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

Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.60 by dl, Sun Nov 28 15:49:49 2010 UTC vs.
Revision 1.70 by dl, Wed Dec 8 15:27:25 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 34 | Line 34 | import java.util.concurrent.locks.LockSu
34		* Phaser} may be repeatedly awaited.  Method {@link
35		* #arriveAndAwaitAdvance} has effect analogous to {@link
36		* java.util.concurrent.CyclicBarrier#await CyclicBarrier.await}. Each
37	<	* generation of a {@code Phaser} has an associated phase number. The
38	<	* phase number starts at zero, and advances when all parties arrive
39	<	* at the barrier, wrapping around to zero after reaching {@code
37	>	* generation of a phaser has an associated phase number. The phase
38	>	* number starts at zero, and advances when all parties arrive at the
39	>	* phaser, wrapping around to zero after reaching {@code
40		* Integer.MAX_VALUE}. The use of phase numbers enables independent
41	<	* control of actions upon arrival at a barrier and upon awaiting
41	>	* control of actions upon arrival at a phaser and upon awaiting
42		* others, via two kinds of methods that may be invoked by any
43		* registered party:
44		*
45		* <ul>
46		*
47		*   <li> <b>Arrival.</b> Methods {@link #arrive} and
48	<	*       {@link #arriveAndDeregister} record arrival at a
49	<	*       barrier. These methods do not block, but return an associated
50	<	*       <em>arrival phase number</em>; that is, the phase number of
51	<	*       the barrier to which the arrival applied. When the final
52	<	*       party for a given phase arrives, an optional barrier action
53	<	*       is performed and the phase advances.  Barrier actions,
54	<	*       performed by the party triggering a phase advance, are
55	<	*       arranged by overriding method {@link #onAdvance(int, int)},
56	<	*       which also controls termination. Overriding this method is
57	<	*       similar to, but more flexible than, providing a barrier
58	<	*       action to a {@code CyclicBarrier}.
48	>	*       {@link #arriveAndDeregister} record arrival.  These methods
49	>	*       do not block, but return an associated <em>arrival phase
50	>	*       number</em>; that is, the phase number of the phaser to which
51	>	*       the arrival applied. When the final party for a given phase
52	>	*       arrives, an optional action is performed and the phase
53	>	*       advances.  These actions are performed by the party
54	>	*       triggering a phase advance, and are arranged by overriding
55	>	*       method {@link #onAdvance(int, int)}, which also controls
56	>	*       termination. Overriding this method is similar to, but more
57	>	*       flexible than, providing a barrier action to a {@code
58	>	*       CyclicBarrier}.
59		*
60		*   <li> <b>Waiting.</b> Method {@link #awaitAdvance} requires an
61		*       argument indicating an arrival phase number, and returns when
62	<	*       the barrier advances to (or is already at) a different phase.
62	>	*       the phaser advances to (or is already at) a different phase.
63		*       Unlike similar constructions using {@code CyclicBarrier},
64		*       method {@code awaitAdvance} continues to wait even if the
65		*       waiting thread is interrupted. Interruptible and timeout
66		*       versions are also available, but exceptions encountered while
67		*       tasks wait interruptibly or with timeout do not change the
68	<	*       state of the barrier. If necessary, you can perform any
68	>	*       state of the phaser. If necessary, you can perform any
69		*       associated recovery within handlers of those exceptions,
70		*       often after invoking {@code forceTermination}.  Phasers may
71		*       also be used by tasks executing in a {@link ForkJoinPool},
#	Line 74 | Line 74 | import java.util.concurrent.locks.LockSu
74		*
75		* </ul>
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
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}. 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.
77	>	* <p> <b>Termination.</b> A phaser may enter a <em>termination</em>
78	>	* state, that may be checked using method {@link #isTerminated}. Upon
79	>	* termination, all synchronization methods immediately return without
80	>	* waiting for advance, as indicated by a negative return value.
81	>	* Similarly, attempts to register upon termination have no effect.
82	>	* Termination is triggered when an invocation of {@code onAdvance}
83	>	* returns {@code true}. The default implementation returns {@code
84	>	* true} if a deregistration has caused the number of registered
85	>	* parties to become zero.  As illustrated below, when phasers control
86	>	* actions with a fixed number of iterations, it is often convenient
87	>	* to override this method to cause termination when the current phase
88	>	* number reaches a threshold. Method {@link #forceTermination} is
89	>	* also available to abruptly release waiting threads and allow them
90	>	* to terminate.
91		*
92		* <p> <b>Tiering.</b> Phasers may be <em>tiered</em> (i.e.,
93		* constructed in tree structures) to reduce contention. Phasers with
#	Line 96 | Line 97 | import java.util.concurrent.locks.LockSu
97		* increase throughput even though it incurs greater per-operation
98		* overhead.
99		*
100	+	* <p>In a tree of tiered phasers, registration and deregistration of
101	+	* child phasers with their parent are managed automatically.
102	+	* Whenever the number of registered parties of a child phaser becomes
103	+	* non-zero (as established in the {@link #Phaser(Phaser,int)}
104	+	* constructor, {@link #register}, or {@link #bulkRegister}), the
105	+	* child phaser is registered with its parent.  Whenever the number of
106	+	* registered parties becomes zero as the result of an invocation of
107	+	* {@link #arriveAndDeregister}, the child phaser is deregistered
108	+	* from its parent.
