/**
* 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 io.dstream.tez.io;
import java.io.Serializable;
import org.apache.hadoop.io.WritableComparable;
import com.google.common.base.Preconditions;
/**
* This class represents a universal Writable with the goal of recognizing
* and properly writing/reading multiple types of data.
* More documentation to follow as its design progresses, but at the moment the mechanism is simple:
* 1. Prepend each value with a byte representing its type
* 2. Write value data as byte[]
* For fixed formats such as Int, Long etc., its standard byte representation is used (e.g., Int = 4 bytes)
* For Objects (variable length) object serialization is used with custom se/deser to be exposed for
* customization and optimization
*
* This class is not public nor it is meant/designed as thread-safe.
*/
@SuppressWarnings({ "rawtypes", "serial" })
public class KeyWritable extends TypeAwareWritable<Object> implements WritableComparable<KeyWritable>, Serializable {
private static boolean ascending = true;
/**
*
*/
@Override
public void setValue(Object value) {
Preconditions.checkState(value != null, "'value' for key must not be null");
super.setValue(value);
}
/**
*
*/
@SuppressWarnings("unchecked")
@Override
public int compareTo(KeyWritable o) {
if (this.value instanceof Comparable<?>){
int cmp = ((Comparable) this.value).compareTo(o.value);
if (!ascending){
cmp *= -1;
}
return cmp;
}
else {
/*
* TODO REVISIT!!!
*/
if (this.value == o.value){
return 0;
} else {
return -1;
}
}
}
/**
*
* @param ascending
*/
protected static void setAscending(boolean ascending) {
KeyWritable.ascending = ascending;
}
}