/*
* 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.builtin;
import java.io.IOException;
import java.util.Iterator;
import org.apache.pig.Accumulator;
import org.apache.pig.Algebraic;
import org.apache.pig.EvalFunc;
import org.apache.pig.PigException;
import org.apache.pig.backend.executionengine.ExecException;
import org.apache.pig.data.DataBag;
import org.apache.pig.data.DataType;
import org.apache.pig.data.Tuple;
import org.apache.pig.data.TupleFactory;
import org.apache.pig.impl.logicalLayer.FrontendException;
import org.apache.pig.impl.logicalLayer.schema.Schema;
/**
* This method should never be used directly, use {@link MAX}.
*/
public class DoubleMax extends EvalFunc<Double> implements Algebraic, Accumulator<Double> {
@Override
public Double exec(Tuple input) throws IOException {
try {
return max(input);
} catch (ExecException ee) {
throw ee;
} catch (Exception e) {
int errCode = 2106;
String msg = "Error while computing max in " + this.getClass().getSimpleName();
throw new ExecException(msg, errCode, PigException.BUG, e);
}
}
public String getInitial() {
return Initial.class.getName();
}
public String getIntermed() {
return Intermediate.class.getName();
}
public String getFinal() {
return Final.class.getName();
}
static public class Initial extends EvalFunc<Tuple> {
private static TupleFactory tfact = TupleFactory.getInstance();
@Override
public Tuple exec(Tuple input) throws IOException {
try {
// input is a bag with one tuple containing
// the column we are trying to max on
DataBag bg = (DataBag) input.get(0);
Double d = null;
if(bg.iterator().hasNext()) {
Tuple tp = bg.iterator().next();
d = (Double)(tp.get(0));
}
return tfact.newTuple(d);
} catch (ExecException ee) {
throw ee;
} catch (Exception e) {
int errCode = 2106;
String msg = "Error while computing max in " + this.getClass().getSimpleName();
throw new ExecException(msg, errCode, PigException.BUG, e);
}
}
}
static public class Intermediate extends EvalFunc<Tuple> {
private static TupleFactory tfact = TupleFactory.getInstance();
@Override
public Tuple exec(Tuple input) throws IOException {
try {
return tfact.newTuple(max(input));
} catch (ExecException ee) {
throw ee;
} catch (Exception e) {
int errCode = 2106;
String msg = "Error while computing max in " + this.getClass().getSimpleName();
throw new ExecException(msg, errCode, PigException.BUG, e);
}
}
}
static public class Final extends EvalFunc<Double> {
@Override
public Double exec(Tuple input) throws IOException {
try {
return max(input);
} catch (ExecException ee) {
throw ee;
} catch (Exception e) {
int errCode = 2106;
String msg = "Error while computing max in " + this.getClass().getSimpleName();
throw new ExecException(msg, errCode, PigException.BUG, e);
}
}
}
static protected Double max(Tuple input) throws ExecException {
DataBag values = (DataBag)input.get(0);
// if we were handed an empty bag, return NULL
// this is in compliance with SQL standard
if(values.size() == 0) {
return null;
}
double curMax = Double.NEGATIVE_INFINITY;
boolean sawNonNull = false;
for (Iterator<Tuple> it = values.iterator(); it.hasNext();) {
Tuple t = it.next();
try {
Double d = (Double)(t.get(0));
if (d == null) continue;
sawNonNull = true;
curMax = java.lang.Math.max(curMax, d);
} catch (RuntimeException exp) {
int errCode = 2103;
String msg = "Problem while computing max of doubles.";
throw new ExecException(msg, errCode, PigException.BUG, exp);
}
}
if(sawNonNull) {
return new Double(curMax);
} else {
return null;
}
}
@Override
public Schema outputSchema(Schema input) {
return new Schema(new Schema.FieldSchema(null, DataType.DOUBLE));
}
/* Accumulator interface */
private Double intermediateMax = null;
@Override
public void accumulate(Tuple b) throws IOException {
try {
Double curMax = max(b);
if (curMax == null) {
return;
}
/* if bag is not null, initialize intermediateMax to negative infinity */
if (intermediateMax == null) {
intermediateMax = Double.NEGATIVE_INFINITY;
}
intermediateMax = java.lang.Math.max(intermediateMax, curMax);
} catch (ExecException ee) {
throw ee;
} catch (Exception e) {
int errCode = 2106;
String msg = "Error while computing max in " + this.getClass().getSimpleName();
throw new ExecException(msg, errCode, PigException.BUG, e);
}
}
@Override
public void cleanup() {
intermediateMax = null;
}
@Override
public Double getValue() {
return intermediateMax;
}
}