109	+	*
110		* <p><b>Monitoring.</b> While synchronization methods may be invoked
111	<	* only by registered parties, the current state of a Phaser may be
111	>	* only by registered parties, the current state of a phaser may be
112		* monitored by any caller.  At any given moment there are {@link
113		* #getRegisteredParties} parties in total, of which {@link
114		* #getArrivedParties} have arrived at the current phase ({@link
#	Line 183 | Line 194 | import java.util.concurrent.locks.LockSu
194		* }}</pre>
195		*
196		*
197	<	* <p>To create a set of tasks using a tree of Phasers,
198	<	* you could use code of the following form, assuming a
199	<	* Task class with a constructor accepting a Phaser that
200	<	* it registers with upon construction:
197	>	* <p>To create a set of {@code n} tasks using a tree of phasers, you
198	>	* could use code of the following form, assuming a Task class with a
199	>	* constructor accepting a {@code Phaser} that it registers with upon
200	>	* construction. After invocation of {@code build(new Task[n], 0, n,
201	>	* new Phaser())}, these tasks could then be started, for example by
202	>	* submitting to a pool:
203		*
204		*  <pre> {@code
205	<	* void build(Task[] actions, int lo, int hi, Phaser ph) {
205	>	* void build(Task[] tasks, int lo, int hi, Phaser ph) {
206		*   if (hi - lo > TASKS_PER_PHASER) {
207		*     for (int i = lo; i < hi; i += TASKS_PER_PHASER) {
208		*       int j = Math.min(i + TASKS_PER_PHASER, hi);
209	<	*       build(actions, i, j, new Phaser(ph));
209	>	*       build(tasks, i, j, new Phaser(ph));
210		*     }
211		*   } else {
212		*     for (int i = lo; i < hi; ++i)
213	<	*       actions[i] = new Task(ph);
213	>	*       tasks[i] = new Task(ph);
214		*       // assumes new Task(ph) performs ph.register()
215		*   }
216	<	* }
204	<	* // .. initially called, for n tasks via
205	<	* build(new Task[n], 0, n, new Phaser());}</pre>
216	>	* }}</pre>
217		*
218		* The best value of {@code TASKS_PER_PHASER} depends mainly on
219	<	* expected barrier synchronization rates. A value as low as four may
220	<	* be appropriate for extremely small per-barrier task bodies (thus
219	>	* expected synchronization rates. A value as low as four may
220	>	* be appropriate for extremely small per-phase task bodies (thus
221		* high rates), or up to hundreds for extremely large ones.
222		*
223		* <p><b>Implementation notes</b>: This implementation restricts the
224		* maximum number of parties to 65535. Attempts to register additional
225		* parties result in {@code IllegalStateException}. However, you can and
226	<	* should create tiered Phasers to accommodate arbitrarily large sets
226	>	* should create tiered phasers to accommodate arbitrarily large sets
227		* of participants.
228		*
229		* @since 1.7
#	Line 226 | Line 237 | public class Phaser {
237		*/
238
239		/**
240	<	* Barrier state representation. Conceptually, a barrier contains
230	<	* four values:
240	>	* Primary state representation, holding four fields:
241		*
242		* * unarrived -- the number of parties yet to hit barrier (bits  0-15)
243		* * parties -- the number of parties to wait              (bits 16-31)
244		* * phase -- the generation of the barrier                (bits 32-62)
245		* * terminated -- set if barrier is terminated            (bit  63 / sign)
246		*
247	<	* However, to efficiently maintain atomicity, these values are
248	<	* packed into a single (atomic) long. Termination uses the sign
249	<	* bit of 32 bit representation of phase, so phase is set to -1 on
250	<	* termination. Good performance relies on keeping state decoding
251	<	* and encoding simple, and keeping race windows short.
247	>	* Except that a phaser with no registered parties is
248	>	* distinguished with the otherwise illegal state of having zero
249	>	* parties and one unarrived parties (encoded as EMPTY below).
250	>	*
251	>	* To efficiently maintain atomicity, these values are packed into
252	>	* a single (atomic) long. Good performance relies on keeping
253	>	* state decoding and encoding simple, and keeping race windows
254	>	* short.
255	>	*
256	>	* All state updates are performed via CAS except initial
257	>	* registration of a sub-phaser (i.e., one with a non-null
258	>	* parent).  In this (relatively rare) case, we use built-in
259	>	* synchronization to lock while first registering with its
260	>	* parent.
261	>	*
262	>	* The phase of a subphaser is allowed to lag that of its
263	>	* ancestors until it is actually accessed -- see method
264	>	* reconcileState.
265		*/
266		private volatile long state;
267
#	Line 246 | Line 269 | public class Phaser {
269		private static final int  MAX_PHASE       = 0x7fffffff;
270		private static final int  PARTIES_SHIFT   = 16;
271		private static final int  PHASE_SHIFT     = 32;
272	+	private static final long PHASE_MASK      = -1L << PHASE_SHIFT;
273		private static final int  UNARRIVED_MASK  = 0xffff;      // to mask ints
274		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;
275		private static final long TERMINATION_BIT = 1L << 63;
276
277	+	// some special values
278	+	private static final int  ONE_ARRIVAL     = 1;
279	+	private static final int  ONE_PARTY       = 1 << PARTIES_SHIFT;
280	+	private static final int  EMPTY           = 1;
281	+
282		// The following unpacking methods are usually manually inlined
283
284		private static int unarrivedOf(long s) {
285	<	return (int)s & UNARRIVED_MASK;
285	>	int counts = (int)s;
286	>	return (counts == EMPTY) ? 0 : counts & UNARRIVED_MASK;
287		}
288
289		private static int partiesOf(long s) {
#	Line 267 | Line 295 | public class Phaser {
295		}
296
297		private static int arrivedOf(long s) {
298	<	return partiesOf(s) - unarrivedOf(s);
298	>	int counts = (int)s;
299	>	return (counts == EMPTY) ? 0 :
300	>	(counts >>> PARTIES_SHIFT) - (counts & UNARRIVED_MASK);
301		}
302
303		/**
#	Line 276 | Line 306 | public class Phaser {
306		private final Phaser parent;
307
308		/**
309	<	* The root of phaser tree. Equals this if not in a tree.  Used to
280	<	* support faster state push-down.
309	>	* The root of phaser tree. Equals this if not in a tree.
310		*/
311		private final Phaser root;
312
#	Line 315 | Line 344 | public class Phaser {
344		* Manually tuned to speed up and minimize race windows for the
345		* common case of just decrementing unarrived field.
346		*
347	<	* @param adj - adjustment to apply to state -- either
319	<	* ONE_ARRIVAL (for arrive) or
320	<	* ONE_ARRIVAL|ONE_PARTY (for arriveAndDeregister)
347	>	* @param deregister false for arrive, true for arriveAndDeregister
348		*/
349	<	private int doArrive(long adj) {
349	>	private int doArrive(boolean deregister) {
350	>	int adj = deregister ? ONE_ARRIVAL|ONE_PARTY : ONE_ARRIVAL;
351	>	final Phaser root = this.root;
352		for (;;) {
353	<	long s = state;
325	<	int unarrived = (int)s & UNARRIVED_MASK;
353	>	long s = (root == this) ? state : reconcileState();
354		int phase = (int)(s >>> PHASE_SHIFT);
355	+	int counts = (int)s;
356	+	int unarrived = (counts & UNARRIVED_MASK) - 1;
357		if (phase < 0)
358		return phase;
359	<	else if (unarrived == 0) {
360	<	if (reconcileState() == s)     // recheck
359	>	else if (counts == EMPTY || unarrived < 0) {
360	>	if (root == this || reconcileState() == s)
361		throw new IllegalStateException(badArrive(s));
362		}
363		else if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s-=adj)) {
364	<	if (unarrived == 1) {
365	<	long p = s & PARTIES_MASK; // unshifted parties field
366	<	long lu = p >>> PARTIES_SHIFT;
367	<	int u = (int)lu;
368	<	int nextPhase = (phase + 1) & MAX_PHASE;
369	<	long next = ((long)nextPhase << PHASE_SHIFT) | p | lu;
370	<	final Phaser parent = this.parent;
371	<	if (parent == null) {
372	<	if (onAdvance(phase, u))
373	<	next |= TERMINATION_BIT;
374	<	UNSAFE.compareAndSwapLong(this, stateOffset, s, next);
375	<	releaseWaiters(phase);
376	<	}
377	<	else {
348	<	parent.doArrive((u == 0) ?
