c - 哲学家就餐问题的仲裁解决方案

Question

在给定的解决方案中，我实现了仲裁解决方案。我的哲学家随便拿起两根筷子。在锁定这些筷子之前，我使用了服务员锁。我无法解决此解决方案的问题。对于这个解决方案，我仍然陷入僵局。

void *philosopher_program(int philosopher_number)
{  
  // In this version of the "philosopher program", the philosopher
  // will think and eat forever.

  int i_want_this;
  int i_want_this_too;

  while (1)
     { // Philosophers always think before they eat.  They need to
       // build up a bit of hunger....
       // usleep(100);

       // That was a lot of thinking.... now hungry... this
       // philosopher is a jerk.  He may not grap the chopsticks
       // closest to him.  In fact, he may grab any two chopsticks at
       // the table.... because he is a jerk.

       i_want_this     = Random_Int(PHILOSOPHER_COUNT);
       usleep(1);
       while ((i_want_this_too = Random_Int(PHILOSOPHER_COUNT)) == i_want_this);

       printf ("Jerk Philosopher %d wants chopsticks %d and %d\n",
                philosopher_number,
                i_want_this,
                i_want_this_too);

       pthread_mutex_lock(&waiter);
       pthread_mutex_lock(&chopstick[i_want_this]);
       pthread_mutex_lock(&chopstick[i_want_this_too]);
       pthread_mutex_unlock(&waiter);

       // Hurray, if I got this far I'm eating
       printf ("Jerk Philosopher %d is eating with chopsticks %d and %d\n",
               philosopher_number,
               i_want_this,
               i_want_this_too);

       // I'm done eating.  Now put the chopsticks back on the table
       pthread_mutex_unlock(&chopstick[i_want_this_too]);
       pthread_mutex_unlock(&chopstick[i_want_this]);
     }

  return(NULL);
 }