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.cassandra.dht;
  
  import java.util.HashSet;
  import java.util.Set;
  
  import org.apache.cassandra.config.DatabaseDescriptor;
  import org.apache.cassandra.tcm.ClusterMetadata;
  
  public class Datacenters
  {
      private static class DCHandle
      {
          private static final String thisDc = DatabaseDescriptor.getLocator().local().datacenter;
      }
  
      public static String thisDatacenter()
      {
          return DCHandle.thisDc;
      }
  
      /*
       * (non-javadoc) Method to generate list of valid data center names to be used to validate the replication parameters during CREATE / ALTER keyspace operations.
       * @return a set of valid DC names
       */
      public static Set<String> getValidDatacenters(ClusterMetadata metadata)
      {
          final Set<String> validDataCenters = new HashSet<>();
          // Add data center of localhost.
          validDataCenters.add(thisDatacenter());
          // Fetch and add DCs of all peers.
          validDataCenters.addAll(metadata.directory.knownDatacenters());
          return validDataCenters;
      }
  }
  