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