Package org.apache.hadoop.util.bloom

Class HashFunction

java.lang.Object

org.apache.hadoop.util.bloom.HashFunction

@Public
@Stable
public final class HashFunction
extends java.lang.Object

Implements a hash object that returns a certain number of hashed values.

See Also:

The general behavior of a key being stored in a filter, The general behavior of a filter

Constructor Summary

Constructors

Constructor	Description
HashFunction(int maxValue, int nbHash, int hashType)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	clear()	Clears this hash function.
int[]	hash(Key k)	Hashes a specified key into several integers.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HashFunction

public HashFunction(int maxValue,
                    int nbHash,
                    int hashType)

Constructor.

Builds a hash function that must obey to a given maximum number of returned values and a highest value.

Parameters:

maxValue - The maximum highest returned value.

nbHash - The number of resulting hashed values.

hashType - type of the hashing function (see Hash).

Method Detail

clear

public void clear()

Clears this hash function. A NOOP

hash

public int[] hash(Key k)

Hashes a specified key into several integers.

Parameters:

k - The specified key.

Returns:

The array of hashed values.