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   * Licensed to the Apache Software Foundation (ASF) under one or more
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   * 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
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   *
   *    http://www.apache.org/licenses/LICENSE-2.0
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   * 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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  package org.apache.kafka.clients.producer.internals;
  
  import org.apache.kafka.common.Cluster;
  import org.apache.kafka.common.Node;
  import org.apache.kafka.common.PartitionInfo;
  import org.apache.kafka.common.utils.LogContext;
  
  import org.junit.jupiter.api.Test;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import static java.util.Arrays.asList;
  import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertNotEquals;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  public class BuiltInPartitionerTest {
      private static final Node[] NODES = new Node[] {
          new Node(0, "localhost", 99),
          new Node(1, "localhost", 100),
          new Node(2, "localhost", 101),
          new Node(11, "localhost", 102)
      };
      static final String TOPIC_A = "topicA";
      static final String TOPIC_B = "topicB";
      static final String TOPIC_C = "topicC";
      final LogContext logContext = new LogContext();
  
      @Test
      public void testStickyPartitioning() {
          List<PartitionInfo> allPartitions = asList(new PartitionInfo(TOPIC_A, 0, NODES[0], NODES, NODES),
              new PartitionInfo(TOPIC_A, 1, NODES[1], NODES, NODES),
              new PartitionInfo(TOPIC_A, 2, NODES[2], NODES, NODES),
              new PartitionInfo(TOPIC_B, 0, NODES[0], NODES, NODES)
          );
          Cluster testCluster = new Cluster("clusterId", asList(NODES), allPartitions,
              Collections.emptySet(), Collections.emptySet());
  
          // Create partitions with "sticky" batch size to accommodate 3 records.
          BuiltInPartitioner builtInPartitionerA = new SequentialPartitioner(logContext, TOPIC_A, 3);
  
          // Test the partition is not switched until sticky batch size is reached.
          BuiltInPartitioner.StickyPartitionInfo partitionInfo = builtInPartitionerA.peekCurrentPartitionInfo(testCluster);
          int partA = partitionInfo.partition();
          builtInPartitionerA.updatePartitionInfo(partitionInfo, 1, testCluster);
  
          partitionInfo = builtInPartitionerA.peekCurrentPartitionInfo(testCluster);
          assertEquals(partA, partitionInfo.partition());
          builtInPartitionerA.updatePartitionInfo(partitionInfo, 1, testCluster);
  
          partitionInfo = builtInPartitionerA.peekCurrentPartitionInfo(testCluster);
          assertEquals(partA, partitionInfo.partition());
          builtInPartitionerA.updatePartitionInfo(partitionInfo, 1, testCluster);
  
          // After producing 3 records, partition must've switched.
          assertNotEquals(partA, builtInPartitionerA.peekCurrentPartitionInfo(testCluster).partition());
  
          // Check that switching works even when there is one partition.
          BuiltInPartitioner builtInPartitionerB = new SequentialPartitioner(logContext, TOPIC_B, 1);
          for (int c = 10; c-- > 0; ) {
              partitionInfo = builtInPartitionerB.peekCurrentPartitionInfo(testCluster);
              assertEquals(0, partitionInfo.partition());
              builtInPartitionerB.updatePartitionInfo(partitionInfo, 1, testCluster);
          }
      }
  
      @Test
      public void unavailablePartitionsTest() {
          // Partition 1 in topic A, partition 0 in topic B and partition 0 in topic C are unavailable partitions.
          List<PartitionInfo> allPartitions = asList(new PartitionInfo(TOPIC_A, 0, NODES[0], NODES, NODES),
              new PartitionInfo(TOPIC_A, 1, null, NODES, NODES),
              new PartitionInfo(TOPIC_A, 2, NODES[2], NODES, NODES),
              new PartitionInfo(TOPIC_B, 0, null, NODES, NODES),
              new PartitionInfo(TOPIC_B, 1, NODES[0], NODES, NODES),
              new PartitionInfo(TOPIC_C, 0, null, NODES, NODES)
          );
  
          Cluster testCluster = new Cluster("clusterId", asList(NODES[0], NODES[1], NODES[2]), allPartitions,
              Collections.emptySet(), Collections.emptySet());
  
          // Create partitions with "sticky" batch size to accommodate 1 record.
          BuiltInPartitioner builtInPartitionerA = new BuiltInPartitioner(logContext, TOPIC_A, 1);
  
