ViewVC Help

View File | Revision Log | Show Annotations | Download File | Root Listing

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

Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.57 by dl, Fri Nov 19 16:03:24 2010 UTC vs.
Revision 1.77 by jsr166, Mon Oct 17 23:37:19 2011 UTC

#	Line 1 | Line 1
1		/*
2		* Written by Doug Lea with assistance from members of JCP JSR-166
3		* Expert Group and released to the public domain, as explained at
4	<	* http://creativecommons.org/licenses/publicdomain
4	>	* http://creativecommons.org/publicdomain/zero/1.0/
5		*/
6
7		package jsr166y;
#	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
83	<	* phasers control actions with a fixed number of iterations, it is
84	<	* often convenient to override this method to cause termination when
85	<	* the current phase number reaches a threshold. Method {@link
86	<	* #forceTermination} is also available to abruptly release waiting
87	<	* threads and allow them to terminate.
88	<	*
89	<	* <p> <b>Tiering.</b> Phasers may be <em>tiered</em> (i.e., arranged
90	<	* in tree structures) to reduce contention. Phasers with large
91	<	* numbers of parties that would otherwise experience heavy
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
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 117 | Line 130 | import java.util.concurrent.locks.LockSu
130		* void runTasks(List<Runnable> tasks) {
131		*   final Phaser phaser = new Phaser(1); // "1" to register self
132		*   // create and start threads
133	<	*   for (Runnable task : tasks) {
133	>	*   for (final Runnable task : tasks) {
134		*     phaser.register();
135		*     new Thread() {
136		*       public void run() {
#	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 bit-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.
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	>	* Except that a phaser with no registered parties is
248	>	* distinguished by 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
268	<	private static final int  MAX_PARTIES    = 0xffff;
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 int  UNARRIVED_MASK = 0xffff;
273	<	private static final long PARTIES_MASK   = 0xffff0000L; // for masking long
274	<	private static final long ONE_ARRIVAL    = 1L;
275	<	private static final long ONE_PARTY      = 1L << PARTIES_SHIFT;
276	<	private static final long TERMINATION_PHASE  = -1L << PHASE_SHIFT;
268	>	private static final int  MAX_PARTIES     = 0xffff;
269	>	private static final int  MAX_PHASE       = Integer.MAX_VALUE;
270	>	private static final int  PARTIES_SHIFT   = 16;
271	>	private static final int  PHASE_SHIFT     = 32;
272	>	private static final int  UNARRIVED_MASK  = 0xffff;      // to mask ints
273	>	private static final long PARTIES_MASK    = 0xffff0000L; // to mask longs
274	>	private static final long COUNTS_MASK     = 0xffffffffL;
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  ONE_DEREGISTER  = ONE_ARRIVAL|ONE_PARTY;
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 261 | Line 292 | public class Phaser {
292		}
293
294		private static int phaseOf(long s) {
295	<	return (int) (s >>> PHASE_SHIFT);
295	>	return (int)(s >>> PHASE_SHIFT);
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 274 | 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
278	<	* 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 293 | 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
349	<	* ONE_ARRIVAL (for arrive) or
350	<	* ONE_ARRIVAL|ONE_PARTY (for arriveAndDeregister)
348	>	* @param adjust value to subtract from state;
349	>	*               ONE_ARRIVAL for arrive,
350	>	*               ONE_DEREGISTER for arriveAndDeregister
351		*/
352	<	private int doArrive(long adj) {
352	>	private int doArrive(int adjust) {
353	>	final Phaser root = this.root;
354		for (;;) {
355	<	long s = state;
355	>	long s = (root == this) ? state : reconcileState();
356		int phase = (int)(s >>> PHASE_SHIFT);
357		if (phase < 0)
358		return phase;
359	<	int unarrived = (int)s & UNARRIVED_MASK;
360	<	if (unarrived == 0)
361	<	checkBadArrive(s);
362	<	else if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s-=adj)) {
359	>	int counts = (int)s;
360	>	int unarrived = (counts == EMPTY) ? 0 : (counts & UNARRIVED_MASK);
361	>	if (unarrived <= 0)
362	>	throw new IllegalStateException(badArrive(s));
363	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s-=adjust)) {
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_PHASE; // obliterate phase
374	<	UNSAFE.compareAndSwapLong(this, stateOffset, s, next);
365	>	long n = s & PARTIES_MASK;  // base of next state
366	>	int nextUnarrived = (int)n >>> PARTIES_SHIFT;
367	>	if (root == this) {
368	>	if (onAdvance(phase, nextUnarrived))
369	>	n |= TERMINATION_BIT;
370	>	else if (nextUnarrived == 0)
371	>	n |= EMPTY;
372	>	else
373	>	n |= nextUnarrived;
374	>	int nextPhase = (phase + 1) & MAX_PHASE;
375	>	n |= (long)nextPhase << PHASE_SHIFT;
376	>	UNSAFE.compareAndSwapLong(this, stateOffset, s, n);
377		releaseWaiters(phase);
378		}
379	<	else {
380	<	parent.doArrive((u == 0) ?
