com.newrelic.agent.util

Class LazyAtomicReference<T>

java.lang.Object

com.newrelic.agent.util.LazyAtomicReference<T>

Type Parameters:

T - the type of the referenced object.

public class LazyAtomicReference<T>
extends java.lang.Object

An atomic reference that is lazily initialized by a Callable if an attempt is made to read the value before it has been set. Null values are not allowed, so the initializing Callable must not return null. The implementation guarantees that the initial value will never overwrite a value set through a setter and that the value will be initialized at most once. The implementation cannot guarantee the initializer will only be invoked only once, or that it will be invoked at all; thus the initializer should not have side effects.

Constructor Summary

Constructors

Constructor and Description
LazyAtomicReference(java.util.concurrent.Callable<T> initializer) Create an atomic that will be lazily initialized if get is invoked before set.

Method Summary

Modifier and Type	Method and Description
T	get() Get the value of the atomic.
void	set(T newValue) Set the value of the atomic.

Methods inherited from class java.lang.Object

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

Constructor Detail

LazyAtomicReference

public LazyAtomicReference(java.util.concurrent.Callable<T> initializer)

Create an atomic that will be lazily initialized if get is invoked before set.

Parameters:

initializer - the lazy initializer. The initializer is only invoked if a client class attempts to get the value before it has been set. The initializer must not return null and must not invoke methods on the instance it is initializing.

Method Detail

get

public T get()

Get the value of the atomic. If the value has not been set, the initializer is invoked to provide a default value. The implementation provides certain guarantees described in the class comment.

Returns:

the value of the atomic, never null.

Throws:

java.lang.NullPointerException - - the initializer was invoked but returned null; internal error.

java.lang.RuntimeException - - wraps any exception thrown in the initializer; internal error.

set

public void set(T newValue)

Set the value of the atomic.

Parameters:

newValue - the value. May not be null.