com.gigaspaces.internal.utils.concurrent

Class UncheckedAtomicReferenceFieldUpdater<T,V>

java.lang.Object

com.gigaspaces.internal.utils.concurrent.UncheckedAtomicReferenceFieldUpdater<T,V>

Type Parameters:

T - The type of the object holding the updatable field

V - The type of the field

public abstract class UncheckedAtomicReferenceFieldUpdater<T,V>
extends Object

A reflection-based utility that enables atomic updates to designated volatile reference fields of designated classes. This class is designed for use in atomic data structures in which several reference fields of the same node are independently subject to atomic updates. For example, a tree node might be declared as

 class Node {
   private volatile Node left, right;
 

   private static final AtomicReferenceFieldUpdater<Node, Node> leftUpdater =
     AtomicReferenceFieldUpdater.newUpdater(Node.class, Node.class, "left");
   private static AtomicReferenceFieldUpdater<Node, Node> rightUpdater =
     AtomicReferenceFieldUpdater.newUpdater(Node.class, Node.class, "right");
 

   Node getLeft() { return left;  }
   boolean compareAndSetLeft(Node expect, Node update) {
     return leftUpdater.compareAndSet(this, expect, update);
   }
   // ... and so on
 }
 

Note that the guarantees of the compareAndSet method in this class are weaker than in other atomic classes. Because this class cannot ensure that all uses of the field are appropriate for purposes of atomic access, it can guarantee atomicity and volatile semantics only with respect to other invocations of compareAndSet and set.

Since:

1.5

Author:

Doug Lea

Constructor Summary

Constructors

Constructor and Description
UncheckedAtomicReferenceFieldUpdater()

Method Summary

Modifier and Type	Method and Description
static <U,W> AtomicReferenceFieldUpdater<U,W>	newUpdater(Class<U> tclass, Class<W> vclass, String fieldName) Creates an updater for objects with the given field.

Methods inherited from class java.lang.Object

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

Constructor Detail

UncheckedAtomicReferenceFieldUpdater

public UncheckedAtomicReferenceFieldUpdater()

Method Detail

newUpdater

public static <U,W> AtomicReferenceFieldUpdater<U,W> newUpdater(Class<U> tclass,
                                                                Class<W> vclass,
                                                                String fieldName)

Creates an updater for objects with the given field. The Class arguments are needed to check that reflective types and generic types match.

Parameters:

tclass - the class of the objects holding the field.

vclass - the class of the field

fieldName - the name of the field to be updated.

Returns:

the updater

Throws:

IllegalArgumentException - if the field is not a volatile reference type.

RuntimeException - with a nested reflection-based exception if the class does not hold field or is the wrong type.