381	<	ONE_ARRIVAL|ONE_PARTY : ONE_ARRIVAL);
382	<	if ((int)(parent.state >>> PHASE_SHIFT) != nextPhase ||
331	<	((int)(state >>> PHASE_SHIFT) != nextPhase &&
332	<	!UNSAFE.compareAndSwapLong(this, stateOffset,
333	<	s, next)))
334	<	reconcileState();
379	>	else if (nextUnarrived == 0) { // propagate deregistration
380	>	phase = parent.doArrive(ONE_DEREGISTER);
381	>	UNSAFE.compareAndSwapLong(this, stateOffset,
382	>	s, s | EMPTY);
383		}
384	+	else
385	+	phase = parent.doArrive(ONE_ARRIVAL);
386		}
387		return phase;
388		}
#	Line 340 | Line 390 | public class Phaser {
390		}
391
392		/**
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	–	/**
393		* Implementation of register, bulkRegister
394		*
395	<	* @param registrations number to add to both parties and unarrived fields
395	>	* @param registrations number to add to both parties and
396	>	* unarrived fields. Must be greater than zero.
397		*/
398		private int doRegister(int registrations) {
359	–	// assert registrations > 0;
399		// adjustment to state
400	<	long adj = ((long)registrations << PARTIES_SHIFT) | registrations;
400	>	long adjust = ((long)registrations << PARTIES_SHIFT) | registrations;
401		final Phaser parent = this.parent;
402	+	int phase;
403		for (;;) {
404		long s = (parent == null) ? state : reconcileState();
405	<	int phase = (int)(s >>> PHASE_SHIFT);
406	<	if (phase < 0)
407	<	return phase;
408	<	int parties = (int)s >>> PARTIES_SHIFT;
369	<	if (parties != 0 && ((int)s & UNARRIVED_MASK) == 0)
370	<	internalAwaitAdvance(phase, null); // wait for onAdvance
371	<	else if (registrations > MAX_PARTIES - parties)
405	>	int counts = (int)s;
406	>	int parties = counts >>> PARTIES_SHIFT;
407	>	int unarrived = counts & UNARRIVED_MASK;
408	>	if (registrations > MAX_PARTIES - parties)
409		throw new IllegalStateException(badRegister(s));
410	<	else if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s + adj))
411	<	return phase;
410	>	phase = (int)(s >>> PHASE_SHIFT);
411	>	if (phase < 0)
412	>	break;
413	>	if (counts != EMPTY) {                  // not 1st registration
414	>	if (parent == null || reconcileState() == s) {
415	>	if (unarrived == 0)             // wait out advance
416	>	root.internalAwaitAdvance(phase, null);
417	>	else if (UNSAFE.compareAndSwapLong(this, stateOffset,
418	>	s, s + adjust))
419	>	break;
420	>	}
421	>	}
422	>	else if (parent == null) {              // 1st root registration
423	>	long next = ((long)phase << PHASE_SHIFT) | adjust;
424	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next))
425	>	break;
426	>	}
427	>	else {
428	>	synchronized (this) {               // 1st sub registration
429	>	if (state == s) {               // recheck under lock
430	>	phase = parent.doRegister(1);
431	>	if (phase < 0)
432	>	break;
433	>	// finish registration whenever parent registration
434	>	// succeeded, even when racing with termination,
435	>	// since these are part of the same "transaction".
436	>	while (!UNSAFE.compareAndSwapLong
437	>	(this, stateOffset, s,
438	>	((long)phase << PHASE_SHIFT) | adjust)) {
439	>	s = state;
440	>	phase = (int)(root.state >>> PHASE_SHIFT);
441	>	// assert (int)s == EMPTY;
442	>	}
443	>	break;
444	>	}
445	>	}
446	>	}
447		}
448	+	return phase;
449		}
450
451		/**
452	<	* Returns message string for out of bounds exceptions on registration.
453	<	*/
454	<	private String badRegister(long s) {
455	<	return "Attempt to register more than " +
456	<	MAX_PARTIES + " parties for " + stateToString(s);
457	<	}
458	<
386	<	/**
387	<	* Recursively resolves lagged phase propagation from root if necessary.
452	>	* Resolves lagged phase propagation from root if necessary.
453	>	* Reconciliation normally occurs when root has advanced but
454	>	* subphasers have not yet done so, in which case they must finish
455	>	* their own advance by setting unarrived to parties (or if
456	>	* parties is zero, resetting to unregistered EMPTY state).
457	>	*
458	>	* @return reconciled state
459		*/
460		private long reconcileState() {
461	<	Phaser par = parent;
461	>	final Phaser root = this.root;
462		long s = state;
463	<	if (par != null) {
464	<	Phaser rt = root;
465	<	int phase, rPhase;
466	<	while ((phase = (int)(s >>> PHASE_SHIFT)) >= 0 &&
467	<	(rPhase = (int)(rt.state >>> PHASE_SHIFT)) != phase) {
468	<	if ((int)(par.state >>> PHASE_SHIFT) != rPhase)
469	<	par.reconcileState();
470	<	else if (rPhase < 0 || ((int)s & UNARRIVED_MASK) == 0) {
471	<	long u = s & PARTIES_MASK; // reset unarrived to parties
472	<	long next = ((((long) rPhase) << PHASE_SHIFT) | u |
473	<	(u >>> PARTIES_SHIFT));
403	<	if (state == s &&
404	<	UNSAFE.compareAndSwapLong(this, stateOffset,
405	<	s, s = next))
406	<	break;
407	<	}
463	>	if (root != this) {
464	>	int phase, p;
465	>	// CAS to root phase with current parties, tripping unarrived
466	>	while ((phase = (int)(root.state >>> PHASE_SHIFT)) !=
467	>	(int)(s >>> PHASE_SHIFT) &&
468	>	!UNSAFE.compareAndSwapLong
469	>	(this, stateOffset, s,
470	>	s = (((long)phase << PHASE_SHIFT) |
471	>	((phase < 0) ? (s & COUNTS_MASK) :
472	>	(((p = (int)s >>> PARTIES_SHIFT) == 0) ? EMPTY :
473	>	((s & PARTIES_MASK) | p))))))
474		s = state;
409	–	}
475		}
476		return s;
477		}
478
479		/**
480	<	* Creates a new phaser without any initially registered parties,
481	<	* initial phase number 0, and no parent. Any thread using this
480	>	* Creates a new phaser with no initially registered parties, no
481	>	* parent, and initial phase number 0. Any thread using this
482		* phaser will need to first register for it.
