com.atlassian.jira.concurrent

Class ResettableLazyReference<T>

java.lang.Object

com.atlassian.jira.concurrent.ResettableLazyReference<T>

public class ResettableLazyReference<T>
extends Object

Lazy reference holder that can be initialized with supplier on call to getOrCreate(Supplier) The reference can be cleared atomically with reset() or safeReset(Object). Once reset, no other thread is able obtain the same value from this reference (though other threads may already have obtained it before the reset occurred).

Since:

v6.3.9

Constructor Summary

Constructors

Constructor and Description
ResettableLazyReference()

Method Summary

Modifier and Type	Method and Description
io.atlassian.fugue.Option<T>	get()
T	getOrCreate(Supplier<T> creator) Gets the reference's value, obtaining the new value from the supplier if it was not previously initialized.
io.atlassian.fugue.Option<T>	reset() Resets this reference to empty, returning the old value.
io.atlassian.fugue.Option<T>	safeReset(T expected) Compares the reference value to the expected value and resets it if and only if it is identical.

Methods inherited from class java.lang.Object

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

Constructor Detail

ResettableLazyReference

public ResettableLazyReference()

Method Detail

reset

public io.atlassian.fugue.Option<T> reset()

Resets this reference to empty, returning the old value.

Returns:

option containing the previous value of the reference, if there was one

safeReset

public io.atlassian.fugue.Option<T> safeReset(T expected)

Compares the reference value to the expected value and resets it if and only if it is identical.

The reset request will fail (return Option.none() and have no effect) if the expected value supplied is null.

Parameters:

expected - the expected value of the reference

Returns:

an option to the reset value. If no reset was performed (either because the expected value was given as null or because it did not match the value currently held by the reference), then Option.none() is returned.

get

public io.atlassian.fugue.Option<T> get()

Returns:

Option.some on the current value for this reference; Option.none() if it has not been initialized yet

getOrCreate

@Nonnull
public T getOrCreate(Supplier<T> creator)

Gets the reference's value, obtaining the new value from the supplier if it was not previously initialized.

Only one thread will be allowed to call the supplier at any given time, and it will not be called again before the reference is reset().

Parameters:

creator - supplier to be used for creating this reference

Returns:

value for this reference or newly created one

Throws:

IllegalArgumentException - if creator.get() returns null