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.hadoop.planner.rule.expression;
023
024import cascading.flow.planner.iso.expression.ElementCapture;
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 BalanceGroupSplitExpression extends RuleExpression
043  {
044  public static final FlowElementExpression SHARED_GROUP = new FlowElementExpression( Group.class, Topo.Split );
045
046  public BalanceGroupSplitExpression()
047    {
048    super(
049      new SyncPipeExpressionGraph(),
050
051      // in order to capture out degree in sub-graph, we need to capture at least two successors
052      new ExpressionGraph()
053        .arc(
054          SHARED_GROUP,
055          ScopeExpression.ANY,
056          or( new FlowElementExpression( HashJoin.class ), new FlowElementExpression( Group.class ), new FlowElementExpression( Tap.class ), new FlowElementExpression( Checkpoint.class ) )
057        )
058
059        .arc(
060          SHARED_GROUP,
061          ScopeExpression.ANY,
062          or( new FlowElementExpression( HashJoin.class ), new FlowElementExpression( Group.class ), new FlowElementExpression( Tap.class ), new FlowElementExpression( Checkpoint.class ) )
063        ),
064
065      // sub-graph to match has out degree captured above
066      new ExpressionGraph()
067        .arcs(
068          new FlowElementExpression( ElementCapture.Primary, Pipe.class, Topo.SplitOnly )
069        )
070    );
071    }
072  }