/*
 * Busy waiting.
 */
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdbool.h>

int coin_flip;
volatile bool coin_flip_done;

static void *
thread1(void *_)
{
    coin_flip = rand() % 2;
    coin_flip_done = true;
    printf("Thread 1: flipped coin %d\n", coin_flip);
    return NULL;
}

static void *
thread2(void *_)
{
    /* Thread 2 spins, "busy-waits" until the coin flip is done.
     * This is an unacceptable solution.  Bad for the planet, too. */
    while (!coin_flip_done)
        continue;

    printf("Thread 2: flipped coin %d\n", coin_flip);
    return NULL;
}

int
main()
{
    int i, N = 2;
    pthread_t t[N];
    srand(getpid());
    pthread_create(&t[1], NULL, thread2, NULL);
    pthread_create(&t[0], NULL, thread1, NULL);

    for (i = 0; i < N; i++)
        pthread_join(t[i], NULL);
    return 0;
}