eu.mais_h.mathsync

Class PadAndHashBucketSelector

java.lang.Object

eu.mais_h.mathsync.PadAndHashBucketSelector

All Implemented Interfaces:

BucketSelector

public class PadAndHashBucketSelector
extends Object
implements BucketSelector

Pads content and hashes it to select buckets.

Method Summary

Methods

Modifier and Type	Method and Description
static BucketSelector	newInstance(Digester digester, int spread) Builds an instance of this selector.
int[]	selectBuckets(int seed, byte[] content) Selects buckets to store items in.

Methods inherited from class java.lang.Object

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

Method Detail

selectBuckets

public int[] selectBuckets(int seed,
                  byte[] content)

Description copied from interface: BucketSelector

Selects buckets to store items in.

The output array must contain integers between 0 and Integer.MAX_VALUE. It is better if all integers in that range have the same probability of appearance.

The output must be consistent, for any byte arraycontent, for any positive integer s, multiple invocations of selectBuckets(s, content) must return the same array.

Different seed values should lead to different resulting arrays.

The number of returned buckets may vary for different contents and the returned array may contain duplicates.

Specified by:

selectBuckets in interface BucketSelector

Parameters:

seed - a seed preventing items to fall in the same buckets at all compression levels.

content - the content to store.

Returns:

an array of buckets to store content in.

newInstance

public static BucketSelector newInstance(Digester digester,
                         int spread)

Builds an instance of this selector.

Parameters:

digester - the digest algorithm to use.

spread - the number of buckets to store each item in, it is recommended using an odd number to prevent items falling an even number of times in the same bucket to become invisible.

Returns:

an instance of this selector with the given spread and digest algorithm.