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root/jsr166/jsr166/src/jsr166y/Phaser.java

Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.52 by dl, Sat Nov 13 01:27:13 2010 UTC vs.
Revision 1.62 by dl, Mon Nov 29 00:52:28 2010 UTC

#	Line 18 | Line 18 | import java.util.concurrent.locks.LockSu
18		* but supporting more flexible usage.
19		*
20		* <p> <b>Registration.</b> Unlike the case for other barriers, the
21	<	* number of parties <em>registered</em> to synchronize on a phaser
21	>	* number of parties <em>registered</em> to synchronize on a Phaser
22		* may vary over time.  Tasks may be registered at any time (using
23		* methods {@link #register}, {@link #bulkRegister}, or forms of
24		* constructors establishing initial numbers of parties), and
#	Line 76 | Line 76 | import java.util.concurrent.locks.LockSu
76		*
77		* <p> <b>Termination.</b> A {@code Phaser} may enter a
78		* <em>termination</em> state in which all synchronization methods
79	<	* immediately return without updating phaser state or waiting for
79	>	* immediately return without updating Phaser state or waiting for
80		* advance, and indicating (via a negative phase value) that execution
81		* is complete.  Termination is triggered when an invocation of {@code
82	<	* onAdvance} returns {@code true}.  As illustrated below, when
83	<	* phasers control actions with a fixed number of iterations, it is
82	>	* onAdvance} returns {@code true}. The default implementation returns
83	>	* {@code true} if a deregistration has caused the number of
84	>	* registered parties to become zero.  As illustrated below, when
85	>	* Phasers control actions with a fixed number of iterations, it is
86		* often convenient to override this method to cause termination when
87		* the current phase number reaches a threshold. Method {@link
88		* #forceTermination} is also available to abruptly release waiting
89		* threads and allow them to terminate.
90		*
91	<	* <p> <b>Tiering.</b> Phasers may be <em>tiered</em> (i.e., arranged
92	<	* in tree structures) to reduce contention. Phasers with large
93	<	* numbers of parties that would otherwise experience heavy
91	>	* <p> <b>Tiering.</b> Phasers may be <em>tiered</em> (i.e.,
92	>	* constructed in tree structures) to reduce contention. Phasers with
93	>	* large numbers of parties that would otherwise experience heavy
94		* synchronization contention costs may instead be set up so that
95		* groups of sub-phasers share a common parent.  This may greatly
96		* increase throughput even though it incurs greater per-operation
97		* overhead.
98		*
99		* <p><b>Monitoring.</b> While synchronization methods may be invoked
100	<	* only by registered parties, the current state of a phaser may be
100	>	* only by registered parties, the current state of a Phaser may be
101		* monitored by any caller.  At any given moment there are {@link
102		* #getRegisteredParties} parties in total, of which {@link
103		* #getArrivedParties} have arrived at the current phase ({@link
#	Line 181 | Line 183 | import java.util.concurrent.locks.LockSu
183		* }}</pre>
184		*
185		*
186	<	* <p>To create a set of tasks using a tree of phasers,
186	>	* <p>To create a set of tasks using a tree of Phasers,
187		* you could use code of the following form, assuming a
188	<	* Task class with a constructor accepting a phaser that
188	>	* Task class with a constructor accepting a Phaser that
189		* it registers with upon construction:
190		*
191		*  <pre> {@code
#	Line 210 | Line 212 | import java.util.concurrent.locks.LockSu
212		* <p><b>Implementation notes</b>: This implementation restricts the
213		* maximum number of parties to 65535. Attempts to register additional
214		* parties result in {@code IllegalStateException}. However, you can and
215	<	* should create tiered phasers to accommodate arbitrarily large sets
215	>	* should create tiered Phasers to accommodate arbitrarily large sets
216		* of participants.
