QThread::sleep() question

DRoscoe

There are three variants of QThread::sleep():

QThread::sleep(); // seconds
QThread::msleep(); // msec
QThread::usleep(); // usec

Are these merely convenience forms allowing you to specify arbitrary sleep durations in these units, or is the input argument assumed to be within a range? For example, if is use:

quint sleep_msec = 6,000;
QThread::msleep(sleep_msec );

Will this work without an overflow since the sleep_msec value is greater than one second?

The documentation doesn't specify.

Thanks!

? Offline

Hi! For Unix-like systems, the definition is in qthread_unix.cpp:

void QThread::sleep(unsigned long secs)
{
    qt_nanosleep(makeTimespec(secs, 0));
}

void QThread::msleep(unsigned long msecs)
{
    qt_nanosleep(makeTimespec(msecs / 1000, msecs % 1000 * 1000 * 1000));
}

void QThread::usleep(unsigned long usecs)
{
    qt_nanosleep(makeTimespec(usecs / 1000 / 1000, usecs % (1000*1000) * 1000));
}

qt_nanosleep is defined in qelapsedtimer_unix.cpp:

void qt_nanosleep(timespec amount)
{
    // We'd like to use clock_nanosleep.
    //
    // But clock_nanosleep is from POSIX.1-2001 and both are *not*
    // affected by clock changes when using relative sleeps, even for
    // CLOCK_REALTIME.
    //
    // nanosleep is POSIX.1-1993

    int r;
    EINTR_LOOP(r, nanosleep(&amount, &amount));
}

So all three functions call nanosleep(2) in the end.

Addendum:
makeTimespec is also defined in qthread_unix.cpp:

static timespec makeTimespec(time_t secs, long nsecs)
{
    struct timespec ts;
    ts.tv_sec = secs;
    ts.tv_nsec = nsecs;
    return ts;
}

DRoscoe

Excellent! Thank you! I really should download the source code for Qt ;-)