examples of the Qt Toolkit.
|
||||
**
|
||||
** $QT_BEGIN_LICENSE:BSD$
|
||||
** You may use this file under the terms of the BSD license as follows:
|
||||
**
|
||||
** "Redistribution and use in source and binary forms, with or without
|
||||
** modification, are permitted provided that the following conditions are
|
||||
** met:
|
||||
** * Redistributions of source code must retain the above copyright
|
||||
** notice, this list of conditions and the following disclaimer.
|
||||
** * Redistributions in binary form must reproduce the above copyright
|
||||
** notice, this list of conditions and the following disclaimer in
|
||||
** the documentation and/or other materials provided with the
|
||||
** distribution.
|
||||
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
|
||||
** of its contributors may be used to endorse or promote products derived
|
||||
** from this software without specific prior written permission.
|
||||
**
|
||||
**
|
||||
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
|
||||
**
|
||||
** $QT_END_LICENSE$
|
||||
**
|
||||
****************************************************************************/
|
||||
|
||||
#include <QtCore>
|
||||
#include "workerobject.h"
|
||||
#include "thread.h"
|
||||
|
||||
/*
|
||||
* moves a class derived from QObject (WorkerObject) to another thread
|
||||
* and calls methods over thread boundaries.
|
||||
*/
|
||||
|
||||
//![1]
|
||||
// movedobject/main.cpp
|
||||
int main(int argc, char *argv[])
|
||||
{
|
||||
QCoreApplication app(argc, argv);
|
||||
Thread thread;
|
||||
qDebug() << "main thread ID: " << app.thread()->currentThreadId();
|
||||
WorkerObject *worker = new WorkerObject;
|
||||
thread.launchWorker(worker);
|
||||
QMetaObject::invokeMethod(worker, "doWork", Qt::QueuedConnection);
|
||||
QMetaObject::invokeMethod(worker, "startPolling", Qt::QueuedConnection, Q_ARG(int, 500));
|
||||
//let application produce output for 3 seconds and quit
|
||||
QTimer::singleShot(3000, &app, SLOT(quit()));
|
||||
app.exec();
|
||||
thread.stop();
|
||||
thread.wait();
|
||||
delete worker;
|
||||
return 0;
|
||||
}
|
||||
//![1]
|
||||
@ -1,15 +0,0 @@
|
||||
QT += widgets
|
||||
CONFIG += console
|
||||
CONFIG -= app_bundle
|
||||
TEMPLATE = app
|
||||
SOURCES += main.cpp \
|
||||
workerobject.cpp \
|
||||
thread.cpp
|
||||
|
||||
HEADERS += \
|
||||
workerobject.h \
|
||||
thread.h
|
||||
|
||||
# install
|
||||
target.path = $$[QT_INSTALL_EXAMPLES]/widgets/tutorials/threads/movedobject
|
||||
INSTALLS += target
|
||||
@ -1,100 +0,0 @@
|
||||
/****************************************************************************
|
||||
**
|
||||
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
|
||||
** Contact: http://www.qt-project.org/legal
|
||||
**
|
||||
** This file is part of the examples of the Qt Toolkit.
|
||||
**
|
||||
** $QT_BEGIN_LICENSE:BSD$
|
||||
** You may use this file under the terms of the BSD license as follows:
|
||||
**
|
||||
** "Redistribution and use in source and binary forms, with or without
|
||||
** modification, are permitted provided that the following conditions are
|
||||
** met:
|
||||
** * Redistributions of source code must retain the above copyright
|
||||
** notice, this list of conditions and the following disclaimer.
|
||||
** * Redistributions in binary form must reproduce the above copyright
|
||||
** notice, this list of conditions and the following disclaimer in
|
||||
** the documentation and/or other materials provided with the
|
||||
** distribution.
|
||||
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
|
||||
** of its contributors may be used to endorse or promote products derived
|
||||
** from this software without specific prior written permission.
|
||||
**
|
||||
**
|
||||
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
|
||||
**
|
||||
** $QT_END_LICENSE$
|
||||
**
|
||||
****************************************************************************/
|
||||
|
||||
#include "thread.h"
|
||||
|
||||
/*
|
||||
* QThread derived class with additional capability to move a QObject to the
|
||||
* new thread, to stop the thread and move the QObject back to the thread where
|
||||
*it came from.