349	<	ONE_ARRIVAL|ONE_PARTY : ONE_ARRIVAL);
350	<	if ((int)(parent.state >>> PHASE_SHIFT) != nextPhase ||
351	<	((int)(state >>> PHASE_SHIFT) != nextPhase &&
352	<	!UNSAFE.compareAndSwapLong(this, stateOffset,
353	<	s, next)))
354	<	reconcileState();
355	<	}
364	>	if (unarrived == 0) {
365	>	long n = s & PARTIES_MASK;  // base of next state
366	>	int nextUnarrived = ((int)n) >>> PARTIES_SHIFT;
367	>	if (root != this)
368	>	return parent.doArrive(nextUnarrived == 0);
369	>	if (onAdvance(phase, nextUnarrived))
370	>	n |= TERMINATION_BIT;
371	>	else if (nextUnarrived == 0)
372	>	n |= EMPTY;
373	>	else
374	>	n |= nextUnarrived;
375	>	n |= ((long)((phase + 1) & MAX_PHASE)) << PHASE_SHIFT;
376	>	UNSAFE.compareAndSwapLong(this, stateOffset, s, n);
377	>	releaseWaiters(phase);
378		}
379		return phase;
380		}
#	Line 368 | Line 390 | public class Phaser {
390		private int doRegister(int registrations) {
391		// adjustment to state
392		long adj = ((long)registrations << PARTIES_SHIFT) | registrations;
393	<	final Phaser parent = this.parent;
393	>	Phaser par = parent;
394	>	int phase;
395		for (;;) {
396	<	long s = (parent == null) ? state : reconcileState();
397	<	int parties = (int)s >>> PARTIES_SHIFT;
398	<	int phase = (int)(s >>> PHASE_SHIFT);
399	<	if (phase < 0)
400	<	return phase;
378	<	else if (registrations > MAX_PARTIES - parties)
396	>	long s = state;
397	>	int counts = (int)s;
398	>	int parties = counts >>> PARTIES_SHIFT;
399	>	int unarrived = counts & UNARRIVED_MASK;
400	>	if (registrations > MAX_PARTIES - parties)
401		throw new IllegalStateException(badRegister(s));
402	<	else if ((parties == 0 && parent == null) || // first reg of root
403	<	((int)s & UNARRIVED_MASK) != 0) {   // not advancing
404	<	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s + adj))
405	<	return phase;
406	<	}
407	<	else if (parties != 0)               // wait for onAdvance
408	<	root.internalAwaitAdvance(phase, null);
409	<	else {                               // 1st registration of child
410	<	synchronized(this) {             // register parent first
411	<	if (reconcileState() == s) { // recheck under lock
412	<	parent.doRegister(1);    // OK if throws IllegalState
413	<	for (;;) {               // simpler form of outer loop
414	<	s = reconcileState();
415	<	phase = (int)(s >>> PHASE_SHIFT);
416	<	if (phase < 0 ||
417	<	UNSAFE.compareAndSwapLong(this, stateOffset,
418	<	s, s + adj))
419	<	return phase;
420	<	}
402	>	else if ((phase = (int)(s >>> PHASE_SHIFT)) < 0)
403	>	break;
404	>	else if (counts != EMPTY) {             // not 1st registration
405	>	if (par == null || reconcileState() == s) {
406	>	if (unarrived == 0)             // wait out advance
407	>	root.internalAwaitAdvance(phase, null);
408	>	else if (UNSAFE.compareAndSwapLong(this, stateOffset,
409	>	s, s + adj))
410	>	break;
411	>	}
412	>	}
413	>	else if (par == null) {                 // 1st root registration
414	>	long next = (((long) phase) << PHASE_SHIFT) | adj;
415	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next))
416	>	break;
417	>	}
418	>	else {
419	>	synchronized (this) {               // 1st sub registration
420	>	if (state == s) {               // recheck under lock
421	>	par.doRegister(1);
422	>	do {                        // force current phase
423	>	phase = (int)(root.state >>> PHASE_SHIFT);
424	>	// assert phase < 0 || (int)state == EMPTY;
425	>	} while (!UNSAFE.compareAndSwapLong
426	>	(this, stateOffset, state,
427	>	(((long) phase) << PHASE_SHIFT) | adj));
428	>	break;
429		}
430		}
431		}
432		}
433	+	return phase;
434		}
435
436		/**
437	<	* Recursively resolves lagged phase propagation from root if necessary.
437	>	* Resolves lagged phase propagation from root if necessary.
438	>	* Reconciliation normally occurs when root has advanced but
439	>	* subphasers have not yet done so, in which case they must finish
440	>	* their own advance by setting unarrived to parties (or if
441	>	* parties is zero, resetting to unregistered EMPTY state).
442	>	* However, this method may also be called when "floating"
443	>	* subphasers with possibly some unarrived parties are merely
444	>	* catching up to current phase, in which case counts are
445	>	* unaffected.
