/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.pig.backend.hadoop.executionengine.mapReduceLayer;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.pig.Accumulator;
import org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.plans.MROpPlanVisitor;
import org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.plans.MROperPlan;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.BinaryExpressionOperator;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.ConstantExpression;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.ExpressionOperator;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POBinCond;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POCast;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POMapLookUp;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POProject;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.PORelationToExprProject;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POUserFunc;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.UnaryExpressionOperator;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.plans.PhysicalPlan;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POPackage;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POSortedDistinct;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.Packager;
import org.apache.pig.data.DataType;
import org.apache.pig.impl.PigContext;
import org.apache.pig.impl.plan.DepthFirstWalker;
import org.apache.pig.impl.plan.VisitorException;
/**
* A visitor to optimize plans that determines if a reduce plan
* can run in accumulative mode.
*/
public class AccumulatorOptimizer extends MROpPlanVisitor {
private Log log = LogFactory.getLog(getClass());
public AccumulatorOptimizer(MROperPlan plan) {
super(plan, new DepthFirstWalker<MapReduceOper, MROperPlan>(plan));
}
public void visitMROp(MapReduceOper mr) throws VisitorException {
// See if this is a map-reduce job
List<PhysicalOperator> pos = mr.reducePlan.getRoots();
if (pos == null || pos.size() == 0) {
return;
}
// See if this is a POPackage
PhysicalOperator po_package = pos.get(0);
if (!po_package.getClass().equals(POPackage.class)) {
return;
}
Packager pkgr = ((POPackage) po_package).getPkgr();
// Check that this is a standard package, not a subclass
if (!pkgr.getClass().equals(Packager.class)) {
return;
}
// if POPackage is for distinct, just return
if (pkgr.isDistinct()) {
return;
}
// if any input to POPackage is inner, just return
boolean[] isInner = pkgr.getInner();
for(boolean b: isInner) {
if (b) {
return;
}
}
List<PhysicalOperator> l = mr.reducePlan.getSuccessors(po_package);
// there should be only one POForEach
if (l == null || l.size() == 0 || l.size() > 1) {
return;
}
PhysicalOperator po_foreach = l.get(0);
if (!(po_foreach instanceof POForEach)) {
return;
}
boolean foundUDF = false;
List<PhysicalPlan> list = ((POForEach)po_foreach).getInputPlans();
for(PhysicalPlan p: list) {
PhysicalOperator po = p.getLeaves().get(0);
// only expression operators are allowed
if (!(po instanceof ExpressionOperator)) {
return;
}
if (((ExpressionOperator)po).containUDF()) {
foundUDF = true;
}
if (!check(po)) {
return;
}
}
if (foundUDF) {
// if all tests are passed, reducer can run in accumulative mode
log.info("Reducer is to run in accumulative mode.");
po_package.setAccumulative();
po_foreach.setAccumulative();
}
}
/**
* Check if an operator is qualified to be under POForEach
* to turn on accumulator. The operator must be in the following list or
* an <code>POUserFunc</code>.
*
* If the operator has sub-operators, they must also belong to this list.
* <li>ConstantExpression</li>
* <li>POProject, whose result type is not BAG, or TUPLE and overloaded</li>
* <li>POMapLookup</li>
* <li>POCase</li>
* <li>UnaryExpressionOperator</li>
* <li>BinaryExpressionOperator</li>
* <li>POBinCond</li>
*
* If the operator is <code>POUserFunc</code>, it must implement
* <code>Accumulator</code> interface and its inputs pass the check
* by calling <code>checkUDFInput()</code>
*
* @param po the operator to be checked on
* @return <code>true</code> if it is ok, <code>false</code>
* if not.
*/
@SuppressWarnings("unchecked")
private boolean check(PhysicalOperator po) {
if (po instanceof ConstantExpression) {
return true;
}
if (po instanceof POCast) {
return check(po.getInputs().get(0));
}
if (po instanceof POMapLookUp) {
return check(po.getInputs().get(0));
}
if (po instanceof POProject) {
// POProject can not project data bag
if (((POProject)po).getResultType() == DataType.BAG) {
return false;
}
// POProject can not overload a data bag
if (((POProject)po).getResultType() == DataType.TUPLE && ((POProject)po).isOverloaded()) {
return false;
}
return true;
}
if (po instanceof UnaryExpressionOperator) {
return check(((UnaryExpressionOperator)po).getExpr());
}
if (po instanceof BinaryExpressionOperator) {
return check(((BinaryExpressionOperator)po).getLhs()) &&
check(((BinaryExpressionOperator)po).getRhs());
}
if (po instanceof POBinCond) {
return check(((POBinCond)po).getLhs()) &&
check(((POBinCond)po).getRhs()) && check(((POBinCond)po).getCond());
}
if (po instanceof POUserFunc) {
String className = ((POUserFunc)po).getFuncSpec().getClassName();
Class c = null;
try {
c = PigContext.resolveClassName(className);
}catch(Exception e) {
return false;
}
if (!Accumulator.class.isAssignableFrom(c)) {
return false;
}
// check input of UDF
List<PhysicalOperator> inputs = po.getInputs();
for(PhysicalOperator p: inputs) {
if (!checkUDFInput(p)) {
return false;
}
}
return true;
}
return false;
}
/**
* Check operators under POUserFunc to verify if this
* is a valid UDF to run as accumulator. The inputs to
* <code>POUserFunc</code> must be in the following list.
* If the operator has sub-operators, they must also belong
* to this list.
*
* <li>PORelationToExprProject</li>
* <li>ConstantExpression</li>
* <li>POProject</li>
* <li>POCase</li>
* <li>UnaryExpressionOperator</li>
* <li>BinaryExpressionOperator</li>
* <li>POBinCond</li>
* <li>POSortedDistinct</li>
* <li>POForEach</li>
*
*/
private boolean checkUDFInput(PhysicalOperator po) {
if (po instanceof PORelationToExprProject) {
return checkUDFInput(po.getInputs().get(0));
}
if (po instanceof POProject) {
if(po.getInputs() == null )
return true;
else
return checkUDFInput(po.getInputs().get(0));
}
if (po instanceof ConstantExpression) {
return true;
}
if (po instanceof UnaryExpressionOperator) {
return checkUDFInput(((UnaryExpressionOperator)po).getExpr());
}
if (po instanceof BinaryExpressionOperator) {
return checkUDFInput(((BinaryExpressionOperator)po).getLhs()) ||
checkUDFInput(((BinaryExpressionOperator)po).getRhs());
}
if (po instanceof POCast) {
return checkUDFInput(po.getInputs().get(0));
}
if (po instanceof POBinCond) {
return checkUDFInput(((POBinCond)po).getLhs()) &&
checkUDFInput(((POBinCond)po).getRhs()) && checkUDFInput(((POBinCond)po).getCond());
}
if (po instanceof POSortedDistinct) {
return true;
}
if (po instanceof POForEach) {
List<PhysicalPlan> list = ((POForEach)po).getInputPlans();
if (list.size() != 1) {
return false;
}
PhysicalOperator p = list.get(0).getLeaves().get(0);
if (checkUDFInput(p)) {
return checkUDFInput(po.getInputs().get(0));
}
}
return false;
}
}