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A highly scalable redis-persistent queuing system for vertx

There is a newer version: 4.1.11

package org.swisspush.redisques.util;

import io.vertx.core.Future;
import io.vertx.core.Promise;
import io.vertx.core.Vertx;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Random;

/**
 * Utility class for the vertx timer functionalities.
 *
 * @author Marc-André Weber
 */
public class RedisQuesTimer {
    private final Vertx vertx;
    private final Random random;

    private final Logger log = LoggerFactory.getLogger(RedisQuesTimer.class);

    public RedisQuesTimer(Vertx vertx) {
        this.vertx = vertx;
        this.random = new Random();
    }

    /**
     * Delay an operation by providing a delay in milliseconds. This method completes the {@link Future} any time
     * between immediately and the delay. When 0 provided as delay, the {@link Future} is resolved immediately.
     *
     * @param delayMs the delay in milliseconds
     * @return A {@link Future} which completes after the delay
     */
    public Future executeDelayedMax(long delayMs) {
        Promise promise = Promise.promise();

        if (delayMs > 0) {
            int delay = random.nextInt((int) (delayMs + 1)) + 1;
            log.debug("starting timer with a delay of {}ms", delay);
            vertx.setTimer(delay, delayed -> promise.complete());
        } else {
            vertx.runOnContext(aVoid -> promise.complete());
        }

        return promise.future();
    }
}