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.flow.hadoop.planner.rule.expression; 022 023import cascading.flow.planner.iso.expression.ElementCapture; 024import cascading.flow.planner.iso.expression.ExpressionGraph; 025import cascading.flow.planner.iso.expression.FlowElementExpression; 026import cascading.flow.planner.iso.expression.PathScopeExpression; 027import cascading.flow.planner.rule.RuleExpression; 028import cascading.flow.planner.rule.expressiongraph.SyncPipeExpressionGraph; 029import cascading.pipe.Group; 030import cascading.pipe.HashJoin; 031import cascading.pipe.Pipe; 032 033/** 034 * This rule is a compliment to GroupNonBlockingHashJoinTransformRule and is intended 035 * to prevent a HashJoin from landing in a Reducer until reduce side HashJoins are supported. 036 */ 037public class BalanceGroupNonBlockingHashJoinExpression extends RuleExpression 038 { 039 public BalanceGroupNonBlockingHashJoinExpression() 040 { 041 super( 042 new SyncPipeExpressionGraph(), 043 044 new ExpressionGraph() 045 .arc( 046 new FlowElementExpression( Group.class ), 047 PathScopeExpression.NON_BLOCKING, 048 new FlowElementExpression( HashJoin.class ) 049 ), 050 051 new ExpressionGraph() 052 .arc( 053 new FlowElementExpression( ElementCapture.Primary, Pipe.class ), 054 PathScopeExpression.NON_BLOCKING, 055 new FlowElementExpression( HashJoin.class ) 056 ) 057 ); 058 } 059 }