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

Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.56 by dl, Wed Nov 17 10:48:59 2010 UTC vs.
Revision 1.68 by dl, Sat Dec 4 15:25:08 2010 UTC

#	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}.  As illustrated below, when
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
81	>	* value. Similarly, attempts to register upon termination have no
82	>	* effect.  Termination is triggered when an invocation of {@code
83	>	* onAdvance} returns {@code true}. The default implementation returns
84	>	* {@code true} if a deregistration has caused the number of
85	>	* registered parties to become zero.  As illustrated below, when
86		* phasers control actions with a fixed number of iterations, it is
87		* often convenient to override this method to cause termination when
88		* the current phase number reaches a threshold. Method {@link
89		* #forceTermination} is also available to abruptly release waiting
90		* threads and allow them to terminate.
91		*
92	<	* <p> <b>Tiering.</b> Phasers may be <em>tiered</em> (i.e., arranged
93	<	* in tree structures) to reduce contention. Phasers with large
94	<	* numbers of parties that would otherwise experience heavy
92	>	* <p> <b>Tiering.</b> Phasers may be <em>tiered</em> (i.e.,
93	>	* constructed in tree structures) to reduce contention. Phasers with
94	>	* large numbers of parties that would otherwise experience heavy
95		* synchronization contention costs may instead be set up so that
96		* groups of sub-phasers share a common parent.  This may greatly
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
112		* monitored by any caller.  At any given moment there are {@link
#	Line 181 | 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	<	* }
202	<	* // .. initially called, for n tasks via
203	<	* 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
#	Line 224 | Line 237 | public class Phaser {
237		*/
238
239		/**
240	<	* Barrier state representation. Conceptually, a barrier contains
228	<	* 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.  Method reconcileState
264	>	* is usually attempted only only when the number of unarrived
265	>	* parties appears to be zero, which indicates a potential lag in
266	>	* updating phase after the root advanced.
267		*/
268		private volatile long state;
269
270	<	private static final int  MAX_PARTIES    = 0xffff;
271	<	private static final int  MAX_PHASE      = 0x7fffffff;
272	<	private static final int  PARTIES_SHIFT  = 16;
273	<	private static final int  PHASE_SHIFT    = 32;
274	<	private static final int  UNARRIVED_MASK = 0xffff;
275	<	private static final int  PARTIES_MASK   = 0xffff0000;
276	<	private static final long LPARTIES_MASK  = 0xffff0000L; // long version
277	<	private static final long ONE_ARRIVAL    = 1L;
278	<	private static final long ONE_PARTY      = 1L << PARTIES_SHIFT;
279	<	private static final long TERMINATION_PHASE  = -1L << PHASE_SHIFT;
270	>	private static final int  MAX_PARTIES     = 0xffff;
271	>	private static final int  MAX_PHASE       = 0x7fffffff;
272	>	private static final int  PARTIES_SHIFT   = 16;
273	>	private static final int  PHASE_SHIFT     = 32;
274	>	private static final int  UNARRIVED_MASK  = 0xffff;      // to mask ints
275	>	private static final long PARTIES_MASK    = 0xffff0000L; // to mask longs
276	>	private static final long TERMINATION_BIT = 1L << 63;
277	>
278	>	// some special values
279	>	private static final int  ONE_ARRIVAL     = 1;
280	>	private static final int  ONE_PARTY       = 1 << PARTIES_SHIFT;
281	>	private static final int  EMPTY           = 1;
282
283		// The following unpacking methods are usually manually inlined
284
285		private static int unarrivedOf(long s) {
286	<	return (int)s & UNARRIVED_MASK;
286	>	int counts = (int)s;
287	>	return (counts == EMPTY) ? 0 : counts & UNARRIVED_MASK;
288		}
289
290		private static int partiesOf(long s) {
#	Line 266 | Line 296 | public class Phaser {
296		}
297
298		private static int arrivedOf(long s) {
299	<	return partiesOf(s) - unarrivedOf(s);
299	>	int counts = (int)s;
300	>	return (counts == EMPTY) ? 0 :
301	>	(counts >>> PARTIES_SHIFT) - (counts & UNARRIVED_MASK);
302		}
303
304		/**
#	Line 275 | Line 307 | public class Phaser {
307		private final Phaser parent;
308
309		/**
310	<	* The root of phaser tree. Equals this if not in a tree.  Used to
279	<	* support faster state push-down.
310	>	* The root of phaser tree. Equals this if not in a tree.
311		*/
312		private final Phaser root;
313
#	Line 294 | Line 325 | public class Phaser {
325		}
326
327		/**
328	+	* Returns message string for bounds exceptions on arrival.
329	+	*/
330	+	private String badArrive(long s) {
331	+	return "Attempted arrival of unregistered party for " +
332	+	stateToString(s);
333	+	}
334	+
335	+	/**
336	+	* Returns message string for bounds exceptions on registration.
337	+	*/
338	+	private String badRegister(long s) {
339	+	return "Attempt to register more than " +
340	+	MAX_PARTIES + " parties for " + stateToString(s);
341	+	}
342	+
343	+	/**
344		* Main implementation for methods arrive and arriveAndDeregister.
345		* Manually tuned to speed up and minimize race windows for the
346		* common case of just decrementing unarrived field.