|
||||
*/
|
||||
|
||||
Thread::Thread( QObject *parent)
|
||||
: QThread (parent)
|
||||
{
|
||||
//we need a class that receives signals from other threads and emits a signal in response
|
||||
shutDownHelper=new QSignalMapper;
|
||||
shutDownHelper->setMapping(this,0);
|
||||
connect(this, SIGNAL(started()), this, SLOT(setReadyStatus() ), Qt::DirectConnection);
|
||||
connect(this, SIGNAL(aboutToStop()), shutDownHelper, SLOT(map()) );
|
||||
}
|
||||
|
||||
//------------------------------------------------------
|
||||
Thread::~Thread()
|
||||
{
|
||||
delete shutDownHelper;
|
||||
}
|
||||
|
||||
//------------------------------------------------------
|
||||
// starts thread, moves worker to this thread and blocks
|
||||
void Thread::launchWorker(QObject *worker)
|
||||
{
|
||||
this->worker = worker;
|
||||
start();
|
||||
worker->moveToThread(this);
|
||||
shutDownHelper->moveToThread(this);
|
||||
connect(shutDownHelper, SIGNAL(mapped(int) ), this, SLOT(stopExecutor()), Qt::DirectConnection );
|
||||
mutex.lock();
|
||||
waitCondition.wait(&mutex);
|
||||
}
|
||||
|
||||
//------------------------------------------------------
|
||||
// puts a command to stop processing in the event queue of worker thread
|
||||
void Thread::stop()
|
||||
{
|
||||
emit aboutToStop();
|
||||
}
|
||||
|
||||
//------------------------------------------------------
|
||||
|
||||
// methods above this line should be called in gui thread context
|
||||
// methods below this line are private and will be run in secondary thread context
|
||||
|
||||
//------------------------------------------------------
|
||||
void Thread::stopExecutor() //secondary thread context
|
||||
{
|
||||
exit();
|
||||
}
|
||||
|
||||
//------------------------------------------------------
|
||||
void Thread::setReadyStatus()
|
||||
{
|
||||
waitCondition.wakeAll();
|
||||
}
|
||||
@ -1,67 +0,0 @@
|
||||
/****************************************************************************
|
||||
**
|
||||
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
|
||||
** Contact: http://www.qt-project.org/legal
|
||||
**
|
||||
** This file is part of the examples of the Qt Toolkit.
|
||||
**
|
||||
** $QT_BEGIN_LICENSE:BSD$
|
||||
** You may use this file under the terms of the BSD license as follows:
|
||||
**
|
||||
** "Redistribution and use in source and binary forms, with or without
|
||||
** modification, are permitted provided that the following conditions are
|
||||
** met:
|
||||
** * Redistributions of source code must retain the above copyright
|
||||
** notice, this list of conditions and the following disclaimer.
|
||||
** * Redistributions in binary form must reproduce the above copyright
|
||||
** notice, this list of conditions and the following disclaimer in
|
||||
** the documentation and/or other materials provided with the
|
||||
** distribution.
|
||||
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
|
||||
** of its contributors may be used to endorse or promote products derived
|
||||
** from this software without specific prior written permission.
|
||||
**
|
||||
**
|
||||
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
|
||||
**
|
||||
** $QT_END_LICENSE$
|
||||
**
|
||||
****************************************************************************/
|
||||
|
||||
|
||||
#ifndef THREAD_H
|
||||
#define THREAD_H
|
||||
|
||||
#include <QtCore>
|
||||
|
||||
class Thread :public QThread
|
||||
{
|
||||
Q_OBJECT
|
||||
public:
|
||||
Thread( QObject *parent=0);
|
||||
~Thread();
|
||||
void stop();
|
||||
void launchWorker(QObject *worker);
|
||||
private:
|
||||
QObject *worker;
|
||||
QSignalMapper *shutDownHelper;
|
||||
QWaitCondition waitCondition;
|
||||
QMutex mutex;
|
||||
private slots:
|
||||
void stopExecutor();
|
||||
void setReadyStatus();
|
||||
signals:
|
||||
void aboutToStop();
|
||||
};
