error_contador_practica.c

/*******************************************
* Author     : Diego Cordoba / @d1cor      *
* Purpose    : juncotic.com  / um.edu.ar   *
*******************************************/

/*
 * Corregir este codigo para que devuelva el resutltado correcto
*/

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

#define NITER 1000000
#define NTHREADS 5

struct params{
    int cnt;
};

typedef struct params params_t;

void* Count(void*);

int main(int argc, char ** argv){
    params_t p;
    pthread_t tid[NTHREADS];

    int i=0;

    p.cnt = 0;

    for(i=0; i<NTHREADS; i++){
        if(pthread_create((tid+i), NULL, Count, (void*)&p)){
            printf("\n ERROR creating thread");
            exit(1);
        }
    }

    for(i=0; i<NTHREADS; i++){
        if(pthread_join(*(tid+i), NULL)){
            printf("\n ERROR joining thread");
            exit(1);
        }
    }

    if (p.cnt < NTHREADS * NITER)
        printf("\n NOOOOOO! cnt es [%d], deberia ser %d\n", p.cnt, NTHREADS*NITER);
    else
        printf("\n BIEN! cnt es [%d]\n", p.cnt);

    pthread_exit(NULL);
}

void* Count(void *p){
    int i, tmp;
    params_t *pp = (params_t*) p;

    for(i = 0; i < NITER; i++){
        tmp = pp->cnt;
        tmp = tmp+1;
        pp->cnt = tmp;
    }
}