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253 lines
11 KiB
253 lines
11 KiB
14 years ago
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/src/kernel/qthread.cpp:52 -->
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<title>QThread Class</title>
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<style type="text/css"><!--
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fn { margin-left: 1cm; text-indent: -1cm; }
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a:link { color: #004faf; text-decoration: none }
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a:visited { color: #672967; text-decoration: none }
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body { background: #ffffff; color: black; }
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--></style>
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</head>
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<body>
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<table border="0" cellpadding="0" cellspacing="0" width="100%">
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<tr bgcolor="#E5E5E5">
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<td valign=center>
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<a href="index.html">
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<font color="#004faf">Home</font></a>
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<font color="#004faf">All Classes</font></a>
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<font color="#004faf">Main Classes</font></a>
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<font color="#004faf">Annotated</font></a>
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<font color="#004faf">Grouped Classes</font></a>
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<font color="#004faf">Functions</font></a>
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</td>
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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QThread Class Reference</h1>
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<p>The QThread class provides platform-independent threads.
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<a href="#details">More...</a>
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<p>All the functions in this class are <a href="threads.html#threadsafe">thread-safe</a> when Qt is built with thread support.</p>
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<p><tt>#include <<a href="qthread-h.html">qthread.h</a>></tt>
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<p>Inherits <a href="qt.html">Qt</a>.
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<p><a href="qthread-members.html">List of all member functions.</a>
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<h2>Public Members</h2>
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<ul>
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<li class=fn><a href="#QThread"><b>QThread</b></a> ( unsigned int stackSize = 0 )</li>
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<li class=fn>virtual <a href="#~QThread"><b>~QThread</b></a> ()</li>
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<li class=fn>bool <a href="#wait"><b>wait</b></a> ( unsigned long time = ULONG_MAX )</li>
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<li class=fn>enum <a href="#Priority-enum"><b>Priority</b></a> { IdlePriority, LowestPriority, LowPriority, NormalPriority, HighPriority, HighestPriority, TimeCriticalPriority, InheritPriority }</li>
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<li class=fn>void <a href="#start"><b>start</b></a> ( Priority priority = InheritPriority )</li>
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<li class=fn>void <a href="#terminate"><b>terminate</b></a> ()</li>
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<li class=fn>bool <a href="#finished"><b>finished</b></a> () const</li>
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<li class=fn>bool <a href="#running"><b>running</b></a> () const</li>
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</ul>
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<h2>Static Public Members</h2>
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<ul>
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<li class=fn>Qt::HANDLE <a href="#currentThread"><b>currentThread</b></a> ()</li>
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<li class=fn>void postEvent ( QObject * receiver, QEvent * event ) <em>(obsolete)</em></li>
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<li class=fn>void <a href="#exit"><b>exit</b></a> ()</li>
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</ul>
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<h2>Protected Members</h2>
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<ul>
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<li class=fn>virtual void <a href="#run"><b>run</b></a> () = 0</li>
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</ul>
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<h2>Static Protected Members</h2>
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<ul>
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<li class=fn>void <a href="#sleep"><b>sleep</b></a> ( unsigned long secs )</li>
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<li class=fn>void <a href="#msleep"><b>msleep</b></a> ( unsigned long msecs )</li>
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<li class=fn>void <a href="#usleep"><b>usleep</b></a> ( unsigned long usecs )</li>
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</ul>
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<hr><a name="details"></a><h2>Detailed Description</h2>
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The QThread class provides platform-independent threads.