347		*
348	<	* @param adj - adjustment to apply to state -- either
302	<	* ONE_ARRIVAL (for arrive) or
303	<	* ONE_ARRIVAL|ONE_PARTY (for arriveAndDeregister)
348	>	* @param deregister false for arrive, true for arriveAndDeregister
349		*/
350	<	private int doArrive(long adj) {
350	>	private int doArrive(boolean deregister) {
351	>	int adj = deregister ? ONE_ARRIVAL|ONE_PARTY : ONE_ARRIVAL;
352	>	final Phaser root = this.root;
353		for (;;) {
354	<	long s;
355	<	int phase, unarrived;
356	<	if ((phase = (int)((s = state) >>> PHASE_SHIFT)) < 0)
354	>	long s = (root == this) ? state : reconcileState();
355	>	int phase = (int)(s >>> PHASE_SHIFT);
356	>	int counts = (int)s;
357	>	int unarrived = (counts & UNARRIVED_MASK) - 1;
358	>	if (phase < 0)
359		return phase;
360	<	else if ((unarrived = (int)s & UNARRIVED_MASK) == 0)
361	<	checkBadArrive(s);
360	>	else if (counts == EMPTY || unarrived < 0) {
361	>	if (root == this || reconcileState() == s)
362	>	throw new IllegalStateException(badArrive(s));
363	>	}
364		else if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s-=adj)) {
365	<	if (unarrived == 1) {
366	<	Phaser par;
367	<	long p = s & LPARTIES_MASK; // unshifted parties field
368	<	long lu = p >>> PARTIES_SHIFT;
369	<	int u = (int)lu;
370	<	int nextPhase = (phase + 1) & MAX_PHASE;
371	<	long next = ((long)nextPhase << PHASE_SHIFT) | p | lu;
372	<	if ((par = parent) == null) {
373	<	if (onAdvance(phase, u))
374	<	next |= TERMINATION_PHASE; // obliterate phase
375	<	UNSAFE.compareAndSwapLong(this, stateOffset, s, next);
376	<	releaseWaiters(phase);
377	<	}
378	<	else {
328	<	par.doArrive(u == 0?
329	<	ONE_ARRIVAL|ONE_PARTY : ONE_ARRIVAL);
330	<	if ((int)(par.state >>> PHASE_SHIFT) != nextPhase ||
331	<	((int)(state >>> PHASE_SHIFT) != nextPhase &&
332	<	!UNSAFE.compareAndSwapLong(this, stateOffset,
333	<	s, next)))
334	<	reconcileState();
335	<	}
365	>	if (unarrived == 0) {
366	>	long n = s & PARTIES_MASK;  // base of next state
367	>	int nextUnarrived = ((int)n) >>> PARTIES_SHIFT;
368	>	if (root != this)
369	>	return parent.doArrive(nextUnarrived == 0);
370	>	if (onAdvance(phase, nextUnarrived))
371	>	n |= TERMINATION_BIT;
372	>	else if (nextUnarrived == 0)
373	>	n |= EMPTY;
374	>	else
375	>	n |= nextUnarrived;
376	>	n |= ((long)((phase + 1) & MAX_PHASE)) << PHASE_SHIFT;
377	>	UNSAFE.compareAndSwapLong(this, stateOffset, s, n);
378	>	releaseWaiters(phase);
379		}
380		return phase;
381		}
#	Line 340 | Line 383 | public class Phaser {
383		}
384
385		/**
343	–	* Rechecks state and throws bounds exceptions on arrival -- called
344	–	* only if unarrived is apparently zero.
345	–	*/
346	–	private void checkBadArrive(long s) {
347	–	if (reconcileState() == s)
348	–	throw new IllegalStateException
349	–	("Attempted arrival of unregistered party for " +
350	–	stateToString(s));
351	–	}
352	–
353	–	/**
386		* Implementation of register, bulkRegister
387		*
388	<	* @param registrations number to add to both parties and unarrived fields
388	>	* @param registrations number to add to both parties and
389	>	* unarrived fields. Must be greater than zero.
390		*/
391		private int doRegister(int registrations) {
392	<	long adj = (long)registrations; // adjustment to state
393	<	adj |= adj << PARTIES_SHIFT;
392	>	// adjustment to state
393	>	long adj = ((long)registrations << PARTIES_SHIFT) | registrations;
394		Phaser par = parent;
395	+	int phase;
396		for (;;) {
397	<	int phase, parties;
398	<	long s = par == null? state : reconcileState();
399	<	if ((phase = (int)(s >>> PHASE_SHIFT)) < 0)
400	<	return phase;
401	<	if ((parties = (int)s >>> PARTIES_SHIFT) != 0 &&
368	<	((int)s & UNARRIVED_MASK) == 0)
369	<	internalAwaitAdvance(phase, null); // wait for onAdvance
370	<	else if (parties + registrations > MAX_PARTIES)
397	>	long s = state;
398	>	int counts = (int)s;
399	>	int parties = counts >>> PARTIES_SHIFT;
400	>	int unarrived = counts & UNARRIVED_MASK;
401	>	if (registrations > MAX_PARTIES - parties)
402		throw new IllegalStateException(badRegister(s));
403	<	else if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s + adj))
404	<	return phase;
403	>	else if ((phase = (int)(s >>> PHASE_SHIFT)) < 0)
404	>	break;
405	>	else if (counts != EMPTY) {             // not 1st registration
406	>	if (par == null || reconcileState() == s) {
407	>	if (unarrived == 0)             // wait out advance
408	>	root.internalAwaitAdvance(phase, null);
409	>	else if (UNSAFE.compareAndSwapLong(this, stateOffset,
410	>	s, s + adj))
411	>	break;
412	>	}
413	>	}
414	>	else if (par == null) {                 // 1st root registration
415	>	long next = (((long) phase) << PHASE_SHIFT) | adj;
416	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next))
417	>	break;
418	>	}
419	>	else {
420	>	synchronized (this) {               // 1st sub registration
421	>	if (state == s) {               // recheck under lock
422	>	par.doRegister(1);
423	>	do {                        // force current phase
424	>	phase = (int)(root.state >>> PHASE_SHIFT);
425	>	// assert phase < 0 || (int)state == EMPTY;
426	>	} while (!UNSAFE.compareAndSwapLong
427	>	(this, stateOffset, state,
428	>	(((long) phase) << PHASE_SHIFT) | adj));
429	>	break;
430	>	}
431	>	}
432	>	}
433		}
434	+	return phase;
435		}
436
437		/**
438	<	* Returns message string for out of bounds exceptions on registration.