446	>	*
447	>	* @return reconciled state
448		*/
449		private long reconcileState() {
450	<	Phaser par = parent;
450	>	final Phaser root = this.root;
451		long s = state;
452	<	if (par != null) {
453	<	Phaser rt = root;
454	<	int phase, rPhase;
455	<	while ((phase = (int)(s >>> PHASE_SHIFT)) >= 0 &&
456	<	(rPhase = (int)(rt.state >>> PHASE_SHIFT)) != phase) {
457	<	if ((int)(par.state >>> PHASE_SHIFT) != rPhase)
458	<	par.reconcileState();
459	<	else if (rPhase < 0 || ((int)s & UNARRIVED_MASK) == 0) {
460	<	long u = s & PARTIES_MASK; // reset unarrived to parties
461	<	long next = ((((long) rPhase) << PHASE_SHIFT) | u |
421	<	(u >>> PARTIES_SHIFT));
422	<	UNSAFE.compareAndSwapLong(this, stateOffset, s, next);
423	<	}
452	>	if (root != this) {
453	>	int phase, u, p;
454	>	// CAS root phase with current parties; possibly trip unarrived
455	>	while ((phase = (int)(root.state >>> PHASE_SHIFT)) !=
456	>	(int)(s >>> PHASE_SHIFT) &&
457	>	!UNSAFE.compareAndSwapLong
458	>	(this, stateOffset, s,
459	>	s = ((((long) phase) << PHASE_SHIFT) | (s & PARTIES_MASK) |
460	>	((p = (int)s >>> PARTIES_SHIFT) == 0 ? EMPTY :
461	>	(u = (int)s & UNARRIVED_MASK) == 0 ? p : u))))
462		s = state;
425	–	}
463		}
464		return s;
465		}
466
467		/**
468	<	* Creates a new Phaser without any initially registered parties,
469	<	* initial phase number 0, and no parent. Any thread using this
470	<	* Phaser will need to first register for it.
468	>	* Creates a new phaser with no initially registered parties, no
469	>	* parent, and initial phase number 0. Any thread using this
470	>	* phaser will need to first register for it.
471		*/
472		public Phaser() {
473		this(null, 0);
474		}
475
476		/**
477	<	* Creates a new Phaser with the given number of registered
478	<	* unarrived parties, initial phase number 0, and no parent.
477	>	* Creates a new phaser with the given number of registered
478	>	* unarrived parties, no parent, and initial phase number 0.
479		*
480	<	* @param parties the number of parties required to trip barrier
480	>	* @param parties the number of parties required to advance to the
481	>	* next phase
482		* @throws IllegalArgumentException if parties less than zero
483		* or greater than the maximum number of parties supported
484		*/
#	Line 451 | Line 489 | public class Phaser {
489		/**
490		* Equivalent to {@link #Phaser(Phaser, int) Phaser(parent, 0)}.
491		*
492	<	* @param parent the parent Phaser
492	>	* @param parent the parent phaser
493		*/
494		public Phaser(Phaser parent) {
495		this(parent, 0);
496		}
497
498		/**
499	<	* Creates a new Phaser with the given parent and number of
500	<	* registered unarrived parties. Registration and deregistration
501	<	* of this child Phaser with its parent are managed automatically.
502	<	* If the given parent is non-null, whenever this child Phaser has
503	<	* any registered parties (as established in this constructor,
504	<	* {@link #register}, or {@link #bulkRegister}), this child Phaser
505	<	* is registered with its parent. Whenever the number of
506	<	* 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
473	<	* @param parties the number of parties required to trip barrier
499	>	* Creates a new phaser with the given parent and number of
500	>	* registered unarrived parties.  When the given parent is non-null
501	>	* and the given number of parties is greater than zero, this
502	>	* child phaser is registered with its parent.
503	>	*
504	>	* @param parent the parent phaser
505	>	* @param parties the number of parties required to advance to the
506	>	* next phase
507		* @throws IllegalArgumentException if parties less than zero
508		* or greater than the maximum number of parties supported
509		*/
510		public Phaser(Phaser parent, int parties) {
511		if (parties >>> PARTIES_SHIFT != 0)
512		throw new IllegalArgumentException("Illegal number of parties");
513	<	long s = ((long) parties) | (((long) parties) << PARTIES_SHIFT);
513	>	int phase = 0;
514		this.parent = parent;
515		if (parent != null) {
516	<	Phaser r = parent.root;
517	<	this.root = r;
518	<	this.evenQ = r.evenQ;
519	<	this.oddQ = r.oddQ;
516	>	final Phaser root = parent.root;
517	>	this.root = root;
518	>	this.evenQ = root.evenQ;
519	>	this.oddQ = root.oddQ;
520		if (parties != 0)
521	<	s |= ((long)(parent.doRegister(1))) << PHASE_SHIFT;
521	>	phase = parent.doRegister(1);
522		}
523		else {
524		this.root = this;
525		this.evenQ = new AtomicReference<QNode>();
526		this.oddQ = new AtomicReference<QNode>();
527		}
528	<	this.state = s;
528	>	this.state = (parties == 0) ? (long) EMPTY :
529	>	((((long) phase) << PHASE_SHIFT) |
530	>	(((long) parties) << PARTIES_SHIFT) |
531	>	((long) parties));
532		}
533
534		/**
535	<	* Adds a new unarrived party to this Phaser.  If an ongoing
535	>	* Adds a new unarrived party to this phaser.  If an ongoing
536		* invocation of {@link #onAdvance} is in progress, this method
537	<	* may await its completion before returning.  If this Phaser has
538	<	* a parent, and this Phaser previously had no registered parties,
539	<	* this Phaser is also registered with its parent.
540	<	*
541	<	* @return the arrival phase number to which this registration applied
537	>	* may await its completion before returning.  If this phaser has
538	>	* a parent, and this phaser previously had no registered parties,
539	>	* this child phaser is also registered with its parent. If
540	>	* this phaser is terminated, the attempt to register has
541	>	* no effect, and a negative value is returned.
542	>	*
543	>	* @return the arrival phase number to which this registration
544	>	* applied.  If this value is negative, then this phaser has
545	>	* terminated, in which case registration has no effect.
546		* @throws IllegalStateException if attempting to register more
547		* than the maximum supported number of parties
548		*/
#	Line 511 | Line 551 | public class Phaser {
551		}
552
553		/**
554	<	* Adds the given number of new unarrived parties to this Phaser.
554	>	* Adds the given number of new unarrived parties to this phaser.
555		* If an ongoing invocation of {@link #onAdvance} is in progress,
556		* this method may await its completion before returning.  If this
557	<	* Phaser has a parent, and the given number of parities is
558	<	* greater than zero, and this Phaser previously had no registered
559	<	* parties, this Phaser is also registered with its parent.
560	<	*
561	<	* @param parties the number of additional parties required to trip barrier
562	<	* @return the arrival phase number to which this registration applied
557	>	* phaser has a parent, and the given number of parties is greater
558	>	* than zero, and this phaser previously had no registered
559	>	* parties, this child phaser is also registered with its parent.
560	>	* If this phaser is terminated, the attempt to register has no
561	>	* effect, and a negative value is returned.
562	>	*
563	>	* @param parties the number of additional parties required to
564	>	* advance to the next phase
565	>	* @return the arrival phase number to which this registration
566	>	* applied.  If this value is negative, then this phaser has
567	>	* terminated, in which case registration has no effect.