217		*
218		* @since 1.7
#	Line 240 | Line 242 | public class Phaser {
242		*/
243		private volatile long state;
244
245	<	private static final int  MAX_COUNT      = 0xffff;
246	<	private static final int  MAX_PHASE      = 0x7fffffff;
247	<	private static final int  PARTIES_SHIFT  = 16;
248	<	private static final int  PHASE_SHIFT    = 32;
249	<	private static final long UNARRIVED_MASK = 0xffffL;
250	<	private static final long PARTIES_MASK   = 0xffff0000L;
251	<	private static final long ONE_ARRIVAL    = 1L;
252	<	private static final long ONE_PARTY      = 1L << PARTIES_SHIFT;
253	<	private static final long TERMINATION_PHASE  = -1L << PHASE_SHIFT;
245	>	private static final int  MAX_PARTIES     = 0xffff;
246	>	private static final int  MAX_PHASE       = 0x7fffffff;
247	>	private static final int  PARTIES_SHIFT   = 16;
248	>	private static final int  PHASE_SHIFT     = 32;
249	>	private static final int  UNARRIVED_MASK  = 0xffff;      // to mask ints
250	>	private static final long PARTIES_MASK    = 0xffff0000L; // to mask longs
251	>	private static final long ONE_ARRIVAL     = 1L;
252	>	private static final long ONE_PARTY       = 1L << PARTIES_SHIFT;
253	>	private static final long TERMINATION_BIT = 1L << 63;
254
255		// The following unpacking methods are usually manually inlined
256
257		private static int unarrivedOf(long s) {
258	<	return (int) (s & UNARRIVED_MASK);
258	>	return (int)s & UNARRIVED_MASK;
259		}
260
261		private static int partiesOf(long s) {
262	<	return ((int) (s & PARTIES_MASK)) >>> PARTIES_SHIFT;
262	>	return (int)s >>> PARTIES_SHIFT;
263		}
264
265		private static int phaseOf(long s) {
#	Line 293 | Line 295 | public class Phaser {
295		}
296
297		/**
298	+	* Returns message string for bounds exceptions on arrival.
299	+	*/
300	+	private String badArrive(long s) {
301	+	return "Attempted arrival of unregistered party for " +
302	+	stateToString(s);
303	+	}
304	+
305	+	/**
306	+	* Returns message string for bounds exceptions on registration.
307	+	*/
308	+	private String badRegister(long s) {
309	+	return "Attempt to register more than " +
310	+	MAX_PARTIES + " parties for " + stateToString(s);
311	+	}
312	+
313	+	/**
314		* Main implementation for methods arrive and arriveAndDeregister.
315		* Manually tuned to speed up and minimize race windows for the
316		* common case of just decrementing unarrived field.
#	Line 302 | Line 320 | public class Phaser {
320		* ONE_ARRIVAL|ONE_PARTY (for arriveAndDeregister)
321		*/
322		private int doArrive(long adj) {
323	<	long s;
324	<	int phase, unarrived;
325	<	while ((phase = (int)((s = state) >>> PHASE_SHIFT)) >= 0) {
326	<	if ((unarrived = (int)(s & UNARRIVED_MASK)) != 0) {
327	<	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s -= adj)) {
328	<	if (unarrived == 1) {
329	<	Phaser par;
330	<	long p = s & PARTIES_MASK; // unshifted parties field
331	<	long lu = p >>> PARTIES_SHIFT;
332	<	int u = (int)lu;
333	<	int nextPhase = (phase + 1) & MAX_PHASE;
334	<	long next = ((long)nextPhase << PHASE_SHIFT) | p | lu;
335	<	if ((par = parent) == null) {
336	<	UNSAFE.compareAndSwapLong
337	<	(this, stateOffset, s, onAdvance(phase, u)?
338	<	next | TERMINATION_PHASE : next);
339	<	releaseWaiters(phase);
340	<	}
341	<	else {
342	<	par.doArrive(u == 0?
343	<	ONE_ARRIVAL|ONE_PARTY : ONE_ARRIVAL);
344	<	if ((int)(par.state >>> PHASE_SHIFT) != nextPhase ||
345	<	((int)(state >>> PHASE_SHIFT) != nextPhase &&
346	<	!UNSAFE.compareAndSwapLong(this, stateOffset,
347	<	s, next)))
348	<	reconcileState();
349	<	}
323	>	for (;;) {
324	>	long s = state;
325	>	int unarrived = (int)s & UNARRIVED_MASK;
326	>	int phase = (int)(s >>> PHASE_SHIFT);
327	>	if (phase < 0)
328	>	return phase;
329	>	else if (unarrived == 0) {
330	>	if (reconcileState() == s)     // recheck
331	>	throw new IllegalStateException(badArrive(s));
332	>	}
333	>	else if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s-=adj)) {
334	>	if (unarrived == 1) {
335	>	long p = s & PARTIES_MASK; // unshifted parties field
336	>	long lu = p >>> PARTIES_SHIFT;
337	>	int u = (int)lu;
338	>	int nextPhase = (phase + 1) & MAX_PHASE;
339	>	long next = ((long)nextPhase << PHASE_SHIFT) | p | lu;
340	>	final Phaser parent = this.parent;
341	>	if (parent == null) {
342	>	if (onAdvance(phase, u))
343	>	next |= TERMINATION_BIT;
344	>	UNSAFE.compareAndSwapLong(this, stateOffset, s, next);
345	>	releaseWaiters(phase);
346	>	}
347	>	else {
348	>	parent.doArrive((u == 0) ?
