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.config.ConfigResource;
  import org.apache.kafka.common.errors.PolicyViolationException;
  
  import java.util.Map;
  import java.util.Objects;
  
  /**
   * <p>An interface for enforcing a policy on alter configs requests.
   *
   * <p>Common use cases are requiring that the replication factor, <code>min.insync.replicas</code> and/or retention settings for a
   * topic remain within an allowable range.
   *
   * <p>If <code>alter.config.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 AlterConfigPolicy extends Configurable, AutoCloseable {
  
      /**
       * Class containing the create request parameters.
       */
      class RequestMetadata {
  
          private final ConfigResource resource;
          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>AlterConfigPolicy</code> implementations easier.
           */
          public RequestMetadata(ConfigResource resource, Map<String, String> configs) {
              this.resource = resource;
              this.configs = configs;
          }
  
          /**
           * Return the configs in the request.
           */
          public Map<String, String> configs() {
              return configs;
          }
  
          public ConfigResource resource() {
              return resource;
          }
  
          @Override
          public int hashCode() {
              return Objects.hash(resource, configs);
          }
  
          @Override
          public boolean equals(Object o) {
              if ((o == null) || (!o.getClass().equals(getClass()))) return false;
              RequestMetadata other = (RequestMetadata) o;
              return resource.equals(other.resource) &&
                  configs.equals(other.configs);
          }
  
          @Override
          public String toString() {
              return "AlterConfigPolicy.RequestMetadata(resource=" + resource +
                      ", configs=" + configs + ")";
          }
      }
  
      /**
       * Validate the request parameters and throw a <code>PolicyViolationException</code> with a suitable error
       * message if the alter configs request parameters for the provided resource 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 resource, other resources in the request will still be processed.
       *
       * @param requestMetadata the alter configs request parameters for the provided resource (topic is the only resource
       *                        type whose configs can be updated currently).
       * @throws PolicyViolationException if the request parameters do not satisfy this policy.
       */
      void validate(RequestMetadata requestMetadata) throws PolicyViolationException;
  }
  