| 21 |
|
* producer. The <em>tail</em> of the queue is that element that has |
| 22 |
|
* been on the queue the shortest time for some producer. |
| 23 |
|
* |
| 24 |
< |
* <p>Beware that, unlike in most collections, the <tt>size</tt> |
| 24 |
> |
* <p>Beware that, unlike in most collections, the {@code size} |
| 25 |
|
* method is <em>NOT</em> a constant-time operation. Because of the |
| 26 |
|
* asynchronous nature of these queues, determining the current number |
| 27 |
|
* of elements requires a traversal of the elements. |
| 51 |
|
private static final long serialVersionUID = -3223113410248163686L; |
| 52 |
|
|
| 53 |
|
/* |
| 54 |
– |
* This is still a work in progress... |
| 55 |
– |
* |
| 54 |
|
* This class extends the approach used in FIFO-mode |
| 55 |
|
* SynchronousQueues. See the internal documentation, as well as |
| 56 |
|
* the PPoPP 2006 paper "Scalable Synchronous Queues" by Scherer, |
| 57 |
|
* Lea & Scott |
| 58 |
|
* (http://www.cs.rice.edu/~wns1/papers/2006-PPoPP-SQ.pdf) |
| 59 |
|
* |
| 60 |
< |
* The main extension is to provide different Wait modes |
| 61 |
< |
* for the main "xfer" method that puts or takes items. |
| 62 |
< |
* These don't impact the basic dual-queue logic, but instead |
| 63 |
< |
* control whether or how threads block upon insertion |
| 64 |
< |
* of request or data nodes into the dual queue. |
| 60 |
> |
* The main extension is to provide different Wait modes for the |
| 61 |
> |
* main "xfer" method that puts or takes items. These don't |
| 62 |
> |
* impact the basic dual-queue logic, but instead control whether |
| 63 |
> |
* or how threads block upon insertion of request or data nodes |
| 64 |
> |
* into the dual queue. It also uses slightly different |
| 65 |
> |
* conventions for tracking whether nodes are off-list or |
| 66 |
> |
* cancelled. |
| 67 |
|
*/ |
| 68 |
|
|
| 69 |
|
// Wait modes for xfer method |
| 97 |
|
static final long spinForTimeoutThreshold = 1000L; |
| 98 |
|
|
| 99 |
|
/** |
| 100 |
< |
* Node class for LinkedTransferQueue. Opportunistically subclasses from |
| 101 |
< |
* AtomicReference to represent item. Uses Object, not E, to allow |
| 102 |
< |
* setting item to "this" after use, to avoid garbage |
| 103 |
< |
* retention. Similarly, setting the next field to this is used as |
| 104 |
< |
* sentinel that node is off list. |
| 100 |
> |
* Node class for LinkedTransferQueue. Opportunistically |
| 101 |
> |
* subclasses from AtomicReference to represent item. Uses Object, |
| 102 |
> |
* not E, to allow setting item to "this" after use, to avoid |
| 103 |
> |
* garbage retention. Similarly, setting the next field to this is |
| 104 |
> |
* used as sentinel that node is off list. |
| 105 |
|
*/ |
| 106 |
|
static final class QNode extends AtomicReference<Object> { |
| 107 |
|
volatile QNode next; |
| 116 |
|
nextUpdater = AtomicReferenceFieldUpdater.newUpdater |