568		* @throws IllegalStateException if attempting to register more
569		* than the maximum supported number of parties
570		* @throws IllegalArgumentException if {@code parties < 0}
#	Line 533 | Line 578 | public class Phaser {
578		}
579
580		/**
581	<	* Arrives at the barrier, without waiting for others to arrive.
581	>	* Arrives at this phaser, without waiting for others to arrive.
582		*
583		* <p>It is a usage error for an unregistered party to invoke this
584		* method.  However, this error may result in an {@code
585		* IllegalStateException} only upon some subsequent operation on
586	<	* this Phaser, if ever.
586	>	* this phaser, if ever.
587		*
588		* @return the arrival phase number, or a negative value if terminated
589		* @throws IllegalStateException if not terminated and the number
590		* of unarrived parties would become negative
591		*/
592		public int arrive() {
593	<	return doArrive(ONE_ARRIVAL);
593	>	return doArrive(false);
594		}
595
596		/**
597	<	* Arrives at the barrier and deregisters from it without waiting
597	>	* Arrives at this phaser and deregisters from it without waiting
598		* for others to arrive. Deregistration reduces the number of
599	<	* parties required to trip the barrier in future phases.  If this
600	<	* Phaser has a parent, and deregistration causes this Phaser to
601	<	* have zero parties, this Phaser is also deregistered from its
557	<	* parent.
599	>	* parties required to advance in future phases.  If this phaser
600	>	* has a parent, and deregistration causes this phaser to have
601	>	* zero parties, this phaser is also deregistered from its parent.
602		*
603		* <p>It is a usage error for an unregistered party to invoke this
604		* method.  However, this error may result in an {@code
605		* IllegalStateException} only upon some subsequent operation on
606	<	* this Phaser, if ever.
606	>	* this phaser, if ever.
607		*
608		* @return the arrival phase number, or a negative value if terminated
609		* @throws IllegalStateException if not terminated and the number
610		* of registered or unarrived parties would become negative
611		*/
612		public int arriveAndDeregister() {
613	<	return doArrive(ONE_ARRIVAL|ONE_PARTY);
613	>	return doArrive(true);
614		}
615
616		/**
617	<	* Arrives at the barrier and awaits others. Equivalent in effect
617	>	* Arrives at this phaser and awaits others. Equivalent in effect
618		* to {@code awaitAdvance(arrive())}.  If you need to await with
619		* interruption or timeout, you can arrange this with an analogous
620		* construction using one of the other forms of the {@code
#	Line 580 | Line 624 | public class Phaser {
624		* <p>It is a usage error for an unregistered party to invoke this
625		* method.  However, this error may result in an {@code
626		* IllegalStateException} only upon some subsequent operation on
627	<	* this Phaser, if ever.
627	>	* this phaser, if ever.
628		*
629	<	* @return the arrival phase number, or a negative number if terminated
629	>	* @return the arrival phase number, or the (negative)
630	>	* {@linkplain #getPhase() current phase} if terminated
631		* @throws IllegalStateException if not terminated and the number
632		* of unarrived parties would become negative
633		*/
634		public int arriveAndAwaitAdvance() {
635	<	return awaitAdvance(arrive());
635	>	// Specialization of doArrive+awaitAdvance eliminating some reads/paths
636	>	final Phaser root = this.root;
637	>	for (;;) {
638	>	long s = (root == this) ? state : reconcileState();
639	>	int phase = (int)(s >>> PHASE_SHIFT);
640	>	int counts = (int)s;
641	>	int unarrived = (counts & UNARRIVED_MASK) - 1;
642	>	if (phase < 0)
643	>	return phase;
644	>	else if (counts == EMPTY || unarrived < 0) {
645	>	if (reconcileState() == s)
646	>	throw new IllegalStateException(badArrive(s));
647	>	}
648	>	else if (UNSAFE.compareAndSwapLong(this, stateOffset, s,
649	>	s -= ONE_ARRIVAL)) {
650	>	if (unarrived != 0)
651	>	return root.internalAwaitAdvance(phase, null);
652	>	if (root != this)
653	>	return parent.arriveAndAwaitAdvance();
654	>	long n = s & PARTIES_MASK;  // base of next state
655	>	int nextUnarrived = ((int)n) >>> PARTIES_SHIFT;
656	>	if (onAdvance(phase, nextUnarrived))
657	>	n |= TERMINATION_BIT;
658	>	else if (nextUnarrived == 0)
659	>	n |= EMPTY;
660	>	else
661	>	n |= nextUnarrived;
662	>	int nextPhase = (phase + 1) & MAX_PHASE;
663	>	n |= (long)nextPhase << PHASE_SHIFT;
664	>	if (!UNSAFE.compareAndSwapLong(this, stateOffset, s, n))
665	>	return (int)(state >>> PHASE_SHIFT); // terminated
666	>	releaseWaiters(phase);
667	>	return nextPhase;
668	>	}
669	>	}
670		}
671
672		/**
673	<	* Awaits the phase of the barrier to advance from the given phase
674	<	* value, returning immediately if the current phase of the
675	<	* barrier is not equal to the given phase value or this barrier
597	<	* is terminated.
673	>	* Awaits the phase of this phaser to advance from the given phase
674	>	* value, returning immediately if the current phase is not equal
675	>	* to the given phase value or this phaser is terminated.
676		*
677		* @param phase an arrival phase number, or negative value if
678		* terminated; this argument is normally the value returned by a
679	<	* previous call to {@code arrive} or its variants
680	<	* @return the next arrival phase number, or a negative value
681	<	* if terminated or argument is negative
679	>	* previous call to {@code arrive} or {@code arriveAndDeregister}.
680	>	* @return the next arrival phase number, or the argument if it is
681	>	* negative, or the (negative) {@linkplain #getPhase() current phase}
682	>	* if terminated
683		*/
684		public int awaitAdvance(int phase) {
685	<	Phaser r;
686	<	int p = (int)(state >>> PHASE_SHIFT);
685	>	final Phaser root = this.root;
686	>	long s = (root == this) ? state : reconcileState();
687	>	int p = (int)(s >>> PHASE_SHIFT);
688		if (phase < 0)
689		return phase;
690	<	if (p == phase &&
691	<	(p = (int)((r = root).state >>> PHASE_SHIFT)) == phase)
612	<	return r.internalAwaitAdvance(phase, null);
690	>	if (p == phase)
691	>	return root.internalAwaitAdvance(phase, null);
692		return p;
693		}
694
695		/**
696	<	* Awaits the phase of the barrier to advance from the given phase
696	>	* Awaits the phase of this phaser to advance from the given phase
697		* value, throwing {@code InterruptedException} if interrupted
698	<	* while waiting, or returning immediately if the current phase of
699	<	* the barrier is not equal to the given phase value or this
700	<	* barrier is terminated.
