/ Compile as: gcc store_solution.c -lpthread -D_REENTRANT -Wall -o store

#include <stdlib.h>
#include <stdio.h>
#include <pthread.h>
#include <semaphore.h>
#include <unistd.h>

#define N_REQUESTS 100
#define MAX_THREADS 4
#define N_CLIENTS 10

typedef struct request{
    int value;
    int client;
    } request;

request requests[N_REQUESTS];
int total_daily_requests=0;

int pos=0; // position in array

// threads id
pthread_t my_thread[N_CLIENTS];
int ids[N_CLIENTS]; // saves id from client threads

// sync resources
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
sem_t threads_limit;


void *generate_requests(void* id_ptr) {
    int id = *((int *)id_ptr);
    int new_request;

    while(1){
        // the maximum threads working at the same time is MAX_THREADS
        // control the access to the 'pos' variable

            /*insert code here*/
        pthread_mutex_lock(&mutex);

        if(pos==N_REQUESTS){
            // exit thread

                /*insert code here*/
                pthread_exit(NULL);

            }
        new_request=rand()%100+1;
        requests[pos].value=new_request;
        requests[pos].client=id;
        pos++;

            /*insert code here*/

        printf("New request of %d products was generated by thread %d\n",new_request,id);
        usleep(10); //waits 10 us
        pthread_mutex_unlock(&mutex);
        }
    }

int main(void) {
  int i;
  sem_init(&threads_limit,0,MAX_THREADS);

  // create threads client

    /*insert code here*/
    for(int i =0;i<N_CLIENTS;i++){
        pthread_create(&my_thread[i], NULL, generate_requests, &ids[i]);
    }


  // wait until all threads client finish

    /*insert code here*/
    for(int i =0;i<N_CLIENTS;i++){
        pthread_join(my_thread[i], NULL);
    }

  // count items sold
  for(i=0;i<N_REQUESTS;i++) total_daily_requests+=requests[i].value;
  printf("Total items sold = %d\n",total_daily_requests);
  exit(0);
  }