Package org.apache.commons.collections4.bloomfilter

Class LayerManager

java.lang.Object

org.apache.commons.collections4.bloomfilter.LayerManager

All Implemented Interfaces:

BloomFilterProducer

public class LayerManager
extends Object
implements BloomFilterProducer

Implementation of the methods to manage the layers in a layered Bloom filter.

The manager comprises a list of Bloom filters that are managed based on various rules. The last filter in the list is known as the target and is the filter into which merges are performed. The Layered manager utilizes three methods to manage the list.

• ExtendCheck - A Predicate that if true causes a new Bloom filter to be created as the new target.
• FilterSupplier - A Supplier that produces empty Bloom filters to be used as a new target.
• Cleanup - A Consumer of a LinkedList of BloomFilter that removes any expired or out dated filters from the list.

When extendCheck returns true the following steps are taken:

1. Cleanup is called
2. FilterSuplier is executed and the new filter added to the list as the target filter.

Since:

4.5

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	LayerManager.Builder	Builder to create Layer Manager
static final class	LayerManager.Cleanup	Static methods to create a Consumer of a LinkedList of BloomFilter perform tests on whether to reduce the collection of Bloom filters.
static final class	LayerManager.ExtendCheck	A collection of common ExtendCheck implementations to test whether to extend the depth of a LayerManager.

Method Summary

Modifier and Type	Method	Description
static LayerManager.Builder	builder()	Creates a new Builder with defaults of ExtendCheck.neverAdvance() and Cleanup.noCleanup().
final void	clear()	Removes all the filters from the layer manager, and sets up a new one as the target.
LayerManager	copy()	Creates a deep copy of this LayerManager.
boolean	forEachBloomFilter(Predicate<BloomFilter> bloomFilterPredicate)	Executes a Bloom filter Predicate on each Bloom filter in the manager in depth order.
final BloomFilter	get(int depth)	Gets the Bloom filter at the specified depth.
final int	getDepth()	Returns the number of filters in the LayerManager.
final BloomFilter	getTarget()	Returns the current target filter.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.commons.collections4.bloomfilter.BloomFilterProducer

asBloomFilterArray, flatten, forEachBloomFilterPair

Method Details

builder

public static LayerManager.Builder builder()

Creates a new Builder with defaults of ExtendCheck.neverAdvance() and Cleanup.noCleanup().

Returns:

A builder.

See Also:

• LayerManager.ExtendCheck.neverAdvance()
• LayerManager.Cleanup.noCleanup()

clear

public final void clear()

Removes all the filters from the layer manager, and sets up a new one as the target.

copy

public LayerManager copy()

Creates a deep copy of this LayerManager.

Filters in the copy are deep copies, not references, so changes in the copy are NOT reflected in the original.

The filterSupplier, extendCheck, and the filterCleanup are shared between the copy and this instance.

Returns:

a copy of this layer Manager.

forEachBloomFilter

public boolean forEachBloomFilter(Predicate<BloomFilter> bloomFilterPredicate)

Executes a Bloom filter Predicate on each Bloom filter in the manager in depth order. Oldest filter first.

Specified by:

forEachBloomFilter in interface BloomFilterProducer

Parameters:

bloomFilterPredicate - the predicate to evaluate each Bloom filter with.

Returns:

false when the a filter fails the predicate test. Returns true if all filters pass the test.

get

public final BloomFilter get(int depth)

Gets the Bloom filter at the specified depth. The filter at depth 0 is the oldest filter.

Parameters:

depth - the depth at which the desired filter is to be found.

Returns:

the filter.

Throws:

NoSuchElementException - if depth is not in the range [0,filters.size())

getDepth

public final int getDepth()

Returns the number of filters in the LayerManager. In the default LayerManager implementation there is alwasy at least one layer.

Returns:

the current depth.

getTarget

public final BloomFilter getTarget()

Returns the current target filter. If a new filter should be created based on extendCheck it will be created before this method returns.

Returns:

the current target filter after any extension.