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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.pig.builtin;
import java.io.IOException;
import java.util.Iterator;
import org.apache.pig.Accumulator;
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.schema.Schema;
/**
* Core logic for applying an accumulative/algebraic math function to a
* bag of doubles.
*/
public abstract class AlgebraicDoubleMathBase extends AlgebraicMathBase implements Accumulator {
protected static Double getSeed(KNOWN_OP op) {
switch (op) {
case SUM: return 0.0;
case MIN: return Double.POSITIVE_INFINITY;
case MAX: return Double.NEGATIVE_INFINITY;
default: return null;
}
}
private static Double doWork(Double arg1, Double arg2, KNOWN_OP op) {
if (arg1 == null) {
return arg2;
} else if (arg2 == null) {
return arg1;
} else {
switch (op) {
case MAX: return Math.max(arg1, arg2);
case MIN: return Math.min(arg1, arg2);
case SUM: return arg1 + arg2;
default: return null;
}
}
}
protected static Double doTupleWork(Tuple input, KnownOpProvider opProvider) 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 == null || values.size() == 0) {
return null;
}
double sofar = AlgebraicDoubleMathBase.getSeed(opProvider.getOp());
boolean sawNonNull = false;
for (Iterator it = values.iterator(); it.hasNext();) {
Tuple t = it.next();
try {
Number n = (Number)(t.get(0));
if (n == null) continue;
Double d = n.doubleValue();
sawNonNull = true;
sofar = doWork(sofar, d, opProvider.getOp());
}catch(RuntimeException exp) {
int errCode = 2103;
throw new ExecException("Problem doing work on Doubles", errCode, PigException.BUG, exp);
}
}
return sawNonNull ? sofar : null;
}
@Override
public Double exec(Tuple input) throws IOException {
try {
return doTupleWork(input, opProvider);
} catch (ExecException ee) {
throw ee;
} catch (Exception e) {
int errCode = 2106;
throw new ExecException("Error executing function on Doubles", errCode, PigException.BUG, e);
}
}
static public abstract class Intermediate extends AlgebraicMathBase.Intermediate {
private static TupleFactory tfact = TupleFactory.getInstance();
@Override
public Tuple exec(Tuple input) throws IOException {
try {
return tfact.newTuple(doTupleWork(input, this));
} catch (ExecException ee) {
throw ee;
} catch (Exception e) {
int errCode = 2106;
throw new ExecException("Error executing function on Doubles", errCode, PigException.BUG, e);
}
}
}
static public abstract class Final extends AlgebraicMathBase.Final {
@Override
public Double exec(Tuple input) throws IOException {
try {
return doTupleWork(input, this);
} catch (ExecException ee) {
throw ee;
} catch (Exception e) {
int errCode = 2106;
throw new ExecException("Error executing function on Doubles", errCode, PigException.BUG, e);
}
}
}
@Override
public Schema outputSchema(Schema input) {
return new Schema(new Schema.FieldSchema(null, DataType.DOUBLE));
}
/* Accumulator interface implementation*/
private Double intermediateVal = null;
@Override
public void accumulate(Tuple b) throws IOException {
try {
Double curVal = doTupleWork(b, opProvider);
if (curVal == null) {
return;
}
if (intermediateVal == null) {
intermediateVal = getSeed(opProvider.getOp());
}
intermediateVal = doWork(intermediateVal, curVal, opProvider.getOp());
} catch (ExecException ee) {
throw ee;
} catch (Exception e) {
int errCode = 2106;
throw new ExecException("Error executing function on Doubles", errCode, PigException.BUG, e);
}
}
@Override
public void cleanup() {
intermediateVal = null;
}
@Override
public Double getValue() {
return intermediateVal;
}
}