349	>	ONE_ARRIVAL|ONE_PARTY : ONE_ARRIVAL);
350	>	if ((int)(parent.state >>> PHASE_SHIFT) != nextPhase)
351	>	reconcileState();
352	>	else if (state == s)
353	>	UNSAFE.compareAndSwapLong(this, stateOffset, s,
354	>	next);
355		}
333	–	break;
356		}
357	+	return phase;
358		}
336	–	else if (state == s && reconcileState() == s) // recheck
337	–	throw new IllegalStateException(badArrive());
359		}
339	–	return phase;
340	–	}
341	–
342	–	/**
343	–	* Returns message string for bounds exceptions on arrival.
344	–	* Declared out of-line from doArrive to reduce string op bulk.
345	–	*/
346	–	private String badArrive() {
347	–	return ("Attempted arrival of unregistered party for " +
348	–	this.toString());
360		}
361
362		/**
363		* Implementation of register, bulkRegister
364		*
365	<	* @param registrations number to add to both parties and unarrived fields
365	>	* @param registrations number to add to both parties and
366	>	* unarrived fields. Must be greater than zero.
367		*/
368		private int doRegister(int registrations) {
369	<	long adj = (long)registrations; // adjustment to state
370	<	adj |= adj << PARTIES_SHIFT;
371	<	Phaser par = parent;
372	<	long s;
373	<	int phase;
374	<	while ((phase = (int)((s = (par == null? state : reconcileState()))
375	<	>>> PHASE_SHIFT)) >= 0) {
376	<	int parties = ((int)(s & PARTIES_MASK)) >>> PARTIES_SHIFT;
377	<	if (parties != 0 && (s & UNARRIVED_MASK) == 0)
378	<	internalAwaitAdvance(phase, null); // wait for onAdvance
379	<	else if (parties + registrations > MAX_COUNT)
380	<	throw new IllegalStateException(badRegister());
381	<	else if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s + adj))
382	<	break;
369	>	// adjustment to state
370	>	long adj = ((long)registrations << PARTIES_SHIFT) | registrations;
371	>	final Phaser parent = this.parent;
372	>	for (;;) {
373	>	long s = (parent == null) ? state : reconcileState();
374	>	int parties = (int)s >>> PARTIES_SHIFT;
375	>	int phase = (int)(s >>> PHASE_SHIFT);
376	>	if (phase < 0)
377	>	return phase;
378	>	else if (registrations > MAX_PARTIES - parties)
379	>	throw new IllegalStateException(badRegister(s));
380	>	else if ((parties == 0 && parent == null) || // first reg of root
381	>	((int)s & UNARRIVED_MASK) != 0) {   // not advancing
382	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s + adj))
383	>	return phase;
384	>	}
385	>	else if (parties != 0)               // wait for onAdvance
386	>	root.internalAwaitAdvance(phase, null);
387	>	else {                               // 1st registration of child
388	>	synchronized (this) {            // register parent first
389	>	if (reconcileState() == s) { // recheck under lock
390	>	parent.doRegister(1);    // OK if throws IllegalState
391	>	for (;;) {               // simpler form of outer loop
392	>	s = reconcileState();
393	>	phase = (int)(s >>> PHASE_SHIFT);
394	>	if (phase < 0 ||
395	>	UNSAFE.compareAndSwapLong(this, stateOffset,
396	>	s, s + adj))
397	>	return phase;
398	>	}
399	>	}
400	>	}
401	>	}
402		}
372	–	return phase;
373	–	}
374	–
375	–	/**
376	–	* Returns message string for bounds exceptions on registration
377	–	*/
378	–	private String badRegister() {
379	–	return ("Attempt to register more than " + MAX_COUNT + " parties for "+
380	–	this.toString());
403		}
404
405		/**
406	<	* Recursively resolves lagged phase propagation from root if
385	<	* necessary.
406	>	* Recursively resolves lagged phase propagation from root if necessary.
407		*/
408		private long reconcileState() {
409		Phaser par = parent;
410	<	if (par == null)
411	<	return state;
412	<	Phaser rt = root;
413	<	long s;
414	<	int phase, rPhase;
415	<	while ((phase = (int)((s = state) >>> PHASE_SHIFT)) >= 0 &&
416	<	(rPhase = (int)(rt.state >>> PHASE_SHIFT)) != phase) {
417	<	if (rPhase < 0 || (s & UNARRIVED_MASK) == 0) {
418	<	long ps = par.parent == null? par.state : par.reconcileState();
419	<	int pPhase = (int)(ps >>> PHASE_SHIFT);
420	<	if (pPhase < 0 || pPhase == ((phase + 1) & MAX_PHASE)) {
421	<	if (state != s)
422	<	continue;
402	<	long p = s & PARTIES_MASK;
403	<	long next = ((((long) pPhase) << PHASE_SHIFT) |
404	<	(p >>> PARTIES_SHIFT) | p);
405	<	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next))
406	<	return next;
410	>	long s = state;
411	>	if (par != null) {
412	>	Phaser rt = root;
413	>	int phase, rPhase;
414	>	while ((phase = (int)(s >>> PHASE_SHIFT)) >= 0 &&
415	>	(rPhase = (int)(rt.state >>> PHASE_SHIFT)) != phase) {
416	>	if (par != rt && (int)(par.state >>> PHASE_SHIFT) != rPhase)
417	>	par.reconcileState();
418	>	else if (rPhase < 0 || ((int)s & UNARRIVED_MASK) == 0) {
419	>	long u = s & PARTIES_MASK; // reset unarrived to parties
420	>	long next = ((((long) rPhase) << PHASE_SHIFT) | u |
421	>	(u >>> PARTIES_SHIFT));
422	>	UNSAFE.compareAndSwapLong(this, stateOffset, s, next);
423		}
424	+	s = state;
425		}
409	–	if (state == s)
410	–	releaseWaiters(phase); // help release others
426		}
427		return s;
428		}
429
430		/**
431	<	* Creates a new phaser without any initially registered parties,
431	>	* Creates a new Phaser without any initially registered parties,
432		* initial phase number 0, and no parent. Any thread using this
433	<	* phaser will need to first register for it.