| 117 |
|
(QNode.class, QNode.class, "next"); |
| 118 |
|
|
| 119 |
< |
boolean casNext(QNode cmp, QNode val) { |
| 119 |
> |
final boolean casNext(QNode cmp, QNode val) { |
| 120 |
|
return nextUpdater.compareAndSet(this, cmp, val); |
| 121 |
|
} |
| 122 |
+ |
|
| 123 |
+ |
final void clearNext() { |
| 124 |
+ |
nextUpdater.lazySet(this, this); |
| 125 |
+ |
} |
| 126 |
+ |
|
| 127 |
|
} |
| 128 |
|
|
| 129 |
|
/** |
| 156 |
|
*/ |
| 157 |
|
private boolean advanceHead(QNode h, QNode nh) { |
| 158 |
|
if (h == head.get() && head.compareAndSet(h, nh)) { |
| 159 |
< |
h.next = h; // forget old next |
| 159 |
> |
h.clearNext(); // forget old next |
| 160 |
|
return true; |
| 161 |
|
} |
| 162 |
|
return false; |
| 164 |
|
|
| 165 |
|
/** |
| 166 |
|
* Puts or takes an item. Used for most queue operations (except |
| 167 |
< |
* poll() and tryTransfer()) |
| 167 |
> |
* poll() and tryTransfer()). See the similar code in |
| 168 |
> |
* SynchronousQueue for detailed explanation. |
| 169 |
|
* @param e the item or if null, signifies that this is a take |
| 170 |
|
* @param mode the wait mode: NOWAIT, TIMEOUT, WAIT |
| 171 |
|
* @param nanos timeout in nanosecs, used only if mode is TIMEOUT |
| 272 |
|
Object x = s.get(); |
| 273 |
|
if (x != e) { // Node was matched or cancelled |
| 274 |
|
advanceHead(pred, s); // unlink if head |
| 275 |
< |
if (x == s) // was cancelled |
| 276 |
< |
return clean(pred, s); |
| 275 |
> |
if (x == s) { // was cancelled |
| 276 |
> |
clean(pred, s); |
| 277 |
> |
return null; |
| 278 |
> |
} |
| 279 |
|
else if (x != null) { |
| 280 |
|
s.set(s); // avoid garbage retention |
| 281 |
|
return x; |
| 283 |
|
else |
| 284 |
|
return e; |
| 285 |
|
} |
| 278 |
– |
|
| 286 |
|
if (mode == TIMEOUT) { |
| 287 |
|
long now = System.nanoTime(); |
| 288 |
|
nanos -= now - lastTime; |
| 303 |
|
else if (s.waiter == null) |
| 304 |
|
s.waiter = w; |
| 305 |
|
else if (mode != TIMEOUT) { |
| 306 |
< |
// LockSupport.park(this); |
| 300 |
< |
LockSupport.park(); // allows run on java5 |
| 306 |
> |
LockSupport.park(this); |
| 307 |
|
s.waiter = null; |
| 308 |
|
spins = -1; |
| 309 |
|
} |
| 310 |
|
else if (nanos > spinForTimeoutThreshold) { |
| 311 |
< |
// LockSupport.parkNanos(this, nanos); |
| 306 |
< |
LockSupport.parkNanos(nanos); |
| 311 |
> |
LockSupport.parkNanos(this, nanos); |
| 312 |
|
s.waiter = null; |
| 313 |
|
spins = -1; |
| 314 |
|
} |
| 316 |
|
} |
| 317 |
|
|
| 318 |
|
/** |
| 319 |
+ |
* Returns validated tail for use in cleaning methods |
| 320 |
+ |
*/ |
| 321 |
+ |
private QNode getValidatedTail() { |
| 322 |
+ |
for (;;) { |
| 323 |
+ |
QNode h = head.get(); |
| 324 |
+ |
QNode first = h.next; |
| 325 |
+ |
if (first != null && first.next == first) { // help advance |
| 326 |
+ |
advanceHead(h, first); |
| 327 |
+ |
continue; |
| 328 |
+ |
} |
| 329 |
