philosopher.c

来自「在linux下实现编制模拟“五个哲学家”问题的程序」· C语言 代码 · 共 103 行

#include<stdlib.h>
#include<stdio.h>
#include<unistd.h>
#include<signal.h>
#include<string.h>
#include"lock.h"
#include "lock.c" 
#define N 5
pid_t cpid[5];
static char* forkfile[5]={"fork0","fork1","fork2","fork3","fork4"};
static void sig_quit(int signo)
{
	if(signo==SIGQUIT||signo==SIGINT)
	{
		int i;
		for(i=0;i<N;i++)
		{
			unlock(forkfile[i]);
			remove(forkfile[i]);
			kill(cpid[i],SIGQUIT);
		}
		exit(0);
	}

}
static void takefork(int i)
{
	if(i==N-1)
	{
		lock(forkfile[0]);
		lock(forkfile[i]);
	}
	else
	{
		lock(forkfile[i]);
		lock(forkfile[(i+1)%N]);
	}
}
static void think(int i,unsigned int time)
{
	printf("Philosopher %d is thinking.\n",i);
	sleep(time);
}
static void eat(int i,unsigned int time)
{
	printf("Philosopher %d is eating.\n",i);
	sleep(time);
}
static void putfork(int i)
{
	if(i==N-1)
	{
		unlock(forkfile[0]);
		unlock(forkfile[i]);
	}
	else
	{
		unlock(forkfile[i]);
		unlock(forkfile[(i+1)%N]);
	}
}
int main(int argc,char* argv[])
{
	unsigned int time;
	if(argc==1) time=2;
	else if(argc==3&&strcmp(argv[1],"-t")==0)
	{
		time=(unsigned int)atoi(argv[2]);
	}
	else
	{
		printf("Usage:philosopher [-t] time\n");
		exit(0);
	}
	if(signal(SIGQUIT,sig_quit)<0)
	{
		printf("SIGQUIT error\n");exit(1);
	}
	if(signal(SIGINT,sig_quit)<0)
	{
		printf("SIGQUIT error\n");exit(1);
	}
	int i;
	for(i=0;i<N;i++)
	{
		if((cpid[i]=fork())<0)
		{	printf("fork error\n");exit(1);}
		else if(cpid[i]==0)
		{
			sleep(i);
			while(1)
			{
				think(i,time);
				takefork(i);
				eat(i,time);
				putfork(i);
			}
		}
	}
	while(1)
		pause();
}