philosopher0.c

linux进程间通信

#include<stdio.h>
#include<sys/types.h>
#include<linux/sem.h>
#include<stdlib.h>
#define N 5
#define TURE 1
#define LEFT (i+4)%N
#define RIGHT  (i+1)%N
#define THINKING 0
#define HUNGRY  1
#define EATING  2
int main ()
{	
	int i;
	pid_t pid;
	int semid;
	int nsems=2*N+1;
	int flags=0666;
	union semun t;
	semid=semget(IPC_PRIVATE,nsems,flags);
	if(semid<0)
        {
                perror("semget");
                exit(-1);
        }

	i=1;
	t.val=0;
	while(i<N+6)
	{
		semctl(semid,i,SETVAL,t);i++;
	}
	t.val=1;
	semctl(semid,0,SETVAL,t);
	i=0;
	while(i<N)
	{
		if((pid=fork())<0)
		{
			printf("Fork()Error\n");
			exit(-1);
		}
		else if(pid==0)
		{
			printf("zijincheng %d ",i);
			philosopher(i,semid);exit(1);
			
		}
		else
		{	printf("fujicheng %d ",i);
		}
		i++;
	}
	return 0;
}
int think(int i)
{
	int s=rand()%11;
	switch(s)
	{	
		case 0:sleep(10);break;
		case 1:sleep(20);break;
		case 2:sleep(12);break;
		case 3:sleep(16);break;
		case 4:sleep(7);break;
		case 5:sleep(15);break;
		case 6:sleep(2);break;
		case 7:sleep(8);break;
		case 8:sleep(22);break;
		case 9:sleep(5);break;
		//case 10:delay(1000);break;
		default:sleep(12);
	}
	printf("philosopher %d is thinking!\n",i);
	return 1;
}
void eat(int i)
{
	printf("philosopher %d is eating!\n",i);
	sleep(5);
}
void take_fork(int i,int semid)
{	
	struct sembuf buf;
	union semun t;
	buf.sem_num=0;
	buf.sem_op=-1;
	buf.sem_flg=0;
	semop(semid,&buf,1);            //p(m)
	//printf("%d",semctl(semid,0,GETVAL));

	/*buf.sem_num=N+1+i;
	buf.sem_op=1;
	buf.sem_flg=0;
	semop(semid,&buf,1);*/
	t.val=HUNGRY;
	semctl(semid,N+1+i,SETVAL,t);           //state[i]=HUNGRY;
	//printf("%d",semctl(semid,N+1+i,GETVAL));
	test(i,semid);
	
	buf.sem_num=0;
        buf.sem_op=1;
        buf.sem_flg=0;
        semop(semid,&buf,1);             //v(m)    
	//printf("%d",semctl(semid,0,GETVAL));
	buf.sem_num=1+i;
        buf.sem_op=1;
        buf.sem_flg=0;
        semop(semid,&buf,1);               //p(s[i])
	//printf("%d",semctl(semid,1+i,GETVAL));
}
void put_fork(int i,int semid)
{	
	struct sembuf buf;
	union semun t;
        buf.sem_num=0;
        buf.sem_op=-1;
        buf.sem_flg=0;
        semop(semid,&buf,1);            //p(m)

       /* buf.sem_num=N+1+i;
        buf.sem_op=-2;
        buf.sem_flg=0;
	semop(semid,&buf,1);*/
	t.val=THINKING;
	semop(semid,N+1+i,SETVAL,t);       //state[i]=THINKING;

	test(LEFT,semid);
	test(RIGHT,semid);

	buf.sem_num=0;
        buf.sem_op=1;
        buf.sem_flg=0;
        semop(semid,&buf,1);             //v(m)

}
int test(int i,int semid)
{	
	int l,r,o;

	struct sembuf buf;
	union semun t;
	o=semctl(semid,N+1+i,GETVAL);
	l=semctl(semid,N+1+LEFT,GETVAL);
	r=semctl(semid,N+1+RIGHT,GETVAL);
	
	if(o==HUNGRY && l!=EATING && r!=EATING)
	{
		/*buf.sem_num=N+1+i;
        	buf.sem_op=1;
        	buf.sem_flg=0;
        	semop(semid,&buf,1);*/
		t.val=EATING;          //state[i]=EATING;
		semctl(semid,N+1+i,SETVAL,t);
		buf.sem_num=1+i;
                buf.sem_op=1;
                buf.sem_flg=0;
                semop(semid,&buf,1);                          // v(s);
	}
	return 1;	
}
int philosopher (int i,int semid)
{
	while (TURE)
	{
		think(i);
		take_fork(i,semid);
		eat(i);
		put_fork(i,semid);
	}	
	return 1;	
}