clients/src/test/java/org/apache/kafka/clients/producer/PartitionerTest.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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,
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 * See the License for the specific language governing permissions and
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package org.apache.kafka.clients.producer;

import org.apache.kafka.clients.producer.internals.Partitioner;
import org.apache.kafka.common.Cluster;
import org.apache.kafka.common.Node;
import org.apache.kafka.common.PartitionInfo;
import org.junit.Test;

import java.util.List;

import static java.util.Arrays.asList;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

public class PartitionerTest {

    private byte[] key = "key".getBytes();
    private byte[] value = "value".getBytes();
    private Partitioner partitioner = new Partitioner();
    private Node node0 = new Node(0, "localhost", 99);
    private Node node1 = new Node(1, "localhost", 100);
    private Node node2 = new Node(2, "localhost", 101);
    private Node[] nodes = new Node[] { node0, node1, node2 };
    private String topic = "test";
    // Intentionally make the partition list not in partition order to test the edge cases.
    private List<PartitionInfo> partitions = asList(new PartitionInfo(topic, 1, null, nodes, nodes),
                                                    new PartitionInfo(topic, 2, node1, nodes, nodes),
                                                    new PartitionInfo(topic, 0, node0, nodes, nodes));
    private Cluster cluster = new Cluster(asList(node0, node1, node2), partitions);

    @Test
    public void testUserSuppliedPartitioning() {
        assertEquals("If the user supplies a partition we should use it.",
                     0,
                     partitioner.partition(new ProducerRecord<byte[], byte[]>("test", 0, key, value), cluster));
    }

    @Test
    public void testKeyPartitionIsStable() {
        int partition = partitioner.partition(new ProducerRecord<byte[], byte[]>("test", key, value), cluster);
        assertEquals("Same key should yield same partition",
                     partition,
                     partitioner.partition(new ProducerRecord<byte[], byte[]>("test", key, "value2".getBytes()), cluster));
    }

    @Test
    public void testRoundRobinWithUnavailablePartitions() {
        // When there are some unavailable partitions, we want to make sure that (1) we always pick an available partition,
        // and (2) the available partitions are selected in a round robin way.
        int countForPart0 = 0;
        int countForPart2 = 0;
        for (int i = 1; i <= 100; i++) {
            int part = partitioner.partition(new ProducerRecord<byte[], byte[]>("test", value), cluster);
            assertTrue("We should never choose a leader-less node in round robin", part == 0 || part == 2);
            if (part == 0)
                countForPart0++;
            else
                countForPart2++;
        }
        assertEquals("The distribution between two available partitions should be even", countForPart0, countForPart2);
    }
}