483		*/
484		public Phaser() {
#	Line 422 | Line 487 | public class Phaser {
487
488		/**
489		* Creates a new phaser with the given number of registered
490	<	* unarrived parties, initial phase number 0, and no parent.
490	>	* unarrived parties, no parent, and initial phase number 0.
491		*
492	<	* @param parties the number of parties required to trip barrier
492	>	* @param parties the number of parties required to advance to the
493	>	* next phase
494		* @throws IllegalArgumentException if parties less than zero
495		* or greater than the maximum number of parties supported
496		*/
#	Line 433 | Line 499 | public class Phaser {
499		}
500
501		/**
502	<	* Creates a new phaser with the given parent, without any
437	<	* initially registered parties. If parent is non-null this phaser
438	<	* is registered with the parent and its initial phase number is
439	<	* the same as that of parent phaser.
502	>	* Equivalent to {@link #Phaser(Phaser, int) Phaser(parent, 0)}.
503		*
504		* @param parent the parent phaser
505		*/
#	Line 446 | Line 509 | public class Phaser {
509
510		/**
511		* Creates a new phaser with the given parent and number of
512	<	* registered unarrived parties. If parent is non-null, this phaser
513	<	* is registered with the parent and its initial phase number is
514	<	* the same as that of parent phaser.
512	>	* registered unarrived parties.  When the given parent is non-null
513	>	* and the given number of parties is greater than zero, this
514	>	* child phaser is registered with its parent.
515		*
516		* @param parent the parent phaser
517	<	* @param parties the number of parties required to trip barrier
517	>	* @param parties the number of parties required to advance to the
518	>	* next phase
519		* @throws IllegalArgumentException if parties less than zero
520		* or greater than the maximum number of parties supported
521		*/
522		public Phaser(Phaser parent, int parties) {
523		if (parties >>> PARTIES_SHIFT != 0)
524		throw new IllegalArgumentException("Illegal number of parties");
525	<	int phase;
525	>	int phase = 0;
526		this.parent = parent;
527		if (parent != null) {
528	<	Phaser r = parent.root;
529	<	this.root = r;
530	<	this.evenQ = r.evenQ;
531	<	this.oddQ = r.oddQ;
532	<	phase = parent.register();
528	>	final Phaser root = parent.root;
529	>	this.root = root;
530	>	this.evenQ = root.evenQ;
531	>	this.oddQ = root.oddQ;
532	>	if (parties != 0)
533	>	phase = parent.doRegister(1);
534		}
535		else {
536		this.root = this;
537		this.evenQ = new AtomicReference<QNode>();
538		this.oddQ = new AtomicReference<QNode>();
474	–	phase = 0;
539		}
540	<	long p = (long)parties;
541	<	this.state = (((long)phase) << PHASE_SHIFT) | p | (p << PARTIES_SHIFT);
540	>	this.state = (parties == 0) ? (long)EMPTY :
541	>	((long)phase << PHASE_SHIFT) |
542	>	((long)parties << PARTIES_SHIFT) |
543	>	((long)parties);
544		}
545
546		/**
547	<	* Adds a new unarrived party to this phaser.
548	<	* If an ongoing invocation of {@link #onAdvance} is in progress,
549	<	* this method may wait until its completion before registering.
550	<	*
551	<	* @return the arrival phase number to which this registration applied
547	>	* Adds a new unarrived party to this phaser.  If an ongoing
548	>	* invocation of {@link #onAdvance} is in progress, this method
549	>	* may await its completion before returning.  If this phaser has
550	>	* a parent, and this phaser previously had no registered parties,
551	>	* this child phaser is also registered with its parent. If
552	>	* this phaser is terminated, the attempt to register has
553	>	* no effect, and a negative value is returned.
554	>	*
555	>	* @return the arrival phase number to which this registration
556	>	* applied.  If this value is negative, then this phaser has
557	>	* terminated, in which case registration has no effect.
558		* @throws IllegalStateException if attempting to register more
559		* than the maximum supported number of parties
560		*/
#	Line 493 | Line 565 | public class Phaser {
565		/**
566		* Adds the given number of new unarrived parties to this phaser.
567		* If an ongoing invocation of {@link #onAdvance} is in progress,
568	<	* this method may wait until its completion before registering.
569	<	*
570	<	* @param parties the number of additional parties required to trip barrier
571	<	* @return the arrival phase number to which this registration applied
568	>	* this method may await its completion before returning.  If this
569	>	* phaser has a parent, and the given number of parties is greater
570	>	* than zero, and this phaser previously had no registered
571	>	* parties, this child phaser is also registered with its parent.
572	>	* If this phaser is terminated, the attempt to register has no
573	>	* effect, and a negative value is returned.
574	>	*
575	>	* @param parties the number of additional parties required to
576	>	* advance to the next phase
577	>	* @return the arrival phase number to which this registration
578	>	* applied.  If this value is negative, then this phaser has
579	>	* terminated, in which case registration has no effect.
