org.apache.hadoop.hive.ql.exec.ExprNodeGenericFuncEvaluator Maven / Gradle / Ivy
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* 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.hadoop.hive.ql.exec;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.plan.ExprNodeDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeGenericFuncDesc;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDF;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDFBaseCompare;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDFCase;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDFWhen;
import org.apache.hadoop.hive.serde2.objectinspector.ConstantObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils;
import java.util.ArrayList;
import java.util.List;
/**
* ExprNodeGenericFuncEvaluator.
*
*/
public class ExprNodeGenericFuncEvaluator extends ExprNodeEvaluator {
private static final Log LOG = LogFactory
.getLog(ExprNodeGenericFuncEvaluator.class.getName());
transient GenericUDF genericUDF;
transient Object rowObject;
transient ExprNodeEvaluator[] children;
transient GenericUDF.DeferredObject[] deferredChildren;
transient GenericUDF.DeferredObject[] childrenNeedingPrepare;
transient boolean isEager;
transient boolean isConstant = false;
/**
* Class to allow deferred evaluation for GenericUDF.
*/
class DeferredExprObject implements GenericUDF.DeferredObject {
private final boolean eager;
private final ExprNodeEvaluator eval;
private transient boolean evaluated;
private transient int version;
private transient Object obj;
DeferredExprObject(ExprNodeEvaluator eval, boolean eager) {
this.eval = eval;
this.eager = eager;
}
@Override
public void prepare(int version) throws HiveException {
this.version = version;
this.evaluated = false;
if (eager) {
get();
}
}
public boolean needsPrepare() {
return !(eval instanceof ExprNodeConstantEvaluator);
}
@Override
public Object get() throws HiveException {
if (!evaluated) {
obj = eval.evaluate(rowObject, version);
evaluated = true;
}
return obj;
}
}
public ExprNodeGenericFuncEvaluator(ExprNodeGenericFuncDesc expr) throws HiveException {
super(expr);
children = new ExprNodeEvaluator[expr.getChildren().size()];
isEager = false;
for (int i = 0; i < children.length; i++) {
ExprNodeDesc child = expr.getChildren().get(i);
ExprNodeEvaluator nodeEvaluator = ExprNodeEvaluatorFactory.get(child);
children[i] = nodeEvaluator;
// If we have eager evaluators anywhere below us, then we are eager too.
if (nodeEvaluator instanceof ExprNodeGenericFuncEvaluator) {
if (((ExprNodeGenericFuncEvaluator) nodeEvaluator).isEager) {
isEager = true;
}
// Base case: we are eager if a child is stateful
GenericUDF childUDF =
((ExprNodeGenericFuncDesc) child).getGenericUDF();
if (FunctionRegistry.isStateful(childUDF)) {
isEager = true;
}
}
}
genericUDF = expr.getGenericUDF();
if (isEager &&
(genericUDF instanceof GenericUDFCase || genericUDF instanceof GenericUDFWhen)) {
throw new HiveException("Stateful expressions cannot be used inside of CASE");
}
}
@Override
public ObjectInspector initialize(ObjectInspector rowInspector) throws HiveException {
deferredChildren = new GenericUDF.DeferredObject[children.length];
List childrenNeedingPrepare =
new ArrayList(children.length);
for (int i = 0; i < deferredChildren.length; i++) {
DeferredExprObject deferredExprObject = new DeferredExprObject(children[i], isEager);
deferredChildren[i] = deferredExprObject;
if (deferredExprObject.needsPrepare()) {
childrenNeedingPrepare.add(deferredExprObject);
}
}
this.childrenNeedingPrepare =
childrenNeedingPrepare.toArray(new GenericUDF.DeferredObject[childrenNeedingPrepare.size()]);
// Initialize all children first
ObjectInspector[] childrenOIs = new ObjectInspector[children.length];
for (int i = 0; i < children.length; i++) {
childrenOIs[i] = children[i].initialize(rowInspector);
}
MapredContext context = MapredContext.get();
if (context != null) {
context.setup(genericUDF);
}
outputOI = genericUDF.initializeAndFoldConstants(childrenOIs);
isConstant = ObjectInspectorUtils.isConstantObjectInspector(outputOI)
&& isDeterministic();
return outputOI;
}
@Override
public boolean isDeterministic() {
boolean result = FunctionRegistry.isDeterministic(genericUDF);
for (ExprNodeEvaluator child : children) {
result = result && child.isDeterministic();
}
return result;
}
@Override
public ExprNodeEvaluator[] getChildren() {
return children;
}
@Override
public boolean isStateful() {
boolean result = FunctionRegistry.isStateful(genericUDF);
for (ExprNodeEvaluator child : children) {
if(result = result || child.isStateful()) {
return result;
}
}
return result;
}
@Override
protected Object _evaluate(Object row, int version) throws HiveException {
if (isConstant) {
// The output of this UDF is constant, so don't even bother evaluating.
return ((ConstantObjectInspector) outputOI).getWritableConstantValue();
}
rowObject = row;
for (GenericUDF.DeferredObject deferredObject : childrenNeedingPrepare) {
deferredObject.prepare(version);
}
return genericUDF.evaluate(deferredChildren);
}
/**
* If the genericUDF is a base comparison, it returns an integer based on the result of comparing
* the two sides of the UDF, like the compareTo method in Comparable.
*
* If the genericUDF is not a base comparison, or there is an error executing the comparison, it
* returns null.
* @param row
* @return the compare results
* @throws HiveException
*/
public Integer compare(Object row) throws HiveException {
if (!expr.isSortedExpr() || !(genericUDF instanceof GenericUDFBaseCompare)) {
for (ExprNodeEvaluator evaluator: children) {
if (evaluator instanceof ExprNodeGenericFuncEvaluator) {
Integer comparison = ((ExprNodeGenericFuncEvaluator) evaluator).compare(row);
if (comparison != null) {
return comparison;
}
}
}
return null;
}
rowObject = row;
for (int i = 0; i < deferredChildren.length; i++) {
deferredChildren[i].prepare(-1);
}
return ((GenericUDFBaseCompare)genericUDF).compare(deferredChildren);
}
}