001/*
002 * Copyright (c) 2007-2017 Xplenty, 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.hadoop;
022
023import java.beans.ConstructorProperties;
024import java.io.IOException;
025
026import cascading.scheme.Scheme;
027import cascading.tap.SinkMode;
028import cascading.tap.TapException;
029import org.apache.hadoop.conf.Configuration;
030import org.apache.hadoop.fs.FileSystem;
031
032/**
033 * Class Lfs is a {@link cascading.tap.Tap} class that provides access to the Local File System via Hadoop.
034 * <p/>
035 * Note that using a Lfs {@link cascading.tap.Tap} instance in a {@link cascading.flow.Flow} will force a portion of not the whole Flow to be executed
036 * in "local" mode forcing the Flow to execute in the current JVM. Mixing with {@link cascading.tap.hadoop.Dfs} and other Tap
037 * types is possible, providing a means to implement complex file/data management functions.
038 * <p/>
039 * Use {@link cascading.tap.hadoop.Hfs} if you need a Tap instance that inherits the default {@link FileSystem} used by Hadoop.
040 */
041public class Lfs extends Hfs
042  {
043  @ConstructorProperties({"scheme"})
044  Lfs( Scheme scheme )
045    {
046    super( scheme );
047    }
048
049  /**
050   * Constructor Lfs creates a new Lfs instance.
051   *
052   * @param scheme     of type Scheme
053   * @param stringPath of type String
054   */
055  @ConstructorProperties({"scheme", "stringPath"})
056  public Lfs( Scheme scheme, String stringPath )
057    {
058    super( scheme, stringPath );
059    }
060
061  /**
062   * Constructor Lfs creates a new Lfs instance.
063   *
064   * @param scheme     of type Scheme
065   * @param stringPath of type String
066   * @param sinkMode   of type SinkMode
067   */
068  @ConstructorProperties({"scheme", "stringPath", "sinkMode"})
069  public Lfs( Scheme scheme, String stringPath, SinkMode sinkMode )
070    {
071    super( scheme, stringPath, sinkMode );
072    }
073
074  protected void setStringPath( String stringPath )
075    {
076    if( stringPath.matches( ".*://.*" ) && !stringPath.startsWith( "file://" ) )
077      throw new IllegalArgumentException( "uri must use the file scheme" );
078
079    super.setStringPath( stringPath );
080    }
081
082  @Override
083  protected FileSystem getFileSystem( Configuration conf )
084    {
085    try
086      {
087      return FileSystem.getLocal( conf );
088      }
089    catch( IOException exception )
090      {
091      throw new TapException( "unable to get handle to get local filesystem", exception );
092      }
093    }
094  }