580		* @throws IllegalStateException if attempting to register more
581		* than the maximum supported number of parties
582		* @throws IllegalArgumentException if {@code parties < 0}
#	Line 510 | Line 590 | public class Phaser {
590		}
591
592		/**
593	<	* Arrives at the barrier, but does not wait for others.  (You can
594	<	* in turn wait for others via {@link #awaitAdvance}).  It is an
595	<	* unenforced usage error for an unregistered party to invoke this
596	<	* method.
593	>	* Arrives at this phaser, without waiting for others to arrive.
594	>	*
595	>	* <p>It is a usage error for an unregistered party to invoke this
596	>	* method.  However, this error may result in an {@code
597	>	* IllegalStateException} only upon some subsequent operation on
598	>	* this phaser, if ever.
599		*
600		* @return the arrival phase number, or a negative value if terminated
601		* @throws IllegalStateException if not terminated and the number
#	Line 524 | Line 606 | public class Phaser {
606		}
607
608		/**
609	<	* Arrives at the barrier and deregisters from it without waiting
610	<	* for others. Deregistration reduces the number of parties
611	<	* required to trip the barrier in future phases.  If this phaser
609	>	* Arrives at this phaser and deregisters from it without waiting
610	>	* for others to arrive. Deregistration reduces the number of
611	>	* parties required to advance in future phases.  If this phaser
612		* has a parent, and deregistration causes this phaser to have
613	<	* zero parties, this phaser also arrives at and is deregistered
614	<	* from its parent.  It is an unenforced usage error for an
615	<	* unregistered party to invoke this method.
613	>	* zero parties, this phaser is also deregistered from its parent.
614	>	*
615	>	* <p>It is a usage error for an unregistered party to invoke this
616	>	* method.  However, this error may result in an {@code
617	>	* IllegalStateException} only upon some subsequent operation on
618	>	* this phaser, if ever.
619		*
620		* @return the arrival phase number, or a negative value if terminated
621		* @throws IllegalStateException if not terminated and the number
622		* of registered or unarrived parties would become negative
623		*/
624		public int arriveAndDeregister() {
625	<	return doArrive(ONE_ARRIVAL|ONE_PARTY);
625	>	return doArrive(ONE_DEREGISTER);
626		}
627
628		/**
629	<	* Arrives at the barrier and awaits others. Equivalent in effect
629	>	* Arrives at this phaser and awaits others. Equivalent in effect
630		* to {@code awaitAdvance(arrive())}.  If you need to await with
631		* interruption or timeout, you can arrange this with an analogous
632		* construction using one of the other forms of the {@code
633		* awaitAdvance} method.  If instead you need to deregister upon
634	<	* arrival, use {@link #arriveAndDeregister}. It is an unenforced
635	<	* usage error for an unregistered party to invoke this method.
634	>	* arrival, use {@code awaitAdvance(arriveAndDeregister())}.
635	>	*
636	>	* <p>It is a usage error for an unregistered party to invoke this
637	>	* method.  However, this error may result in an {@code
638	>	* IllegalStateException} only upon some subsequent operation on
639	>	* this phaser, if ever.
640		*
641	<	* @return the arrival phase number, or a negative number if terminated
641	>	* @return the arrival phase number, or the (negative)
642	>	* {@linkplain #getPhase() current phase} if terminated
643		* @throws IllegalStateException if not terminated and the number
644		* of unarrived parties would become negative
645		*/
646		public int arriveAndAwaitAdvance() {
647	<	return awaitAdvance(arrive());
647	>	// Specialization of doArrive+awaitAdvance eliminating some reads/paths
648	>	final Phaser root = this.root;
649	>	for (;;) {
650	>	long s = (root == this) ? state : reconcileState();
651	>	int phase = (int)(s >>> PHASE_SHIFT);
652	>	if (phase < 0)
653	>	return phase;
654	>	int counts = (int)s;
655	>	int unarrived = (counts == EMPTY) ? 0 : (counts & UNARRIVED_MASK);
656	>	if (unarrived <= 0)
657	>	throw new IllegalStateException(badArrive(s));
658	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s,
659	>	s -= ONE_ARRIVAL)) {
660	>	if (unarrived > 1)
661	>	return root.internalAwaitAdvance(phase, null);
662	>	if (root != this)
663	>	return parent.arriveAndAwaitAdvance();
664	>	long n = s & PARTIES_MASK;  // base of next state
665	>	int nextUnarrived = (int)n >>> PARTIES_SHIFT;
666	>	if (onAdvance(phase, nextUnarrived))
667	>	n |= TERMINATION_BIT;
668	>	else if (nextUnarrived == 0)
669	>	n |= EMPTY;
670	>	else
671	>	n |= nextUnarrived;
672	>	int nextPhase = (phase + 1) & MAX_PHASE;
673	>	n |= (long)nextPhase << PHASE_SHIFT;
674	>	if (!UNSAFE.compareAndSwapLong(this, stateOffset, s, n))
675	>	return (int)(state >>> PHASE_SHIFT); // terminated
676	>	releaseWaiters(phase);
677	>	return nextPhase;
678	>	}
679	>	}
680		}
681
682		/**
683	<	* Awaits the phase of the barrier to advance from the given phase
684	<	* value, returning immediately if the current phase of the
685	<	* barrier is not equal to the given phase value or this barrier
564	<	* is terminated.
683	>	* Awaits the phase of this phaser to advance from the given phase
684	>	* value, returning immediately if the current phase is not equal
685	>	* to the given phase value or this phaser is terminated.
686		*
687		* @param phase an arrival phase number, or negative value if
688		* terminated; this argument is normally the value returned by a
689	<	* previous call to {@code arrive} or its variants
690	<	* @return the next arrival phase number, or a negative value
691	<	* if terminated or argument is negative
689	>	* previous call to {@code arrive} or {@code arriveAndDeregister}.