379	<	*/
380	<	private String badRegister(long s) {
381	<	return "Attempt to register more than " +
382	<	MAX_PARTIES + " parties for " + stateToString(s);
383	<	}
384	<
385	<	/**
386	<	* Recursively resolves lagged phase propagation from root if necessary.
438	>	* Resolves lagged phase propagation from root if necessary.
439		*/
440		private long reconcileState() {
389	–	Phaser par = parent;
390	–	if (par == null)
391	–	return state;
441		Phaser rt = root;
442	<	for (;;) {
443	<	long s, u;
444	<	int phase, rPhase, pPhase;
445	<	if ((phase = (int)((s = state)>>> PHASE_SHIFT)) < 0 ||
446	<	(rPhase = (int)(rt.state >>> PHASE_SHIFT)) == phase)
447	<	return s;
448	<	long pState = par.parent == null? par.state : par.reconcileState();
449	<	if (state == s) {
450	<	if ((rPhase < 0 || ((int)s & UNARRIVED_MASK) == 0) &&
451	<	((pPhase = (int)(pState >>> PHASE_SHIFT)) < 0 ||
452	<	pPhase == ((phase + 1) & MAX_PHASE)))
453	<	UNSAFE.compareAndSwapLong
454	<	(this, stateOffset, s,
455	<	(((long) pPhase) << PHASE_SHIFT) |
456	<	(u = s & LPARTIES_MASK) |
457	<	(u >>> PARTIES_SHIFT)); // reset unarrived to parties
458	<	else
459	<	releaseWaiters(phase); // help release others
442	>	long s = state;
443	>	if (rt != this) {
444	>	int phase;
445	>	while ((phase = (int)(rt.state >>> PHASE_SHIFT)) !=
446	>	(int)(s >>> PHASE_SHIFT)) {
447	>	// assert phase < 0 || unarrivedOf(s) == 0
448	>	long t;                             // to reread s
449	>	long p = s & PARTIES_MASK;          // unshifted parties field
450	>	long n = (((long) phase) << PHASE_SHIFT) | p;
451	>	if (phase >= 0) {
452	>	if (p == 0L)
453	>	n |= EMPTY;                 // reset to empty
454	>	else
455	>	n |= p >>> PARTIES_SHIFT;   // set unarr to parties
456	>	}
457	>	if ((t = state) == s &&
458	>	UNSAFE.compareAndSwapLong(this, stateOffset, s, s = n))
459	>	break;
460	>	s = t;
461		}
462		}
463	+	return s;
464		}
465
466		/**
467	<	* Creates a new phaser without any initially registered parties,
468	<	* initial phase number 0, and no parent. Any thread using this
467	>	* Creates a new phaser with no initially registered parties, no
468	>	* parent, and initial phase number 0. Any thread using this
469		* phaser will need to first register for it.
470		*/
471		public Phaser() {
#	Line 423 | Line 474 | public class Phaser {
474
475		/**
476		* Creates a new phaser with the given number of registered
477	<	* unarrived parties, initial phase number 0, and no parent.
477	>	* unarrived parties, no parent, and initial phase number 0.
478		*
479	<	* @param parties the number of parties required to trip barrier
479	>	* @param parties the number of parties required to advance to the
480	>	* next phase
481		* @throws IllegalArgumentException if parties less than zero
482		* or greater than the maximum number of parties supported
483		*/
#	Line 434 | Line 486 | public class Phaser {
486		}
487
488		/**
489	<	* 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.
489	>	* Equivalent to {@link #Phaser(Phaser, int) Phaser(parent, 0)}.
490		*
491		* @param parent the parent phaser
492		*/
#	Line 447 | Line 496 | public class Phaser {
496
497		/**
498		* Creates a new phaser with the given parent and number of
499	<	* registered unarrived parties. If parent is non-null, this phaser
500	<	* is registered with the parent and its initial phase number is
501	<	* the same as that of parent phaser.
499	>	* registered unarrived parties.  When the given parent is non-null
500	>	* and the given number of parties is greater than zero, this
501	>	* child phaser is registered with its parent.
502		*
503		* @param parent the parent phaser
504	<	* @param parties the number of parties required to trip barrier
504	>	* @param parties the number of parties required to advance to the
505	>	* next phase
506		* @throws IllegalArgumentException if parties less than zero
507		* or greater than the maximum number of parties supported
508		*/
509		public Phaser(Phaser parent, int parties) {
510		if (parties >>> PARTIES_SHIFT != 0)
511		throw new IllegalArgumentException("Illegal number of parties");
512	<	int phase;
512	>	int phase = 0;
513		this.parent = parent;
514		if (parent != null) {
515	<	Phaser r = parent.root;
516	<	this.root = r;
517	<	this.evenQ = r.evenQ;
518	<	this.oddQ = r.oddQ;
519	<	phase = parent.register();
515	>	final Phaser root = parent.root;
516	>	this.root = root;
517	>	this.evenQ = root.evenQ;
518	>	this.oddQ = root.oddQ;
519	>	if (parties != 0)
520	>	phase = parent.doRegister(1);
521		}
522		else {
523		this.root = this;
524		this.evenQ = new AtomicReference<QNode>();
525		this.oddQ = new AtomicReference<QNode>();
475	–	phase = 0;
526		}
527	<	long p = (long)parties;
528	<	this.state = (((long)phase) << PHASE_SHIFT) | p | (p << PARTIES_SHIFT);
527	>	this.state = (parties == 0) ? (long) EMPTY :
528	>	((((long) phase) << PHASE_SHIFT) |
529	>	(((long) parties) << PARTIES_SHIFT) |
530	>	((long) parties));
531		}
532
533		/**
534	<	* Adds a new unarrived party to this phaser.
535	<	* If an ongoing invocation of {@link #onAdvance} is in progress,
536	<	* this method may wait until its completion before registering.
