com.firefly.utils.collection.AtomicFieldUpdaterUtil Maven / Gradle / Ivy
/*
* Copyright 2009 Red Hat, Inc.
*
* Red Hat licenses this file to you under the Apache License, version 2.0
* (the "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package com.firefly.utils.collection;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
/**
* @author The Netty Project
* @author Trustin Lee
* @version $Rev: 2080 $, $Date: 2010-01-26 18:04:19 +0900 (Tue, 26 Jan 2010) $
*/
class AtomicFieldUpdaterUtil {
private static final boolean AVAILABLE;
static final class Node {
volatile Node next;
Node() {
super();
}
}
static {
boolean available = false;
try {
AtomicReferenceFieldUpdater tmp =
AtomicReferenceFieldUpdater.newUpdater(
Node.class, Node.class, "next");
// Test if AtomicReferenceFieldUpdater is really working.
Node testNode = new Node();
tmp.set(testNode, testNode);
if (testNode.next != testNode) {
// Not set as expected - fall back to the safe mode.
throw new Exception();
}
available = true;
} catch (Throwable t) {
// Running in a restricted environment with a security manager.
}
AVAILABLE = available;
}
static AtomicReferenceFieldUpdater newRefUpdater(Class tclass, Class vclass, String fieldName) {
if (AVAILABLE) {
return AtomicReferenceFieldUpdater.newUpdater(tclass, vclass, fieldName);
} else {
return null;
}
}
static AtomicIntegerFieldUpdater newIntUpdater(Class tclass, String fieldName) {
if (AVAILABLE) {
return AtomicIntegerFieldUpdater.newUpdater(tclass, fieldName);
} else {
return null;
}
}
static boolean isAvailable() {
return AVAILABLE;
}
private AtomicFieldUpdaterUtil() {
// Unused
}
}