433	>	* Phaser will need to first register for it.
434		*/
435		public Phaser() {
436		this(null, 0);
437		}
438
439		/**
440	<	* Creates a new phaser with the given number of registered
440	>	* Creates a new Phaser with the given number of registered
441		* unarrived parties, initial phase number 0, and no parent.
442		*
443		* @param parties the number of parties required to trip barrier
#	Line 434 | Line 449 | public class Phaser {
449		}
450
451		/**
452	<	* Creates a new phaser with the given parent, without any
438	<	* initially registered parties. If parent is non-null this phaser
439	<	* is registered with the parent and its initial phase number is
440	<	* the same as that of parent phaser.
452	>	* Equivalent to {@link #Phaser(Phaser, int) Phaser(parent, 0)}.
453		*
454	<	* @param parent the parent phaser
454	>	* @param parent the parent Phaser
455		*/
456		public Phaser(Phaser parent) {
457		this(parent, 0);
458		}
459
460		/**
461	<	* Creates a new phaser with the given parent and number of
462	<	* registered unarrived parties. If parent is non-null, this phaser
463	<	* is registered with the parent and its initial phase number is
464	<	* the same as that of parent phaser.
461	>	* Creates a new Phaser with the given parent and number of
462	>	* registered unarrived parties. Registration and deregistration
463	>	* of this child Phaser with its parent are managed automatically.
464	>	* If the given parent is non-null, whenever this child Phaser has
465	>	* any registered parties (as established in this constructor,
466	>	* {@link #register}, or {@link #bulkRegister}), this child Phaser
467	>	* is registered with its parent. Whenever the number of
468	>	* registered parties becomes zero as the result of an invocation
469	>	* of {@link #arriveAndDeregister}, this child Phaser is
470	>	* deregistered from its parent.
471		*
472	<	* @param parent the parent phaser
472	>	* @param parent the parent Phaser
473		* @param parties the number of parties required to trip barrier
474		* @throws IllegalArgumentException if parties less than zero
475		* or greater than the maximum number of parties supported
476		*/
477		public Phaser(Phaser parent, int parties) {
478	<	if (parties < 0 || parties > MAX_COUNT)
478	>	if (parties >>> PARTIES_SHIFT != 0)
479		throw new IllegalArgumentException("Illegal number of parties");
480	<	int phase;
480	>	long s = ((long) parties) | (((long) parties) << PARTIES_SHIFT);
481		this.parent = parent;
482		if (parent != null) {
483		Phaser r = parent.root;
484		this.root = r;
485		this.evenQ = r.evenQ;
486		this.oddQ = r.oddQ;
487	<	phase = parent.register();
487	>	if (parties != 0)
488	>	s |= ((long)(parent.doRegister(1))) << PHASE_SHIFT;
489		}
490		else {
491		this.root = this;
492		this.evenQ = new AtomicReference<QNode>();
493		this.oddQ = new AtomicReference<QNode>();
475	–	phase = 0;
494		}
495	<	long p = (long)parties;
478	<	this.state = (((long) phase) << PHASE_SHIFT) | p | (p << PARTIES_SHIFT);
495	>	this.state = s;
496		}
497
498		/**
499	<	* Adds a new unarrived party to this phaser.
500	<	* If an ongoing invocation of {@link #onAdvance} is in progress,
501	<	* this method may wait until its completion before registering.
499	>	* Adds a new unarrived party to this Phaser.  If an ongoing
500	>	* invocation of {@link #onAdvance} is in progress, this method
501	>	* may await its completion before returning.  If this Phaser has
502	>	* a parent, and this Phaser previously had no registered parties,
503	>	* this Phaser is also registered with its parent.
504		*
505		* @return the arrival phase number to which this registration applied
506		* @throws IllegalStateException if attempting to register more
#	Line 492 | Line 511 | public class Phaser {
511		}
512
513		/**
514	<	* Adds the given number of new unarrived parties to this phaser.
