QThread(3qt)QThread(3qt)NAME
QThread - Platform-independent threads
#include <qthread.h>
Inherits Qt.
Public Members
QThread ()
virtual ~QThread ()
bool wait ( unsigned long time = ULONG_MAX )
void start ()
bool finished () const
bool running () const
Static Public Members
HANDLE currentThread ()
void postEvent ( QObject *, QEvent * )
void exit ()
Protected Members
virtual void run ()
Static Protected Members
void sleep ( unsigned long )
void msleep ( unsigned long )
void usleep ( unsigned long )
DESCRIPTION
The QThread class provides platform-independent threads
A QThread represents a separate thread of control within
the program; it shares all data with other threads within
the process but executes independently in the way that a
separate program does on a multitasking operating system.
Instead of starting in main(), however, QThreads begin
executing in run(), which you inherit to provide your
code. For instance:
class MyThread : public QThread {
public:
virtual void run();
};
void MyThread::run()
{
for(int count=0;count<20;count++) {
sleep(1);
qDebug("Ping!");
}
}
int main()
{
MyThread a;
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MyThread b;
a.start();
b.start();
a.wait();
b.wait();
}
This will start two threads, each of which writes Ping! 20
times to the screen and exits. The wait() calls at the end
of main() are necessary because exiting main() ends the
program, unceremoniously killing all other threads. Each
MyThread stops executing when it reaches the end of
MyThread::run(), just as an application does when it
leaves main().
See also the paragraph on Thread Support in Qt
MEMBER FUNCTION DOCUMENTATIONQThread::QThread ()
Constructs a new thread. The thread does not actually
begin executing until start() is called.
QThread::~QThread () [virtual]
QThread destructor. Note that deleting a QThread object
will not stop the execution of the thread it represents,
and that deleting a QThread object while the thread is
running is unsafe.
HANDLE QThread::currentThread () [static]
This returns the thread handle of the currently executing
thread. The handle returned by this function is used for
internal reasons and should not be used in any application
code. On Windows, the returned value is a pseudo handle
for the current thread, and it can not be used for
numerical comparison.
void QThread::exit () [static]
Ends execution of the calling thread and wakes up any
threads waiting for its termination.
bool QThread::finished () const
Returns TRUE is the thread is finished.
void QThread::msleep ( unsigned long msecs ) [static protected]
System independent sleep. This causes the current thread
to sleep for msecs milliseconds.
void QThread::postEvent ( QObject * receiver, QEvent * event )
[static]
Provides a way of posting an event from a thread which is
not the event thread to an object. The event is put into a
queue, then the event thread is woken which then sends the
event to the object. It is important to note that the
event handler for the event, when called, will be called
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QThread(3qt)QThread(3qt)
from the event thread and not from the thread calling
QThread::postEvent().
Same as with QApplication::postEvent(), event must be
allocated on the heap, as it is deleted when the event has
been posted.
void QThread::run () [virtual protected]
This method is pure virtual, and it must be implemented in
derived classes in order to do useful work. Returning from
this method will end execution of the thread.
bool QThread::running () const
Returns TRUE if the thread is running.
void QThread::sleep ( unsigned long secs ) [static protected]
System independent sleep. This causes the current thread
to sleep for secs seconds.
void QThread::start ()
This begins actual execution of the thread by calling
run(), which should be reimplemented in a QThread subclass
to contain your code. If you try to start a thread that is
already running, this call will wait until the thread has
finished, and then restart the thread.
void QThread::usleep ( unsigned long usecs ) [static protected]
System independent sleep. This causes the current thread
to sleep for usecs microseconds.
bool QThread::wait ( unsigned long time = ULONG_MAX )
This allows similar functionality to POSIX pthread_join. A
thread calling this will block until one of 2 conditions
is met:
The thread associated with this QThread object has
finished execution (i.e. when it returns from run() ).
This function will return TRUE if the thread has finished.
It also returns TRUE if the thread has not been started
yet.
time milliseconds has elapsed. If time is ULONG_MAX
(default
argument), then the wait will never timeout (the
thread must return from run() ). This function
will return FALSE if the wait timed out.
SEE ALSO
http://doc.trolltech.com/qthread.html
http://www.trolltech.com/faq/tech.html
COPYRIGHT
Copyright 1992-2001 Trolltech AS,
http://www.trolltech.com. See the license file included
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QThread(3qt)QThread(3qt)
in the distribution for a complete license statement.
AUTHOR
Generated automatically from the source code.
BUGS
If you find a bug in Qt, please report it as described in
http://doc.trolltech.com/bughowto.html. Good bug reports
make our job much simpler. Thank you.
In case of content or formattting problems with this
manual page, please report them to qt-bugs@trolltech.com.
Please include the name of the manual page (qthread.3qt)
and the Qt version (2.3.1).
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