537	<	*
538	<	* @return the arrival phase number to which this registration applied
534	>	* Adds a new unarrived party to this phaser.  If an ongoing
535	>	* invocation of {@link #onAdvance} is in progress, this method
536	>	* may await its completion before returning.  If this phaser has
537	>	* a parent, and this phaser previously had no registered parties,
538	>	* this child phaser is also registered with its parent. If
539	>	* this phaser is terminated, the attempt to register has
540	>	* no effect, and a negative value is returned.
541	>	*
542	>	* @return the arrival phase number to which this registration
543	>	* applied.  If this value is negative, then this phaser has
544	>	* terminated, in which casem registration has no effect.
545		* @throws IllegalStateException if attempting to register more
546		* than the maximum supported number of parties
547		*/
#	Line 494 | Line 552 | public class Phaser {
552		/**
553		* Adds the given number of new unarrived parties to this phaser.
554		* If an ongoing invocation of {@link #onAdvance} is in progress,
555	<	* this method may wait until its completion before registering.
556	<	*
557	<	* @param parties the number of additional parties required to trip barrier
558	<	* @return the arrival phase number to which this registration applied
555	>	* this method may await its completion before returning.  If this
556	>	* phaser has a parent, and the given number of parties is greater
557	>	* than zero, and this phaser previously had no registered
558	>	* parties, this child phaser is also registered with its parent.
559	>	* If this phaser is terminated, the attempt to register has no
560	>	* effect, and a negative value is returned.
561	>	*
562	>	* @param parties the number of additional parties required to
563	>	* advance to the next phase
564	>	* @return the arrival phase number to which this registration
565	>	* applied.  If this value is negative, then this phaser has
566	>	* terminated, in which casem registration has no effect.
567		* @throws IllegalStateException if attempting to register more
568		* than the maximum supported number of parties
569		* @throws IllegalArgumentException if {@code parties < 0}
#	Line 505 | Line 571 | public class Phaser {
571		public int bulkRegister(int parties) {
572		if (parties < 0)
573		throw new IllegalArgumentException();
508	–	if (parties > MAX_PARTIES)
509	–	throw new IllegalStateException(badRegister(state));
574		if (parties == 0)
575		return getPhase();
576		return doRegister(parties);
577		}
578
579		/**
580	<	* Arrives at the barrier, but does not wait for others.  (You can
581	<	* in turn wait for others via {@link #awaitAdvance}).  It is an
582	<	* unenforced usage error for an unregistered party to invoke this
583	<	* method.
580	>	* Arrives at this phaser, without waiting for others to arrive.
581	>	*
582	>	* <p>It is a usage error for an unregistered party to invoke this
583	>	* method.  However, this error may result in an {@code
584	>	* IllegalStateException} only upon some subsequent operation on
585	>	* this phaser, if ever.
586		*
587		* @return the arrival phase number, or a negative value if terminated
588		* @throws IllegalStateException if not terminated and the number
589		* of unarrived parties would become negative
590		*/
591		public int arrive() {
592	<	return doArrive(ONE_ARRIVAL);
592	>	return doArrive(false);
593		}
594
595		/**
596	<	* Arrives at the barrier and deregisters from it without waiting
597	<	* for others. Deregistration reduces the number of parties
598	<	* required to trip the barrier in future phases.  If this phaser
596	>	* Arrives at this phaser and deregisters from it without waiting
597	>	* for others to arrive. Deregistration reduces the number of
598	>	* parties required to advance in future phases.  If this phaser
599		* has a parent, and deregistration causes this phaser to have
600	<	* zero parties, this phaser also arrives at and is deregistered
601	<	* from its parent.  It is an unenforced usage error for an
602	<	* unregistered party to invoke this method.
600	>	* zero parties, this phaser is also deregistered from its parent.
601	>	*
602	>	* <p>It is a usage error for an unregistered party to invoke this
603	>	* method.  However, this error may result in an {@code
604	>	* IllegalStateException} only upon some subsequent operation on
605	>	* this phaser, if ever.
606		*
607		* @return the arrival phase number, or a negative value if terminated
608		* @throws IllegalStateException if not terminated and the number
609		* of registered or unarrived parties would become negative
610		*/
611		public int arriveAndDeregister() {
612	<	return doArrive(ONE_ARRIVAL|ONE_PARTY);
612	>	return doArrive(true);
613		}
614
615		/**
616	<	* Arrives at the barrier and awaits others. Equivalent in effect
616	>	* Arrives at this phaser and awaits others. Equivalent in effect
617		* to {@code awaitAdvance(arrive())}.  If you need to await with
618		* interruption or timeout, you can arrange this with an analogous
619		* construction using one of the other forms of the {@code
620		* awaitAdvance} method.  If instead you need to deregister upon
621	<	* arrival, use {@link #arriveAndDeregister}. It is an unenforced
622	<	* usage error for an unregistered party to invoke this method.
621	>	* arrival, use {@code awaitAdvance(arriveAndDeregister())}.
622	>	*
623	>	* <p>It is a usage error for an unregistered party to invoke this
624	>	* method.  However, this error may result in an {@code
625	>	* IllegalStateException} only upon some subsequent operation on
626	>	* this phaser, if ever.