690	>	* @return the next arrival phase number, or the argument if it is
691	>	* negative, or the (negative) {@linkplain #getPhase() current phase}
692	>	* if terminated
693		*/
694		public int awaitAdvance(int phase) {
695	+	final Phaser root = this.root;
696	+	long s = (root == this) ? state : reconcileState();
697	+	int p = (int)(s >>> PHASE_SHIFT);
698		if (phase < 0)
699		return phase;
700	<	long s = (parent == null) ? state : reconcileState();
701	<	int p = (int)(s >>> PHASE_SHIFT);
702	<	return (p != phase) ? p : internalAwaitAdvance(phase, null);
700	>	if (p == phase)
701	>	return root.internalAwaitAdvance(phase, null);
702	>	return p;
703		}
704
705		/**
706	<	* Awaits the phase of the barrier to advance from the given phase
706	>	* Awaits the phase of this phaser to advance from the given phase
707		* value, throwing {@code InterruptedException} if interrupted
708	<	* while waiting, or returning immediately if the current phase of
709	<	* the barrier is not equal to the given phase value or this
710	<	* barrier is terminated.
708	>	* while waiting, or returning immediately if the current phase is
709	>	* not equal to the given phase value or this phaser is
710	>	* terminated.
711		*
712		* @param phase an arrival phase number, or negative value if
713		* terminated; this argument is normally the value returned by a
714	<	* previous call to {@code arrive} or its variants
715	<	* @return the next arrival phase number, or a negative value
716	<	* if terminated or argument is negative
714	>	* previous call to {@code arrive} or {@code arriveAndDeregister}.
715	>	* @return the next arrival phase number, or the argument if it is
716	>	* negative, or the (negative) {@linkplain #getPhase() current phase}
717	>	* if terminated
718		* @throws InterruptedException if thread interrupted while waiting
719		*/
720		public int awaitAdvanceInterruptibly(int phase)
721		throws InterruptedException {
722	+	final Phaser root = this.root;
723	+	long s = (root == this) ? state : reconcileState();
724	+	int p = (int)(s >>> PHASE_SHIFT);
725		if (phase < 0)
726		return phase;
598	–	long s = (parent == null) ? state : reconcileState();
599	–	int p = (int)(s >>> PHASE_SHIFT);
727		if (p == phase) {
728		QNode node = new QNode(this, phase, true, false, 0L);
729	<	p = internalAwaitAdvance(phase, node);
729	>	p = root.internalAwaitAdvance(phase, node);
730		if (node.wasInterrupted)
731		throw new InterruptedException();
732		}
#	Line 607 | Line 734 | public class Phaser {
734		}
735
736		/**
737	<	* Awaits the phase of the barrier to advance from the given phase
737	>	* Awaits the phase of this phaser to advance from the given phase
738		* value or the given timeout to elapse, throwing {@code
739		* InterruptedException} if interrupted while waiting, or
740	<	* returning immediately if the current phase of the barrier is
741	<	* not equal to the given phase value or this barrier is
615	<	* terminated.
740	>	* returning immediately if the current phase is not equal to the
741	>	* given phase value or this phaser is terminated.
742		*
743		* @param phase an arrival phase number, or negative value if
744		* terminated; this argument is normally the value returned by a
745	<	* previous call to {@code arrive} or its variants
745	>	* previous call to {@code arrive} or {@code arriveAndDeregister}.
746		* @param timeout how long to wait before giving up, in units of
747		*        {@code unit}
748		* @param unit a {@code TimeUnit} determining how to interpret the
749		*        {@code timeout} parameter
750	<	* @return the next arrival phase number, or a negative value
751	<	* if terminated or argument is negative
750	>	* @return the next arrival phase number, or the argument if it is
751	>	* negative, or the (negative) {@linkplain #getPhase() current phase}
752	>	* if terminated
753		* @throws InterruptedException if thread interrupted while waiting
754		* @throws TimeoutException if timed out while waiting
755		*/
756		public int awaitAdvanceInterruptibly(int phase,
757		long timeout, TimeUnit unit)
758		throws InterruptedException, TimeoutException {
759	+	long nanos = unit.toNanos(timeout);
760	+	final Phaser root = this.root;
761	+	long s = (root == this) ? state : reconcileState();
762	+	int p = (int)(s >>> PHASE_SHIFT);
763		if (phase < 0)
764		return phase;
634	–	long s = (parent == null) ? state : reconcileState();
635	–	int p = (int)(s >>> PHASE_SHIFT);
765		if (p == phase) {
637	–	long nanos = unit.toNanos(timeout);
766		QNode node = new QNode(this, phase, true, true, nanos);
767	<	p = internalAwaitAdvance(phase, node);
767	>	p = root.internalAwaitAdvance(phase, node);
768		if (node.wasInterrupted)
769		throw new InterruptedException();
770		else if (p == phase)
#	Line 646 | Line 774 | public class Phaser {
774		}
775
776		/**
777	<	* Forces this barrier to enter termination state.  Counts of
778	<	* arrived and registered parties are unaffected.  If this phaser
779	<	* is a member of a tiered set of phasers, then all of the phasers
780	<	* in the set are terminated.  If this phaser is already
781	<	* terminated, this method has no effect.  This method may be
782	<	* useful for coordinating recovery after one or more tasks
783	<	* encounter unexpected exceptions.
777	>	* Forces this phaser to enter termination state.  Counts of
778	>	* registered parties are unaffected.  If this phaser is a member
779	>	* of a tiered set of phasers, then all of the phasers in the set
780	>	* are terminated.  If this phaser is already terminated, this
781	>	* method has no effect.  This method may be useful for
782	>	* coordinating recovery after one or more tasks encounter
783	>	* unexpected exceptions.
