content: /*
   * 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,
   * 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 org.apache.kafka.server.policy;
  
  import org.apache.kafka.common.Configurable;
  import org.apache.kafka.common.errors.PolicyViolationException;
  
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  import java.util.Objects;
  
  /**
   * <p>An interface for enforcing a policy on create topics requests.
   *
   * <p>Common use cases are requiring that the replication factor, <code>min.insync.replicas</code> and/or retention settings for a
   * topic are within an allowable range.
   *
   * <p>If <code>create.topic.policy.class.name</code> is defined, Kafka will create an instance of the specified class
   * using the default constructor and will then pass the broker configs to its <code>configure()</code> method. During
   * broker shutdown, the <code>close()</code> method will be invoked so that resources can be released (if necessary).
   */
  public interface CreateTopicPolicy extends Configurable, AutoCloseable {
  
      /**
       * Class containing the create request parameters.
       */
      class RequestMetadata {
          private final String topic;
          private final Integer numPartitions;
          private final Short replicationFactor;
          private final Map<Integer, List<Integer>> replicasAssignments;
          private final Map<String, String> configs;
  
          /**
           * Create an instance of this class with the provided parameters.
           *
           * This constructor is public to make testing of <code>CreateTopicPolicy</code> implementations easier.
           *
           * @param topic the name of the topic to create.
           * @param numPartitions the number of partitions to create or null if replicasAssignments is set.
           * @param replicationFactor the replication factor for the topic or null if replicaAssignments is set.
           * @param replicasAssignments replica assignments or null if numPartitions and replicationFactor is set. The
           *                            assignment is a map from partition id to replica (broker) ids.
           * @param configs topic configs for the topic to be created, not including broker defaults. Broker configs are
           *                passed via the {@code configure()} method of the policy implementation.
           */
          public RequestMetadata(String topic, Integer numPartitions, Short replicationFactor,
                          Map<Integer, List<Integer>> replicasAssignments, Map<String, String> configs) {
              this.topic = topic;
              this.numPartitions = numPartitions;
              this.replicationFactor = replicationFactor;
              this.replicasAssignments = replicasAssignments == null ? null : Collections.unmodifiableMap(replicasAssignments);
              this.configs = Collections.unmodifiableMap(configs);
          }
  
          /**
           * Return the name of the topic to create.
           */
          public String topic() {
              return topic;
          }
  
          /**
           * Return the number of partitions to create or null if replicaAssignments is not null.
           */
          public Integer numPartitions() {
              return numPartitions;
          }
  
          /**
           * Return the number of replicas to create or null if replicaAssignments is not null.
           */
          public Short replicationFactor() {
              return replicationFactor;
          }
  
          /**
           * Return a map from partition id to replica (broker) ids or null if numPartitions and replicationFactor are
           * set instead.
           */
          public Map<Integer, List<Integer>> replicasAssignments() {
              return replicasAssignments;
          }
  
          /**
           * Return topic configs in the request, not including broker defaults. Broker configs are passed via
           * the {@code configure()} method of the policy implementation.
           */
          public Map<String, String> configs() {
              return configs;
          }
  
          @Override
          public int hashCode() {
              return Objects.hash(topic, numPartitions, replicationFactor,
                  replicasAssignments, configs);
          }
  
          @Override
          public boolean equals(Object o) {
              if (this == o) return true;
              if (o == null || getClass() != o.getClass()) return false;
              RequestMetadata other = (RequestMetadata) o;
              return topic.equals(other.topic) &&
                  Objects.equals(numPartitions, other.numPartitions) &&
                  Objects.equals(replicationFactor, other.replicationFactor) &&
                  Objects.equals(replicasAssignments, other.replicasAssignments) &&
                  configs.equals(other.configs);
          }
  
          @Override
          public String toString() {
              return "CreateTopicPolicy.RequestMetadata(topic=" + topic +
                      ", numPartitions=" + numPartitions +
                      ", replicationFactor=" + replicationFactor +
                      ", replicasAssignments=" + replicasAssignments +
                      ", configs=" + configs + ")";
          }
      }
  
      /**
       * Validate the request parameters and throw a <code>PolicyViolationException</code> with a suitable error
       * message if the create topics request parameters for the provided topic do not satisfy this policy.
       *
       * Clients will receive the POLICY_VIOLATION error code along with the exception's message. Note that validation
       * failure only affects the relevant topic, other topics in the request will still be processed.
       *
       * @param requestMetadata the create topics request parameters for the provided topic.
       * @throws PolicyViolationException if the request parameters do not satisfy this policy.
       */
      void validate(RequestMetadata requestMetadata) throws PolicyViolationException;
  }
  