/*
 * prodCon1.c++ Producer-Consumer Problem on 
 *         shared memory                                                 
 * $ g++ -Wall prodCon1.c++ queue.o        
*/
#include <iostream>
using namespace std;
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/wait.h>
#include <unistd.h>
#include "queue.h"

void producer(queue *);
void consumer(queue *);
int *countP, *countC; // global counters

int main() {
	int shmID, chID1, chID2, status ;
	struct shmid_ds buff ;
        queue *qP ;

	shmID = shmget(IPC_PRIVATE, 
                       sizeof(queue), 
                       IPC_CREAT | 0777);
	if(shmID == -1) {
		perror("Error in shmget\n") ;
		exit(1) ;
	}
        qP = (queue *) shmat(shmID, 0, 0777);
        countP = (int *)(qP+1);
        countC = countP+1;
        *countP = *countC = 0; // counter init
	if((chID1 = fork()) != 0) { // Parent
           if((chID2 = fork()) != 0) { // Parent now
               waitpid(chID1, &status, 0);
               waitpid(chID2, &status, 0);
               cout << *countP << " data produced\n";
               cout << *countC << " data consumed\n";
               shmdt(qP) ;
               shmctl(shmID, IPC_RMID, &buff);
           }
           else  producer(qP);
		// consumer(qP) ;
                // Child 2: producer
	}
	else  consumer(qP);
                // producer(qP) ;
                // Child I: consumer
	return 0 ;
}

void producer(queue *qP){
     int added = 1, i;
     for(i=1;i<=500000;++i) {
        int data, err;

        if(added) {
           data = rand() ;
           added = 0 ;
        }
        err = qP->addQ(data) ;
        if(err == OK) {
           added = 1 ;
           cout << "Produced Data " << ++(*countP) 
                << " " << data << "\n" ;
        }
     }
}

void consumer(queue *qP) {
     int i;
     for(i=1; i<= 500000; ++i) {
        int data, dataOK;
    
        dataOK = qP -> frontQ(data);
        qP -> deleteQ(); // where to put this code
        if(dataOK == OK){
           // qP -> deleteQ() ;
           cout << "\tConsumed Data " << ++(*countC)
                << " " << data << "\n" ;
        }
     }
}