784		*/
785		public void forceTermination() {
786		// Only need to change root state
#	Line 660 | Line 788 | public class Phaser {
788		long s;
789		while ((s = root.state) >= 0) {
790		if (UNSAFE.compareAndSwapLong(root, stateOffset,
791	<	s, s | TERMINATION_PHASE)) {
792	<	releaseWaiters(0); // signal all threads
793	<	releaseWaiters(1);
791	>	s, s | TERMINATION_BIT)) {
792	>	// signal all threads
793	>	releaseWaiters(0); // Waiters on evenQ
794	>	releaseWaiters(1); // Waiters on oddQ
795		return;
796		}
797		}
#	Line 671 | Line 800 | public class Phaser {
800		/**
801		* Returns the current phase number. The maximum phase number is
802		* {@code Integer.MAX_VALUE}, after which it restarts at
803	<	* zero. Upon termination, the phase number is negative.
803	>	* zero. Upon termination, the phase number is negative,
804	>	* in which case the prevailing phase prior to termination
805	>	* may be obtained via {@code getPhase() + Integer.MIN_VALUE}.
806		*
807		* @return the phase number, or a negative value if terminated
808		*/
#	Line 680 | Line 811 | public class Phaser {
811		}
812
813		/**
814	<	* Returns the number of parties registered at this barrier.
814	>	* Returns the number of parties registered at this phaser.
815		*
816		* @return the number of parties
817		*/
#	Line 690 | Line 821 | public class Phaser {
821
822		/**
823		* Returns the number of registered parties that have arrived at
824	<	* the current phase of this barrier.
824	>	* the current phase of this phaser. If this phaser has terminated,
825	>	* the returned value is meaningless and arbitrary.
826		*
827		* @return the number of arrived parties
828		*/
829		public int getArrivedParties() {
830	<	return arrivedOf(parent==null? state : reconcileState());
830	>	return arrivedOf(reconcileState());
831		}
832
833		/**
834		* Returns the number of registered parties that have not yet
835	<	* arrived at the current phase of this barrier.
835	>	* arrived at the current phase of this phaser. If this phaser has
836	>	* terminated, the returned value is meaningless and arbitrary.
837		*
838		* @return the number of unarrived parties
839		*/
840		public int getUnarrivedParties() {
841	<	return unarrivedOf(parent==null? state : reconcileState());
841	>	return unarrivedOf(reconcileState());
842		}
843
844		/**
#	Line 728 | Line 861 | public class Phaser {
861		}
862
863		/**
864	<	* Returns {@code true} if this barrier has been terminated.
864	>	* Returns {@code true} if this phaser has been terminated.
865		*
866	<	* @return {@code true} if this barrier has been terminated
866	>	* @return {@code true} if this phaser has been terminated
867		*/
868		public boolean isTerminated() {
869		return root.state < 0L;
#	Line 739 | Line 872 | public class Phaser {
872		/**
873		* Overridable method to perform an action upon impending phase
874		* advance, and to control termination. This method is invoked
875	<	* upon arrival of the party tripping the barrier (when all other
875	>	* upon arrival of the party advancing this phaser (when all other
876		* waiting parties are dormant).  If this method returns {@code
877	<	* true}, then, rather than advance the phase number, this barrier
878	<	* will be set to a final termination state, and subsequent calls
879	<	* to {@link #isTerminated} will return true. Any (unchecked)
880	<	* Exception or Error thrown by an invocation of this method is
881	<	* propagated to the party attempting to trip the barrier, in
882	<	* which case no advance occurs.
877	>	* true}, this phaser will be set to a final termination state
878	>	* upon advance, and subsequent calls to {@link #isTerminated}
879	>	* will return true. Any (unchecked) Exception or Error thrown by
880	>	* an invocation of this method is propagated to the party
881	>	* attempting to advance this phaser, in which case no advance
882	>	* occurs.
883		*
884		* <p>The arguments to this method provide the state of the phaser
885		* prevailing for the current transition.  The effects of invoking
886	<	* arrival, registration, and waiting methods on this Phaser from
886	>	* arrival, registration, and waiting methods on this phaser from
887		* within {@code onAdvance} are unspecified and should not be
888		* relied on.
889		*
890	<	* <p>If this Phaser is a member of a tiered set of Phasers, then
891	<	* {@code onAdvance} is invoked only for its root Phaser on each
890	>	* <p>If this phaser is a member of a tiered set of phasers, then
891	>	* {@code onAdvance} is invoked only for its root phaser on each
892		* advance.
893		*
894	<	* <p>The default version returns {@code true} when the number of
895	<	* registered parties is zero. Normally, overrides that arrange
896	<	* termination for other reasons should also preserve this
897	<	* property.
894	>	* <p>To support the most common use cases, the default
895	>	* implementation of this method returns {@code true} when the
896	>	* number of registered parties has become zero as the result of a
897	>	* party invoking {@code arriveAndDeregister}.  You can disable
898	>	* this behavior, thus enabling continuation upon future
899	>	* registrations, by overriding this method to always return
900	>	* {@code false}:
901	>	*
902	>	* <pre> {@code
903	>	* Phaser phaser = new Phaser() {
904	>	*   protected boolean onAdvance(int phase, int parties) { return false; }
905	>	* }}</pre>
906		*
907	<	* @param phase the phase number on entering the barrier
907	>	* @param phase the current phase number on entry to this method,
908	>	* before this phaser is advanced
909		* @param registeredParties the current number of registered parties
910	<	* @return {@code true} if this barrier should terminate
910	>	* @return {@code true} if this phaser should terminate
911		*/
912		protected boolean onAdvance(int phase, int registeredParties) {
913	<	return registeredParties <= 0;
913	>	return registeredParties == 0;
914		}
915
916		/**
#	Line 778 | Line 920 | public class Phaser {
920		* followed by the number of registered parties, and {@code
921		* "arrived = "} followed by the number of arrived parties.
