Bakery algorithm for mutual exclusion.

Bakery.java

// pid goes from 0 to THREAD_POOL_SIZE - 1
public class Bakery {

    private static int THREAD_POOL_SIZE = 10;
    private volatile static boolean[] guests = new boolean[THREAD_POOL_SIZE];
    private volatile static int[] tickets = new int[THREAD_POOL_SIZE];

    public void lock(int pid) {
        guests[pid] = true;
        synchronized (tickets) {
            OptionalInt max = Arrays.stream(tickets).max();
            int ticket = 1;
            if (max.isPresent()) {
                ticket += max.getAsInt();
            }
            tickets[pid] = ticket;
        }
        guests[pid] = false;
        //
        for(int i = 0; i < THREAD_POOL_SIZE; i++) {
            while(guests[i]) {
                /*wait*/
            }
            while(tickets[i] != 0 && (tickets[i] < tickets[pid])) {
                /*wait*/
            }
            break;
        };
    }

    public void unlock(int pid) {
        tickets[pid] = 0;
    }
}