| /* |
| * 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.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators; |
| |
| import java.io.IOException; |
| import java.util.Iterator; |
| |
| import org.apache.pig.data.Tuple; |
| |
| /** |
| * This interface is used during Reduce phrase to process tuples |
| * in batch mode. It is used by POPackage when all of the UDFs can be |
| * called in accumulative mode. Tuples are not pulled all at once, |
| * instead, each time, only a specified number of tuples are pulled out |
| * of iterator and put in an buffer. Then this buffer is wrapped into |
| * a bag to be passed to the operators in reduce plan. |
| * |
| * The purpose of doing this is to reduce memory usage and avoid spilling. |
| */ |
| public interface AccumulativeTupleBuffer { |
| |
| /** |
| * Pull next batch of tuples from iterator and put them into this buffer |
| */ |
| public void nextBatch() throws IOException; |
| |
| /** |
| * Whether there are more tuples to pull out of iterator |
| */ |
| public boolean hasNextBatch() ; |
| |
| /** |
| * Clear internal buffer, this should be called after all data are retreived |
| */ |
| public void clear(); |
| |
| /** |
| * Get iterator of tuples in the buffer |
| * @param index the index of tuple |
| */ |
| public Iterator<Tuple> getTuples(int index); |
| } |