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.distributedlog.impl.metadata;
  
  import java.io.IOException;
  import java.net.URI;
  import org.apache.commons.lang3.StringUtils;
  import org.apache.distributedlog.ZooKeeperClient;
  import org.apache.distributedlog.metadata.DLMetadata;
  import org.apache.distributedlog.metadata.MetadataResolver;
  import org.apache.zookeeper.KeeperException;
  import org.apache.zookeeper.common.PathUtils;
  import org.apache.zookeeper.data.Stat;
  
  
  /**
   * zookeeper metadata resolver.
   */
  public class ZkMetadataResolver implements MetadataResolver {
  
      private final ZooKeeperClient zkc;
  
      public ZkMetadataResolver(ZooKeeperClient zkc) {
          this.zkc = zkc;
      }
  
      @Override
      public DLMetadata resolve(URI uri) throws IOException {
          String dlPath = uri.getPath();
          PathUtils.validatePath(dlPath);
          // Normal case the dl metadata is stored in the last segment
          // so lookup last segment first.
          String[] parts = StringUtils.split(dlPath, '/');
          if (null == parts || 0 == parts.length) {
              throw new IOException("Invalid dlPath to resolve dl metadata : " + dlPath);
          }
          for (int i = parts.length; i >= 0; i--) {
              String pathToResolve = String.format("/%s", StringUtils.join(parts, '/', 0, i));
              byte[] data;
              try {
                  data = zkc.get().getData(pathToResolve, false, new Stat());
              } catch (KeeperException.NoNodeException nne) {
                  continue;
              } catch (KeeperException ke) {
                  throw new IOException("Fail to resolve dl path : " + pathToResolve);
              } catch (InterruptedException ie) {
                  Thread.currentThread().interrupt();
                  throw new IOException("Interrupted when resolving dl path : " + pathToResolve);
              }
              if (null == data || data.length == 0) {
                  continue;
              }
              try {
                  return DLMetadata.deserialize(uri, data);
              } catch (IOException ie) {
                  throw new IOException("Failed to deserialize uri : " + uri);
              }
          }
          throw new IOException("No bkdl config bound under dl path : " + dlPath);
      }
  }
  