/*
* Copyright (c) 2007-2014 Concurrent, Inc. All Rights Reserved.
*
* Project and contact information: http://www.cascading.org/
*
* This file is part of the Cascading project.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cascading.flow.hadoop.planner.rule.expression;
import cascading.flow.planner.iso.expression.ElementCapture;
import cascading.flow.planner.iso.expression.ExpressionGraph;
import cascading.flow.planner.iso.expression.FlowElementExpression;
import cascading.flow.planner.iso.expression.NonSafeOperationExpression;
import cascading.flow.planner.iso.expression.TypeExpression;
import cascading.flow.planner.rule.RuleExpression;
import cascading.flow.planner.rule.expressiongraph.NonSafeAndSplitAndSyncPipeExpressionGraph;
import cascading.pipe.Pipe;
import cascading.tap.Tap;
/**
* Captures a split against a non-safe Operation to prevent the operation from running
* in parallel mappers.
* <p/>
* THis variant allows a non-safe operation to be followed by any Pipe. this assumes other rules
* enforce splitting to only be on Each or Pipe types.
*/
public class BalanceNonSafePipeSplitExpression extends RuleExpression
{
public BalanceNonSafePipeSplitExpression()
{
super(
new NonSafeAndSplitAndSyncPipeExpressionGraph(),
new ExpressionGraph()
.arcs(
new FlowElementExpression( Tap.class ),
new NonSafeOperationExpression(),
new FlowElementExpression( Pipe.class, TypeExpression.Topo.SplitOnly )
),
new ExpressionGraph()
.arcs(
new FlowElementExpression( ElementCapture.Primary, Pipe.class, TypeExpression.Topo.Tail )
)
);
}
}