core/org.eclipse.smila.importing.compounds.compress/code/src/org/eclipse/smila/importing/compounds/compress/AttachmentSettingIterator.java

/*********************************************************************************************************************
 * Copyright (c) 2008, 2013 Empolis Information Management GmbH and brox IT Solutions GmbH. All rights reserved.
 * This program and the accompanying materials are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at http://www.eclipse.org/legal/epl-v10.html
 *********************************************************************************************************************/
package org.eclipse.smila.importing.compounds.compress;

import static org.eclipse.smila.importing.compounds.compress.CommonsCompressCompoundExtractorService.KEY_TMP_FILE_NAME;

import java.io.File;
import java.io.IOException;
import java.nio.file.Path;
import java.util.Iterator;
import java.util.List;

import org.apache.commons.io.FileUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.eclipse.smila.datamodel.Record;

/**
 * Iterator on given record list, that attaches an attachment from a file in tmpDir. Name of attachment file must be
 * stored in each record as attribute {@link CommonsCompressCompoundExtractorService#KEY_TMP_FILE_NAME}. The records are
 * removed from the list after returned by next() in order to save memory.
 */
public final class AttachmentSettingIterator implements Iterator<Record> {
  /** log. */
  private final Log _log = LogFactory.getLog(CommonsCompressCompoundExtractorService.class);

  private final String _contentAttachmentName;

  private final List<Record> _records;

  private final Path _tmpDir;

  private int _index;

  /**
   * create instance.
   * 
   * @param records
   *          list of records
   * @param contentAttachmentName
   *          name of attachment to use
   * @param tmpDir
   *          directory in which the attachment files are stored.
   */
  public AttachmentSettingIterator(final List<Record> records, final String contentAttachmentName, final Path tmpDir) {
    _contentAttachmentName = contentAttachmentName;
    _records = records;
    _tmpDir = tmpDir;
  }

  /** {@inheritDoc} */
  @Override
  public boolean hasNext() {
    return _index < _records.size();
  }

  /** {@inheritDoc} */
  @Override
  public Record next() {
    final Record record = _records.set(_index, null);
    _index++;
    if (record != null && record.getMetadata().containsKey(KEY_TMP_FILE_NAME)) {
      final File file = new File(record.getMetadata().getStringValue(KEY_TMP_FILE_NAME));
      try {
        record.setAttachment(_contentAttachmentName, FileUtils.readFileToByteArray(file));
      } catch (final IOException e) {
        _log.warn("Cannot access temporary extracted file '" + file.getAbsolutePath() + "'.", e);
      }
      if (!file.delete()) {
        file.deleteOnExit();
      }
    }
    if (!hasNext()) {
      try {
        FileUtils.deleteDirectory(_tmpDir.toFile());
      } catch (final IOException e) {
        _log.warn("Could not remove temporary directory '" + _tmpDir.toAbsolutePath().toString() + "'.");
      }
    }
    return record;
  }

  /**
   * {@inheritDoc}. Yes, I know what you're thinking. And you're right. But the files should be discarded... At least if
   * we have the chance to do so. On system start the rest is eliminated (e.g. if the JRE had been killed or the files
   * could not be deleted, etc.)
   */
  @Override
  protected void finalize() {
    try {
      if (hasNext()) {
        FileUtils.deleteDirectory(_tmpDir.toFile());
      }
    } catch (final IOException e) {
      _log.warn("Could not remove temporary directory '" + _tmpDir.toAbsolutePath().toString() + "'.");
    }
    try {
      super.finalize();
    } catch (final Throwable t) {
      _log.warn("Error while cleaning up iterator. ", t);
    }
  }

  /** {@inheritDoc} */
  @Override
  public void remove() {
    throw new UnsupportedOperationException();
  }
}