usleep()

Suspend a thread for a given number of microseconds

Synopsis:

#include <unistd.h>

int usleep( useconds_t useconds );

Arguments:

useconds: The number of microseconds that you want to process to sleep for. This must be less than 1,000,000.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The usleep() function suspends the calling thread until useconds microseconds of realtime have elapsed, or until a signal that isn't ignored is received. The time spent suspended could be longer than the requested amount due to the nature of time measurement (see the Tick, Tock: Understanding the Microkernel's Concept of Time chapter of the QNX Neutrino Programmer's Guide), or due to the scheduling of other, higher-priority threads.

If useconds is 0, usleep() has no effect.

Returns:

0: Success.
-1: An error occurred (errno is set).

Errors:

EAGAIN: No timer resources are available to satisfy the request.
EINTR: The call was interrupted by a signal.
EINVAL: The useconds argument is too large.

Examples:

/*
 * The following program sleeps for the
 * number of microseconds specified in argv[1].
 */
#include <stdlib.h>
#include <unistd.h>

int main( int argc, char **argv )
{
    useconds_t microseconds;

    microseconds = (useconds_t)strtol( argv[1], NULL, 0 );
    if( usleep( microseconds ) == 0 ) {
        return EXIT_SUCCESS;
    }
    
    return EXIT_FAILURE;
}

Classification:

Standard Unix; removed from POSIX.1-2008

Safety:
Cancellation point	Yes
Interrupt handler	No
Signal handler	Yes
Thread	Yes