    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.NonSafeOperationExpression;
    027import cascading.flow.planner.iso.expression.TypeExpression;
    028import cascading.flow.planner.rule.RuleExpression;
    029import cascading.flow.planner.rule.expressiongraph.NonSafeAndSplitAndSyncPipeExpressionGraph;
    030import cascading.pipe.Pipe;
    031import cascading.tap.Tap;
    032
    033/**
    034 * Captures a split against a non-safe Operation to prevent the operation from running
    035 * in parallel mappers
    036 */
    037public class BalanceNonSafeSplitExpression extends RuleExpression
    038  {
    039  public BalanceNonSafeSplitExpression()
    040    {
    041    super(
    042      new NonSafeAndSplitAndSyncPipeExpressionGraph(),
    043
    044      new ExpressionGraph()
    045        .arcs(
    046          new FlowElementExpression( Tap.class ),
    047          new NonSafeOperationExpression( TypeExpression.Topo.SplitOnly )
    048        ),
    049
    050      new ExpressionGraph()
    051        .arcs(
    052          new FlowElementExpression( ElementCapture.Primary, Pipe.class, TypeExpression.Topo.Tail )
    053        )
    054    );
    055    }
    056  }