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.bookkeeper.metadata.etcd;
  
  import java.util.Optional;
  import java.util.concurrent.ScheduledExecutorService;
  import lombok.extern.slf4j.Slf4j;
  import org.apache.bookkeeper.conf.ClientConfiguration;
  import org.apache.bookkeeper.discover.RegistrationClient;
  import org.apache.bookkeeper.meta.MetadataClientDriver;
  import org.apache.bookkeeper.meta.MetadataDrivers;
  import org.apache.bookkeeper.meta.exceptions.MetadataException;
  import org.apache.bookkeeper.stats.StatsLogger;
  
  /**
   * Etcd based metadata client driver.
   */
  @Slf4j
  public class EtcdMetadataClientDriver extends EtcdMetadataDriverBase implements MetadataClientDriver {
  
      // register myself to driver manager
      static {
          MetadataDrivers.registerClientDriver(
              SCHEME, EtcdMetadataClientDriver.class);
          log.info("Registered etcd metadata client driver.");
      }
  
      ClientConfiguration conf;
      ScheduledExecutorService scheduler;
      RegistrationClient regClient;
  
      @Override
      public MetadataClientDriver initialize(ClientConfiguration conf,
                                             ScheduledExecutorService scheduler,
                                             StatsLogger statsLogger,
                                             Optional<Object> ctx)
              throws MetadataException {
          super.initialize(conf, statsLogger);
          this.conf = conf;
          this.statsLogger = statsLogger;
          return this;
      }
  
      @Override
      public synchronized RegistrationClient getRegistrationClient() {
          if (null == regClient) {
              regClient = new EtcdRegistrationClient(keyPrefix, client);
          }
          return regClient;
      }
  
      @Override
      public synchronized void close() {
          if (null != regClient) {
              regClient.close();
              regClient = null;
          }
          super.close();
      }
  
      @Override
      public void setSessionStateListener(SessionStateListener sessionStateListener) {
          /*
           * TODO: EtcdMetadataClientDriver has to implement this method.
           */
          throw new UnsupportedOperationException();
      }
  }
  