doc: add code samples from uvbook (unadapted)

PR-URL: https://github.com/libuv/libuv/pull/1246
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>

1 files changed, 59 insertions, 0 deletions

diff --git a/docs/code/queue-cancel/main.c b/docs/code/queue-cancel/main.c
new file mode 100644
index 00000000..3f7836cb
--- /dev/null
+++ b/docs/code/queue-cancel/main.c
@@ -0,0 +1,59 @@
+#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);
+}