627		*
628	<	* @return the arrival phase number, or a negative number if terminated
628	>	* @return the arrival phase number, or the (negative)
629	>	* {@linkplain #getPhase() current phase} if terminated
630		* @throws IllegalStateException if not terminated and the number
631		* of unarrived parties would become negative
632		*/
633		public int arriveAndAwaitAdvance() {
634	<	return awaitAdvance(arrive());
634	>	// Specialization of doArrive+awaitAdvance eliminating some reads/paths
635	>	final Phaser root = this.root;
636	>	for (;;) {
637	>	long s = (root == this) ? state : reconcileState();
638	>	int phase = (int)(s >>> PHASE_SHIFT);
639	>	int counts = (int)s;
640	>	int unarrived = (counts & UNARRIVED_MASK) - 1;
641	>	if (phase < 0)
642	>	return phase;
643	>	else if (counts == EMPTY || unarrived < 0) {
644	>	if (reconcileState() == s)
645	>	throw new IllegalStateException(badArrive(s));
646	>	}
647	>	else if (UNSAFE.compareAndSwapLong(this, stateOffset, s,
648	>	s -= ONE_ARRIVAL)) {
649	>	if (unarrived != 0)
650	>	return root.internalAwaitAdvance(phase, null);
651	>	if (root != this)
652	>	return parent.arriveAndAwaitAdvance();
653	>	long n = s & PARTIES_MASK;  // base of next state
654	>	int nextUnarrived = ((int)n) >>> PARTIES_SHIFT;
655	>	if (onAdvance(phase, nextUnarrived))
656	>	n |= TERMINATION_BIT;
657	>	else if (nextUnarrived == 0)
658	>	n |= EMPTY;
659	>	else
660	>	n |= nextUnarrived;
661	>	int nextPhase = (phase + 1) & MAX_PHASE;
662	>	n |= (long)nextPhase << PHASE_SHIFT;
663	>	if (!UNSAFE.compareAndSwapLong(this, stateOffset, s, n))
664	>	return (int)(state >>> PHASE_SHIFT); // terminated
665	>	releaseWaiters(phase);
666	>	return nextPhase;
667	>	}
668	>	}
669		}
670
671		/**
672	<	* Awaits the phase of the barrier to advance from the given phase
673	<	* value, returning immediately if the current phase of the
674	<	* barrier is not equal to the given phase value or this barrier
567	<	* is terminated.
672	>	* Awaits the phase of this phaser to advance from the given phase
673	>	* value, returning immediately if the current phase is not equal
674	>	* to the given phase value or this phaser is terminated.
675		*
676		* @param phase an arrival phase number, or negative value if
677		* terminated; this argument is normally the value returned by a
678	<	* previous call to {@code arrive} or its variants
679	<	* @return the next arrival phase number, or a negative value
680	<	* if terminated or argument is negative
678	>	* previous call to {@code arrive} or {@code arriveAndDeregister}.
679	>	* @return the next arrival phase number, or the argument if it is
680	>	* negative, or the (negative) {@linkplain #getPhase() current phase}
681	>	* if terminated
682		*/
683		public int awaitAdvance(int phase) {
684	<	int p;
684	>	final Phaser root = this.root;
685	>	int p = (int)((root == this? state : reconcileState()) >>> PHASE_SHIFT);
686		if (phase < 0)
687		return phase;
688	<	else if ((p = (int)((parent == null? state : reconcileState())
689	<	>>> PHASE_SHIFT)) == phase)
690	<	return internalAwaitAdvance(phase, null);
582	<	else
583	<	return p;
688	>	if (p == phase)
689	>	return root.internalAwaitAdvance(phase, null);
690	>	return p;
691		}
692
693		/**
694	<	* Awaits the phase of the barrier to advance from the given phase
694	>	* Awaits the phase of this phaser to advance from the given phase
695		* value, throwing {@code InterruptedException} if interrupted
696	<	* while waiting, or returning immediately if the current phase of
697	<	* the barrier is not equal to the given phase value or this
698	<	* barrier is terminated.
696	>	* while waiting, or returning immediately if the current phase is
697	>	* not equal to the given phase value or this phaser is
698	>	* terminated.
699		*
700		* @param phase an arrival phase number, or negative value if
701		* terminated; this argument is normally the value returned by a
702	<	* previous call to {@code arrive} or its variants
703	<	* @return the next arrival phase number, or a negative value
704	<	* if terminated or argument is negative
702	>	* previous call to {@code arrive} or {@code arriveAndDeregister}.
703	>	* @return the next arrival phase number, or the argument if it is
704	>	* negative, or the (negative) {@linkplain #getPhase() current phase}
705	>	* if terminated
706		* @throws InterruptedException if thread interrupted while waiting
707		*/
708		public int awaitAdvanceInterruptibly(int phase)
709		throws InterruptedException {
710	<	int p;
710	>	final Phaser root = this.root;
711	>	int p = (int)((root == this? state : reconcileState()) >>> PHASE_SHIFT);
712		if (phase < 0)
713		return phase;
714	<	if ((p = (int)((parent == null? state : reconcileState())
606	<	>>> PHASE_SHIFT)) == phase) {
714	>	if (p == phase) {
715		QNode node = new QNode(this, phase, true, false, 0L);
716	<	p = internalAwaitAdvance(phase, node);
716	>	p = root.internalAwaitAdvance(phase, node);
717		if (node.wasInterrupted)
718		throw new InterruptedException();
719		}
#	Line 613 | Line 721 | public class Phaser {
721		}
722
723		/**
724	<	* Awaits the phase of the barrier to advance from the given phase
724	>	* Awaits the phase of this phaser to advance from the given phase
725		* value or the given timeout to elapse, throwing {@code
726		* InterruptedException} if interrupted while waiting, or
727	<	* returning immediately if the current phase of the barrier is
728	<	* not equal to the given phase value or this barrier is
621	<	* terminated.
727	>	* returning immediately if the current phase is not equal to the
728	>	* given phase value or this phaser is terminated.
729		*
730		* @param phase an arrival phase number, or negative value if
731		* terminated; this argument is normally the value returned by a
732	<	* previous call to {@code arrive} or its variants
732	>	* previous call to {@code arrive} or {@code arriveAndDeregister}.
