diner.c

来自「多线程库」· C语言 代码 · 共 48 行

//
// This is a philosopher demo, using process scoping.
#include <thread.h>

#define MAX_PHILOSOPHERS          5

int main()
{
  mutex *p_fork;
  semaphore *sem;
  bool fork_v = false;
  int lfork, rfork, _nr, _forks = MAX_PHILOSOPHERS, _count;
  
  pthread::set_project( "/tmp/philosophy" );
  sem    = new semaphore(attributes::process_shared);
  p_fork = new mutex[MAX_PHILOSOPHERS](attributes::process_shared);
  if ( (_nr = sem->post()) > MAX_PHILOSOPHERS ) {
    sem->trywait();
    exit(0);
  }
  _count = _forks;
  _nr -= 1;
  lfork = _nr-1 >= 0 ? _nr-1 : _forks-1;
  rfork = lfork+1 >= _forks ? 0 : lfork+1;
  while(_count-- > 0) {
    cout.form("Philosopher %d: looking for %d,%d\n", _nr, lfork, rfork);
    while( fork_v == false ) {
      if (p_fork[lfork].trylock() == 0) {
	if (p_fork[rfork].trylock() == 0)
	  fork_v = true;
	else
	  p_fork[lfork].unlock();
      }
    }
    cout.form("Philosopher %d: using (%d,%d).\n", _nr, lfork, rfork);
    sleep(2);
    fork_v = false;
    cout.form("Philosopher %d: sleeping\n", _nr);
    p_fork[lfork].unlock();
    p_fork[rfork].unlock();
    sleep(2);
  }
  cout << _nr << " has finished dining." << endl;
  sem->trywait();
  return 0;
}