514	>	* Adds the given number of new unarrived parties to this Phaser.
515		* If an ongoing invocation of {@link #onAdvance} is in progress,
516	<	* this method may wait until its completion before registering.
516	>	* this method may await its completion before returning.  If this
517	>	* Phaser has a parent, and the given number of parities is
518	>	* greater than zero, and this Phaser previously had no registered
519	>	* parties, this Phaser is also registered with its parent.
520		*
521		* @param parties the number of additional parties required to trip barrier
522		* @return the arrival phase number to which this registration applied
#	Line 505 | Line 527 | public class Phaser {
527		public int bulkRegister(int parties) {
528		if (parties < 0)
529		throw new IllegalArgumentException();
508	–	if (parties > MAX_COUNT)
509	–	throw new IllegalStateException(badRegister());
530		if (parties == 0)
531		return getPhase();
532		return doRegister(parties);
533		}
534
535		/**
536	<	* Arrives at the barrier, but does not wait for others.  (You can
537	<	* in turn wait for others via {@link #awaitAdvance}).  It is an
538	<	* unenforced usage error for an unregistered party to invoke this
539	<	* method.
536	>	* Arrives at the barrier, without waiting for others to arrive.
537	>	*
538	>	* <p>It is a usage error for an unregistered party to invoke this
539	>	* method.  However, this error may result in an {@code
540	>	* IllegalStateException} only upon some subsequent operation on
541	>	* this Phaser, if ever.
542		*
543		* @return the arrival phase number, or a negative value if terminated
544		* @throws IllegalStateException if not terminated and the number
#	Line 528 | Line 550 | public class Phaser {
550
551		/**
552		* Arrives at the barrier and deregisters from it without waiting
553	<	* for others. Deregistration reduces the number of parties
554	<	* required to trip the barrier in future phases.  If this phaser
555	<	* has a parent, and deregistration causes this phaser to have
556	<	* zero parties, this phaser also arrives at and is deregistered
557	<	* from its parent.  It is an unenforced usage error for an
558	<	* unregistered party to invoke this method.
553	>	* for others to arrive. Deregistration reduces the number of
554	>	* parties required to trip the barrier in future phases.  If this
555	>	* Phaser has a parent, and deregistration causes this Phaser to
556	>	* have zero parties, this Phaser is also deregistered from its
557	>	* parent.
558	>	*
559	>	* <p>It is a usage error for an unregistered party to invoke this
560	>	* method.  However, this error may result in an {@code
561	>	* IllegalStateException} only upon some subsequent operation on
562	>	* this Phaser, if ever.
563		*
564		* @return the arrival phase number, or a negative value if terminated
565		* @throws IllegalStateException if not terminated and the number
#	Line 549 | Line 575 | public class Phaser {
575		* interruption or timeout, you can arrange this with an analogous
576		* construction using one of the other forms of the {@code
577		* awaitAdvance} method.  If instead you need to deregister upon
578	<	* arrival, use {@link #arriveAndDeregister}. It is an unenforced
579	<	* usage error for an unregistered party to invoke this method.
578	>	* arrival, use {@code awaitAdvance(arriveAndDeregister())}.
579	>	*
580	>	* <p>It is a usage error for an unregistered party to invoke this
581	>	* method.  However, this error may result in an {@code
582	>	* IllegalStateException} only upon some subsequent operation on
583	>	* this Phaser, if ever.