922		*
923	<	* @return a string identifying this barrier, as well as its state
923	>	* @return a string identifying this phaser, as well as its state
924		*/
925		public String toString() {
926		return stateToString(reconcileState());
#	Line 800 | Line 942 | public class Phaser {
942		* Removes and signals threads from queue for phase.
943		*/
944		private void releaseWaiters(int phase) {
945	<	AtomicReference<QNode> head = queueFor(phase);
946	<	QNode q;
947	<	int p;
945	>	QNode q;   // first element of queue
946	>	Thread t;  // its thread
947	>	AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ;
948		while ((q = head.get()) != null &&
949	<	((p = q.phase) == phase ||
950	<	(int)(root.state >>> PHASE_SHIFT) != p)) {
951	<	if (head.compareAndSet(q, q.next))
952	<	q.signal();
949	>	q.phase != (int)(root.state >>> PHASE_SHIFT)) {
950	>	if (head.compareAndSet(q, q.next) &&
951	>	(t = q.thread) != null) {
952	>	q.thread = null;
953	>	LockSupport.unpark(t);
954	>	}
955	>	}
956	>	}
957	>
958	>	/**
959	>	* Variant of releaseWaiters that additionally tries to remove any
960	>	* nodes no longer waiting for advance due to timeout or
961	>	* interrupt. Currently, nodes are removed only if they are at
962	>	* head of queue, which suffices to reduce memory footprint in
963	>	* most usages.
964	>	*
965	>	* @return current phase on exit
966	>	*/
967	>	private int abortWait(int phase) {
968	>	AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ;
969	>	for (;;) {
970	>	Thread t;
971	>	QNode q = head.get();
972	>	int p = (int)(root.state >>> PHASE_SHIFT);
973	>	if (q == null || ((t = q.thread) != null && q.phase == p))
974	>	return p;
975	>	if (head.compareAndSet(q, q.next) && t != null) {
976	>	q.thread = null;
977	>	LockSupport.unpark(t);
978	>	}
979		}
980		}
981
#	Line 822 | Line 990 | public class Phaser {
990		* avoid it when threads regularly arrive: When a thread in
991		* internalAwaitAdvance notices another arrival before blocking,
992		* and there appear to be enough CPUs available, it spins
993	<	* SPINS_PER_ARRIVAL more times before blocking. Plus, even on
994	<	* uniprocessors, there is at least one intervening Thread.yield
827	<	* before blocking. The value trades off good-citizenship vs big
828	<	* unnecessary slowdowns.
993	>	* SPINS_PER_ARRIVAL more times before blocking. The value trades
994	>	* off good-citizenship vs big unnecessary slowdowns.
995		*/
996		static final int SPINS_PER_ARRIVAL = (NCPU < 2) ? 1 : 1 << 8;
997
998		/**
999		* Possibly blocks and waits for phase to advance unless aborted.
1000	+	* Call only on root phaser.
1001		*
1002		* @param phase current phase
1003		* @param node if non-null, the wait node to track interrupt and timeout;
#	Line 838 | Line 1005 | public class Phaser {
1005		* @return current phase
1006		*/
1007		private int internalAwaitAdvance(int phase, QNode node) {
1008	<	Phaser current = this;       // to eventually wait at root if tiered
1009	<	boolean queued = false;      // true when node is enqueued
1010	<	int lastUnarrived = -1;      // to increase spins upon change
1008	>	// assert root == this;
1009	>	releaseWaiters(phase-1);          // ensure old queue clean
1010	>	boolean queued = false;           // true when node is enqueued
1011	>	int lastUnarrived = 0;            // to increase spins upon change
1012		int spins = SPINS_PER_ARRIVAL;
1013		long s;
1014		int p;
1015	<	while ((p = (int)((s = current.state) >>> PHASE_SHIFT)) == phase) {
1016	<	Phaser par;
1017	<	int unarrived = (int)s & UNARRIVED_MASK;
1018	<	if (unarrived != lastUnarrived) {
1019	<	if (lastUnarrived == -1) // ensure old queue clean
852	<	releaseWaiters(phase-1);
853	<	if ((lastUnarrived = unarrived) < NCPU)
1015	>	while ((p = (int)((s = state) >>> PHASE_SHIFT)) == phase) {
1016	>	if (node == null) {           // spinning in noninterruptible mode
1017	>	int unarrived = (int)s & UNARRIVED_MASK;
1018	>	if (unarrived != lastUnarrived &&
1019	>	(lastUnarrived = unarrived) < NCPU)
1020		spins += SPINS_PER_ARRIVAL;
1021	<	}
1022	<	else if (unarrived == 0 && (par = current.parent) != null) {
1023	<	current = par;       // if all arrived, use parent
1024	<	par = par.parent;
859	<	lastUnarrived = -1;
860	<	}
861	<	else if (spins > 0) {
862	<	if (--spins == (SPINS_PER_ARRIVAL >>> 1))
863	<	Thread.yield();  // yield midway through spin
864	<	}
865	<	else if (node == null)   // must be noninterruptible
866	<	node = new QNode(this, phase, false, false, 0L);
867	<	else if (node.isReleasable()) {
868	<	if ((p = (int)(root.state >>> PHASE_SHIFT)) != phase)
