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 java.io.IOException;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.cassandra.exceptions.ConfigurationException;
  import org.apache.cassandra.tcm.membership.Location;
  
  import static java.lang.String.format;
  
  public class CloudMetadataLocationProvider implements InitialLocationProvider
  {
      static final Logger logger = LoggerFactory.getLogger(CloudMetadataLocationProvider.class);
  
      protected final AbstractCloudMetadataServiceConnector connector;
      private final LocationResolver locationResolver;
      private volatile Location location;
  
      public CloudMetadataLocationProvider(AbstractCloudMetadataServiceConnector connector, LocationResolver locationResolver)
      {
          this.connector = connector;
          this.locationResolver = locationResolver;
      }
  
      @Override
      public final Location initialLocation()
      {
          if (location == null)
          {
              try
              {
                  location = locationResolver.resolve(connector);
                  logger.info(format("%s using datacenter: %s, rack: %s, connector: %s, properties: %s",
                                     getClass().getName(), location.datacenter, location.rack, connector, connector.getProperties()));
              }
              catch (IOException e)
              {
                  throw new ConfigurationException("Unable to resolve initial location using cloud metadata service connector", e);
              }
          }
          return location;
      }
  
      public interface LocationResolver
      {
          Location resolve(AbstractCloudMetadataServiceConnector connector) throws IOException;
      }
  }
  