+ |
QNode t = tail.get(); |
| 330 |
+ |
QNode last = t.next; |
| 331 |
+ |
if (t == tail.get()) { |
| 332 |
+ |
if (last != null) |
| 333 |
+ |
tail.compareAndSet(t, last); // help advance |
| 334 |
+ |
else |
| 335 |
+ |
return t; |
| 336 |
+ |
} |
| 337 |
+ |
} |
| 338 |
+ |
} |
| 339 |
+ |
|
| 340 |
+ |
/** |
| 341 |
|
* Gets rid of cancelled node s with original predecessor pred. |
| 342 |
< |
* @return null (to simplify use by callers) |
| 342 |
> |
* @param pred predecessor of cancelled node |
| 343 |
> |
* @param s the cancelled node |
| 344 |
|
*/ |
| 345 |
< |
private Object clean(QNode pred, QNode s) { |
| 345 |
> |
private void clean(QNode pred, QNode s) { |
| 346 |
|
Thread w = s.waiter; |
| 347 |
|
if (w != null) { // Wake up thread |
| 348 |
|
s.waiter = null; |
| 350 |
|
LockSupport.unpark(w); |
| 351 |
|
} |
| 352 |
|
|
| 353 |
< |
for (;;) { |
| 354 |
< |
if (pred.next != s) // already cleaned |
| 355 |
< |
return null; |
| 356 |
< |
QNode h = head.get(); |
| 357 |
< |
QNode hn = h.next; // Absorb cancelled first node as head |
| 358 |
< |
if (hn != null && hn.next == hn) { |
| 359 |
< |
advanceHead(h, hn); |
| 360 |
< |
continue; |
| 361 |
< |
} |
| 362 |
< |
QNode t = tail.get(); // Ensure consistent read for tail |
| 363 |
< |
if (t == h) |
| 364 |
< |
return null; |
| 365 |
< |
QNode tn = t.next; |
| 366 |
< |
if (t != tail.get()) |
| 367 |
< |
continue; |
| 368 |
< |
if (tn != null) { // Help advance tail |
| 341 |
< |
tail.compareAndSet(t, tn); |
| 342 |
< |
continue; |
| 343 |
< |
} |
| 344 |
< |
if (s != t) { // If not tail, try to unsplice |
| 345 |
< |
QNode sn = s.next; |
| 353 |
> |
if (pred == null) |
| 354 |
> |
return; |
| 355 |
> |
|
| 356 |
> |
/* |
| 357 |
> |
* At any given time, exactly one node on list cannot be |
| 358 |
> |
* deleted -- the last inserted node. To accommodate this, if |
| 359 |
> |
* we cannot delete s, we save its predecessor as "cleanMe", |
| 360 |
> |
* processing the previously saved version first. At least one |
| 361 |
> |
* of node s or the node previously saved can always be |
| 362 |
> |
* processed, so this always terminates. |
| 363 |
> |
*/ |
| 364 |
> |
while (pred.next == s) { |
| 365 |
> |
QNode oldpred = reclean(); // First, help get rid of cleanMe |
| 366 |
> |
QNode t = getValidatedTail(); |
| 367 |
> |
if (s != t) { // If not tail, try to unsplice |
| 368 |
> |
QNode sn = s.next; // s.next == s means s already off list |
| 369 |
|
if (sn == s || pred.casNext(s, sn)) |
| 370 |
< |
return null; |
| 370 |
> |
break; |
| 371 |
|
} |
| 372 |
< |
QNode dp = cleanMe.get(); |
| 373 |
< |
if (dp != null) { // Try unlinking previous cancelled node |
| 374 |
< |
QNode d = dp.next; |
| 375 |
< |
QNode dn; |
| 376 |
< |
if (d == null || // d is gone or |
| 377 |
< |
d == dp || // d is off list or |
| 378 |
< |
d.get() != d || // d not cancelled or |
