001/* 002 * Copyright (c) 2007-2016 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.Checkpoint; 030import cascading.pipe.Group; 031import cascading.pipe.HashJoin; 032import cascading.pipe.Pipe; 033import cascading.tap.Tap; 034 035import static cascading.flow.planner.iso.expression.OrElementExpression.or; 036 037/** 038 * 039 */ 040public class BalanceGroupSplitExpression extends RuleExpression 041 { 042 public static final FlowElementExpression SHARED_GROUP = new FlowElementExpression( Group.class ); 043 044 public BalanceGroupSplitExpression() 045 { 046 super( 047 new SyncPipeExpressionGraph(), 048 049 // in order to capture out degree in sub-graph, we need to capture at least two successors 050 new ExpressionGraph() 051 .arcs( SHARED_GROUP, or( new FlowElementExpression( HashJoin.class ), new FlowElementExpression( Group.class ), new FlowElementExpression( Tap.class ), new FlowElementExpression( Checkpoint.class ) ) ) 052 .arcs( SHARED_GROUP, or( new FlowElementExpression( HashJoin.class ), new FlowElementExpression( Group.class ), new FlowElementExpression( Tap.class ), new FlowElementExpression( Checkpoint.class ) ) ), 053 054 // sub-graph to match has out degree captured above 055 new ExpressionGraph() 056 .arcs( 057 new FlowElementExpression( ElementCapture.Primary, Pipe.class, TypeExpression.Topo.SplitOnly ) 058 ) 059 ); 060 } 061 }