semcons.c~

来自「word count information using message que」· C~ 代码 · 共 64 行

#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>
#include<sys/types.h>
#include<sys/ipc.h>
#include<sys/sem.h>
#include<string.h>
#define BUF "temp"               //check this
#define SEM1 0
#define SEM2 1
union semun
	{
	int val;
	struct semid_ds *buf ;
	ushort *array;
	};
int main()
{
printf("sayooj\n");
struct sembuf acquire ={0,-1,SEM_UNDO};
struct sembuf release ={0,1,SEM_UNDO};
key_t uniqkey;
uniqkey=ftok(".",'A');


int semid=semget(uniqkey,2,0);                           //dont create it again .open already existing
if(semid==-1)
	{
	printf("error in making semaphore\n");
	}
 

FILE *fp;
int i=0;

while(1)
{
//printf("generating %d \n",i);
acquire.sem_num=SEM2;
if(semop(semid,&acquire,1)==-1)
	{
	printf("waiting for producer to make something new \n");
	}

fp=fopen(BUF,"r");
if(fp==NULL)
	{
	printf("error filepointe\n");
	}
fscanf(fp,"%d",&i);//i++;
fclose(fp);
release.sem_num=SEM1;
printf("number read %d by %d\n",i,getpid());
if(semop(semid,&release,1)==-1)
	{
	printf("no more numbers seen \n");
	exit(1);
	}
sleep(1);
}


return 0;
}