001/*
002 * Copyright (c) 2016-2017 Chris K Wensel <chris@wensel.net>. All Rights Reserved.
003 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved.
004 *
005 * Project and contact information: http://www.cascading.org/
006 *
007 * This file is part of the Cascading project.
008 *
009 * Licensed under the Apache License, Version 2.0 (the "License");
010 * you may not use this file except in compliance with the License.
011 * You may obtain a copy of the License at
012 *
013 *     http://www.apache.org/licenses/LICENSE-2.0
014 *
015 * Unless required by applicable law or agreed to in writing, software
016 * distributed under the License is distributed on an "AS IS" BASIS,
017 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
018 * See the License for the specific language governing permissions and
019 * limitations under the License.
020 */
021
022package cascading.tap.partition;
023
024import java.io.Serializable;
025
026import cascading.tuple.Fields;
027import cascading.tuple.TupleEntry;
028
029/**
030 * The Partition interface allows for custom partitioning mechanisms to be created with the {@link BasePartitionTap}
031 * sub-classes.
032 * <p>
033 * A partition is a directory on a filesystem, where the directory contains data related to the files underneath
034 * the partition directory.
035 * <p>
036 * For example, a partition could be {@code "2012/09/01"}, which would contain log files for that day.
037 */
038public interface Partition extends Serializable
039  {
040  /**
041   * Returns the directory search depth of the partition.
042   * <p>
043   * For example, a Partition implementation that returns values like {@code "2012/09/01"} would have a depth of 3.
044   *
045   * @return an int
046   */
047  int getPathDepth();
048
049  /**
050   * The {@link Fields} used to populate the partition.
051   *
052   * @return a Fields instance
053   */
054  Fields getPartitionFields();
055
056  /**
057   * Converts the given partition String to a {@link TupleEntry} using the given TupleEntry instance for re-use.
058   *
059   * @param partition  a String
060   * @param tupleEntry a TupleEntry
061   */
062  void toTuple( String partition, TupleEntry tupleEntry );
063
064  /**
065   * Converts the given tupleEntry into a partition string.
066   *
067   * @param tupleEntry a TupleEntry
068   * @return a String
069   */
070  String toPartition( TupleEntry tupleEntry );
071  }