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dining_ipc.c
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dining_ipc.c
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#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ipc.h>
#include <sys/sem.h>
const int ITERATIONS=100;
int chopstick[5];
int philosphor(int n)
{
int i,j,first,second;
struct sembuf op;
op.sem_num=0;
op.sem_flg=0;
printf("Philosopher %d was born ! \n",n);
first=(n<4)?n:0;
second=(n<4)?n+1:4;
for(i=0;i<ITERATIONS;i++)
{
if(n&1){
printf("Philosophor %d is thinking...\n",n);
op.sem_op=-1;
semop(chopstick[first],&op,1);
op.sem_op=-1;
semop(chopstick[second],&op,1);
printf("Philosophor %d is eating....\n",n);
sleep(rand()%5);
printf("Philosopher %d finished eating \n",n);
op.sem_op=+1;
semop(chopstick[first],&op,1);
op.sem_op=+1;
semop(chopstick[second],&op,1);
}
else{
printf("Philosophor %d is thinking...\n",n);
op.sem_op=-1;
semop(chopstick[second],&op,1);
op.sem_op=-1;
semop(chopstick[first],&op,1);
printf("Philosophor %d is eating....\n",n);
sleep(rand()%5);
printf("Philosopher %d finished eating \n",n);
op.sem_op=+1;
semop(chopstick[second],&op,1);
op.sem_op=+1;
semop(chopstick[first],&op,1);
}
}
exit(n);
}
int main()
{
int i,status;
pid_t phil[5];
for(i=0;i<5;i++)
{
if((chopstick[i]=semget(IPC_PRIVATE,1,IPC_CREAT|0600))<0)
return -1;
if(semctl(chopstick[i],0,SETVAL,1)<0)
return -1;
}
for(i=0;i<5;i++)
{
if((phil[i]=fork())==0)
exit(philosphor(i));
}
for(i=0;i<5;i++)
{
waitpid(phil[i],&status,0);
if(WEXITSTATUS(status)==i)
printf("Philosophor %d went to heaven \n",i);
else
printf("Philosophor %d went to hell \n",i);
}
for(i=0;i<5;i++)
{
semctl(chopstick[i],0,IPC_RMID,0);
}
return 0;
}