Class Functions.WeakMemoizer<A,B>

java.lang.Object

io.atlassian.fugue.Functions.WeakMemoizer<A,B>

Type Parameters:

A - comparable descriptor, the usual rules for any HashMap key apply.

B - the value

All Implemented Interfaces:

Function<A,B>

Enclosing class:

Functions

static final class Functions.WeakMemoizer<A,B>
extends Object
implements Function<A,B>

Class supports the implementation of Functions.weakMemoize(Function) and is not intended for general use. Functions.WeakMemoizer caches the result of another function. The result is weakly referenced internally. This is useful if the result is expensive to compute or the identity of the result is particularly important.

If the results from this function are further cached then they will tend to stay in this cache for longer.

Since:

1.1

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static final class	Functions.WeakMemoizer.MappedReference<K,V>	A weak reference that maintains a reference to the key so that it can be removed from the map when the value is garbage collected.

Field Summary

Fields

Modifier and Type	Field	Description
private final Function<A,B>	delegate
private final ConcurrentMap<A, Functions.WeakMemoizer.MappedReference<A,B>>	map
private final ReferenceQueue<B>	queue

Constructor Summary

Constructors

Constructor	Description
WeakMemoizer(Function<A,B> delegate)	Construct a new Functions.WeakMemoizer instance.

Method Summary

Modifier and Type	Method	Description
B	apply(A descriptor)	Get a result for the supplied Descriptor.
private void	expungeStaleEntries()
(package private) static <A,B> Functions.WeakMemoizer<A,B>	weakMemoizer(Function<A,B> delegate)

Methods inherited from class Object

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

Methods inherited from interface Function

andThen, compose

Field Details

map

private final ConcurrentMap<A, Functions.WeakMemoizer.MappedReference<A,B>> map

queue

private final ReferenceQueue<B> queue

delegate

private final Function<A,B> delegate

Constructor Details

WeakMemoizer

WeakMemoizer(Function<A,B> delegate)

Construct a new Functions.WeakMemoizer instance.

Parameters:

delegate - for creating the initial values.

Method Details

weakMemoizer

static <A,B> Functions.WeakMemoizer<A,B> weakMemoizer(Function<A,B> delegate)

apply

public B apply(A descriptor)

Get a result for the supplied Descriptor.

Specified by:

apply in interface Function<A,B>

Parameters:

descriptor - must not be null

Returns:

descriptor lock

expungeStaleEntries

private void expungeStaleEntries()