FileIteratingFirehose.java

/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  Metamarkets 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 io.druid.data.input.impl;

import com.google.common.base.Throwables;
import io.druid.data.input.Firehose;
import io.druid.data.input.InputRow;
import io.druid.utils.Runnables;
import org.apache.commons.io.LineIterator;

import java.io.IOException;
import java.util.Iterator;

/**
 */
public class FileIteratingFirehose implements Firehose
{
  private final Iterator<LineIterator> lineIterators;
  private final StringInputRowParser parser;

  private LineIterator lineIterator = null;

  public FileIteratingFirehose(
      Iterator<LineIterator> lineIterators,
      StringInputRowParser parser
  )
  {
    this.lineIterators = lineIterators;
    this.parser = parser;
  }

  @Override
  public boolean hasMore()
  {
    while ((lineIterator == null || !lineIterator.hasNext()) && lineIterators.hasNext()) {
      lineIterator = lineIterators.next();
    }

    return lineIterator != null && lineIterator.hasNext();
  }

  @Override
  public InputRow nextRow()
  {
    try {
      if (lineIterator == null || !lineIterator.hasNext()) {
        // Close old streams, maybe.
        if (lineIterator != null) {
          lineIterator.close();
        }

        lineIterator = lineIterators.next();
      }

      return parser.parse(lineIterator.next());
    }
    catch (Exception e) {
      throw Throwables.propagate(e);
    }
  }

  @Override
  public Runnable commit()
  {
    return Runnables.getNoopRunnable();
  }

  @Override
  public void close() throws IOException
  {
    if (lineIterator != null) {
      lineIterator.close();
    }
  }
}