MockLatency.java

/*
 * The MIT License
 *
 * Copyright (c) 2017 CloudBees, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
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 *
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package jenkins.scm.impl.mock;

import java.util.Random;
import java.util.concurrent.TimeUnit;

/**
 * Represents latency in connecting to the {@link MockSCM}.
 *
 * @since 2.0.5
 */
public abstract class MockLatency {

    private static final MockLatency NONE = new MockLatency() {
        @Override
        public void apply() throws InterruptedException {
        }
    };
    private static final MockLatency YIELD = new MockLatency() {
        @Override
        public void apply() throws InterruptedException {
            Thread.yield();
        }
    };

    public abstract void apply() throws InterruptedException;

    /**
     * A fixed latency.
     * @param time the latency.
     * @param units the units.
     * @return a fixed latency.
     */
    public static MockLatency fixed(final long time, final TimeUnit units) {
        return new MockLatency() {
            @Override
            public void apply() throws InterruptedException {
                units.sleep(time);
            }
        };
    }

    /**
     * A fixed latency for all threads except the current thread.
     * 
     * @param time the latency.
     * @param units the units.
     * @return a fixed latency.
     */
    public static MockLatency fixedForOtherThreads(final long time, final TimeUnit units) {
        final Thread safe = Thread.currentThread();
        return new MockLatency() {
            @Override
            public void apply() throws InterruptedException {
                if (Thread.currentThread() != safe) {
                    units.sleep(time);
                }
            }
        };
    }

    /**
     * A random latency that has an expected average time.
     *
     * @param time  the expected average latency.
     * @param units the units.
     * @return a fixed latency.
     */
    public static MockLatency average(final long time, final TimeUnit units) {
        return new MockLatency() {
            final Random entropy = new Random();
            @Override
            public void apply() throws InterruptedException {
                long ms = units.toMillis(time);
                ms = Math.min(ms * 3L, Math.max((long) (ms + (ms * entropy.nextGaussian())), 1L));
                Thread.sleep(ms);
            }
        };
    }
    /**
     * A latency that just forces the thread scheduler to yield.
     *
     * @return a minimal latency that causes background threads to run.
     */
    public static MockLatency yield() {
        return YIELD;
    }
    /**
     * A latency that just forces the thread scheduler to yield.
     *
     * @return a minimal latency that causes background threads to run.
     */
    public static MockLatency none() {
        return NONE;
    }
}