ualarm — schedule signal after given number of microseconds
#define _XOPEN_SOURCE 500 /* Or: #define _BSD_SOURCE */ #include <unistd.h>
useconds_t ualarm( |
useconds_t | usecs, |
useconds_t | interval) ; |
The ualarm
() function causes
the signal SIGALRM
to be sent
to the invoking process after (not less than) usecs
microseconds. The delay
may be lengthened slightly by any system activity or by the
time spent processing the call or by the granularity of
system timers.
Unless caught or ignored, the SIGALRM
signal will terminate the
process.
If the interval
argument is non-zero, further SIGALRM
signals will be sent every
interval
microseconds
after the first.
This function returns the number of microseconds remaining for any alarm that was previously set, or 0 if no alarm was pending.
Interrupted by a signal.
usecs
or
interval
is not
smaller than 1000000. (On systems where that is
considered an error.)
4.3BSD, POSIX.1-2001. POSIX.1-2001 marks ualarm
() as obsolete. 4.3BSD, SUSv2, and
POSIX do not define any errors.
The type useconds_t
is an unsigned
integer type capable of holding integers in the range
[0,1000000]. On the original BSD implementation, and in glibc
before version 2.1, the arguments to ualarm
() were instead typed as unsigned int. Programs will be
more portable if they never mention useconds_t
explicitly.
The interaction of this function with other timer functions such as alarm(2), sleep(3), nanosleep(2), setitimer(2), timer_create(3), timer_delete(3), timer_getoverrun(3), timer_gettime(3), timer_settime(3), usleep(3) is unspecified.
This function is obsolete. Use setitimer(2) or POSIX
interval timers (timer_create
(3), etc.)
instead.
alarm(2), getitimer(2), nanosleep(2), select(2), setitimer(2), usleep(3), feature_test_macros(7), time(7)
|