| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.hadoop.mapreduce.lib.join; |
| |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.Iterator; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.io.Writable; |
| import org.apache.hadoop.io.WritableUtils; |
| import org.apache.hadoop.util.ReflectionUtils; |
| |
| /** |
| * This class provides an implementation of ResetableIterator. The |
| * implementation uses an {@link java.util.ArrayList} to store elements |
| * added to it, replaying them as requested. |
| * Prefer {@link StreamBackedIterator}. |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public class ArrayListBackedIterator<X extends Writable> |
| implements ResetableIterator<X> { |
| |
| private Iterator<X> iter; |
| private ArrayList<X> data; |
| private X hold = null; |
| private Configuration conf = new Configuration(); |
| |
| public ArrayListBackedIterator() { |
| this(new ArrayList<X>()); |
| } |
| |
| public ArrayListBackedIterator(ArrayList<X> data) { |
| this.data = data; |
| this.iter = this.data.iterator(); |
| } |
| |
| public boolean hasNext() { |
| return iter.hasNext(); |
| } |
| |
| public boolean next(X val) throws IOException { |
| if (iter.hasNext()) { |
| ReflectionUtils.copy(conf, iter.next(), val); |
| if (null == hold) { |
| hold = WritableUtils.clone(val, null); |
| } else { |
| ReflectionUtils.copy(conf, val, hold); |
| } |
| return true; |
| } |
| return false; |
| } |
| |
| public boolean replay(X val) throws IOException { |
| ReflectionUtils.copy(conf, hold, val); |
| return true; |
| } |
| |
| public void reset() { |
| iter = data.iterator(); |
| } |
| |
| public void add(X item) throws IOException { |
| data.add(WritableUtils.clone(item, null)); |
| } |
| |
| public void close() throws IOException { |
| iter = null; |
| data = null; |
| } |
| |
| public void clear() { |
| data.clear(); |
| reset(); |
| } |
| } |