001/* 002 * Copyright (c) 2007-2015 Concurrent, 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.TypeExpression; 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; 032import cascading.tap.Tap; 033 034import static cascading.flow.planner.iso.expression.OrElementExpression.or; 035 036/** 037 * 038 */ 039public class BalanceGroupSplitExpression extends RuleExpression 040 { 041 public static final FlowElementExpression SHARED_GROUP = new FlowElementExpression( Group.class ); 042 043 public BalanceGroupSplitExpression() 044 { 045 super( 046 new SyncPipeExpressionGraph(), 047 048 // in order to capture out degree in sub-graph, we need to capture at least two successors 049 new ExpressionGraph() 050 .arcs( SHARED_GROUP, or( new FlowElementExpression( HashJoin.class ), new FlowElementExpression( Group.class ), new FlowElementExpression( Tap.class ) ) ) 051 .arcs( SHARED_GROUP, or( new FlowElementExpression( HashJoin.class ), new FlowElementExpression( Group.class ), new FlowElementExpression( Tap.class ) ) ), 052 053 // sub-graph to match has out degree captured above 054 new ExpressionGraph() 055 .arcs( 056 new FlowElementExpression( ElementCapture.Primary, Pipe.class, TypeExpression.Topo.SplitOnly ) 057 ) 058 ); 059 } 060 }