| 379 |
< |
(d != t && // d not tail and |
| 380 |
< |
(dn = d.next) != null && // has successor |
| 381 |
< |
dn != d && // that is on list |
| 382 |
< |
dp.casNext(d, dn))) // d unspliced |
| 383 |
< |
cleanMe.compareAndSet(dp, null); |
| 384 |
< |
if (dp == pred) |
| 385 |
< |
return null; // s is already saved node |
| 372 |
> |
else if (oldpred == pred || // Already saved |
| 373 |
> |
(oldpred == null && cleanMe.compareAndSet(null, pred))) |
| 374 |
> |
break; // Postpone cleaning |
| 375 |
> |
} |
| 376 |
> |
} |
| 377 |
> |
|
| 378 |
> |
/** |
| 379 |
> |
* Tries to unsplice the cancelled node held in cleanMe that was |
| 380 |
> |
* previously uncleanable because it was at tail. |
| 381 |
> |
* @return current cleanMe node (or null) |
| 382 |
> |
*/ |
| 383 |
> |
private QNode reclean() { |
| 384 |
> |
/* |
| 385 |
> |
* cleanMe is, or at one time was, predecessor of cancelled |
| 386 |
> |
* node s that was the tail so could not be unspliced. If s |
| 387 |
> |
* is no longer the tail, try to unsplice if necessary and |
| 388 |
> |
* make cleanMe slot available. This differs from similar |
| 389 |
> |
* code in clean() because we must check that pred still |
| 390 |
> |
* points to a cancelled node that must be unspliced -- if |
| 391 |
> |
* not, we can (must) clear cleanMe without unsplicing. |
| 392 |
> |
* This can loop only due to contention on casNext or |
| 393 |
> |
* clearing cleanMe. |
| 394 |
> |
*/ |
| 395 |
> |
QNode pred; |
| 396 |
> |
while ((pred = cleanMe.get()) != null) { |
| 397 |
> |
QNode t = getValidatedTail(); |
| 398 |
> |
QNode s = pred.next; |
| 399 |
> |
if (s != t) { |
| 400 |
> |
QNode sn; |
| 401 |
> |
if (s == null || s == pred || s.get() != s || |
| 402 |
> |
(sn = s.next) == s || pred.casNext(s, sn)) |
| 403 |
> |
cleanMe.compareAndSet(pred, null); |
| 404 |
|
} |
| 405 |
< |
else if (cleanMe.compareAndSet(null, pred)) |
| 406 |
< |
return null; // Postpone cleaning s |
| 405 |
> |
else // s is still tail; cannot clean |
| 406 |
> |
break; |
| 407 |
|
} |
| 408 |
+ |
return pred; |
| 409 |
|
} |
| 410 |
|
|
| 411 |
|
/** |
| 412 |
< |
* Creates an initially empty <tt>LinkedTransferQueue</tt>. |
| 412 |
> |
* Creates an initially empty {@code LinkedTransferQueue}. |
| 413 |
|
*/ |
| 414 |
|
public LinkedTransferQueue() { |
| 415 |
|
QNode dummy = new QNode(null, false); |
| 419 |
|
} |
| 420 |
|
|
| 421 |
|
/** |
| 422 |
< |
* Creates a <tt>LinkedTransferQueue</tt> |
| 422 |
> |
* Creates a {@code LinkedTransferQueue} |
| 423 |
|
* initially containing the elements of the given collection, |
| 424 |
|
* added in traversal order of the collection's iterator. |
| 425 |
|
* @param c the collection of elements to initially contain |
| 451 |
|
return true; |
| 452 |
|
} |
| 453 |
|
|
| 454 |
+ |
public boolean add(E e) { |
| 455 |
+ |
if (e == null) throw new NullPointerException(); |