869	<	break;
870	<	else
871	<	return phase;    // aborted
872	<	}
873	<	else if (!queued) {      // push onto queue
874	<	AtomicReference<QNode> head = queueFor(phase);
875	<	QNode q = head.get();
876	<	if (q == null || q.phase == phase) {
877	<	node.next = q;
878	<	if ((p = (int)(root.state >>> PHASE_SHIFT)) != phase)
879	<	break;       // recheck to avoid stale enqueue
880	<	else
881	<	queued = head.compareAndSet(q, node);
1021	>	boolean interrupted = Thread.interrupted();
1022	>	if (interrupted || --spins < 0) { // need node to record intr
1023	>	node = new QNode(this, phase, false, false, 0L);
1024	>	node.wasInterrupted = interrupted;
1025		}
1026		}
1027	+	else if (node.isReleasable()) // done or aborted
1028	+	break;
1029	+	else if (!queued) {           // push onto queue
1030	+	AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ;
1031	+	QNode q = node.next = head.get();
1032	+	if ((q == null || q.phase == phase) &&
1033	+	(int)(state >>> PHASE_SHIFT) == phase) // avoid stale enq
1034	+	queued = head.compareAndSet(q, node);
1035	+	}
1036		else {
1037		try {
1038		ForkJoinPool.managedBlock(node);
#	Line 889 | Line 1041 | public class Phaser {
1041		}
1042		}
1043		}
1044	+
1045	+	if (node != null) {
1046	+	if (node.thread != null)
1047	+	node.thread = null;       // avoid need for unpark()
1048	+	if (node.wasInterrupted && !node.interruptible)
1049	+	Thread.currentThread().interrupt();
1050	+	if (p == phase && (p = (int)(state >>> PHASE_SHIFT)) == phase)
1051	+	return abortWait(phase); // possibly clean up on abort
1052	+	}
1053		releaseWaiters(phase);
893	–	if (node != null)
894	–	node.onRelease();
1054		return p;
1055		}
1056
#	Line 916 | Line 1075 | public class Phaser {
1075		this.interruptible = interruptible;
1076		this.nanos = nanos;
1077		this.timed = timed;
1078	<	this.lastTime = timed? System.nanoTime() : 0L;
1078	>	this.lastTime = timed ? System.nanoTime() : 0L;
1079		thread = Thread.currentThread();
1080		}
1081
1082		public boolean isReleasable() {
1083	<	Thread t = thread;
1084	<	if (t != null) {
1085	<	if (phaser.getPhase() != phase)
1086	<	t = null;
1087	<	else {
1088	<	if (Thread.interrupted())
1089	<	wasInterrupted = true;
1090	<	if (interruptible && wasInterrupted)
1091	<	t = null;
933	<	else if (timed) {
934	<	if (nanos > 0) {
935	<	long now = System.nanoTime();
936	<	nanos -= now - lastTime;
937	<	lastTime = now;
938	<	}
939	<	if (nanos <= 0)
940	<	t = null;
941	<	}
942	<	}
943	<	if (t != null)
944	<	return false;
1083	>	if (thread == null)
1084	>	return true;
1085	>	if (phaser.getPhase() != phase) {
1086	>	thread = null;
1087	>	return true;
1088	>	}
1089	>	if (Thread.interrupted())
1090	>	wasInterrupted = true;
1091	>	if (wasInterrupted && interruptible) {
1092		thread = null;
1093	+	return true;
1094	+	}
1095	+	if (timed) {
1096	+	if (nanos > 0L) {
1097	+	long now = System.nanoTime();
1098	+	nanos -= now - lastTime;
1099	+	lastTime = now;
1100	+	}
1101	+	if (nanos <= 0L) {
1102	+	thread = null;
1103	+	return true;
1104	+	}
1105		}
1106	<	return true;
1106	>	return false;
1107		}
1108
1109		public boolean block() {
#	Line 956 | Line 1115 | public class Phaser {
1115		LockSupport.parkNanos(this, nanos);
1116		return isReleasable();
1117		}
959	–
960	–	void signal() {
961	–	Thread t = thread;
962	–	if (t != null) {
963	–	thread = null;
964	–	LockSupport.unpark(t);
965	–	}
966	–	}
967	–
968	–	void onRelease() { // actions upon return from internalAwaitAdvance
969	–	if (!interruptible && wasInterrupted)
970	–	Thread.currentThread().interrupt();
971	–	if (thread != null)
972	–	thread = null;
973	–	}
974	–
1118		}
1119
1120		// Unsafe mechanics
1121
1122	<	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1123	<	private static final long stateOffset =
1124	<	objectFieldOffset("state", Phaser.class);
982	<
983	<	private static long objectFieldOffset(String field, Class<?> klazz) {
1122	>	private static final sun.misc.Unsafe UNSAFE;
1123	>	private static final long stateOffset;
1124	>	static {
1125		try {
1126	<	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1127	<	} catch (NoSuchFieldException e) {
1128	<	// Convert Exception to corresponding Error
1129	<	NoSuchFieldError error = new NoSuchFieldError(field);
1130	<	error.initCause(e);
1131	<	throw error;
1126	>	UNSAFE = getUnsafe();
1127	>	Class<?> k = Phaser.class;
1128	>	stateOffset = UNSAFE.objectFieldOffset
1129	>	(k.getDeclaredField("state"));
1130	>	} catch (Exception e) {
1131	>	throw new Error(e);
1132		}
1133		}
1134

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines