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authorQt by Nokia <qt-info@nokia.com>2011-04-27 12:05:43 +0200
committeraxis <qt-info@nokia.com>2011-04-27 12:05:43 +0200
commit38be0d13830efd2d98281c645c3a60afe05ffece (patch)
tree6ea73f3ec77f7d153333779883e8120f82820abe /src/corelib/concurrent/qtconcurrentrun.cpp
Initial import from the monolithic Qt.
This is the beginning of revision history for this module. If you want to look at revision history older than this, please refer to the Qt Git wiki for how to use Git history grafting. At the time of writing, this wiki is located here: http://qt.gitorious.org/qt/pages/GitIntroductionWithQt If you have already performed the grafting and you don't see any history beyond this commit, try running "git log" with the "--follow" argument. Branched from the monolithic repo, Qt master branch, at commit 896db169ea224deb96c59ce8af800d019de63f12
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+/****************************************************************************
+**
+** Copyright (C) 2011 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.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+ \headerfile <QtConcurrentRun>
+ \title Asynchronous Run
+
+ \brief The <QtConcurrentRun> header provides a way to run a function in a
+ separate thread.
+
+ \ingroup thread
+
+ This function is a part of the \l {Concurrent Programming}{Qt Concurrent} framework.
+
+ The QtConcurrent::run() function runs a function in a separate thread.
+ The return value of the function is made available through the QFuture API.
+
+ \section1 Running a Function in a Separate Thread
+
+ To run a function in another thread, use QtConcurrent::run():
+
+ \snippet doc/src/snippets/code/src_corelib_concurrent_qtconcurrentrun.cpp 0
+
+ This will run \e aFunction in a separate thread obtained from the default
+ QThreadPool. You can use the QFuture and QFutureWatcher classes to monitor
+ the status of the function.
+
+ \section1 Passing Arguments to the Function
+
+ Passing arguments to the function is done by adding them to the
+ QtConcurrent::run() call immediately after the function name. For example:
+
+ \snippet doc/src/snippets/code/src_corelib_concurrent_qtconcurrentrun.cpp 1
+
+ A copy of each argument is made at the point where QtConcurrent::run() is
+ called, and these values are passed to the thread when it begins executing
+ the function. Changes made to the arguments after calling
+ QtConcurrent::run() are \e not visible to the thread.
+
+ \section1 Returning Values from the Function
+
+ Any return value from the function is available via QFuture:
+
+ \snippet doc/src/snippets/code/src_corelib_concurrent_qtconcurrentrun.cpp 2
+
+ As documented above, passing arguments is done like this:
+
+ \snippet doc/src/snippets/code/src_corelib_concurrent_qtconcurrentrun.cpp 3
+
+ Note that the QFuture::result() function blocks and waits for the result
+ to become available. Use QFutureWatcher to get notification when the
+ function has finished execution and the result is available.
+
+ \section1 Additional API Features
+
+ \section2 Using Member Functions
+
+ QtConcurrent::run() also accepts pointers to member functions. The first
+ argument must be either a const reference or a pointer to an instance of
+ the class. Passing by const reference is useful when calling const member
+ functions; passing by pointer is useful for calling non-const member
+ functions that modify the instance.
+
+ For example, calling QByteArray::split() (a const member function) in a
+ separate thread is done like this:
+
+ \snippet doc/src/snippets/code/src_corelib_concurrent_qtconcurrentrun.cpp 4
+
+ Calling a non-const member function is done like this:
+
+ \snippet doc/src/snippets/code/src_corelib_concurrent_qtconcurrentrun.cpp 5
+
+ \section2 Using Bound Function Arguments
+
+ Note that Qt does not provide support for bound functions. This is
+ provided by 3rd party libraries like
+ \l{http://www.boost.org/libs/bind/bind.html}{Boost} or
+ \l{http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1836.pdf}
+ {C++ TR1 Library Extensions}.
+
+ You can use boost::bind() or std::tr1::bind() to \e bind a number of
+ arguments to a function when called. There are number of reasons for doing
+ this:
+
+ \list
+ \o To call a function that takes more than 5 arguments.
+ \o To simplify calling a function with constant arguments.
+ \o Changing the order of arguments.
+ \endlist
+
+ See the documentation for the relevant functions for details on how to use
+ the bind API.
+
+ Calling a bound function is done like this:
+
+ \snippet doc/src/snippets/code/src_corelib_concurrent_qtconcurrentrun.cpp 6
+*/
+
+/*!
+ \fn QFuture<T> QtConcurrent::run(Function function, ...);
+ \relates <QtConcurrentRun>
+
+ Runs \a function in a separate thread. The thread is taken from the global
+ QThreadPool. Note that the function may not run immediately; the function
+ will only be run when a thread is available.
+
+ T is the same type as the return value of \a function. Non-void return
+ values can be accessed via the QFuture::result() function.
+
+ Note that the QFuture returned by QtConcurrent::run() does not support
+ canceling, pausing, or progress reporting. The QFuture returned can only
+ be used to query for the running/finished status and the return value of
+ the function.
+*/