| 456 |
+ |
xfer(e, NOWAIT, 0); |
| 457 |
+ |
return true; |
| 458 |
+ |
} |
| 459 |
+ |
|
| 460 |
|
public void transfer(E e) throws InterruptedException { |
| 461 |
|
if (e == null) throw new NullPointerException(); |
| 462 |
|
if (xfer(e, WAIT, 0) == null) { |
| 553 |
|
return h; |
| 554 |
|
} |
| 555 |
|
} |
| 556 |
+ |
reclean(); |
| 557 |
|
} |
| 558 |
|
} |
| 559 |
|
|
| 570 |
|
* if subsequently removed. |
| 571 |
|
*/ |
| 572 |
|
class Itr implements Iterator<E> { |
| 573 |
< |
QNode nextNode; // Next node to return next |
| 574 |
< |
QNode currentNode; // last returned node, for remove() |
| 575 |
< |
QNode prevNode; // predecessor of last returned node |
| 573 |
> |
QNode next; // node to return next |
| 574 |
> |
QNode pnext; // predecessor of next |
| 575 |
> |
QNode snext; // successor of next |
| 576 |
> |
QNode curr; // last returned node, for remove() |
| 577 |
> |
QNode pcurr; // predecessor of curr, for remove() |
| 578 |
|
E nextItem; // Cache of next item, once commited to in next |
| 579 |
|
|
| 580 |
|
Itr() { |
| 581 |
< |
nextNode = traversalHead(); |
| 531 |
< |
advance(); |
| 581 |
> |
findNext(); |
| 582 |
|
} |
| 583 |
|
|
| 584 |
< |
E advance() { |
| 585 |
< |
prevNode = currentNode; |
| 586 |
< |
currentNode = nextNode; |
| 587 |
< |
E x = nextItem; |
| 538 |
< |
|
| 539 |
< |
QNode p = nextNode.next; |
| 584 |
> |
/** |
| 585 |
> |
* Ensure next points to next valid node, or null if none. |
| 586 |
> |
*/ |
| 587 |
> |
void findNext() { |
| 588 |
|
for (;;) { |
| 589 |
< |
if (p == null || !p.isData) { |
| 590 |
< |
nextNode = null; |
| 591 |
< |
nextItem = null; |
| 592 |
< |
return x; |
| 589 |
> |
QNode pred = pnext; |
| 590 |
> |
QNode q = next; |
| 591 |
> |
if (pred == null || pred == q) { |
| 592 |
> |
pred = traversalHead(); |
| 593 |
> |
q = pred.next; |
| 594 |
|
} |
| 595 |
< |
Object item = p.get(); |
| 596 |
< |
if (item != p && item != null) { |
| 597 |
< |
nextNode = p; |
| 549 |
< |
nextItem = (E)item; |
| 550 |
< |
return x; |
| 595 |
> |
if (q == null || !q.isData) { |
| 596 |
> |
next = null; |
| 597 |
> |
return; |
| 598 |
|
} |
| 599 |
< |
prevNode = p; |
| 600 |
< |
p = p.next; |
| 599 |
> |
Object x = q.get(); |
| 600 |
> |
QNode s = q.next; |
| 601 |
> |
if (x != null && q != x && q != s) { |
| 602 |
> |
nextItem = (E)x; |
| 603 |
> |
snext = s; |
| 604 |
> |
pnext = pred; |
| 605 |
> |
next = q; |
| 606 |
> |
return; |
| 607 |
> |
} |
| 608 |
> |
pnext = q; |
| 609 |
> |
next = s; |
| 610 |
|
} |
| 611 |
|
} |
| 612 |
|
|
| 613 |
|
public boolean hasNext() { |
| 614 |
< |
return nextNode != null; |
| 614 |
> |
return next != null; |
| 615 |
|
} |
| 616 |
|
|
| 617 |
|
public E next() { |
| 618 |
< |
if (nextNode == null) throw new NoSuchElementException(); |
| 619 |
< |
return advance(); |
| 618 |
> |
if (next == null) throw new NoSuchElementException(); |