698	>	* while waiting, or returning immediately if the current phase is
699	>	* not equal to the given phase value or this phaser is
700	>	* terminated.
701		*
702		* @param phase an arrival phase number, or negative value if
703		* terminated; this argument is normally the value returned by a
704	<	* previous call to {@code arrive} or its variants
705	<	* @return the next arrival phase number, or a negative value
706	<	* if terminated or argument is negative
704	>	* previous call to {@code arrive} or {@code arriveAndDeregister}.
705	>	* @return the next arrival phase number, or the argument if it is
706	>	* negative, or the (negative) {@linkplain #getPhase() current phase}
707	>	* if terminated
708		* @throws InterruptedException if thread interrupted while waiting
709		*/
710		public int awaitAdvanceInterruptibly(int phase)
711		throws InterruptedException {
712	<	Phaser r;
713	<	int p = (int)(state >>> PHASE_SHIFT);
712	>	final Phaser root = this.root;
713	>	long s = (root == this) ? state : reconcileState();
714	>	int p = (int)(s >>> PHASE_SHIFT);
715		if (phase < 0)
716		return phase;
717	<	if (p == phase &&
637	<	(p = (int)((r = root).state >>> PHASE_SHIFT)) == phase) {
717	>	if (p == phase) {
718		QNode node = new QNode(this, phase, true, false, 0L);
719	<	p = r.internalAwaitAdvance(phase, node);
719	>	p = root.internalAwaitAdvance(phase, node);
720		if (node.wasInterrupted)
721		throw new InterruptedException();
722		}
#	Line 644 | Line 724 | public class Phaser {
724		}
725
726		/**
727	<	* Awaits the phase of the barrier to advance from the given phase
727	>	* Awaits the phase of this phaser to advance from the given phase
728		* value or the given timeout to elapse, throwing {@code
729		* InterruptedException} if interrupted while waiting, or
730	<	* returning immediately if the current phase of the barrier is
731	<	* not equal to the given phase value or this barrier is
652	<	* terminated.
730	>	* returning immediately if the current phase is not equal to the
731	>	* given phase value or this phaser is terminated.
732		*
733		* @param phase an arrival phase number, or negative value if
734		* terminated; this argument is normally the value returned by a
735	<	* previous call to {@code arrive} or its variants
735	>	* previous call to {@code arrive} or {@code arriveAndDeregister}.
736		* @param timeout how long to wait before giving up, in units of
737		*        {@code unit}
738		* @param unit a {@code TimeUnit} determining how to interpret the
739		*        {@code timeout} parameter
740	<	* @return the next arrival phase number, or a negative value
741	<	* if terminated or argument is negative
740	>	* @return the next arrival phase number, or the argument if it is
741	>	* negative, or the (negative) {@linkplain #getPhase() current phase}
742	>	* if terminated
743		* @throws InterruptedException if thread interrupted while waiting
744		* @throws TimeoutException if timed out while waiting
745		*/
#	Line 667 | Line 747 | public class Phaser {
747		long timeout, TimeUnit unit)
748		throws InterruptedException, TimeoutException {
749		long nanos = unit.toNanos(timeout);
750	<	Phaser r;
751	<	int p = (int)(state >>> PHASE_SHIFT);
750	>	final Phaser root = this.root;
751	>	long s = (root == this) ? state : reconcileState();
752	>	int p = (int)(s >>> PHASE_SHIFT);
753		if (phase < 0)
754		return phase;
755	<	if (p == phase &&
675	<	(p = (int)((r = root).state >>> PHASE_SHIFT)) == phase) {
755	>	if (p == phase) {
756		QNode node = new QNode(this, phase, true, true, nanos);
757	<	p = r.internalAwaitAdvance(phase, node);
757	>	p = root.internalAwaitAdvance(phase, node);
758		if (node.wasInterrupted)
759		throw new InterruptedException();
760		else if (p == phase)
#	Line 684 | Line 764 | public class Phaser {
764		}
765
766		/**
767	<	* Forces this barrier to enter termination state.  Counts of
768	<	* arrived and registered parties are unaffected.  If this Phaser
769	<	* is a member of a tiered set of Phasers, then all of the Phasers
770	<	* in the set are terminated.  If this Phaser is already
771	<	* terminated, this method has no effect.  This method may be
772	<	* useful for coordinating recovery after one or more tasks
773	<	* encounter unexpected exceptions.
767	>	* Forces this phaser to enter termination state.  Counts of
768	>	* registered parties are unaffected.  If this phaser is a member
769	>	* of a tiered set of phasers, then all of the phasers in the set
770	>	* are terminated.  If this phaser is already terminated, this
771	>	* method has no effect.  This method may be useful for
772	>	* coordinating recovery after one or more tasks encounter
773	>	* unexpected exceptions.
774		*/
775		public void forceTermination() {
776		// Only need to change root state
#	Line 699 | Line 779 | public class Phaser {
779		while ((s = root.state) >= 0) {
780		if (UNSAFE.compareAndSwapLong(root, stateOffset,
781		s, s | TERMINATION_BIT)) {
782	<	releaseWaiters(0); // signal all threads
782	>	// signal all threads
783	>	releaseWaiters(0);
784		releaseWaiters(1);
785		return;
786		}
#	Line 709 | Line 790 | public class Phaser {
790		/**
791		* Returns the current phase number. The maximum phase number is
792		* {@code Integer.MAX_VALUE}, after which it restarts at
793	<	* zero. Upon termination, the phase number is negative.
793	>	* zero. Upon termination, the phase number is negative,
794	>	* in which case the prevailing phase prior to termination
795	>	* may be obtained via {@code getPhase() + Integer.MIN_VALUE}.
796		*
797		* @return the phase number, or a negative value if terminated
798		*/
#	Line 718 | Line 801 | public class Phaser {
801		}
802
803		/**
804	<	* Returns the number of parties registered at this barrier.
804	>	* Returns the number of parties registered at this phaser.
805		*
806		* @return the number of parties
807		*/
#	Line 728 | Line 811 | public class Phaser {
811
812		/**
813		* Returns the number of registered parties that have arrived at
814	<	* the current phase of this barrier.
814	>	* the current phase of this phaser. If this phaser has terminated,
815	>	* the returned value is meaningless and arbitrary.
