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.meta.zk;
  
  import com.google.common.annotations.VisibleForTesting;
  import java.util.Optional;
  import java.util.concurrent.CompletableFuture;
  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.discover.ZKRegistrationClient;
  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;
  import org.apache.bookkeeper.zookeeper.BoundExponentialBackoffRetryPolicy;
  import org.apache.zookeeper.Watcher.Event.EventType;
  import org.apache.zookeeper.Watcher.Event.KeeperState;
  import org.apache.zookeeper.ZooKeeper;
  
  /**
   * ZooKeeper based metadata client driver.
   */
  @Slf4j
  public class ZKMetadataClientDriver
      extends ZKMetadataDriverBase
      implements MetadataClientDriver {
  
      // register myself to driver manager
      static {
          MetadataDrivers.registerClientDriver(
              SCHEME, ZKMetadataClientDriver.class);
      }
  
      ClientConfiguration clientConf;
      ScheduledExecutorService scheduler;
      RegistrationClient regClient;
      boolean bookieAddressTracking = true;
  
      @Override
      public synchronized MetadataClientDriver initialize(ClientConfiguration conf,
                                                          ScheduledExecutorService scheduler,
                                                          StatsLogger statsLogger,
  
                                                          Optional<Object> optionalCtx)
              throws MetadataException {
          super.initialize(
              conf,
              statsLogger,
              new BoundExponentialBackoffRetryPolicy(
                  conf.getZkTimeout(),
                  conf.getZkTimeout(),
                  conf.getZkRetryBackoffMaxRetries()),
              optionalCtx);
          this.statsLogger = statsLogger;
          this.clientConf = conf;
          this.scheduler = scheduler;
          this.bookieAddressTracking = conf.getEnableBookieAddressTracking();
          return this;
      }
  
      @Override
      public synchronized RegistrationClient getRegistrationClient() {
          if (null == regClient) {
              regClient = newZKRegistrationClient(
                      zk,
                      ledgersRootPath,
                      scheduler,
                      bookieAddressTracking);
          }
          return regClient;
      }
  
      @VisibleForTesting
      ZKRegistrationClient newZKRegistrationClient(ZooKeeper zk, String ledgersRootPath,
                                                   ScheduledExecutorService scheduler, boolean bookieAddressTracking) {
          return new ZKRegistrationClient(zk, ledgersRootPath, scheduler, bookieAddressTracking);
      }
  
      @Override
      public synchronized void close() {
          if (null != regClient) {
              regClient.close();
              regClient = null;
          }
          super.close();
      }
  
      @Override
      public void setSessionStateListener(SessionStateListener sessionStateListener) {
          zk.register((event) -> {
              // Check for expired connection.
              if (event.getType().equals(EventType.None) && event.getState().equals(KeeperState.Expired)) {
                  sessionStateListener.onSessionExpired();
              }
          });
      }
  
      public CompletableFuture<Boolean> isMetadataServiceAvailable() {
          return CompletableFuture.completedFuture(metadataServiceAvailable);
      }
  }
  