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This function is obsolete.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)
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