NAME
ualarm —
schedule high resolution SIGALRM
delivery
SYNOPSIS
#include
<unistd.h>
useconds_t
ualarm(useconds_t
microseconds, useconds_t
interval);
DESCRIPTION
The
ualarm()
function schedules the SIGALRM signal for delivery
to the calling process after at least the given number of
microseconds have elapsed. If
interval is non-zero, the
SIGALRM signal is scheduled for redelivery to the
calling process every interval microseconds
thereafter.
If an alarm is already pending, an additional call
to
ualarm()
supersedes the prior call.
If microseconds is zero, any pending alarm is cancelled and the value of interval is ignored.
RETURN VALUES
The ualarm() function returns the number
of microseconds remaining until the next alarm is scheduled for delivery, or
zero if no alarm is pending.
SEE ALSO
setitimer(2), sigaction(2), sigsuspend(2), alarm(3), signal(3), sleep(3), usleep(3)
STANDARDS
The ualarm() function conforms to
X/Open Portability Guide Issue 4, Version 2
(“XPG4.2”).
HISTORY
The ualarm() function first appeared in
4.3BSD.
CAVEATS
The ualarm() function is implemented with
the per-process ITIMER_REAL timer described in
setitimer(2). Use of both ualarm() and
setitimer(2) in the same program may yield confusing behavior.