text: /**
   * 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.pulsar.zookeeper;
  
  import static com.google.common.base.Preconditions.checkArgument;
  
  import java.io.IOException;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  import java.util.concurrent.CompletableFuture;
  
  import org.apache.zookeeper.KeeperException;
  import org.apache.zookeeper.Watcher.Event;
  import org.apache.zookeeper.ZooKeeper;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  public class ZookeeperClientFactoryImpl implements ZooKeeperClientFactory {
      public static final Charset ENCODING_SCHEME = StandardCharsets.UTF_8;
  
      @Override
      public CompletableFuture<ZooKeeper> create(String serverList, SessionType sessionType, int zkSessionTimeoutMillis) {
          // Create a normal ZK client
          boolean canBeReadOnly = sessionType == SessionType.AllowReadOnly;
  
          CompletableFuture<ZooKeeper> future = new CompletableFuture<>();
          try {
              CompletableFuture<Void> internalFuture = new CompletableFuture<>();
  
              ZooKeeper zk = new ZooKeeper(serverList, zkSessionTimeoutMillis, event -> {
                  if (event.getType() == Event.EventType.None) {
                      switch (event.getState()) {
  
                      case ConnectedReadOnly:
                          checkArgument(canBeReadOnly);
                          // Fall through
                      case SyncConnected:
                          // ZK session is ready to use
                          internalFuture.complete(null);
                          break;
  
                      case Expired:
                          internalFuture
                                  .completeExceptionally(KeeperException.create(KeeperException.Code.SESSIONEXPIRED));
                          break;
  
                      default:
                          log.warn("Unexpected ZK event received: {}", event);
                          break;
                      }
                  }
              }, canBeReadOnly);
  
              internalFuture.thenRun(() -> {
                  log.info("ZooKeeper session established: {}", zk);
                  future.complete(zk);
              }).exceptionally((exception) -> {
                  log.error("Failed to establish ZooKeeper session: {}", exception.getMessage());
                  future.completeExceptionally(exception);
                  return null;
              });
  
          } catch (IllegalArgumentException | IOException e) {
              future.completeExceptionally(e);
          }
  
          return future;
      }
  
      private static final Logger log = LoggerFactory.getLogger(ZookeeperClientFactoryImpl.class);
  }
  