| 619 |
> |
pcurr = pnext; |
| 620 |
> |
curr = next; |
| 621 |
> |
pnext = next; |
| 622 |
> |
next = snext; |
| 623 |
> |
E x = nextItem; |
| 624 |
> |
findNext(); |
| 625 |
> |
return x; |
| 626 |
|
} |
| 627 |
|
|
| 628 |
|
public void remove() { |
| 629 |
< |
QNode p = currentNode; |
| 630 |
< |
QNode prev = prevNode; |
| 569 |
< |
if (prev == null || p == null) |
| 629 |
> |
QNode p = curr; |
| 630 |
> |
if (p == null) |
| 631 |
|
throw new IllegalStateException(); |
| 632 |
|
Object x = p.get(); |
| 633 |
|
if (x != null && x != p && p.compareAndSet(x, p)) |
| 634 |
< |
clean(prev, p); |
| 634 |
> |
clean(pcurr, p); |
| 635 |
|
} |
| 636 |
|
} |
| 637 |
|
|
| 681 |
|
|
| 682 |
|
/** |
| 683 |
|
* Returns the number of elements in this queue. If this queue |
| 684 |
< |
* contains more than <tt>Integer.MAX_VALUE</tt> elements, returns |
| 685 |
< |
* <tt>Integer.MAX_VALUE</tt>. |
| 684 |
> |
* contains more than {@code Integer.MAX_VALUE} elements, returns |
| 685 |
> |
* {@code Integer.MAX_VALUE}. |
| 686 |
|
* |
| 687 |
|
* <p>Beware that, unlike in most collections, this method is |
| 688 |
|
* <em>NOT</em> a constant-time operation. Because of the |
| 720 |
|
return Integer.MAX_VALUE; |
| 721 |
|
} |
| 722 |
|
|
| 723 |
+ |
public boolean remove(Object o) { |
| 724 |
+ |
if (o == null) |
| 725 |
+ |
return false; |
| 726 |
+ |
for (;;) { |
| 727 |
+ |
QNode pred = traversalHead(); |
| 728 |
+ |
for (;;) { |
| 729 |
+ |
QNode q = pred.next; |
| 730 |
+ |
if (q == null || !q.isData) |
| 731 |
+ |
return false; |
| 732 |
+ |
if (q == pred) // restart |
| 733 |
+ |
break; |
| 734 |
+ |
Object x = q.get(); |
| 735 |
+ |
if (x != null && x != q && o.equals(x) && |
| 736 |
+ |
q.compareAndSet(x, q)) { |
| 737 |
+ |
clean(pred, q); |
| 738 |
+ |
return true; |
| 739 |
+ |
} |
| 740 |
+ |
pred = q; |
| 741 |
+ |
} |
| 742 |
+ |
} |
| 743 |
+ |
} |
| 744 |
+ |
|
| 745 |
|
/** |
| 746 |
|
* Save the state to a stream (that is, serialize it). |
| 747 |
|
* |
| 748 |
< |
* @serialData All of the elements (each an <tt>E</tt>) in |
| 748 |
> |
* @serialData All of the elements (each an {@code E}) in |
| 749 |
|
* the proper order, followed by a null |
| 750 |
|
* @param s the stream |
| 751 |
|
*/ |
| 778 |
|
|
| 779 |
|
|
| 780 |
|
// Support for resetting head/tail while deserializing |
| 781 |
+ |
private void resetHeadAndTail() { |
| 782 |
+ |
QNode dummy = new QNode(null, false); |
| 783 |
+ |
_unsafe.putObjectVolatile(this, headOffset, |
| 784 |
+ |
new PaddedAtomicReference<QNode>(dummy)); |
| 785 |
+ |
_unsafe.putObjectVolatile(this, tailOffset, |
| 786 |
+ |
new PaddedAtomicReference<QNode>(dummy)); |
| 787 |
+ |
_unsafe.putObjectVolatile(this, cleanMeOffset, |
| 788 |
+ |
new PaddedAtomicReference<QNode>(null)); |
| 789 |
+ |
} |
| 790 |
|
|
| 791 |
|
// Temporary Unsafe mechanics for preliminary release |
