bounce back and forth between threads using semaphores

sem-bounce.c

/* Compiled with
 *   clang -pthread -fno-omit-frame-pointer -Wall -g -fstrict-aliasing -O3 \
 *     -o sem-bounce sem-bounce.c libuv.a -Iuv/include
 */

#include "uv.h"

#define ITER 1e6

static uv_thread_t thread;
static uv_sem_t msem;
static uv_sem_t tsem;
static unsigned int iter;


static void tq_thread_cb(void* arg) {
  for (;;) {
    //while (uv_sem_trywait(&tsem) != 0);
    uv_sem_wait(&tsem);
    uv_sem_post(&msem);
    if (ITER - 1 == iter)
      break;
  }
}


int main() {
  /* initialize */
  uv_thread_create(&thread, tq_thread_cb, NULL);
  uv_sem_init(&msem, 0);
  uv_sem_init(&tsem, 0);
  iter = 0;

  for (; iter < ITER; iter++) {
    uv_sem_post(&tsem);
    uv_sem_wait(&msem);
    //while (uv_sem_trywait(&msem) != 0);
  }

  /* cleanup */
  uv_sem_destroy(&msem);
  uv_sem_destroy(&tsem);
  uv_thread_join(&thread);

  return 0;
}