|
||||
|
||||
#endif // THREAD_H
|
||||
@ -1,87 +0,0 @@
|
||||
/****************************************************************************
|
||||
**
|
||||
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
|
||||
** Contact: http://www.qt-project.org/legal
|
||||
**
|
||||
** This file is part of the examples of the Qt Toolkit.
|
||||
**
|
||||
** $QT_BEGIN_LICENSE:BSD$
|
||||
** You may use this file under the terms of the BSD license as follows:
|
||||
**
|
||||
** "Redistribution and use in source and binary forms, with or without
|
||||
** modification, are permitted provided that the following conditions are
|
||||
** met:
|
||||
** * Redistributions of source code must retain the above copyright
|
||||
** notice, this list of conditions and the following disclaimer.
|
||||
** * Redistributions in binary form must reproduce the above copyright
|
||||
** notice, this list of conditions and the following disclaimer in
|
||||
** the documentation and/or other materials provided with the
|
||||
** distribution.
|
||||
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
|
||||
** of its contributors may be used to endorse or promote products derived
|
||||
** from this software without specific prior written permission.
|
||||
**
|
||||
**
|
||||
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
|
||||
**
|
||||
** $QT_END_LICENSE$
|
||||
**
|
||||
****************************************************************************/
|
||||
#include <QtCore>
|
||||
#include "workerobject.h"
|
||||
|
||||
/*
|
||||
* represents an object that lives in another thread where it polls a resource
|
||||
* and communicates with the gui thread
|
||||
*/
|
||||
|
||||
WorkerObject::WorkerObject(QObject *parent)
|
||||
: QObject(parent)
|
||||
{
|
||||
timer = new QTimer(this);
|
||||
connect(timer, SIGNAL(timeout()), this, SLOT(poll()));
|
||||
}
|
||||
|
||||
//---------------------------------------------------------------
|
||||
void WorkerObject::doWork()
|
||||
{
|
||||
|
||||
qDebug() << "doing work in thread " << thread()->currentThreadId() ;
|
||||
}
|
||||
|
||||
//---------------------------------------------------------------
|
||||
WorkerObject::~WorkerObject()
|
||||
{
|
||||
qDebug() << "destruction WorkerObject in thread " << thread()->currentThreadId();
|
||||
}
|
||||
|
||||
//---------------------------------------------------------------
|
||||
void WorkerObject::startPolling(int milliseconds)
|
||||
{
|
||||
count=0;
|
||||
timer->start(milliseconds);
|
||||
}
|
||||
|
||||
//---------------------------------------------------------------
|
||||
void WorkerObject::stopPolling()
|
||||
{
|
||||
timer->stop();
|
||||
}
|
||||
|
||||
//---------------------------------------------------------------
|
||||
void WorkerObject::poll()
|
||||
{
|
||||
qDebug() << QString("timer hit %1").arg(count);
|
||||
count++;