816		*
817		* @return the number of arrived parties
818		*/
819		public int getArrivedParties() {
820	<	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());
820	>	return arrivedOf(reconcileState());
821		}
822
823		/**
824		* Returns the number of registered parties that have not yet
825	<	* arrived at the current phase of this barrier.
825	>	* arrived at the current phase of this phaser. If this phaser has
826	>	* terminated, the returned value is meaningless and arbitrary.
827		*
828		* @return the number of unarrived parties
829		*/
830		public int getUnarrivedParties() {
831	<	int u = unarrivedOf(state);
751	<	return (u != 0 || parent == null) ? u : unarrivedOf(reconcileState());
831	>	return unarrivedOf(reconcileState());
832		}
833
834		/**
835	<	* Returns the parent of this Phaser, or {@code null} if none.
835	>	* Returns the parent of this phaser, or {@code null} if none.
836		*
837	<	* @return the parent of this Phaser, or {@code null} if none
837	>	* @return the parent of this phaser, or {@code null} if none
838		*/
839		public Phaser getParent() {
840		return parent;
841		}
842
843		/**
844	<	* Returns the root ancestor of this Phaser, which is the same as
845	<	* this Phaser if it has no parent.
844	>	* Returns the root ancestor of this phaser, which is the same as
845	>	* this phaser if it has no parent.
846		*
847	<	* @return the root ancestor of this Phaser
847	>	* @return the root ancestor of this phaser
848		*/
849		public Phaser getRoot() {
850		return root;
851		}
852
853		/**
854	<	* Returns {@code true} if this barrier has been terminated.
854	>	* Returns {@code true} if this phaser has been terminated.
855		*
856	<	* @return {@code true} if this barrier has been terminated
856	>	* @return {@code true} if this phaser has been terminated
857		*/
858		public boolean isTerminated() {
859		return root.state < 0L;
#	Line 782 | Line 862 | public class Phaser {
862		/**
863		* Overridable method to perform an action upon impending phase
864		* advance, and to control termination. This method is invoked
865	<	* upon arrival of the party tripping the barrier (when all other
865	>	* upon arrival of the party advancing this phaser (when all other
866		* waiting parties are dormant).  If this method returns {@code
867	<	* true}, then, rather than advance the phase number, this barrier
868	<	* will be set to a final termination state, and subsequent calls
869	<	* to {@link #isTerminated} will return true. Any (unchecked)
870	<	* Exception or Error thrown by an invocation of this method is
871	<	* propagated to the party attempting to trip the barrier, in
872	<	* which case no advance occurs.
867	>	* true}, this phaser will be set to a final termination state
868	>	* upon advance, and subsequent calls to {@link #isTerminated}
869	>	* will return true. Any (unchecked) Exception or Error thrown by
870	>	* an invocation of this method is propagated to the party
871	>	* attempting to advance this phaser, in which case no advance
872	>	* occurs.
873		*
874	<	* <p>The arguments to this method provide the state of the Phaser
874	>	* <p>The arguments to this method provide the state of the phaser
875		* prevailing for the current transition.  The effects of invoking
876	<	* arrival, registration, and waiting methods on this Phaser from
876	>	* arrival, registration, and waiting methods on this phaser from
877		* within {@code onAdvance} are unspecified and should not be
878		* relied on.
879		*
880	<	* <p>If this Phaser is a member of a tiered set of Phasers, then
881	<	* {@code onAdvance} is invoked only for its root Phaser on each
880	>	* <p>If this phaser is a member of a tiered set of phasers, then
881	>	* {@code onAdvance} is invoked only for its root phaser on each
882		* advance.
883		*
884		* <p>To support the most common use cases, the default
#	Line 814 | Line 894 | public class Phaser {
894		*   protected boolean onAdvance(int phase, int parties) { return false; }
895		* }}</pre>
896		*
897	<	* @param phase the phase number on entering the barrier
897	>	* @param phase the current phase number on entry to this method,
898	>	* before this phaser is advanced
899		* @param registeredParties the current number of registered parties
900	<	* @return {@code true} if this barrier should terminate
900	>	* @return {@code true} if this phaser should terminate
901		*/
902		protected boolean onAdvance(int phase, int registeredParties) {
903	<	return registeredParties <= 0;
903	>	return registeredParties == 0;
904		}
905
906		/**
907	<	* Returns a string identifying this Phaser, as well as its
907	>	* Returns a string identifying this phaser, as well as its
908		* state.  The state, in brackets, includes the String {@code
909		* "phase = "} followed by the phase number, {@code "parties = "}
910		* followed by the number of registered parties, and {@code
911		* "arrived = "} followed by the number of arrived parties.
912		*
913	<	* @return a string identifying this barrier, as well as its state
913	>	* @return a string identifying this phaser, as well as its state
914		*/
915		public String toString() {
916		return stateToString(reconcileState());
#	Line 851 | Line 932 | public class Phaser {
932		* Removes and signals threads from queue for phase.
933		*/
934		private void releaseWaiters(int phase) {
935	<	AtomicReference<QNode> head = queueFor(phase);
936	<	QNode q;
937	<	int p;
935	>	QNode q;   // first element of queue
936	>	Thread t;  // its thread
937	>	AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ;
938		while ((q = head.get()) != null &&
939	<	((p = q.phase) == phase ||
940	<	(int)(root.state >>> PHASE_SHIFT) != p)) {
941	<	if (head.compareAndSet(q, q.next))
942	<	q.signal();
939	>	q.phase != (int)(root.state >>> PHASE_SHIFT)) {
940	>	if (head.compareAndSet(q, q.next) &&
941	>	(t = q.thread) != null) {
942	>	q.thread = null;
943	>	LockSupport.unpark(t);
944	>	}
945	>	}
946	>	}
947	>
948	>	/**
949	>	* Variant of releaseWaiters that additionally tries to remove any
950	>	* nodes no longer waiting for advance due to timeout or
951	>	* interrupt. Currently, nodes are removed only if they are at
952	>	* head of queue, which suffices to reduce memory footprint in
953	>	* most usages.
954	>	*
955	>	* @return current phase on exit
956	>	*/
957	>	private int abortWait(int phase) {
958	>	AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ;
959	>	for (;;) {
960	>	Thread t;
961	>	QNode q = head.get();
962	>	int p = (int)(root.state >>> PHASE_SHIFT);
963	>	if (q == null || ((t = q.thread) != null && q.phase == p))
964	>	return p;
965	>	if (head.compareAndSet(q, q.next) && t != null) {
966	>	q.thread = null;
967	>	LockSupport.unpark(t);
968	>	}
969		}
970		}
971
#	Line 873 | Line 980 | public class Phaser {
980		* avoid it when threads regularly arrive: When a thread in
981		* internalAwaitAdvance notices another arrival before blocking,
982		* and there appear to be enough CPUs available, it spins
983	<	* SPINS_PER_ARRIVAL more times before blocking. Plus, even on
984	<	* uniprocessors, there is at least one intervening Thread.yield
878	<	* before blocking. The value trades off good-citizenship vs big
879	<	* unnecessary slowdowns.
