co.paralleluniverse.strands.queues.SingleConsumerLinkedObjectQueue Maven / Gradle / Ivy
/*
* Quasar: lightweight threads and actors for the JVM.
* Copyright (c) 2013-2015, Parallel Universe Software Co. All rights reserved.
*
* This program and the accompanying materials are dual-licensed under
* either the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation
*
* or (per the licensee's choosing)
*
* under the terms of the GNU Lesser General Public License version 3.0
* as published by the Free Software Foundation.
*/
package co.paralleluniverse.strands.queues;
import co.paralleluniverse.common.util.Objects;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.VarHandle;
/**
*
* @author pron
*/
public class SingleConsumerLinkedObjectQueue extends SingleConsumerLinkedQueue {
@Override
Node newNode() {
return new ObjectNode();
}
@Override
public boolean enq(E item) {
if (item == null)
throw new IllegalArgumentException("null values not allowed");
ObjectNode node = new ObjectNode();
node.value = item;
return enq(node);
}
@Override
E value(Node node) {
return ((ObjectNode) node).value;
}
static class ObjectNode extends Node {
E value;
@Override
public String toString() {
return "Node{" + "value: " + value + ", next: " + next + ", prev: " + Objects.systemToString(prev) + '}';
}
}
private static final VarHandle VALUE;
static {
try {
MethodHandles.Lookup l = MethodHandles.lookup();
VALUE = l.findVarHandle(ObjectNode.class, "value", Object.class);
} catch (ReflectiveOperationException e) {
throw new ExceptionInInitializerError(e);
}
}
@Override
void clearValue(Node node) {
VALUE.setOpaque(node, null); // UNSAFE.putOrderedObject(node, valueOffset, null);
}
// private static final long valueOffset;
//
// static {
// try {
// valueOffset = UNSAFE.objectFieldOffset(ObjectNode.class.getDeclaredField("value"));
// } catch (Exception ex) {
// throw new Error(ex);
// }
// }
//
// @Override
// void clearValue(Node node) {
// UNSAFE.putOrderedObject(node, valueOffset, null);
// }
}