733		* @param timeout how long to wait before giving up, in units of
734		*        {@code unit}
735		* @param unit a {@code TimeUnit} determining how to interpret the
736		*        {@code timeout} parameter
737	<	* @return the next arrival phase number, or a negative value
738	<	* if terminated or argument is negative
737	>	* @return the next arrival phase number, or the argument if it is
738	>	* negative, or the (negative) {@linkplain #getPhase() current phase}
739	>	* if terminated
740		* @throws InterruptedException if thread interrupted while waiting
741		* @throws TimeoutException if timed out while waiting
742		*/
#	Line 636 | Line 744 | public class Phaser {
744		long timeout, TimeUnit unit)
745		throws InterruptedException, TimeoutException {
746		long nanos = unit.toNanos(timeout);
747	<	int p;
747	>	final Phaser root = this.root;
748	>	int p = (int)((root == this? state : reconcileState()) >>> PHASE_SHIFT);
749		if (phase < 0)
750		return phase;
751	<	if ((p = (int)((parent == null? state : reconcileState())
643	<	>>> PHASE_SHIFT)) == phase) {
751	>	if (p == phase) {
752		QNode node = new QNode(this, phase, true, true, nanos);
753	<	p = internalAwaitAdvance(phase, node);
753	>	p = root.internalAwaitAdvance(phase, node);
754		if (node.wasInterrupted)
755		throw new InterruptedException();
756		else if (p == phase)
#	Line 652 | Line 760 | public class Phaser {
760		}
761
762		/**
763	<	* Forces this barrier to enter termination state.  Counts of
764	<	* arrived and registered parties are unaffected.  If this phaser
765	<	* is a member of a tiered set of phasers, then all of the phasers
766	<	* in the set are terminated.  If this phaser is already
767	<	* terminated, this method has no effect.  This method may be
768	<	* useful for coordinating recovery after one or more tasks
769	<	* encounter unexpected exceptions.
763	>	* Forces this phaser to enter termination state.  Counts of
764	>	* registered parties are unaffected.  If this phaser is a member
765	>	* of a tiered set of phasers, then all of the phasers in the set
766	>	* are terminated.  If this phaser is already terminated, this
767	>	* method has no effect.  This method may be useful for
768	>	* coordinating recovery after one or more tasks encounter
769	>	* unexpected exceptions.
770		*/
771		public void forceTermination() {
772		// Only need to change root state
773		final Phaser root = this.root;
774		long s;
775		while ((s = root.state) >= 0) {
776	<	if (UNSAFE.compareAndSwapLong(root, stateOffset,
777	<	s, s | TERMINATION_PHASE)) {
778	<	releaseWaiters(0); // signal all threads
776	>	long next = (s & ~((long)UNARRIVED_MASK)) | TERMINATION_BIT;
777	>	if (UNSAFE.compareAndSwapLong(root, stateOffset, s, next)) {
778	>	// signal all threads
779	>	releaseWaiters(0);
780		releaseWaiters(1);
781		return;
782		}
#	Line 677 | Line 786 | public class Phaser {
786		/**
787		* Returns the current phase number. The maximum phase number is
788		* {@code Integer.MAX_VALUE}, after which it restarts at
789	<	* zero. Upon termination, the phase number is negative.
789	>	* zero. Upon termination, the phase number is negative,
790	>	* in which case the prevailing phase prior to termination
791	>	* may be obtained via {@code getPhase() + Integer.MIN_VALUE}.
792		*
793		* @return the phase number, or a negative value if terminated
794		*/
795		public final int getPhase() {
796	<	return (int)((parent==null? state : reconcileState()) >>> PHASE_SHIFT);
796	>	return (int)(root.state >>> PHASE_SHIFT);
797		}
798
799		/**
800	<	* Returns the number of parties registered at this barrier.
800	>	* Returns the number of parties registered at this phaser.
801		*
802		* @return the number of parties
803		*/
804		public int getRegisteredParties() {
805	<	return partiesOf(parent==null? state : reconcileState());
805	>	return partiesOf(state);
806		}
807
808		/**
809		* Returns the number of registered parties that have arrived at
810	<	* the current phase of this barrier.
810	>	* the current phase of this phaser.
811		*
812		* @return the number of arrived parties
813		*/
814		public int getArrivedParties() {
815	<	return arrivedOf(parent==null? state : reconcileState());
815	>	return arrivedOf(reconcileState());
816		}
817
818		/**
819		* Returns the number of registered parties that have not yet
820	<	* arrived at the current phase of this barrier.
820	>	* arrived at the current phase of this phaser.
821		*
822		* @return the number of unarrived parties
823		*/
824		public int getUnarrivedParties() {
825	<	return unarrivedOf(parent==null? state : reconcileState());
825	>	return unarrivedOf(reconcileState());
826		}
827
828		/**
#	Line 734 | Line 845 | public class Phaser {
845		}
846
847		/**
848	<	* Returns {@code true} if this barrier has been terminated.
848	>	* Returns {@code true} if this phaser has been terminated.
849		*
850	<	* @return {@code true} if this barrier has been terminated
850	>	* @return {@code true} if this phaser has been terminated
851		*/
852		public boolean isTerminated() {
853	<	return (parent == null? state : reconcileState()) < 0;
853	>	return root.state < 0L;
854		}
855
856		/**
857		* Overridable method to perform an action upon impending phase
858		* advance, and to control termination. This method is invoked
859	<	* upon arrival of the party tripping the barrier (when all other
859	>	* upon arrival of the party advancing this phaser (when all other
860		* waiting parties are dormant).  If this method returns {@code
861	<	* true}, then, rather than advance the phase number, this barrier
862	<	* will be set to a final termination state, and subsequent calls
863	<	* to {@link #isTerminated} will return true. Any (unchecked)
864	<	* Exception or Error thrown by an invocation of this method is
865	<	* propagated to the party attempting to trip the barrier, in
866	<	* which case no advance occurs.
861	>	* true}, this phaser will be set to a final termination state
862	>	* upon advance, and subsequent calls to {@link #isTerminated}
863	>	* will return true. Any (unchecked) Exception or Error thrown by
864	>	* an invocation of this method is propagated to the party
865	>	* attempting to advance this phaser, in which case no advance
866	>	* occurs.
