// TO COMPILE:  gcc -g3 -O0 THIS_FILE -pthread
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>

pthread_mutex_t mutex1;
pthread_mutex_t mutex2;
pthread_t thread1, thread2;
int quiet = 0;

void * thread_worker1(void *forks_arg) {
  int i;
  for (i = 0; i < 100; i++) {
    pthread_mutex_lock(&mutex2);
    pthread_mutex_lock(&mutex1);
    pthread_mutex_unlock(&mutex1);
    pthread_mutex_unlock(&mutex2);
    sleep( rand() % 3 ); // Simulate useful work
    if (!quiet) {printf("WORKER 1 DID A TASK.\n");}
  }
  return NULL;
}

void * thread_worker2(void *forks_arg) {
  int i;
  for (i = 0; i < 100; i++) {
    pthread_mutex_lock(&mutex1);
    pthread_mutex_lock(&mutex2);
    pthread_mutex_unlock(&mutex2);
    pthread_mutex_unlock(&mutex1);
    sleep( rand() % 3 ); // Simulate useful work
    if (!quiet) {printf("WORKER 2 DID A TASK.\n");}
  }
  return NULL;
}

int main(int argc, char* argv[]) {
  if (argc == 2 && strcmp(argv[1], "--quiet") == 0) {
    quiet = 1;
  }
  pthread_mutex_init(&mutex1, NULL);
  pthread_mutex_init(&mutex2, NULL);

  pthread_create(&thread1, NULL, &thread_worker1, NULL);
  pthread_create(&thread2, NULL, &thread_worker2, NULL);

  pthread_join(thread1, NULL);
  pthread_join(thread2, NULL);

  return 0;
}