|
||||
}
|
||||
|
||||
@ -1,64 +0,0 @@
|
||||
/****************************************************************************
|
||||
**
|
||||
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
|
||||
** Contact: http://www.qt-project.org/legal
|
||||
**
|
||||
** This file is part of the examples of the Qt Toolkit.
|
||||
**
|
||||
** $QT_BEGIN_LICENSE:BSD$
|
||||
** You may use this file under the terms of the BSD license as follows:
|
||||
**
|
||||
** "Redistribution and use in source and binary forms, with or without
|
||||
** modification, are permitted provided that the following conditions are
|
||||
** met:
|
||||
** * Redistributions of source code must retain the above copyright
|
||||
** notice, this list of conditions and the following disclaimer.
|
||||
** * Redistributions in binary form must reproduce the above copyright
|
||||
** notice, this list of conditions and the following disclaimer in
|
||||
** the documentation and/or other materials provided with the
|
||||
** distribution.
|
||||
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
|
||||
** of its contributors may be used to endorse or promote products derived
|
||||
** from this software without specific prior written permission.
|
||||
**
|
||||
**
|
||||
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
|
||||
**
|
||||
** $QT_END_LICENSE$
|
||||
**
|
||||
****************************************************************************/
|
||||
|
||||
|
||||
#ifndef WORKEROBJECT_H
|
||||
#define WORKEROBJECT_H
|
||||
|
||||
#include <QtCore>
|
||||
|
||||
class WorkerObject : public QObject
|
||||
{
|
||||
Q_OBJECT
|
||||
public:
|
||||
explicit WorkerObject(QObject *parent = 0);
|
||||
~WorkerObject();
|
||||
public slots:
|
||||
void doWork();
|
||||
void startPolling(int milliseconds);
|
||||
void stopPolling();
|
||||
private slots:
|
||||
void poll();
|
||||
private:
|
||||
QTimer *timer;
|
||||
int count;
|
||||
};
|
||||
|
||||
#endif // WORKEROBJECT_H
|
||||
@ -1,8 +0,0 @@
|
||||
TEMPLATE = subdirs
|
||||
|
||||
SUBDIRS = hellothread \
|
||||
hellothreadpool \
|
||||
clock \
|
||||
movedobject
|
||||
|
||||
qtHaveModule(concurrent): SUBDIRS += helloconcurrent
|
||||
@ -1,2 +1,2 @@
|
||||
TEMPLATE = subdirs
|
||||
SUBDIRS += threads addressbook widgets modelview gettingStarted
|
||||
SUBDIRS += addressbook widgets modelview gettingStarted
|
||||
|
||||
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|
Before Width: | Height: | Size: 5.8 KiB |
@ -219,130 +219,9 @@
|
||||
|
||||
\section1 Examples
|
||||
|
||||
This tutorial comes with examples for Qt's three basic ways of working with
|
||||
threads. Two more examples show how to communicate with a running thread
|
||||
and how a QObject can be placed in another thread, providing service to the
|
||||
main thread.
|
||||
|
||||
\list
|
||||
\li Using QThread as shown \l{Qt thread basics}{above}
|
||||
\li \l{Example 1: Using the Thread Pool}{Using the global QThreadPool}
|
||||
\li \l{Example 2: Using QtConcurrent}{Using QtConcurrent}
|
||||
\li \l{Example 3: Clock}{Communication with the GUI thread}
|
||||
\li \l{Example 4: A Permanent Thread}{A permanent QObject in another thread
|
||||
provides service to the main thread}
|
||||
\endlist
|
||||
|
||||
The following examples can all be compiled and run independently. The source can
|
||||
be found in the examples directory: examples/tutorials/threads/
|
||||
|
||||
\section2 Example 1: Using the Thread Pool
|
||||
|
||||
Creating and destroying threads frequently can be expensive. To avoid the
|
||||
cost of thread creation, a thread pool can be used. A thread pool is a
|
||||
place where threads can be parked and fetched. We can write the same
|
||||
"hello thread" program as \l{Qt Thread Basics}{above} using the global
|
||||
thread pool. We derive a class from QRunnable. The code we want to run in
|
||||
another thread needs to be placed in the reimplemented QRunnable::run()
|
||||
method.
|
||||
|
||||
\snippet ../widgets/tutorials/threads/hellothreadpool/hellothreadpool.cpp 1
|
||||
|
||||
We instantiate Work in main(), locate the global thread pool and use the
|
||||
QThreadPool::start() method. Now the thread pool runs our worker in another
|
||||
thread. Using the thread pool has a performance advantage because threads
|
||||
are not destroyed after they have finished running. They are kept in a pool
|
||||
and wait to be used again later.
|
||||
|
||||
\section2 Example 2: Using QtConcurrent
|
||||
|
||||
\snippet ../widgets/tutorials/threads/helloconcurrent/helloconcurrent.cpp 1
|
||||
|
||||
We write a global function hello() to implement the work. QtConcurrent::run()
|
||||
is used to run the function in another thread. The result is a QFuture.
|
||||
QFuture provides a method called \l{QFuture::}{waitForFinished()}, which
|
||||
blocks until the calculation is completed. The real power of QtConcurrent
|
||||
becomes visible when data can be made available in a container. QtConcurrent
|
||||
provides several functions that are able to process itemized data on all
|
||||
available cores simultaneously. The use of QtConcurrent is very similar to
|
||||
applying an STL algorithm to an STL container.
