org.corfudb.util.concurrent

Class SingletonResource<T>

java.lang.Object

org.corfudb.util.concurrent.SingletonResource<T>

Type Parameters:

T - The type of resource this SingletonResource holds.

public class SingletonResource<T>
extends Object

Utility class which implements a singleton resource pattern.

A SingletonResource is a common resource pattern where the first thread that needs to use a resource instantiates it. Subsequent threads should re-use the resource instantiated by the first thread.

Method Summary

Modifier and Type	Method and Description
void	cleanup(Consumer<T> cleaner) Note(Maithem): We need to remove this method, it shouldn't be used.
T	get() Get the resource, potentially generating it by calling the generator if necessary.
static <R> SingletonResource<R>	withInitial(Supplier<R> generator) Factory method with similar semantics as a ThreadLocal.

Methods inherited from class java.lang.Object

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

Method Detail

withInitial

public static <R> SingletonResource<R> withInitial(@Nonnull
                                                   Supplier<R> generator)

Factory method with similar semantics as a ThreadLocal.

Type Parameters:

R - The type of the resource to be provided.

Parameters:

generator - A method to be called when a new R is needed.

Returns:

A new SingletonResource.

get

public T get()

Get the resource, potentially generating it by calling the generator if necessary.

Returns:

The resource provided by this SingletonResource.

cleanup

public void cleanup(@Nonnull
                    Consumer<T> cleaner)

Note(Maithem): We need to remove this method, it shouldn't be used. This singleton class is misused by other classes that depend on this method. To elaborate, the ManagementServer class uses the lazy evaluation property of the singleton to create a runtime, but not connect at construction time (to avoid blocking). Removing this method would mean, callers would have to get the reference to the object and call clean up directly, instead of calling cleanup on the singleton. For some tests, this would block because in singleton.get().cleanup would cause a creation of a CorfuRuntime and connect, where the connection would fail. Cleanup the resource if it has been generated. Otherwise does nothing.

Parameters:

cleaner - A Consumer which is provided the resource to perform cleanup actions.