com.sonatype.nexus.perftest.RequestRate.java Source code

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Here is the source code for com.sonatype.nexus.perftest.RequestRate.java

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/*
 * Copyright (c) 2007-2013 Sonatype, Inc. All rights reserved.
 *
 * This program and the accompanying materials are made available under the terms of the Eclipse Public License Version 1.0,
 * which accompanies this distribution and is available at http://www.eclipse.org/legal/epl-v10.html.
 */
package com.sonatype.nexus.perftest;

import java.util.Random;
import java.util.StringTokenizer;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import com.fasterxml.jackson.annotation.JsonCreator;

/**
 * Schedules test client requests according to specified rate.
 */
public class RequestRate {
    private final Random rnd = new Random();

    private final long start;

    private final AtomicInteger count = new AtomicInteger();

    private final int period;

    /**
     * @param rate average number of requests per time {@code unit}
     * @param unit time unit of {@code rate} parameter
     */
    public RequestRate(int rate, TimeUnit unit) {
        this((int) (unit.toMillis(1) / rate));
    }

    private RequestRate(int period) {
        // TODO assert period is at least 10
        this.period = period;
        this.start = System.currentTimeMillis() + rnd.nextInt(period); // delay first event
    }

    @JsonCreator
    public RequestRate(String value) {
        this(parseRate(value));
    }

    private static int parseRate(String value) {
        StringTokenizer st = new StringTokenizer(value, " /");
        int time = Integer.parseInt(st.nextToken());
        TimeUnit unit = TimeUnit.valueOf(st.nextToken() + "S");
        return (int) (unit.toMillis(1) / time);
    }

    public void delay() throws InterruptedException {
        long next = start + (((long) period) * ((long) count.getAndIncrement())); // time of the next event
        long delay = Math.max(0, next - System.currentTimeMillis()); // delay until the next event

        Thread.sleep(delay);
    }

    public int getPeriod() {
        return period;
    }
}