584		*
585		* @return the arrival phase number, or a negative number if terminated
586		* @throws IllegalStateException if not terminated and the number
587		* of unarrived parties would become negative
588		*/
589		public int arriveAndAwaitAdvance() {
590	<	return awaitAdvance(arrive());
590	>	return awaitAdvance(doArrive(ONE_ARRIVAL));
591		}
592
593		/**
#	Line 573 | Line 603 | public class Phaser {
603		* if terminated or argument is negative
604		*/
605		public int awaitAdvance(int phase) {
606	+	Phaser rt;
607	+	int p = (int)(state >>> PHASE_SHIFT);
608		if (phase < 0)
609		return phase;
610	<	int p = (int)((parent==null? state : reconcileState()) >>> PHASE_SHIFT);
611	<	if (p != phase)
612	<	return p;
613	<	return internalAwaitAdvance(phase, null);
610	>	if (p == phase &&
611	>	(p = (int)((rt = root).state >>> PHASE_SHIFT)) == phase)
612	>	return rt.internalAwaitAdvance(phase, null);
613	>	return p;
614		}
615
616		/**
#	Line 597 | Line 629 | public class Phaser {
629		*/
630		public int awaitAdvanceInterruptibly(int phase)
631		throws InterruptedException {
632	+	Phaser rt;
633	+	int p = (int)(state >>> PHASE_SHIFT);
634		if (phase < 0)
635		return phase;
636	<	int p = (int)((parent==null? state : reconcileState()) >>> PHASE_SHIFT);
637	<	if (p != phase)
638	<	return p;
639	<	QNode node = new QNode(this, phase, true, false, 0L);
640	<	p = internalAwaitAdvance(phase, node);
641	<	if (node.wasInterrupted)
642	<	throw new InterruptedException();
643	<	else
610	<	return p;
636	>	if (p == phase &&
637	>	(p = (int)((rt = root).state >>> PHASE_SHIFT)) == phase) {
638	>	QNode node = new QNode(this, phase, true, false, 0L);
639	>	p = rt.internalAwaitAdvance(phase, node);
640	>	if (node.wasInterrupted)
641	>	throw new InterruptedException();
642	>	}
643	>	return p;
644		}
645
646		/**
#	Line 634 | Line 667 | public class Phaser {
667		long timeout, TimeUnit unit)
668		throws InterruptedException, TimeoutException {
669		long nanos = unit.toNanos(timeout);
670	+	Phaser rt;
671	+	int p = (int)(state >>> PHASE_SHIFT);
672		if (phase < 0)
673		return phase;
674	<	int p = (int)((parent==null? state : reconcileState()) >>> PHASE_SHIFT);
675	<	if (p != phase)
676	<	return p;
677	<	QNode node = new QNode(this, phase, true, true, nanos);
678	<	p = internalAwaitAdvance(phase, node);
679	<	if (node.wasInterrupted)
680	<	throw new InterruptedException();
681	<	else if (p == phase)
682	<	throw new TimeoutException();
683	<	else
649	<	return p;
674	>	if (p == phase &&
675	>	(p = (int)((rt = root).state >>> PHASE_SHIFT)) == phase) {
676	>	QNode node = new QNode(this, phase, true, true, nanos);
677	>	p = rt.internalAwaitAdvance(phase, node);
678	>	if (node.wasInterrupted)
679	>	throw new InterruptedException();
680	>	else if (p == phase)
681	>	throw new TimeoutException();
682	>	}
683	>	return p;
684		}
685
686		/**
687	<	* Forces this barrier to enter termination state. Counts of
688	<	* arrived and registered parties are unaffected. If this phaser
689	<	* has a parent, it too is terminated. This method may be useful
690	<	* for coordinating recovery after one or more tasks encounter
691	<	* unexpected exceptions.
687	>	* Forces this barrier to enter termination state.  Counts of
688	>	* arrived and registered parties are unaffected.  If this Phaser
689	>	* is a member of a tiered set of Phasers, then all of the Phasers
690	>	* in the set are terminated.  If this Phaser is already
691	>	* terminated, this method has no effect.  This method may be
692	>	* useful for coordinating recovery after one or more tasks
693	>	* encounter unexpected exceptions.
694		*/
695		public void forceTermination() {
696	<	Phaser r = root;    // force at root then reconcile
696	>	// Only need to change root state
697	>	final Phaser root = this.root;
698		long s;
699	<	while ((s = r.state) >= 0)
700	<	UNSAFE.compareAndSwapLong(r, stateOffset, s, s | TERMINATION_PHASE);
701	<	reconcileState();
702	<	releaseWaiters(0); // signal all threads
703	<	releaseWaiters(1);
699	>	while ((s = root.state) >= 0) {
700	>	if (UNSAFE.compareAndSwapLong(root, stateOffset,
701	>	s, s | TERMINATION_BIT)) {
702	>	releaseWaiters(0); // signal all threads
703	>	releaseWaiters(1);
704	>	return;
705	>	}
706	>	}
707		}
708
709		/**
#	Line 674 | Line 714 | public class Phaser {
714		* @return the phase number, or a negative value if terminated
715		*/
716		public final int getPhase() {
717	<	return (int)((parent == null? state : reconcileState()) >>> PHASE_SHIFT);
717	>	return (int)(root.state >>> PHASE_SHIFT);
718		}
719
720		/**
#	Line 683 | Line 723 | public class Phaser {
723		* @return the number of parties
724		*/
725		public int getRegisteredParties() {
726	<	return partiesOf(parent == null? state : reconcileState());
726	>	return partiesOf(state);
727		}
728
729		/**
#	Line 693 | Line 733 | public class Phaser {
733		* @return the number of arrived parties
734		*/
735		public int getArrivedParties() {
736	<	return arrivedOf(parent == null? state : reconcileState());
736	>	long s = state;
737	>	int u = unarrivedOf(s); // only reconcile if possibly needed
738	>	return (u != 0 || parent == null) ?
