BoundedConcurrency

BoundedConcurrency.java

public class BoundedConcurrency {

    // https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/locks/Condition.html

    private final Lock lock = new ReentrantLock();
    private final Condition notFull = lock.newCondition();
    private final Condition notEmpty = lock.newCondition();
    private int count;
    private int max;

    public BoundedConcurrency(int max) {
        this.max = max;
    }

    public int getCount() {
        lock.lock();
        try {
            return count;
        } finally {
            lock.unlock();
        }
    }

    public int getMax() {
        lock.lock();
        try {
            return max;
        } finally {
            lock.unlock();
        }
    }

    public void incr() {
        this.incr(1, TimeUnit.HOURS);
    }

    public void incr(long time, TimeUnit unit) {
        if (this.max == 0) {
            return;
        }
        lock.lock();
        try {
            while (count >= max) {
                try {
                    notFull.await(time, unit);
                } catch (InterruptedException e) {
                }
            }
            count++;
            notEmpty.signal();
        } finally {
            lock.unlock();
        }
        return;
    }

    public void decr() {
        if (this.max == 0) {
            return;
        }
        lock.lock();
        try {
            while (count <= 0) {
                try {
                    notEmpty.await();
                } catch (InterruptedException e) {
                    continue;
                }
            }
            count--;
            notFull.signal();
        } finally {
            lock.unlock();
        }
    }
}