          // Assure we never choose partition 1 because it is unavailable.
          BuiltInPartitioner.StickyPartitionInfo partitionInfo = builtInPartitionerA.peekCurrentPartitionInfo(testCluster);
          int partA = partitionInfo.partition();
          builtInPartitionerA.updatePartitionInfo(partitionInfo, 1, testCluster);
  
          boolean foundAnotherPartA = false;
          assertNotEquals(1, partA);
          for (int aPartitions = 0; aPartitions < 100; aPartitions++) {
              partitionInfo = builtInPartitionerA.peekCurrentPartitionInfo(testCluster);
              int anotherPartA = partitionInfo.partition();
              builtInPartitionerA.updatePartitionInfo(partitionInfo, 1, testCluster);
  
              assertNotEquals(1, anotherPartA);
              foundAnotherPartA = foundAnotherPartA || anotherPartA != partA;
          }
          assertTrue(foundAnotherPartA, "Expected to find partition other than " + partA);
  
          BuiltInPartitioner builtInPartitionerB = new BuiltInPartitioner(logContext, TOPIC_B, 1);
          // Assure we always choose partition 1 for topic B.
          partitionInfo = builtInPartitionerB.peekCurrentPartitionInfo(testCluster);
          int partB = partitionInfo.partition();
          builtInPartitionerB.updatePartitionInfo(partitionInfo, 1, testCluster);
  
          assertEquals(1, partB);
          for (int bPartitions = 0; bPartitions < 100; bPartitions++) {
              partitionInfo = builtInPartitionerB.peekCurrentPartitionInfo(testCluster);
              assertEquals(1, partitionInfo.partition());
              builtInPartitionerB.updatePartitionInfo(partitionInfo, 1, testCluster);
          }
  
          // Assure that we still choose the partition when there are no partitions available.
          BuiltInPartitioner builtInPartitionerC = new BuiltInPartitioner(logContext, TOPIC_C, 1);
          partitionInfo = builtInPartitionerC.peekCurrentPartitionInfo(testCluster);
          int partC = partitionInfo.partition();
          builtInPartitionerC.updatePartitionInfo(partitionInfo, 1, testCluster);
          assertEquals(0, partC);
  
          partitionInfo = builtInPartitionerC.peekCurrentPartitionInfo(testCluster);
          partC = partitionInfo.partition();
          assertEquals(0, partC);
      }
  
      @Test
      public void adaptivePartitionsTest() {
          BuiltInPartitioner builtInPartitioner = new SequentialPartitioner(logContext, TOPIC_A, 1);
  
          // Simulate partition queue sizes.
          int[] queueSizes = {5, 0, 3, 0, 1};
          int[] partitionIds = new int[queueSizes.length];
          int[] expectedFrequencies = new int[queueSizes.length];
          List<PartitionInfo> allPartitions = new ArrayList<>();
          for (int i = 0; i < partitionIds.length; i++) {
              partitionIds[i] = i;
              allPartitions.add(new PartitionInfo(TOPIC_A, i, NODES[i % NODES.length], NODES, NODES));
              expectedFrequencies[i] = 6 - queueSizes[i];  // 6 is max(queueSizes) + 1
          }
  
          builtInPartitioner.updatePartitionLoadStats(queueSizes, partitionIds, queueSizes.length);
  
          Cluster testCluster = new Cluster("clusterId", asList(NODES), allPartitions,
              Collections.emptySet(), Collections.emptySet());
  
          // Issue a certain number of partition calls to validate that the partitions would be
          // distributed with frequencies that are reciprocal to the queue sizes.  The number of
          // iterations is defined by the last element of the cumulative frequency table which is
          // the sum of all frequencies.  We do 2 cycles, just so it's more than 1.
          final int numberOfCycles = 2;
          int numberOfIterations = builtInPartitioner.loadStatsRangeEnd() * numberOfCycles;
          int[] frequencies = new int[queueSizes.length];
  
          for (int i = 0; i < numberOfIterations; i++) {
              BuiltInPartitioner.StickyPartitionInfo partitionInfo = builtInPartitioner.peekCurrentPartitionInfo(testCluster);
              ++frequencies[partitionInfo.partition()];
              builtInPartitioner.updatePartitionInfo(partitionInfo, 1, testCluster);
          }
  
          // Verify that frequencies are reciprocal of queue sizes.
          for (int i = 0; i < frequencies.length; i++) {
              assertEquals(expectedFrequencies[i] * numberOfCycles, frequencies[i],
                  "Partition " + i + " was chosen " + frequencies[i] + " times");
          }
      }
  
      @Test
      void testStickyBatchSizeMoreThatZero() {
          assertThrows(IllegalArgumentException.class, () -> new BuiltInPartitioner(logContext, TOPIC_A, 0));
          assertDoesNotThrow(() -> new BuiltInPartitioner(logContext, TOPIC_A, 1));
      }
  
  
      private static class SequentialPartitioner extends BuiltInPartitioner {
  
          AtomicInteger mockRandom = new AtomicInteger();
  
          public SequentialPartitioner(LogContext logContext, String topic, int stickyBatchSize) {
              super(logContext, topic, stickyBatchSize);
          }
  
          @Override
          int randomPartition() {
              return mockRandom.getAndAdd(1);
          }
      }
  }
  