|
||||
\l{examples-threadandconcurrent.html}{QtConcurrent Map} is a very short and
|
||||
clear example about how a container of images can be scaled on all available
|
||||
cores. The image scaling example uses the blocking variants of the functions
|
||||
used. For every blocking function there is also a non-blocking, asynchronous
|
||||
counterpart. Getting results asynchronously is implemented with QFuture and
|
||||
QFutureWatcher.
|
||||
|
||||
\section2 Example 3: Clock
|
||||
|
||||
\image thread_clock.png "clock"
|
||||
|
||||
We want to produce a clock application. The application has a GUI and a
|
||||
worker thread. The worker thread checks every 10 milliseconds what time it
|
||||
is. If the formatted time has changed, the result will be sent to the GUI
|
||||
thread where it is displayed.
|
||||
|
||||
Of course, this is an overly complicated way of designing a clock and,
|
||||
actually, a separate thread is unnecessary. We would be better off placing
|
||||
the timer in the main thread because the calculation made in the timer slot
|
||||
is very short-lived. This example is purely for instructional use and shows
|
||||
how to communicate from a worker thread to a GUI thread. Note that
|
||||
communication in this direction is easy. We only need to add a signal
|
||||
to QThread and make a queued signal/slot connection to the main thread.
|
||||
Communication from the GUI to the worker thread is shown in the next
|
||||
example.
|
||||
|
||||
\snippet ../widgets/tutorials/threads/clock/main.cpp 1
|
||||
|
||||
We've connected the \c clockThread with the label. The connection must be a
|
||||
queued signal-slot connection because we want to put the call in the event
|
||||
loop.
|
||||
|
||||
\snippet ../widgets/tutorials/threads/clock/clockthread.h 1
|
||||
|
||||
We have derived a class from QThread and declared the \c sendTime() signal.
|
||||
|
||||
\snippet ../widgets/tutorials/threads/clock/clockthread.cpp 1
|
||||
|
||||
The trickiest part of this example is that the timer is connected to its
|
||||
slot via a direct connection. A default connection would produce a queued
|
||||
signal-slot connection because the connected objects live in different
|
||||
threads; remember that QThread does not live in the thread it creates.
|
||||
|
||||
Still it is safe to access ClockThread::timerHit() from the worker thread
|
||||
because ClockThread::timerHit() is private and only touches local variables
|
||||
and a private member that isn't touched by public methods.
|
||||
QDateTime::currentDateTime() isn't marked as thread-safe in Qt
|
||||
documentation, however we can get away with using it in this small
|
||||
example because we know that the QDateTime::currentDateTime() static
|
||||
method isn't used in any other threads.
|
||||
|
||||
\section2 Example 4: A Permanent Thread
|
||||
|
||||
This example shows how it is possible to have a QObject in a worker thread
|
||||
that accepts requests from the GUI thread, does polling using a timer and
|
||||
continuously reports results back to the GUI thread. The actual work
|
||||
including the polling must be implemented in a class derived from QObject.
|
||||
We have called this class \c WorkerObject in the code shown below. The
|
||||
thread-specific code is hidden in a class called \c Thread, derived from
|
||||
QThread.
|
||||
\c Thread has two additional public members. The \c launchWorker() member
|
||||
takes the worker object and moves it to another thread with a started event
|
||||
loop.
|
||||
The call blocks for a very short moment until the thread creation operation
|
||||
is completed, allowing the worker object to be used again on the next line.
|
||||
The \c Thread class's code is short but somewhat involved, so we only show
|
||||
how to use the class.
|
||||
|
||||
\snippet ../widgets/tutorials/threads/movedobject/main.cpp 1
|
||||
|
||||
QMetaObject::invokeMethod() calls a slot via the event loop. The worker
|
||||
object's methods should not be called directly after the object has been
|
||||
moved to another thread. We let the worker thread do some work and polling,
|
||||
and use a timer to shut the application down after 3 seconds. Shutting the
|
||||
worker down needs some care. We call \c{Thread::stop()} to exit the event
|
||||
loop. We wait for the thread to terminate and, after this has occurred, we
|
||||
delete the worker.
|
||||
Qt comes with several examples for using threads. See the class references
|
||||
for QThread and QThreadPool for simple examples. See the \l{Threading and
|
||||
Concurrent Programming Examples} page for more advanced ones.
|
||||
|
||||
\section1 Digging Deeper
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user