sem.cc

#include <pthread.h>
#include <signal.h>
#include <unistd.h>
#include <stdio.h>
#include <assert.h>

#include <mach/mach_init.h>
#include <mach/task.h>
#include <mach/thread_act.h>
#include <mach/semaphore.h>

static semaphore_t sem;
static semaphore_t a_done;
static thread_act_t a_act;

void* ThreadA(void* arg) {
  a_act = mach_thread_self();
  semaphore_signal(a_done);

  fprintf(stdout, "wait!\n");
  fprintf(stdout, "%d\n", semaphore_wait(sem));
  fprintf(stdout, "wait end!\n");
  return NULL;
}

void* ThreadB(void* arg) {
  semaphore_wait(a_done);
  sleep(1);
  return NULL;
}

int main() {
  pthread_t a, b;

  semaphore_create(mach_task_self(), &sem, 0, 0);
  semaphore_create(mach_task_self(), &a_done, 0, 0);

  pthread_create(&a, NULL, ThreadA, NULL);
  pthread_create(&b, NULL, ThreadB, NULL);

  sleep(1);
  pthread_cancel(a);
  pthread_join(a, NULL);
  pthread_join(b, NULL);

  semaphore_destroy(mach_task_self(), sem);
  semaphore_destroy(mach_task_self(), a_done);

  return 0;
}