org.forgerock.bloomfilter

Class ConcurrentRollingBloomFilter<T>

java.lang.Object

org.forgerock.bloomfilter.ConcurrentRollingBloomFilter<T>

All Implemented Interfaces:

BloomFilter<T>

@ThreadSafe
public final class ConcurrentRollingBloomFilter<T>
extends Object
implements BloomFilter<T>

A thread-safe implementation of a Bloom Filter that can expand over time to accommodate arbitrary numbers of elements, while also allowing old elements to be deleted after they have expired. Rolling bloom filters are useful for maintaining on-going blacklists of short-lived elements.

This implementation is optimised for concurrent read performance. Concurrent writes performance is likely to be considerably slower than reads, so this implementation is only suitable for situations where read performance is critical and writes are relatively rare. Write performance may be improved by batching writes via the addAll(Collection) method, or by using some external synchronisation mechanism to perform pre-emptive locking (at the cost of reducing read performance).

Method Summary

Modifier and Type	Method and Description
void	add(T element) Adds the specified element to this set if it is not already possibly present.
void	addAll(Collection<? extends T> elements) Adds all of the specified elements to this set if they are not possibly already present.
BloomFilterStatistics	getStatistics() Gets a snapshot of the current statistics of the set.
boolean	mightContain(T element) Checks if the given element might be a member of this set.
String	toString()

Methods inherited from class java.lang.Object

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

Method Detail

add

public void add(T element)

Description copied from interface: BloomFilter

Adds the specified element to this set if it is not already possibly present. After a call to this method, subsequent calls to BloomFilter.mightContain(Object) will return true for the same object.

Specified by:

add in interface BloomFilter<T>

Parameters:

element - the element to add to this set.

addAll

public void addAll(Collection<? extends T> elements)

Description copied from interface: BloomFilter

Adds all of the specified elements to this set if they are not possibly already present.

Specified by:

addAll in interface BloomFilter<T>

Parameters:

elements - the elements to add to the set.

mightContain

public boolean mightContain(T element)

Description copied from interface: BloomFilter

Checks if the given element might be a member of this set. If this method returns false, then the given object is definitely not a member of the set. If the result is true then the object may or may not be a member of this set, with a certain probability of false positives.

Specified by:

mightContain in interface BloomFilter<T>

Parameters:

element - the element to check for membership in this set.

Returns:

false if the element is definitely not in the set, or true if it might be.

getStatistics

public BloomFilterStatistics getStatistics()

Description copied from interface: BloomFilter

Gets a snapshot of the current statistics of the set.

Specified by:

getStatistics in interface BloomFilter<T>

toString

public String toString()

Overrides:

toString in class Object