867		*
868		* <p>The arguments to this method provide the state of the phaser
869		* prevailing for the current transition.  The effects of invoking
870	<	* arrival, registration, and waiting methods on this Phaser from
870	>	* arrival, registration, and waiting methods on this phaser from
871		* within {@code onAdvance} are unspecified and should not be
872		* relied on.
873		*
874	<	* <p>If this Phaser is a member of a tiered set of Phasers, then
875	<	* {@code onAdvance} is invoked only for its root Phaser on each
874	>	* <p>If this phaser is a member of a tiered set of phasers, then
875	>	* {@code onAdvance} is invoked only for its root phaser on each
876		* advance.
877		*
878	<	* <p>The default version returns {@code true} when the number of
879	<	* registered parties is zero. Normally, overrides that arrange
880	<	* termination for other reasons should also preserve this
881	<	* property.
878	>	* <p>To support the most common use cases, the default
879	>	* implementation of this method returns {@code true} when the
880	>	* number of registered parties has become zero as the result of a
881	>	* party invoking {@code arriveAndDeregister}.  You can disable
882	>	* this behavior, thus enabling continuation upon future
883	>	* registrations, by overriding this method to always return
884	>	* {@code false}:
885	>	*
886	>	* <pre> {@code
887	>	* Phaser phaser = new Phaser() {
888	>	*   protected boolean onAdvance(int phase, int parties) { return false; }
889	>	* }}</pre>
890		*
891	<	* @param phase the phase number on entering the barrier
891	>	* @param phase the current phase number on entry to this method,
892	>	* before this phaser is advanced
893		* @param registeredParties the current number of registered parties
894	<	* @return {@code true} if this barrier should terminate
894	>	* @return {@code true} if this phaser should terminate
895		*/
896		protected boolean onAdvance(int phase, int registeredParties) {
897	<	return registeredParties <= 0;
897	>	return registeredParties == 0;
898		}
899
900		/**
#	Line 784 | Line 904 | public class Phaser {
904		* followed by the number of registered parties, and {@code
905		* "arrived = "} followed by the number of arrived parties.
906		*
907	<	* @return a string identifying this barrier, as well as its state
907	>	* @return a string identifying this phaser, as well as its state
908		*/
909		public String toString() {
910		return stateToString(reconcileState());
#	Line 803 | Line 923 | public class Phaser {
923		// Waiting mechanics
924
925		/**
926	<	* Removes and signals threads from queue for phase
926	>	* Removes and signals threads from queue for phase.
927		*/
928		private void releaseWaiters(int phase) {
929	<	AtomicReference<QNode> head = queueFor(phase);
930	<	QNode q;
931	<	int p;
929	>	QNode q;   // first element of queue
930	>	Thread t;  // its thread
931	>	AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ;
932		while ((q = head.get()) != null &&
933	<	((p = q.phase) == phase ||
934	<	(int)(root.state >>> PHASE_SHIFT) != p)) {
935	<	if (head.compareAndSet(q, q.next))
936	<	q.signal();
933	>	q.phase != (int)(root.state >>> PHASE_SHIFT)) {
934	>	if (head.compareAndSet(q, q.next) &&
935	>	(t = q.thread) != null) {
936	>	q.thread = null;
937	>	LockSupport.unpark(t);
938	>	}
939		}
940		}
941
942		/**
943	<	* Tries to enqueue given node in the appropriate wait queue.
943	>	* Variant of releaseWaiters that additionally tries to remove any
944	>	* nodes no longer waiting for advance due to timeout or
945	>	* interrupt. Currently, nodes are removed only if they are at
946	>	* head of queue, which suffices to reduce memory footprint in
947	>	* most usages.
948		*
949	<	* @return true if successful
949	>	* @return current phase on exit
950		*/
951	<	private boolean tryEnqueue(int phase, QNode node) {
952	<	releaseWaiters(phase-1); // ensure old queue clean
953	<	AtomicReference<QNode> head = queueFor(phase);
954	<	QNode q = head.get();
955	<	return ((q == null || q.phase == phase) &&
956	<	(int)(root.state >>> PHASE_SHIFT) == phase &&
957	<	head.compareAndSet(node.next = q, node));
951	>	private int abortWait(int phase) {
952	>	AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ;
953	>	for (;;) {
954	>	Thread t;
955	>	QNode q = head.get();
956	>	int p = (int)(root.state >>> PHASE_SHIFT);
957	>	if (q == null || ((t = q.thread) != null && q.phase == p))
958	>	return p;
959	>	if (head.compareAndSet(q, q.next) && t != null) {
960	>	q.thread = null;
961	>	LockSupport.unpark(t);
962	>	}
963	>	}
964		}
965
966		/** The number of CPUs, for spin control */
#	Line 842 | Line 974 | public class Phaser {
974		* avoid it when threads regularly arrive: When a thread in
975		* internalAwaitAdvance notices another arrival before blocking,
976		* and there appear to be enough CPUs available, it spins
977	<	* SPINS_PER_ARRIVAL more times before blocking. Plus, even on
978	<	* uniprocessors, there is at least one intervening Thread.yield
847	<	* before blocking. The value trades off good-citizenship vs big
848	<	* unnecessary slowdowns.
977	>	* SPINS_PER_ARRIVAL more times before blocking. The value trades
978	>	* off good-citizenship vs big unnecessary slowdowns.
979		*/
980		static final int SPINS_PER_ARRIVAL = (NCPU < 2) ? 1 : 1 << 8;
981
982		/**
983		* Possibly blocks and waits for phase to advance unless aborted.
984	+	* Call only from root node.
