worker 内で単一の async ハンドラを操作すると thread safe なのかチェックするテスト

main.c

#include <stdio.h>
#include <stdlib.h>
#include "uv.h"

uv_loop_t *loop;
uv_async_t async;
static int closed = 0;
static int async_called = 0;

void print_progress(uv_async_t *handle, int status /*UNUSED*/) {
  char *msg;
  msg = (char*) handle->data;
  async_called++;
  // fprintf(stderr, "%s", msg);
}


void fake_download0(uv_work_t *req) {
  int size = *((int*) req->data);
  char msg[256];
  double percentage;
  int downloaded = 0;
  while (downloaded < size) {
    percentage = downloaded*100.0/size;
    sprintf(msg, "#0 Downloaded %.2f%%\n", percentage);
    async.data = (void*) &msg;
    uv_async_send(&async);
    downloaded++;
  }
  req->data = (void*) &downloaded;
}


void after0(uv_work_t *req, int status) {
  int downloaded = *((int*) req->data);
  closed++;
  fprintf(stderr, "#0 Download complete. async_send: %d\n", downloaded);
  if (closed == 1) {
    uv_close((uv_handle_t*) &async, NULL);
  }
}


void fake_download1(uv_work_t *req) {
  int size = *((int*) req->data);
  char msg[256];
  double percentage;
  int downloaded = 0;
  while (downloaded < size) {
    percentage = downloaded*100.0/size;
    sprintf(msg, "#1 Downloaded %.2f%%\n", percentage);
    async.data = (void*) &msg;
    uv_async_send(&async);
    downloaded++;
  }
  req->data = (void*) &downloaded;
}


void after1(uv_work_t *req, int status) {
  int downloaded = *((int*) req->data);
  closed++;
  fprintf(stderr, "#1 Download complete. async_send: %d\n", downloaded);
  if (closed == 1) {
    uv_close((uv_handle_t*) &async, NULL);
  }
}


int main() {
  loop = uv_default_loop();
  int size = 10240;
  uv_work_t req[2];
  uv_async_init(loop, &async, print_progress);
  req[0].data = (void*) &size;
  req[1].data = (void*) &size;

  uv_queue_work(loop, req, fake_download0, after0);
  uv_queue_work(loop, req + 1, fake_download1, after1);
  uv_run(loop, UV_RUN_DEFAULT);
  fprintf(stderr, "async_called: %d\n", async_called);
}

result.txt

> ./worker-test
#0 Download complete. async_send: 10240
#1 Download complete. async_send: 10240
async_called: 183