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package shz.core.node;

import shz.core.UnsafeHelp;

/**
 * 元素类型为long支持并发的双向链表节点
 * 

* 24*n(n为元素个数) *

* B=16+24*n */ @SuppressWarnings("restriction") public class ConcurrentJDNode implements DNode { public volatile long val; protected volatile ConcurrentJDNode next; protected volatile ConcurrentJDNode prev; protected ConcurrentJDNode(long val) { this.val = val; } public static ConcurrentJDNode of(long e) { return new ConcurrentJDNode(e); } public static ConcurrentJDNode of() { return of(0L); } private static final long valOffset; private static final long nextOffset; private static final long prevOffset; static { try { Class k = ConcurrentJDNode.class; valOffset = UnsafeHelp.getUnsafe().objectFieldOffset(k.getDeclaredField("val")); nextOffset = UnsafeHelp.getUnsafe().objectFieldOffset(k.getDeclaredField("next")); prevOffset = UnsafeHelp.getUnsafe().objectFieldOffset(k.getDeclaredField("prev")); } catch (Exception e) { throw new Error(e); } } public boolean casVal(long expect, long val) { return UnsafeHelp.getUnsafe().compareAndSwapLong(this, valOffset, expect, val); } public boolean casNext(ConcurrentJDNode expect, ConcurrentJDNode next) { return UnsafeHelp.getUnsafe().compareAndSwapObject(this, nextOffset, expect, next); } public boolean casPrev(ConcurrentJDNode expect, ConcurrentJDNode prev) { return UnsafeHelp.getUnsafe().compareAndSwapObject(this, prevOffset, expect, prev); } @Override public final ConcurrentJDNode next() { return next; } @Override public final void next(ConcurrentJDNode node) { next = node; } @Override public final ConcurrentJDNode prev() { return prev; } @Override public final void prev(ConcurrentJDNode node) { prev = node; } @Override public final ConcurrentJDNode addNext(ConcurrentJDNode node) { while (true) { ConcurrentJDNode next = this.next; node.prev = this; node.next = next; if (!casNext(next, node)) continue; if (next != null) next.prev = node; break; } return node; } @Override public final ConcurrentJDNode addPrev(ConcurrentJDNode node) { while (true) { ConcurrentJDNode prev = this.prev; node.prev = prev; node.next = this; if (!casPrev(prev, node)) continue; if (prev != null) prev.next = node; break; } return node; } @Override public final void poll() { ConcurrentJDNode prev = this.prev; ConcurrentJDNode next = this.next; if (prev != null) { if (prev.casNext(this, next)) if (next != null) next.prev = prev; } else if (next != null) next.casPrev(this, null); } public final ConcurrentJDNode addNext(long e) { return addNext(of(e)); } public final ConcurrentJDNode addNext(long... es) { ConcurrentJDNode next = this; for (long e : es) next = next.addNext(e); return next; } public final ConcurrentJDNode addPrev(long e) { return addPrev(of(e)); } public final ConcurrentJDNode addPrev(long... es) { ConcurrentJDNode prev = this; for (long e : es) prev = prev.addPrev(e); return prev; } }





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