001/* 002 * Copyright (c) 2016 Chris K Wensel <chris@wensel.net>. All Rights Reserved. 003 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved. 004 * 005 * Project and contact information: http://www.cascading.org/ 006 * 007 * This file is part of the Cascading project. 008 * 009 * Licensed under the Apache License, Version 2.0 (the "License"); 010 * you may not use this file except in compliance with the License. 011 * You may obtain a copy of the License at 012 * 013 * http://www.apache.org/licenses/LICENSE-2.0 014 * 015 * Unless required by applicable law or agreed to in writing, software 016 * distributed under the License is distributed on an "AS IS" BASIS, 017 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 018 * See the License for the specific language governing permissions and 019 * limitations under the License. 020 */ 021 022package cascading.flow.stream.duct; 023 024import java.util.Iterator; 025 026/** 027 * 028 */ 029public class OpenReducingDuct<Incoming, Outgoing> extends Duct<Grouping<Incoming, Iterator<Incoming>>, Outgoing> implements OpenWindow 030 { 031 final Reducing reducing; 032 033 public OpenReducingDuct( Duct<Outgoing, ?> next ) 034 { 035 super( next ); 036 037 reducing = (Reducing) getNext(); 038 } 039 040 @Override 041 public void receive( Duct previous, int ordinal, Grouping<Incoming, Iterator<Incoming>> grouping ) 042 { 043 // don't start a grouping if there are no values in the group 044 if( !grouping.joinIterator.hasNext() ) 045 return; 046 047 reducing.startGroup( previous, grouping.key ); 048 049 while( grouping.joinIterator.hasNext() ) 050 next.receive( this, 0, (Outgoing) grouping.joinIterator.next() ); 051 052 reducing.completeGroup( previous, grouping.key ); 053 } 054 }