| 792 |
+ |
private static Unsafe getUnsafe() throws Throwable { |
| 793 |
+ |
try { |
| 794 |
+ |
return Unsafe.getUnsafe(); |
| 795 |
+ |
} catch (SecurityException se) { |
| 796 |
+ |
try { |
| 797 |
+ |
return java.security.AccessController.doPrivileged |
| 798 |
+ |
(new java.security.PrivilegedExceptionAction<Unsafe>() { |
| 799 |
+ |
public Unsafe run() throws Exception { |
| 800 |
+ |
return getUnsafePrivileged(); |
| 801 |
+ |
}}); |
| 802 |
+ |
} catch (java.security.PrivilegedActionException e) { |
| 803 |
+ |
throw e.getCause(); |
| 804 |
+ |
} |
| 805 |
+ |
} |
| 806 |
+ |
} |
| 807 |
+ |
|
| 808 |
+ |
private static Unsafe getUnsafePrivileged() |
| 809 |
+ |
throws NoSuchFieldException, IllegalAccessException { |
| 810 |
+ |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
| 811 |
+ |
f.setAccessible(true); |
| 812 |
+ |
return (Unsafe) f.get(null); |
| 813 |
+ |
} |
| 814 |
+ |
|
| 815 |
+ |
private static long fieldOffset(String fieldName) |
| 816 |
+ |
throws NoSuchFieldException { |
| 817 |
+ |
return _unsafe.objectFieldOffset |
| 818 |
+ |
(LinkedTransferQueue.class.getDeclaredField(fieldName)); |
| 819 |
+ |
} |
| 820 |
+ |
|
| 821 |
|
private static final Unsafe _unsafe; |
| 822 |
|
private static final long headOffset; |
| 823 |
|
private static final long tailOffset; |
| 824 |
|
private static final long cleanMeOffset; |
| 825 |
|
static { |
| 826 |
|
try { |
| 827 |
< |
if (LinkedTransferQueue.class.getClassLoader() != null) { |
| 828 |
< |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
| 829 |
< |
f.setAccessible(true); |
| 830 |
< |
_unsafe = (Unsafe)f.get(null); |
| 831 |
< |
} |
| 711 |
< |
else |
| 712 |
< |
_unsafe = Unsafe.getUnsafe(); |
| 713 |
< |
headOffset = _unsafe.objectFieldOffset |
| 714 |
< |
(LinkedTransferQueue.class.getDeclaredField("head")); |
| 715 |
< |
tailOffset = _unsafe.objectFieldOffset |
| 716 |
< |
(LinkedTransferQueue.class.getDeclaredField("tail")); |
| 717 |
< |
cleanMeOffset = _unsafe.objectFieldOffset |
| 718 |
< |
(LinkedTransferQueue.class.getDeclaredField("cleanMe")); |
| 719 |
< |
} catch (Exception e) { |
| 827 |
> |
_unsafe = getUnsafe(); |
| 828 |
> |
headOffset = fieldOffset("head"); |
| 829 |
> |
tailOffset = fieldOffset("tail"); |
| 830 |
> |
cleanMeOffset = fieldOffset("cleanMe"); |
| 831 |
> |
} catch (Throwable e) { |
| 832 |
|
throw new RuntimeException("Could not initialize intrinsics", e); |
| 833 |
|
} |
| 834 |
|
} |
| 835 |
|
|
| 724 |
– |
private void resetHeadAndTail() { |
| 725 |
– |
QNode dummy = new QNode(null, false); |
| 726 |
– |
_unsafe.putObjectVolatile(this, headOffset, dummy); |
| 727 |
– |
_unsafe.putObjectVolatile(this, tailOffset, dummy); |
| 728 |
– |
_unsafe.putObjectVolatile(this, cleanMeOffset, |
| 729 |
– |
new PaddedAtomicReference<QNode>(null)); |
| 730 |
– |
|
| 731 |
– |
} |
| 732 |
– |
|
| 836 |
|
} |
