com.unister.semweb.drums.bucket.hashfunction
Class AbstractHashFunction

java.lang.Object
  com.unister.semweb.drums.bucket.hashfunction.AbstractHashFunction

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

RangeHashFunction

public abstract class AbstractHashFunction
extends java.lang.Object
implements java.io.Serializable

This abstract class reflects the usage of a consistent hash-function. To work properly, the number of buckets ( getNumberOfBuckets()) and a mapping of a key to a bucket-id ( getBucketId(byte[])) is needed.

Author:

Martin Nettling

See Also:

Serialized Form

Constructor Summary

AbstractHashFunction()

Method Summary

abstract int	getBucketId(AbstractKVStorable key)
abstract int	getBucketId(byte[] key)
abstract int	getBucketId(java.lang.String dbFilename)
abstract java.lang.String	getFilename(int bucketId)
int	getNumberOfBuckets()
abstract void	load(java.io.InputStream in) Loads the hashfunction from the given InputStream
abstract void	store(java.io.OutputStream os) Writes this hashfunction to the given OutputStream

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractHashFunction

public AbstractHashFunction()

Method Detail

getNumberOfBuckets

public int getNumberOfBuckets()

Returns:

the number of buckets, addressed by this hash-function

getBucketId

public abstract int getBucketId(byte[] key)

Parameters:

key - the key to map to a bucket-id

Returns:

the bucket-id belonging to the given key

getBucketId

public abstract int getBucketId(AbstractKVStorable key)

Parameters:

key - the element containing the key to map a bucket-id

Returns:

the bucket-id belonging to the given AbstractKVStorable

getFilename

public abstract java.lang.String getFilename(int bucketId)

Parameters:

bucketId -

Returns:

the filename of the bucket for the given bucket-id.

getBucketId

public abstract int getBucketId(java.lang.String dbFilename)

Parameters:

dbFilename -

Returns:

the bucket-id of the bucket belonging to the given filename.

store

public abstract void store(java.io.OutputStream os)
                    throws java.io.IOException

Writes this hashfunction to the given OutputStream

Parameters:

os -

Throws:

java.io.IOException

load

public abstract void load(java.io.InputStream in)
                   throws java.io.IOException

Loads the hashfunction from the given InputStream

Parameters:

in -

Throws:

java.io.IOException