opinionated-vertx/src/de/pzzz/vertx/worker/QueueProcessingStatus.java

package de.pzzz.vertx.worker;

import java.io.Serializable;
import java.util.LinkedList;
import java.util.Queue;

public class QueueProcessingStatus<T> implements Serializable {
	private static final long serialVersionUID = 7560765077464782742L;

	private transient Queue<T> requestsToProcess = new LinkedList<>();
	private boolean calculate = false;
	private int runningCalculations = 0;

	public T startProcessing() {
		if (requestsToProcess.isEmpty()) {
			throw new IllegalStateException("No requests to process!");
		}
		calculate = true;
		runningCalculations = 1;
		return requestsToProcess.poll();
	}

	public void stopProcessing() {
		calculate = false;
	}

	public boolean hasNext() {
		return !requestsToProcess.isEmpty();
	}

	public T processNext() {
		runningCalculations += 1;
		return requestsToProcess.poll();
	}

	public void complete() {
		runningCalculations -= 1;
		if (runningCalculations == 0 && requestsToProcess.isEmpty()) {
			calculate = false;
		}
	}

	public void enqueue(final T request) {
		requestsToProcess.add(request);
	}

	public void clear() {
		requestsToProcess.clear();
	}

	public boolean isCalculate() {
		return calculate;
	}

	public void setCalculate(final boolean calculate) {
		this.calculate = calculate;
	}

	public int getRunningCalculations() {
		return runningCalculations;
	}

	public void setRunningCalculations(final int running) {
		this.runningCalculations = running;
	}

	public int getQueueLength() {
		return requestsToProcess.size();
	}
}