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<p>
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<p> A QThread represents a separate thread of control within the
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program; it shares data with all the other threads within the
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process but executes independently in the way that a separate
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program does on a multitasking operating system. Instead of
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starting in main(), QThreads begin executing in <a href="#run">run</a>(). You inherit
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run() to include your code. For example:
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<p> <pre>
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class MyThread : public QThread {
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public:
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virtual void run();
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};
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void MyThread::<a href="#run">run</a>()
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{
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for( int count = 0; count < 20; count++ ) {
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<a href="#sleep">sleep</a>( 1 );
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<a href="qapplication.html#qDebug">qDebug</a>( "Ping!" );
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}
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}
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int main()
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{
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MyThread a;
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MyThread b;
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a.<a href="#start">start</a>();
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b.<a href="#start">start</a>();
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a.<a href="#wait">wait</a>();
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b.<a href="#wait">wait</a>();
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}
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</pre>
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<p> This will start two threads, each of which writes Ping! 20 times
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to the screen and exits. The <a href="#wait">wait</a>() calls at the end of main() are
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necessary because exiting main() ends the program, unceremoniously
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killing all other threads. Each MyThread stops executing when it
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reaches the end of MyThread::run(), just as an application does
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when it leaves main().
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<p> <p>See also <a href="threads.html">Thread Support in Qt</a>, <a href="environment.html">Environment Classes</a>, and <a href="thread.html">Threading</a>.
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<hr><h2>Member Type Documentation</h2>
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<h3 class=fn><a name="Priority-enum"></a>QThread::Priority</h3>
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<p> This enum type indicates how the operating system should schedule
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newly created threads.
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<ul>
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<li><tt>QThread::IdlePriority</tt> - scheduled only when no other threads are
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running.
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<li><tt>QThread::LowestPriority</tt> - scheduled less often than LowPriority.
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<li><tt>QThread::LowPriority</tt> - scheduled less often than NormalPriority.
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<li><tt>QThread::NormalPriority</tt> - the default priority of the operating
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system.
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<li><tt>QThread::HighPriority</tt> - scheduled more often than NormalPriority.
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<li><tt>QThread::HighestPriority</tt> - scheduled more often then HighPriority.
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<li><tt>QThread::TimeCriticalPriority</tt> - scheduled as often as possible.
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<li><tt>QThread::InheritPriority</tt> - use the same priority as the creating
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thread. This is the default.
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</ul>
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<hr><h2>Member Function Documentation</h2>
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<h3 class=fn><a name="QThread"></a>QThread::QThread ( unsigned int stackSize = 0 )
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</h3>
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Constructs a new thread. The thread does not begin executing until
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<a href="#start">start</a>() is called.
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<p> If <em>stackSize</em> is greater than zero, the maximum stack size is
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set to <em>stackSize</em> bytes, otherwise the maximum stack size is
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automatically determined by the operating system.
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<p> <b>Warning:</b> Most operating systems place minimum and maximum limits
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on thread stack sizes. The thread will fail to start if the stack
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size is outside these limits.
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<h3 class=fn><a name="~QThread"></a>QThread::~QThread ()<tt> [virtual]</tt>
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</h3>
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QThread destructor.
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<p> Note that deleting a QThread object will not stop the execution of
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the thread it represents. Deleting a running QThread (i.e.
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<a href="#finished">finished</a>() returns FALSE) will probably result in a program crash.
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You can <a href="#wait">wait</a>() on a thread to make sure that it has finished.
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<h3 class=fn>Qt::HANDLE <a name="currentThread"></a>QThread::currentThread ()<tt> [static]</tt>
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</h3>
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This returns the thread handle of the currently executing thread.
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<p> <b>Warning:</b> The handle returned by this function is used for internal
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purposes and should <em>not</em> be used in any application code. On
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Windows, the returned value is a pseudo handle for the current
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thread, and it cannot be used for numerical comparison.
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<h3 class=fn>void <a name="exit"></a>QThread::exit ()<tt> [static]</tt>
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</h3>
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Ends the execution of the calling thread and wakes up any threads
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waiting for its termination.
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<h3 class=fn>bool <a name="finished"></a>QThread::finished () const
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</h3>
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Returns TRUE if the thread is finished; otherwise returns FALSE.
