001/** 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018 019package org.apache.hadoop.mapred.join; 020 021import org.apache.hadoop.classification.InterfaceAudience; 022import org.apache.hadoop.classification.InterfaceStability; 023import org.apache.hadoop.io.Writable; 024 025/** 026 * Writable type storing multiple {@link org.apache.hadoop.io.Writable}s. 027 * 028 * This is *not* a general-purpose tuple type. In almost all cases, users are 029 * encouraged to implement their own serializable types, which can perform 030 * better validation and provide more efficient encodings than this class is 031 * capable. TupleWritable relies on the join framework for type safety and 032 * assumes its instances will rarely be persisted, assumptions not only 033 * incompatible with, but contrary to the general case. 034 * 035 * @see org.apache.hadoop.io.Writable 036 */ 037@InterfaceAudience.Public 038@InterfaceStability.Stable 039public class TupleWritable 040 extends org.apache.hadoop.mapreduce.lib.join.TupleWritable { 041 042 /** 043 * Create an empty tuple with no allocated storage for writables. 044 */ 045 public TupleWritable() { 046 super(); 047 } 048 049 /** 050 * Initialize tuple with storage; unknown whether any of them contain 051 * "written" values. 052 */ 053 public TupleWritable(Writable[] vals) { 054 super(vals); 055 } 056 057 /** 058 * Record that the tuple contains an element at the position provided. 059 */ 060 void setWritten(int i) { 061 written.set(i); 062 } 063 064 /** 065 * Record that the tuple does not contain an element at the position 066 * provided. 067 */ 068 void clearWritten(int i) { 069 written.clear(i); 070 } 071 072 /** 073 * Clear any record of which writables have been written to, without 074 * releasing storage. 075 */ 076 void clearWritten() { 077 written.clear(); 078 } 079 080 081}