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.locator;
  
  import org.apache.cassandra.exceptions.ConfigurationException;
  import org.apache.cassandra.tcm.membership.Location;
  
  /**
   * Emulates the previous behaviour of GossipingPropertyFileSnitch; reads cassandra-rackdc.properties
   * to identify the local datacenter and rack for one time use during node registration.
   *
   * Based on a properties file in the following format:
   *
   * dc=DC1
   * rack=RAC1
   */
  public class RackDCFileLocationProvider implements InitialLocationProvider
  {
      private final Location local;
      private static final Location DEFAULT = new Location("UNKNOWN_DC", "UNKNOWN_RACK");
  
      /**
       * Used via reflection by DatabaseDescriptor::createInitialLocationProvider
       */
      public RackDCFileLocationProvider()
      {
          this(loadConfiguration());
      }
  
      /**
       * Used in legacy compatibility mode by GossipingPropertyFileSnitch
       * @param properties
       */
      RackDCFileLocationProvider(SnitchProperties properties)
      {
          local = new Location(properties.get("dc", DEFAULT.datacenter).trim(),
                               properties.get("rack", DEFAULT.rack).trim());
      }
  
      @Override
      public Location initialLocation()
      {
          return local;
      }
  
      public static SnitchProperties loadConfiguration() throws ConfigurationException
      {
          final SnitchProperties properties = new SnitchProperties();
          if (!properties.contains("dc") || !properties.contains("rack"))
              throw new ConfigurationException("DC or rack not found in snitch properties, check your configuration in: " + SnitchProperties.RACKDC_PROPERTY_FILENAME);
  
          return properties;
      }
  
  
  }
  