739	>	partiesOf(s) - u :
740	>	arrivedOf(reconcileState());
741		}
742
743		/**
#	Line 703 | Line 747 | public class Phaser {
747		* @return the number of unarrived parties
748		*/
749		public int getUnarrivedParties() {
750	<	return unarrivedOf(parent == null? state : reconcileState());
750	>	int u = unarrivedOf(state);
751	>	return (u != 0 || parent == null) ? u : unarrivedOf(reconcileState());
752		}
753
754		/**
755	<	* Returns the parent of this phaser, or {@code null} if none.
755	>	* Returns the parent of this Phaser, or {@code null} if none.
756		*
757	<	* @return the parent of this phaser, or {@code null} if none
757	>	* @return the parent of this Phaser, or {@code null} if none
758		*/
759		public Phaser getParent() {
760		return parent;
761		}
762
763		/**
764	<	* Returns the root ancestor of this phaser, which is the same as
765	<	* this phaser if it has no parent.
764	>	* Returns the root ancestor of this Phaser, which is the same as
765	>	* this Phaser if it has no parent.
766		*
767	<	* @return the root ancestor of this phaser
767	>	* @return the root ancestor of this Phaser
768		*/
769		public Phaser getRoot() {
770		return root;
#	Line 731 | Line 776 | public class Phaser {
776		* @return {@code true} if this barrier has been terminated
777		*/
778		public boolean isTerminated() {
779	<	return (parent == null? state : reconcileState()) < 0;
779	>	return root.state < 0L;
780		}
781
782		/**
#	Line 746 | Line 791 | public class Phaser {
791		* propagated to the party attempting to trip the barrier, in
792		* which case no advance occurs.
793		*
794	<	* <p>The arguments to this method provide the state of the phaser
794	>	* <p>The arguments to this method provide the state of the Phaser
795		* prevailing for the current transition.  The effects of invoking
796		* arrival, registration, and waiting methods on this Phaser from
797		* within {@code onAdvance} are unspecified and should not be
#	Line 756 | Line 801 | public class Phaser {
801		* {@code onAdvance} is invoked only for its root Phaser on each
802		* advance.
803		*
804	<	* <p>The default version returns {@code true} when the number of
805	<	* registered parties is zero. Normally, overrides that arrange
806	<	* termination for other reasons should also preserve this
807	<	* property.
804	>	* <p>To support the most common use cases, the default
805	>	* implementation of this method returns {@code true} when the
806	>	* number of registered parties has become zero as the result of a
807	>	* party invoking {@code arriveAndDeregister}.  You can disable
808	>	* this behavior, thus enabling continuation upon future
809	>	* registrations, by overriding this method to always return
810	>	* {@code false}:
811	>	*
812	>	* <pre> {@code
813	>	* Phaser phaser = new Phaser() {
814	>	*   protected boolean onAdvance(int phase, int parties) { return false; }
815	>	* }}</pre>
816		*
817		* @param phase the phase number on entering the barrier
818		* @param registeredParties the current number of registered parties
819		* @return {@code true} if this barrier should terminate
820		*/
821		protected boolean onAdvance(int phase, int registeredParties) {
822	<	return registeredParties <= 0;
822	>	return registeredParties == 0;
823		}
824
825		/**
826	<	* Returns a string identifying this phaser, as well as its
826	>	* Returns a string identifying this Phaser, as well as its
827		* state.  The state, in brackets, includes the String {@code
828		* "phase = "} followed by the phase number, {@code "parties = "}
829		* followed by the number of registered parties, and {@code
#	Line 779 | Line 832 | public class Phaser {
832		* @return a string identifying this barrier, as well as its state
833		*/
834		public String toString() {
835	<	long s = reconcileState();
835	>	return stateToString(reconcileState());
836	>	}
837	>
838	>	/**
839	>	* Implementation of toString and string-based error messages
840	>	*/
841	>	private String stateToString(long s) {
842		return super.toString() +
843		"[phase = " + phaseOf(s) +
844		" parties = " + partiesOf(s) +
845		" arrived = " + arrivedOf(s) + "]";
846		}
847
848	+	// Waiting mechanics
849	+
850		/**
851	<	* Removes and signals threads from queue for phase
851	>	* Removes and signals threads from queue for phase.
852		*/
853		private void releaseWaiters(int phase) {
854	<	AtomicReference<QNode> head = queueFor(phase);
854	>	AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ;
855		QNode q;
856		int p;
857		while ((q = head.get()) != null &&
#	Line 801 | Line 862 | public class Phaser {
862		}
863		}
864
804	–	/**
805	–	* Tries to enqueue given node in the appropriate wait queue.
