com.spotify.spydra.historytools.RemoteIteratorAdaptor Maven / Gradle / Ivy

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/*-
 * -\-\-
 * Spydra
 * --
 * Copyright (C) 2016 - 2018 Spotify AB
 * --
 * Licensed 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 com.spotify.spydra.historytools;

import java.io.IOException;
import java.util.Iterator;
import org.apache.hadoop.fs.RemoteIterator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Simple adaptor for Hadoop's RemoteIterator to the Iterator interface to be able to
 * use all the nice libraries/functions around iterators.
 *
 * @param  Type of the objects this iterator yields
 */
public class RemoteIteratorAdaptor implements RemoteIterator, Iterator {

  static final Logger logger = LoggerFactory.getLogger(RemoteIteratorAdaptor.class);
  private final RemoteIterator wrappedRemoteIter;

  public RemoteIteratorAdaptor(RemoteIterator remoteIterator) {
    this.wrappedRemoteIter = remoteIterator;
  }

  @Override
  public boolean hasNext() {
    try {
      return this.wrappedRemoteIter.hasNext();
    } catch (IOException e) {
      logger.error("Remote iterator failed checking for next element in remote iterator", e);
      throw new WrappedRemoteIteratorException(e);
    }
  }

  @Override
  public T next() {
    try {
      return this.wrappedRemoteIter.next();
    } catch (IOException e) {
      logger.error("Failed retrieving next element from remote iterator", e);
      throw new WrappedRemoteIteratorException(e);
    }
  }

  public static class WrappedRemoteIteratorException extends RuntimeException {
    public WrappedRemoteIteratorException(Throwable cause) {
      super(cause);
    }
  }
}