985		*
986		* @param phase current phase
987		* @param node if non-null, the wait node to track interrupt and timeout;
#	Line 858 | Line 989 | public class Phaser {
989		* @return current phase
990		*/
991		private int internalAwaitAdvance(int phase, QNode node) {
992	<	Phaser current = this;       // to eventually wait at root if tiered
993	<	boolean queued = false;      // true when node is enqueued
994	<	int lastUnarrived = -1;      // to increase spins upon change
992	>	releaseWaiters(phase-1);          // ensure old queue clean
993	>	boolean queued = false;           // true when node is enqueued
994	>	int lastUnarrived = 0;            // to increase spins upon change
995		int spins = SPINS_PER_ARRIVAL;
996	<	for (;;) {
997	<	int p, unarrived;
998	<	Phaser par;
999	<	long s = current.state;
1000	<	if ((p = (int)(s >>> PHASE_SHIFT)) != phase) {
1001	<	if (node != null)
1002	<	node.onRelease();
872	<	releaseWaiters(phase);
873	<	return p;
874	<	}
875	<	else if ((unarrived = (int)s & UNARRIVED_MASK) == 0 &&
876	<	(par = current.parent) != null) {
877	<	current = par;       // if all arrived, use parent
878	<	par = par.parent;
879	<	lastUnarrived = -1;
880	<	}
881	<	else if (unarrived != lastUnarrived) {
882	<	if ((lastUnarrived = unarrived) < NCPU)
996	>	long s;
997	>	int p;
998	>	while ((p = (int)((s = state) >>> PHASE_SHIFT)) == phase) {
999	>	if (node == null) {           // spinning in noninterruptible mode
1000	>	int unarrived = (int)s & UNARRIVED_MASK;
1001	>	if (unarrived != lastUnarrived &&
1002	>	(lastUnarrived = unarrived) < NCPU)
1003		spins += SPINS_PER_ARRIVAL;
1004	+	boolean interrupted = Thread.interrupted();
1005	+	if (interrupted || --spins < 0) { // need node to record intr
1006	+	node = new QNode(this, phase, false, false, 0L);
1007	+	node.wasInterrupted = interrupted;
1008	+	}
1009		}
1010	<	else if (spins > 0) {
1011	<	if (--spins == (SPINS_PER_ARRIVAL >>> 1))
1012	<	Thread.yield();  // yield midway through spin
1013	<	}
1014	<	else if (node == null)   // must be noninterruptible
1015	<	node = new QNode(this, phase, false, false, 0L);
1016	<	else if (node.isReleasable()) {
1017	<	if ((int)(reconcileState() >>> PHASE_SHIFT) == phase)
893	<	return phase;    // aborted
1010	>	else if (node.isReleasable()) // done or aborted
1011	>	break;
1012	>	else if (!queued) {           // push onto queue
1013	>	AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ;
1014	>	QNode q = node.next = head.get();
1015	>	if ((q == null || q.phase == phase) &&
1016	>	(int)(state >>> PHASE_SHIFT) == phase) // avoid stale enq
1017	>	queued = head.compareAndSet(q, node);
1018		}
895	–	else if (!queued)
896	–	queued = tryEnqueue(phase, node);
1019		else {
1020		try {
1021		ForkJoinPool.managedBlock(node);
#	Line 902 | Line 1024 | public class Phaser {
1024		}
1025		}
1026		}
1027	+
1028	+	if (node != null) {
1029	+	if (node.thread != null)
1030	+	node.thread = null;       // avoid need for unpark()
1031	+	if (node.wasInterrupted && !node.interruptible)
1032	+	Thread.currentThread().interrupt();
1033	+	if (p == phase && (p = (int)(state >>> PHASE_SHIFT)) == phase)
1034	+	return abortWait(phase); // possibly clean up on abort
1035	+	}
1036	+	releaseWaiters(phase);
1037	+	return p;
1038		}
1039
1040		/**
#	Line 925 | Line 1058 | public class Phaser {
1058		this.interruptible = interruptible;
1059		this.nanos = nanos;
1060		this.timed = timed;
1061	<	this.lastTime = timed? System.nanoTime() : 0L;
1061	>	this.lastTime = timed ? System.nanoTime() : 0L;
1062		thread = Thread.currentThread();
1063		}
1064
1065		public boolean isReleasable() {
1066	<	Thread t = thread;
1067	<	if (t != null) {
1068	<	if (phaser.getPhase() != phase)
1069	<	t = null;
1070	<	else {
1071	<	if (Thread.interrupted())
1072	<	wasInterrupted = true;
1073	<	if (interruptible && wasInterrupted)
1074	<	t = null;
942	<	else if (timed) {
943	<	if (nanos > 0) {
944	<	long now = System.nanoTime();
945	<	nanos -= now - lastTime;
946	<	lastTime = now;
947	<	}
948	<	if (nanos <= 0)
949	<	t = null;
950	<	}
951	<	}
952	<	if (t != null)
953	<	return false;
1066	>	if (thread == null)
1067	>	return true;
1068	>	if (phaser.getPhase() != phase) {
1069	>	thread = null;
1070	>	return true;
1071	>	}
1072	>	if (Thread.interrupted())
1073	>	wasInterrupted = true;
1074	>	if (wasInterrupted && interruptible) {
1075		thread = null;
1076	+	return true;
1077		}
1078	<	return true;
1078	>	if (timed) {
1079	>	if (nanos > 0L) {
1080	>	long now = System.nanoTime();
1081	>	nanos -= now - lastTime;
1082	>	lastTime = now;
1083	>	}
1084	>	if (nanos <= 0L) {
1085	>	thread = null;
1086	>	return true;
1087	>	}
1088	>	}
1089	>	return false;
1090		}
1091
1092		public boolean block() {
#	Line 965 | Line 1098 | public class Phaser {
1098		LockSupport.parkNanos(this, nanos);
1099		return isReleasable();
1100		}
968	–
969	–	void signal() {
970	–	Thread t = thread;
971	–	if (t != null) {
972	–	thread = null;
973	–	LockSupport.unpark(t);
974	–	}
975	–	}
976	–
977	–	void onRelease() { // actions upon return from internalAwaitAdvance
978	–	if (!interruptible && wasInterrupted)
979	–	Thread.currentThread().interrupt();
980	–	if (thread != null)
981	–	thread = null;
982	–	}
983	–
1101		}
1102
1103		// Unsafe mechanics

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