66 lines
2.0 KiB
Java
66 lines
2.0 KiB
Java
/*
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* Copyright 2014 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.util.internal;
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import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
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public abstract class MpscLinkedQueueNode<T> {
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@SuppressWarnings("rawtypes")
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private static final AtomicReferenceFieldUpdater<MpscLinkedQueueNode, MpscLinkedQueueNode> nextUpdater;
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static {
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@SuppressWarnings("rawtypes")
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AtomicReferenceFieldUpdater<MpscLinkedQueueNode, MpscLinkedQueueNode> u;
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u = PlatformDependent.newAtomicReferenceFieldUpdater(MpscLinkedQueueNode.class, "next");
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if (u == null) {
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u = AtomicReferenceFieldUpdater.newUpdater(MpscLinkedQueueNode.class, MpscLinkedQueueNode.class, "next");
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}
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nextUpdater = u;
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}
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@SuppressWarnings("unused")
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private volatile MpscLinkedQueueNode<T> next;
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final MpscLinkedQueueNode<T> next() {
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return next;
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}
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final void setNext(final MpscLinkedQueueNode<T> newNext) {
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// Similar to 'next = newNext', but slightly faster (storestore vs loadstore)
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// See: http://robsjava.blogspot.com/2013/06/a-faster-volatile.html
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nextUpdater.lazySet(this, newNext);
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}
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public abstract T value();
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/**
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* Sets the element this node contains to {@code null} so that the node can be used as a tombstone.
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*/
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protected T clearMaybe() {
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return value();
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}
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/**
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* Unlink to allow GC'ed
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*/
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void unlink() {
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setNext(null);
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}
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}
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