/**
> gcc -o thread_mutex thread_mutex.c -pthread
> ./thread_mutex
Thread:  1 Counter:  1
Thread:  3 Counter:  2
Thread:  2 Counter:  3
Thread:  0 Counter:  4
Thread:  4 Counter:  5
>
**/


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

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
int counter = 0;

void *perform_work(void *argument)
{
    pthread_mutex_lock(&mutex);
    counter++;
    int passed_in_value;
    passed_in_value = *((int *) argument);
    printf("Thread: %2d Counter: %2d\n", passed_in_value, counter);
    pthread_mutex_unlock(&mutex);
    pthread_exit(NULL);

    return NULL;
}

int main(void)
{
    const int NUM_THREADS = 5;

    pthread_t threads[NUM_THREADS];
    int thread_args[NUM_THREADS];
    int result_code, index;

    for (index = 0; index < NUM_THREADS; ++index) {
        thread_args[index] = index;
        result_code = pthread_create(&threads[index], NULL, perform_work, (void *) &thread_args[index]);
        assert(0 == result_code);
    }

    for (index = 0; index < NUM_THREADS; ++index) {
        result_code = pthread_join(threads[index], NULL);
        assert(0 == result_code);
    }

    exit(EXIT_SUCCESS);
}