org.apache.hudi.common.bloom.Key Maven / Gradle / Ivy
/*
* 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.hudi.common.bloom;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
/**
* The general behavior of a key that must be stored in a bloom filter.
*
* The code in class is adapted from {@link org.apache.hadoop.util.bloom.Key} in Apache Hadoop.
*
* @see InternalBloomFilter The general behavior of a bloom filter and how the key is used.
*/
public class Key implements Comparable {
/**
* 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;
}
/**
* Serialize the fields of this object to out.
*
* @param out DataOutput to serialize this object into.
* @throws IOException
*/
public void write(DataOutput out) throws IOException {
out.writeInt(bytes.length);
out.write(bytes);
out.writeDouble(weight);
}
/**
* Deserialize the fields of this object from in.
*
*
For efficiency, implementations should attempt to re-use storage in the
* existing object where possible.
*
* @param in DataInput to deseriablize this object from.
* @throws IOException
*/
public void readFields(DataInput in) throws IOException {
this.bytes = new byte[in.readInt()];
in.readFully(this.bytes);
weight = in.readDouble();
}
// Comparable
@Override
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 = (int) (this.weight - other.weight);
}
return result;
}
}