001/*
002 * Copyright (c) 2016 Chris K Wensel <chris@wensel.net>. 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.ElementExpression;
025import cascading.flow.planner.iso.expression.ExpressionGraph;
026import cascading.flow.planner.iso.expression.FlowElementExpression;
027import cascading.flow.planner.iso.expression.ScopeExpression;
028import cascading.flow.planner.iso.expression.TypeExpression.Topo;
029import cascading.flow.planner.rule.RuleExpression;
030import cascading.flow.planner.rule.expressiongraph.SyncPipeExpressionGraph;
031import cascading.pipe.Checkpoint;
032import cascading.pipe.Group;
033import cascading.pipe.HashJoin;
034import cascading.pipe.Pipe;
035import cascading.tap.Tap;
036
037import static cascading.flow.planner.iso.expression.OrElementExpression.or;
038
039/**
040 *
041 */
042public class BalanceGroupSplitTriangleExpression extends RuleExpression
043  {
044  public static final FlowElementExpression SHARED_GROUP = new FlowElementExpression( Group.class, Topo.Split );
045  public static final ElementExpression SHARED_LHS = or( new FlowElementExpression( HashJoin.class ), new FlowElementExpression( Group.class ), new FlowElementExpression( Tap.class ), new FlowElementExpression( Checkpoint.class ) );
046  public static final ElementExpression SHARED_RHS = or( new FlowElementExpression( HashJoin.class ), new FlowElementExpression( Group.class ), new FlowElementExpression( Tap.class ), new FlowElementExpression( Checkpoint.class ) );
047
048  public BalanceGroupSplitTriangleExpression()
049    {
050    super(
051      new SyncPipeExpressionGraph(),
052
053      new ExpressionGraph()
054        .arc(
055          SHARED_GROUP,
056          ScopeExpression.ANY,
057          SHARED_LHS
058        )
059
060        .arc(
061          SHARED_GROUP,
062          ScopeExpression.ANY,
063          SHARED_RHS
064        )
065
066        .arc(
067          SHARED_LHS,
068          ScopeExpression.ANY,
069          SHARED_RHS
070        ),
071
072      // sub-graph to match has out degree captured above
073      new ExpressionGraph()
074        .arcs(
075          new FlowElementExpression( ElementCapture.Primary, Pipe.class, Topo.SplitOnly )
076        )
077    );
078    }
079  }