/*
 prodConTaS.c++ Producer-Consumer Problem on 
          shared memory - mutual exclusion 
          using test and set (btsl)
 $ g++ -Wall prodConTaS.c++ queue1c.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 "queue1c.h"

void producer(queue *);
void consumer(queue *);
int *countC, *countP;
int *lockP; // Global

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);
        countC = (int *)(qP+1);
        countP = countC+1;
        lockP = countP+1;
        *lockP = 0; // lock initialized to 0
        *countC = *countP = 0;
	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 consumer(qP) ;
                // Child 2: consumer
	}
	else  producer(qP) ;
                // Child I: producer
	return 0 ;
}

void producer(queue *qP){
     int added = 1, i ;
     for(i=1;i<=1000000;++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<= 1000000; ++i) {
        int data, dataOK;
    
        dataOK = qP -> frontQ(data);
        if(dataOK == OK){
           qP -> deleteQ() ;
           cout << "\tConsumed Data " 
                << ++(*countC)
                << " " << data << "\n" ;
        }
     }
}