org.apache.pig.ComparisonFunc Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
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* 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,
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* limitations under the License.
*/
package org.apache.pig;
import java.io.IOException;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.WritableComparator;
import org.apache.pig.classification.InterfaceAudience;
import org.apache.pig.classification.InterfaceStability;
import org.apache.pig.data.Tuple;
import org.apache.pig.data.TupleFactory;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.PigProgressable;
import org.apache.pig.impl.io.NullableTuple;
/**
* An interface for custom order by comparator function.
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
@Deprecated
public abstract class ComparisonFunc extends WritableComparator {
// If the comparison is a time consuming process
// this reporter must be used to report progress
protected PigProgressable reporter;
public ComparisonFunc() {
super(NullableTuple.class, true);
}
/**
* Compare two tuples. Note that even though both args are given type of
* WritableComparable to match the WritableComparable interface, they
* must both be tuples.
* @param a first tuple
* @param b tuple to compare a to
* @return -1 if a < b, 1 if a > b, 0 if a = b
*/
public int compare(WritableComparable a, WritableComparable b) {
// The incoming key will be in a NullableTuple. But the comparison
// function needs a tuple, so pull the tuple out.
return compare((Tuple)((NullableTuple)a).getValueAsPigType(), (Tuple)((NullableTuple)b).getValueAsPigType());
}
/**
* This callback method must be implemented by all subclasses. Compares
* its two arguments for order. The order of elements of the tuples correspond
* to the fields specified in the order by clause.
* Same semantics as {@link java.util.Comparator}.
*
* @param t1 the first Tuple to be compared.
* @param t2 the second Tuple to be compared.
* @return Returns a negative integer, zero, or a positive integer as the first
* argument is less than, equal to, or greater than the second.
* @throws IOException
* @see java.util.Comparator
*/
abstract public int compare(Tuple t1, Tuple t2);
/**
* Set the reporter. If the comparison takes a long time the
* reporter should be called occasionally to avoid Hadoop timing out
* underneath. The default Hadoop timeout is 600 seconds.
* @param reporter Progress reporter
*/
public void setReporter(PigProgressable reporter) {
this.reporter = reporter;
}
}