libuv/docs/code/queue-cancel/main.c

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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
 
#include <uv.h>
 
#define FIB_UNTIL 25
uv_loop_t *loop;
uv_work_t fib_reqs[FIB_UNTIL];
 
long fib_(long t) {
    if (t == 0 || t == 1)
        return 1;
    else
        return fib_(t-1) + fib_(t-2);
}
 
void fib(uv_work_t *req) {
    int n = *(int *) req->data;
    if (random() % 2)
        sleep(1);
    else
        sleep(3);
    long fib = fib_(n);
    fprintf(stderr, "%dth fibonacci is %lu\n", n, fib);
}
 
void after_fib(uv_work_t *req, int status) {
    if (status == UV_ECANCELED)
        fprintf(stderr, "Calculation of %d cancelled.\n", *(int *) req->data);
}
 
void signal_handler(uv_signal_t *req, int signum)
{
    printf("Signal received!\n");
    int i;
    for (i = 0; i < FIB_UNTIL; i++) {
        uv_cancel((uv_req_t*) &fib_reqs[i]);
    }
    uv_signal_stop(req);
}
 
int main() {
    loop = uv_default_loop();
 
    int data[FIB_UNTIL];
    int i;
    for (i = 0; i < FIB_UNTIL; i++) {
        data[i] = i;
        fib_reqs[i].data = (void *) &data[i];
        uv_queue_work(loop, &fib_reqs[i], fib, after_fib);
    }
 
    uv_signal_t sig;
    uv_signal_init(loop, &sig);
    uv_signal_start(&sig, signal_handler, SIGINT);
 
    return uv_run(loop, UV_RUN_DEFAULT);
}