org.apache.pig.newplan.logical.optimizer.DanglingNestedNodeRemover Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.pig.newplan.logical.optimizer;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.apache.pig.impl.logicalLayer.FrontendException;
import org.apache.pig.newplan.DependencyOrderWalker;
import org.apache.pig.newplan.Operator;
import org.apache.pig.newplan.OperatorPlan;
import org.apache.pig.newplan.logical.relational.LOForEach;
import org.apache.pig.newplan.logical.relational.LOGenerate;
import org.apache.pig.newplan.logical.relational.LogicalPlan;
import org.apache.pig.newplan.logical.relational.LogicalRelationalNodesVisitor;
public class DanglingNestedNodeRemover extends LogicalRelationalNodesVisitor {
public DanglingNestedNodeRemover(OperatorPlan plan)
throws FrontendException {
super(plan, new DependencyOrderWalker(plan));
}
@Override
public void visit(LOForEach foreach) throws FrontendException {
LogicalPlan innerPlan = foreach.getInnerPlan();
List opsToRemove = new ArrayList();
Iterator ops = innerPlan.getOperators();
while (ops.hasNext()) {
Operator op = ops.next();
// Check if op leads to LOGenerate, otherwise, candidate to remove
Operator currentOp = op;
boolean endWithNoLOGenerate = false;
while (!(currentOp instanceof LOGenerate)) {
if (innerPlan.getSuccessors(currentOp)==null) {
endWithNoLOGenerate = true;
break;
}
currentOp = innerPlan.getSuccessors(currentOp).get(0);
}
if (endWithNoLOGenerate)
opsToRemove.add(op);
}
for (Operator op : opsToRemove) {
innerPlan.removeAndReconnect(op);
}
}
}