org.apache.hadoop.util.bloom.Key Maven / Gradle / Ivy
/**
*
* Copyright (c) 2005, European Commission project OneLab under contract 034819 (http://www.one-lab.org)
* All rights reserved.
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the distribution.
* - Neither the name of the University Catholique de Louvain - UCL
* nor the names of its contributors may be used to endorse or
* promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/**
* 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.util.bloom;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.io.WritableComparable;
/**
* The general behavior of a key that must be stored in a filter.
*
* @see Filter The general behavior of a filter
*/
@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
@InterfaceStability.Unstable
public class Key implements WritableComparable {
/** Byte value of key */
byte[] bytes;
/**
* The weight associated to this key.
*
* Invariant: if it is not specified, each instance of
* Key will have a default weight of 1.0
*/
double weight;
/** default constructor - use with readFields */
public Key() {}
/**
* Constructor.
*
* Builds a key with a default weight.
* @param value The byte value of this key.
*/
public Key(byte[] value) {
this(value, 1.0);
}
/**
* Constructor.
*
* Builds a key with a specified weight.
* @param value The value of this key.
* @param weight The weight associated to this key.
*/
public Key(byte[] value, double weight) {
set(value, weight);
}
/**
* @param value
* @param weight
*/
public void set(byte[] value, double weight) {
if (value == null) {
throw new IllegalArgumentException("value can not be null");
}
this.bytes = value;
this.weight = weight;
}
/** @return byte[] The value of this key. */
public byte[] getBytes() {
return this.bytes;
}
/** @return Returns the weight associated to this key. */
public double getWeight() {
return weight;
}
/**
* Increments the weight of this key with a specified value.
* @param weight The increment.
*/
public void incrementWeight(double weight) {
this.weight += weight;
}
/** Increments the weight of this key by one. */
public void incrementWeight() {
this.weight++;
}
@Override
public boolean equals(Object o) {
if (!(o instanceof Key)) {
return false;
}
return this.compareTo((Key)o) == 0;
}
@Override
public int hashCode() {
int result = 0;
for (int i = 0; i < bytes.length; i++) {
result ^= Byte.valueOf(bytes[i]).hashCode();
}
result ^= Double.valueOf(weight).hashCode();
return result;
}
// Writable
public void write(DataOutput out) throws IOException {
out.writeInt(bytes.length);
out.write(bytes);
out.writeDouble(weight);
}
public void readFields(DataInput in) throws IOException {
this.bytes = new byte[in.readInt()];
in.readFully(this.bytes);
weight = in.readDouble();
}
// Comparable
public int compareTo(Key other) {
int result = this.bytes.length - other.getBytes().length;
for (int i = 0; result == 0 && i < bytes.length; i++) {
result = this.bytes[i] - other.bytes[i];
}
if (result == 0) {
result = Double.valueOf(this.weight - other.weight).intValue();
}
return result;
}
}