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

int* thread_counts;
pthread_t* threads;
int tcount = 0;

pthread_mutex_t mutex;

void* threadAction(void* arg) {
  int tid;
  pthread_mutex_lock(&mutex);
  tid=tcount;
  tcount++;
  pthread_mutex_unlock(&mutex);

  while (1) {
    pthread_mutex_lock(&mutex);
    thread_counts[tid]++;
    pthread_mutex_unlock(&mutex);
  }
}

int main(int argc, char *argv[]) {
  int error, n_threads;
  if (argc < 2) {
    printf("USAGE: %s NUM_THREADS\n", argv[0]);
    return 1;
  }
  n_threads = atoi(argv[1]);
  thread_counts = malloc(sizeof(int) * n_threads);
  threads = malloc(sizeof(int) * n_threads);

  if (pthread_mutex_init(&mutex, NULL) != 0) {
    printf("Could not initialize mutex");
    return 1;
  }

  for (int i=0; i < n_threads; i++) {
    error = pthread_create(&(threads[i]), NULL, &threadAction, NULL);
    if (error != 0) {
      printf("Error creating thread %u", i);
      return 1;
    }
  }
  printf("Set everything up, sleeping now...\n");
  sleep(1);

  for (int i=0; i < n_threads; i++) {
    thread_counts[i] = 0;
  }

  sleep(3);
  for (int i=0; i < n_threads; i++) {
    printf("Counter %u has value %u\n", i, thread_counts[i]);
  }
  return 0;
}