983	>	* SPINS_PER_ARRIVAL more times before blocking. The value trades
984	>	* off good-citizenship vs big unnecessary slowdowns.
985		*/
986		static final int SPINS_PER_ARRIVAL = (NCPU < 2) ? 1 : 1 << 8;
987
#	Line 890 | Line 995 | public class Phaser {
995		* @return current phase
996		*/
997		private int internalAwaitAdvance(int phase, QNode node) {
998	<	boolean queued = false;      // true when node is enqueued
999	<	int lastUnarrived = -1;      // to increase spins upon change
998	>	releaseWaiters(phase-1);          // ensure old queue clean
999	>	boolean queued = false;           // true when node is enqueued
1000	>	int lastUnarrived = 0;            // to increase spins upon change
1001		int spins = SPINS_PER_ARRIVAL;
1002		long s;
1003		int p;
1004		while ((p = (int)((s = state) >>> PHASE_SHIFT)) == phase) {
1005	<	int unarrived = (int)s & UNARRIVED_MASK;
1006	<	if (unarrived != lastUnarrived) {
1007	<	if (lastUnarrived == -1) // ensure old queue clean
1008	<	releaseWaiters(phase-1);
903	<	if ((lastUnarrived = unarrived) < NCPU)
1005	>	if (node == null) {           // spinning in noninterruptible mode
1006	>	int unarrived = (int)s & UNARRIVED_MASK;
1007	>	if (unarrived != lastUnarrived &&
1008	>	(lastUnarrived = unarrived) < NCPU)
1009		spins += SPINS_PER_ARRIVAL;
1010	<	}
1011	<	else if (spins > 0) {
1012	<	if (--spins == (SPINS_PER_ARRIVAL >>> 1))
1013	<	Thread.yield();  // yield midway through spin
909	<	}
910	<	else if (node == null)   // must be noninterruptible
911	<	node = new QNode(this, phase, false, false, 0L);
912	<	else if (node.isReleasable()) {
913	<	p = (int)(state >>> PHASE_SHIFT);
914	<	break;               // aborted
915	<	}
916	<	else if (!queued) {      // push onto queue
917	<	AtomicReference<QNode> head = queueFor(phase);
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	<	else
924	<	queued = head.compareAndSet(q, node);
1010	>	boolean interrupted = Thread.interrupted();
1011	>	if (interrupted || --spins < 0) { // need node to record intr
1012	>	node = new QNode(this, phase, false, false, 0L);
1013	>	node.wasInterrupted = interrupted;
1014		}
1015		}
1016	+	else if (node.isReleasable()) // done or aborted
1017	+	break;
1018	+	else if (!queued) {           // push onto queue
1019	+	AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ;
1020	+	QNode q = node.next = head.get();
1021	+	if ((q == null || q.phase == phase) &&
1022	+	(int)(state >>> PHASE_SHIFT) == phase) // avoid stale enq
1023	+	queued = head.compareAndSet(q, node);
1024	+	}
1025		else {
1026		try {
1027		ForkJoinPool.managedBlock(node);
#	Line 935 | Line 1033 | public class Phaser {
1033
1034		if (node != null) {
1035		if (node.thread != null)
1036	<	node.thread = null; // disable unpark() in node.signal
1037	<	if (!node.interruptible && node.wasInterrupted)
1036	>	node.thread = null;       // avoid need for unpark()
1037	>	if (node.wasInterrupted && !node.interruptible)
1038		Thread.currentThread().interrupt();
1039	+	if (p == phase && (p = (int)(state >>> PHASE_SHIFT)) == phase)
1040	+	return abortWait(phase); // possibly clean up on abort
1041		}
1042	<	if (p != phase)
943	<	releaseWaiters(phase);
1042	>	releaseWaiters(phase);
1043		return p;
1044		}
1045
#	Line 965 | Line 1064 | public class Phaser {
1064		this.interruptible = interruptible;
1065		this.nanos = nanos;
1066		this.timed = timed;
1067	<	this.lastTime = timed? System.nanoTime() : 0L;
1067	>	this.lastTime = timed ? System.nanoTime() : 0L;
1068		thread = Thread.currentThread();
1069		}
1070
1071		public boolean isReleasable() {
1072	<	Thread t = thread;
1073	<	if (t != null) {
1074	<	if (phaser.getPhase() != phase)
1075	<	t = null;
1076	<	else {
1077	<	if (Thread.interrupted())
1078	<	wasInterrupted = true;
1079	<	if (interruptible && wasInterrupted)
1080	<	t = null;
982	<	else if (timed) {
983	<	if (nanos > 0) {
984	<	long now = System.nanoTime();
985	<	nanos -= now - lastTime;
986	<	lastTime = now;
987	<	}
988	<	if (nanos <= 0)
989	<	t = null;
990	<	}
991	<	}
992	<	if (t != null)
993	<	return false;
1072	>	if (thread == null)
1073	>	return true;
1074	>	if (phaser.getPhase() != phase) {
1075	>	thread = null;
1076	>	return true;
1077	>	}
1078	>	if (Thread.interrupted())
1079	>	wasInterrupted = true;
1080	>	if (wasInterrupted && interruptible) {
1081		thread = null;
1082	+	return true;
1083		}
1084	<	return true;
1084	>	if (timed) {
1085	>	if (nanos > 0L) {
1086	>	long now = System.nanoTime();
1087	>	nanos -= now - lastTime;
1088	>	lastTime = now;
1089	>	}
1090	>	if (nanos <= 0L) {
1091	>	thread = null;
1092	>	return true;
1093	>	}
1094	>	}
1095	>	return false;
1096		}
1097
1098		public boolean block() {
#	Line 1005 | Line 1104 | public class Phaser {
1104		LockSupport.parkNanos(this, nanos);
1105		return isReleasable();
1106		}
1008	–
1009	–	void signal() {
1010	–	Thread t = thread;
1011	–	if (t != null) {
1012	–	thread = null;
1013	–	LockSupport.unpark(t);
1014	–	}
1015	–	}
1107		}
1108
1109		// Unsafe mechanics

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