uloop interval timer example

timer-test.c

#include <inttypes.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <time.h>

#include <libubox/uloop.h>

static void timer_cb(struct uloop_timer *utm)
{
    struct timespec ts;

    clock_gettime(CLOCK_MONOTONIC, &ts);
    int64_t t1 = ts.tv_sec * 1000 + ts.tv_nsec / 1000000;

    printf("[%u:%u] Timer iteration: %" PRIu64 " ... ",
        (unsigned int)ts.tv_sec, (unsigned int)ts.tv_nsec,
        utm->expirations);

    usleep((random() % 1000000));

    clock_gettime(CLOCK_MONOTONIC, &ts);
    int64_t t2 = ts.tv_sec * 1000 + ts.tv_nsec / 1000000;

    printf("slept %" PRId64 " ms, next run in %" PRId64 " ms\n",
        t2 - t1, uloop_timer_next(utm));
}

int main(int argc, char **argv)
{
    struct uloop_timer utm = { .cb = timer_cb };

    uloop_init();

    uloop_timer_set(&utm, 1000);

    uloop_run();
}

usage example

$ gcc -o test -L. test.c -lubox
$ ./test
[54530:581458532] Timer iteration: 1 ... slept 289 ms, next run in 710 ms
[54531:581453377] Timer iteration: 2 ... slept 931 ms, next run in 69 ms
[54532:581447881] Timer iteration: 3 ... slept 693 ms, next run in 307 ms
[54533:581454526] Timer iteration: 4 ... slept 637 ms, next run in 362 ms
[54534:581452631] Timer iteration: 5 ... slept 748 ms, next run in 252 ms
[54535:581452526] Timer iteration: 6 ... slept 238 ms, next run in 761 ms
[54536:581451541] Timer iteration: 7 ... slept 885 ms, next run in 114 ms
[54537:581452415] Timer iteration: 8 ... slept 761 ms, next run in 239 ms
[54538:581454711] Timer iteration: 9 ... slept 517 ms, next run in 483 ms
[54539:581451415] Timer iteration: 10 ... slept 641 ms, next run in 358 ms
[54540:581452000] Timer iteration: 11 ... slept 202 ms, next run in 797 ms
[54541:581451465] Timer iteration: 12 ... slept 490 ms, next run in 509 ms
[54542:581453650] Timer iteration: 13 ... slept 369 ms, next run in 631 ms
[54543:581453775] Timer iteration: 14 ... slept 520 ms, next run in 479 ms
[54544:581452421] Timer iteration: 15 ... slept 898 ms, next run in 102 ms
[54545:581451896] Timer iteration: 16 ... slept 514 ms, next run in 485 ms
^C