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<h3 class=fn>void <a name="msleep"></a>QThread::msleep ( unsigned long msecs )<tt> [static protected]</tt>
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</h3>
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System independent sleep. This causes the current thread to sleep
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for <em>msecs</em> milliseconds
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<h3 class=fn>void <a name="postEvent"></a>QThread::postEvent ( <a href="qobject.html">QObject</a> * receiver, <a href="qevent.html">QEvent</a> * event )<tt> [static]</tt>
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</h3> <b>This function is obsolete.</b> It is provided to keep old source working. We strongly advise against using it in new code.
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<p> Use <a href="qapplication.html#postEvent">QApplication::postEvent</a>() instead.
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<h3 class=fn>void <a name="run"></a>QThread::run ()<tt> [pure virtual protected]</tt>
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</h3>
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<p> This method is pure virtual, and must be implemented in derived
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classes in order to do useful work. Returning from this method
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will end the execution of the thread.
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<p> <p>See also <a href="#wait">wait</a>().
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<h3 class=fn>bool <a name="running"></a>QThread::running () const
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</h3>
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Returns TRUE if the thread is running; otherwise returns FALSE.
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<h3 class=fn>void <a name="sleep"></a>QThread::sleep ( unsigned long secs )<tt> [static protected]</tt>
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</h3>
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System independent sleep. This causes the current thread to sleep
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for <em>secs</em> seconds.
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<h3 class=fn>void <a name="start"></a>QThread::start ( <a href="qthread.html#Priority-enum">Priority</a> priority = InheritPriority )
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</h3>
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Begins execution of the thread by calling <a href="#run">run</a>(), which should be
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reimplemented in a QThread subclass to contain your code. The
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operating system will schedule the thread according to the <em>priority</em> argument.
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<p> If you try to start a thread that is already running, this
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function will wait until the the thread has finished and then
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restart the thread.
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<p> <p>See also <a href="#Priority-enum">Priority</a>.
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<h3 class=fn>void <a name="terminate"></a>QThread::terminate ()
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</h3>
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This function terminates the execution of the thread. The thread
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may or may not be terminated immediately, depending on the
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operating system's scheduling policies. Use <a href="#wait">QThread::wait</a>()
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after <a href="#terminate">terminate</a>() for synchronous termination.
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<p> When the thread is terminated, all threads waiting for the
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the thread to finish will be woken up.
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<p> <b>Warning:</b> This function is dangerous, and its use is discouraged.
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The thread can be terminated at any point in its code path. Threads
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can be terminated while modifying data. There is no chance for
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the thread to cleanup after itself, unlock any held mutexes, etc.
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In short, use this function only if <em>absolutely</em> necessary.
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<h3 class=fn>void <a name="usleep"></a>QThread::usleep ( unsigned long usecs )<tt> [static protected]</tt>
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</h3>
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System independent sleep. This causes the current thread to sleep
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for <em>usecs</em> microseconds
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<h3 class=fn>bool <a name="wait"></a>QThread::wait ( unsigned long time = ULONG_MAX )
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</h3>
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A thread calling this function will block until either of these
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conditions is met:
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<p> <ul>
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<li> The thread associated with this QThread object has finished
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execution (i.e. when it returns from <a href="#run">run</a>()). This function
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will return TRUE if the thread has finished. It also returns
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TRUE if the thread has not been started yet.
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<li> <em>time</em> milliseconds has elapsed. If <em>time</em> is ULONG_MAX (the
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default), then the wait will never timeout (the thread must
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return from <a href="#run">run</a>()). This function will return FALSE if the
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wait timed out.
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</ul>
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<p> This provides similar functionality to the POSIX <tt>pthread_join()</tt> function.
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<!-- eof -->
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<hr><p>
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This file is part of the <a href="index.html">Qt toolkit</a>.
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Copyright © 1995-2007
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<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center>
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<table width=100% cellspacing=0 border=0><tr>
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<td>Copyright © 2007
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<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
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<td align=right><div align=right>Qt 3.3.8</div>
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</table></div></address></body>
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</html>
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