806	–	*
807	–	* @return true if successful
808	–	*/
809	–	private boolean tryEnqueue(int phase, QNode node) {
810	–	releaseWaiters(phase-1); // ensure old queue clean
811	–	AtomicReference<QNode> head = queueFor(phase);
812	–	QNode q = head.get();
813	–	return ((q == null || q.phase == phase) &&
814	–	(int)(root.state >>> PHASE_SHIFT) == phase &&
815	–	head.compareAndSet(node.next = q, node));
816	–	}
817	–
865		/** The number of CPUs, for spin control */
866		private static final int NCPU = Runtime.getRuntime().availableProcessors();
867
#	Line 826 | Line 873 | public class Phaser {
873		* avoid it when threads regularly arrive: When a thread in
874		* internalAwaitAdvance notices another arrival before blocking,
875		* and there appear to be enough CPUs available, it spins
876	<	* SPINS_PER_ARRIVAL more times before continuing to try to
877	<	* block. The value trades off good-citizenship vs big unnecessary
831	<	* slowdowns.
876	>	* SPINS_PER_ARRIVAL more times before blocking. The value trades
877	>	* off good-citizenship vs big unnecessary slowdowns.
878		*/
879	<	static final int SPINS_PER_ARRIVAL = NCPU < 2? 1 : 1 << 8;
879	>	static final int SPINS_PER_ARRIVAL = (NCPU < 2) ? 1 : 1 << 8;
880
881		/**
882		* Possibly blocks and waits for phase to advance unless aborted.
883	+	* Call only from root node.
884		*
885		* @param phase current phase
886	<	* @param node if nonnull, the wait node to track interrupt and timeout;
886	>	* @param node if non-null, the wait node to track interrupt and timeout;
887		* if null, denotes noninterruptible wait
888		* @return current phase
889		*/
890		private int internalAwaitAdvance(int phase, QNode node) {
891	<	Phaser current = this;       // to eventually wait at root if tiered
845	<	Phaser par = parent;
846	<	boolean queued = false;
847	<	int spins = SPINS_PER_ARRIVAL;
891	>	boolean queued = false;      // true when node is enqueued
892		int lastUnarrived = -1;      // to increase spins upon change
893	+	int spins = SPINS_PER_ARRIVAL;
894		long s;
895		int p;
896	<	while ((p = (int)((s = current.state) >>> PHASE_SHIFT)) == phase) {
897	<	int unarrived = (int)(s & UNARRIVED_MASK);
898	<	if (unarrived != lastUnarrived) {
896	>	while ((p = (int)((s = state) >>> PHASE_SHIFT)) == phase) {
897	>	int unarrived = (int)s & UNARRIVED_MASK;
898	>	if (node != null && node.isReleasable()) {
899	>	p = (int)(state >>> PHASE_SHIFT);
900	>	break;               // done or aborted
901	>	}
902	>	else if (node == null && Thread.interrupted()) {
903	>	node = new QNode(this, phase, false, false, 0L);
904	>	node.wasInterrupted = true;
905	>	}
906	>	else if (unarrived != lastUnarrived) {
907	>	if (lastUnarrived == -1) // ensure old queue clean
908	>	releaseWaiters(phase-1);
909		if ((lastUnarrived = unarrived) < NCPU)
910		spins += SPINS_PER_ARRIVAL;
911		}
857	–	else if (unarrived == 0 && par != null) {
858	–	current = par;       // if all arrived, use parent
859	–	par = par.parent;
860	–	}
912		else if (spins > 0)
913		--spins;
914	<	else if (node == null)
914	>	else if (node == null)   // null if noninterruptible mode
915		node = new QNode(this, phase, false, false, 0L);
916	<	else if (node.isReleasable())
917	<	break;
918	<	else if (!queued)
919	<	queued = tryEnqueue(phase, node);
916	>	else if (!queued) {      // push onto queue
917	>	AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ;
918	>	QNode q = head.get();
919	>	if (q == null || q.phase == phase) {
920	>	node.next = q;
921	>	if ((p = (int)(state >>> PHASE_SHIFT)) != phase)
922	>	break;       // recheck to avoid stale enqueue
923	>	queued = head.compareAndSet(q, node);
924	>	}
925	>	}
926		else {
927		try {
928		ForkJoinPool.managedBlock(node);
#	Line 874 | Line 931 | public class Phaser {
931		}
932		}
933		}
934	+
935		if (node != null) {
936		if (node.thread != null)
937	<	node.thread = null;
938	<	if (!node.interruptible && node.wasInterrupted)
937	>	node.thread = null; // disable unpark() in node.signal
938	>	if (node.wasInterrupted && !node.interruptible)
939		Thread.currentThread().interrupt();
940		}
883	–	if (p == phase)
884	–	p = (int)(reconcileState() >>> PHASE_SHIFT);
941		if (p != phase)
942		releaseWaiters(phase);
943		return p;
#	Line 920 | Line 976 | public class Phaser {
976		else {
977		if (Thread.interrupted())
978		wasInterrupted = true;
979	<	if (interruptible && wasInterrupted)
979	>	if (wasInterrupted && interruptible)
980		t = null;
981		else if (timed) {
982		if (nanos > 0) {

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