com.netflix.curator.x.discovery.TestStrategies.java Source code

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Here is the source code for com.netflix.curator.x.discovery.TestStrategies.java

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/*
 *
 *  Copyright 2011 Netflix, Inc.
 *
 *     Licensed under the Apache License, Version 2.0 (the "License");
 *     you may not use this file except in compliance with the License.
 *     You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 *     Unless required by applicable law or agreed to in writing, software
 *     distributed under the License is distributed on an "AS IS" BASIS,
 *     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *     See the License for the specific language governing permissions and
 *     limitations under the License.
 *
 */

package com.netflix.curator.x.discovery;

import com.google.common.collect.Lists;
import com.netflix.curator.x.discovery.details.InstanceProvider;
import com.netflix.curator.x.discovery.strategies.RandomStrategy;
import com.netflix.curator.x.discovery.strategies.RoundRobinStrategy;
import com.netflix.curator.x.discovery.strategies.StickyStrategy;
import org.apache.commons.math.stat.descriptive.SummaryStatistics;
import org.testng.Assert;
import org.testng.annotations.Test;
import java.util.List;

public class TestStrategies {
    private static class TestInstanceProvider implements InstanceProvider<Void> {
        private final List<ServiceInstance<Void>> instances;

        private TestInstanceProvider(int qty) throws Exception {
            this(qty, 0);
        }

        private TestInstanceProvider(int qty, int startingAt) throws Exception {
            instances = Lists.newArrayList();
            for (int i = 0; i < qty; ++i) {
                ServiceInstanceBuilder<Void> builder = ServiceInstance.builder();
                instances.add(builder.id(Integer.toString(i + startingAt)).name("foo").build());
            }
        }

        @Override
        public List<ServiceInstance<Void>> getInstances() throws Exception {
            return instances;
        }
    }

    @Test
    public void testRandom() throws Exception {
        final int QTY = 10;
        final int ITERATIONS = 1000;

        TestInstanceProvider instanceProvider = new TestInstanceProvider(QTY, 0);
        ProviderStrategy<Void> strategy = new RandomStrategy<Void>();

        long[] counts = new long[QTY];
        for (int i = 0; i < ITERATIONS; ++i) {
            ServiceInstance<Void> instance = strategy.getInstance(instanceProvider);
            int id = Integer.parseInt(instance.getId());
            counts[id]++;
        }

        SummaryStatistics statistic = new SummaryStatistics();
        for (int i = 0; i < QTY; ++i) {
            statistic.addValue(counts[i]);
        }
        Assert.assertTrue(statistic.getStandardDeviation() <= (QTY * 2), "" + statistic.getStandardDeviation()); // meager check for even distribution
    }

    @Test
    public void testRoundRobin() throws Exception {
        final int QTY = 10;

        TestInstanceProvider instanceProvider = new TestInstanceProvider(QTY);
        ProviderStrategy<Void> strategy = new RoundRobinStrategy<Void>();

        for (int i = 0; i < QTY; ++i) {
            ServiceInstance<Void> instance = strategy.getInstance(instanceProvider);
            Assert.assertEquals(instance.getId(), Integer.toString(i));
        }

        for (int i = 0; i < (1234 * QTY); ++i) {
            ServiceInstance<Void> instance = strategy.getInstance(instanceProvider);
            Assert.assertEquals(instance.getId(), Integer.toString(i % QTY));
        }
    }

    @Test
    public void testSticky() throws Exception {
        final int QTY = 10;

        TestInstanceProvider instanceProvider = new TestInstanceProvider(QTY);
        StickyStrategy<Void> strategy = new StickyStrategy<Void>(new RandomStrategy<Void>());

        ServiceInstance<Void> theInstance = strategy.getInstance(instanceProvider);
        int instanceNumber = strategy.getInstanceNumber();
        for (int i = 0; i < 1000; ++i) {
            Assert.assertEquals(strategy.getInstance(instanceProvider), theInstance);
        }

        // assert what happens when an instance goes down
        instanceProvider = new TestInstanceProvider(QTY, QTY);
        Assert.assertFalse(strategy.getInstance(instanceProvider).equals(theInstance));
        Assert.assertFalse(instanceNumber == strategy.getInstanceNumber());

        theInstance = strategy.getInstance(instanceProvider);
        for (int i = 0; i < 1000; ++i) {
            Assert.assertEquals(strategy.getInstance(instanceProvider), theInstance);
        }
    }
}