五个哲学家进程实现

#include  " apue.h "
#include  " lock.h "
#include  " lock.c "

/* define some important variable */
/*=======================================*/
pid_t  pid;

static char  * forks[ 5 ] = {
" fork0 " ,  " fork1 " ,  " fork2 "  , " fork3 "  , " fork4 "
};

static  int  necs;

#define N  5

/*======================================*/
void takeFork( int  i)
{
if (i == N - 1 )
  {
     lock(forks[ 0 ]);
     lock(forks[i]);
  }
else
{
lock(forks[i]);
lock(forks[i + 1 ]);
}
}


void putFork( int  i)
{
    if (i == N - 1 )
    {
    unlock(forks[ 0 ]);
    unlock(forks[i]);
    }
   else
   {
   unlock(forks[i]);
   unlock(forks[i + 1 ]);

   }
}
int
thinking( int  i, int  necs){
printf( " pholosopher %d is thinking\n " ,i);
return sleep(necs);
}
int  
eating( int  i, int  necs)
{printf( " pholosopher %d is eating\n " ,i);
return sleep(necs);
}
void philosopher( int  i)
{
while ( 1 )
{
thinking(i,necs);
takeFork(i);
eating(i,necs);
putFork(i);

}
}
int
 main( int  argc ,char  * argv[])
{
  if (argc = 1 )
      necs = 2 ;
else   if (argc == 2 )
     necs = atoi(argv[ 1 ]);
else   return  0 ;
 
int  i;   
for (i = 0 ;i < N;i ++ )
{
 pid = fork();
  if (pid  == 0 )
     philosopher(i);
}
return  0 ;
}