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

Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.54 by dl, Sat Nov 13 13:10:04 2010 UTC vs.
Revision 1.57 by dl, Fri Nov 19 16:03:24 2010 UTC

#	Line 240 | Line 240 | public class Phaser {
240		*/
241		private volatile long state;
242
243	<	private static final int  MAX_COUNT      = 0xffff;
243	>	private static final int  MAX_PARTIES    = 0xffff;
244		private static final int  MAX_PHASE      = 0x7fffffff;
245		private static final int  PARTIES_SHIFT  = 16;
246		private static final int  PHASE_SHIFT    = 32;
247	<	private static final long UNARRIVED_MASK = 0xffffL;
248	<	private static final long PARTIES_MASK   = 0xffff0000L;
247	>	private static final int  UNARRIVED_MASK = 0xffff;
248	>	private static final long PARTIES_MASK   = 0xffff0000L; // for masking long
249		private static final long ONE_ARRIVAL    = 1L;
250		private static final long ONE_PARTY      = 1L << PARTIES_SHIFT;
251		private static final long TERMINATION_PHASE  = -1L << PHASE_SHIFT;
#	Line 253 | Line 253 | public class Phaser {
253		// The following unpacking methods are usually manually inlined
254
255		private static int unarrivedOf(long s) {
256	<	return (int) (s & UNARRIVED_MASK);
256	>	return (int)s & UNARRIVED_MASK;
257		}
258
259		private static int partiesOf(long s) {
260	<	return ((int) (s & PARTIES_MASK)) >>> PARTIES_SHIFT;
260	>	return (int)s >>> PARTIES_SHIFT;
261		}
262
263		private static int phaseOf(long s) {
#	Line 303 | Line 303 | public class Phaser {
303		*/
304		private int doArrive(long adj) {
305		for (;;) {
306	<	long s;
307	<	int phase, unarrived;
308	<	if ((phase = (int)((s = state) >>> PHASE_SHIFT)) < 0)
306	>	long s = state;
307	>	int phase = (int)(s >>> PHASE_SHIFT);
308	>	if (phase < 0)
309		return phase;
310	<	else if ((unarrived = (int)(s & UNARRIVED_MASK)) == 0)
310	>	int unarrived = (int)s & UNARRIVED_MASK;
311	>	if (unarrived == 0)
312		checkBadArrive(s);
313	<	else if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s -= adj)){
313	>	else if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s-=adj)) {
314		if (unarrived == 1) {
314	–	Phaser par;
315		long p = s & PARTIES_MASK; // unshifted parties field
316		long lu = p >>> PARTIES_SHIFT;
317		int u = (int)lu;
318		int nextPhase = (phase + 1) & MAX_PHASE;
319		long next = ((long)nextPhase << PHASE_SHIFT) | p | lu;
320	<	if ((par = parent) == null) {
321	<	UNSAFE.compareAndSwapLong
322	<	(this, stateOffset, s, onAdvance(phase, u)?
323	<	next | TERMINATION_PHASE : next);
320	>	final Phaser parent = this.parent;
321	>	if (parent == null) {
322	>	if (onAdvance(phase, u))
323	>	next |= TERMINATION_PHASE; // obliterate phase
324	>	UNSAFE.compareAndSwapLong(this, stateOffset, s, next);
325		releaseWaiters(phase);
326		}
327		else {
328	<	par.doArrive(u == 0?
329	<	ONE_ARRIVAL|ONE_PARTY : ONE_ARRIVAL);
330	<	if ((int)(par.state >>> PHASE_SHIFT) != nextPhase ||
328	>	parent.doArrive((u == 0) ?
329	>	ONE_ARRIVAL|ONE_PARTY : ONE_ARRIVAL);
330	>	if ((int)(parent.state >>> PHASE_SHIFT) != nextPhase ||
331		((int)(state >>> PHASE_SHIFT) != nextPhase &&
332		!UNSAFE.compareAndSwapLong(this, stateOffset,
333		s, next)))
#	Line 355 | Line 356 | public class Phaser {
356		* @param registrations number to add to both parties and unarrived fields
357		*/
358		private int doRegister(int registrations) {
359	<	long adj = (long)registrations; // adjustment to state
360	<	adj |= adj << PARTIES_SHIFT;
361	<	Phaser par = parent;
359	>	// assert registrations > 0;
360	>	// adjustment to state
361	>	long adj = ((long)registrations << PARTIES_SHIFT) | registrations;
362	>	final Phaser parent = this.parent;
363		for (;;) {
364	<	int phase, parties;
365	<	long s = par == null? state : reconcileState();
366	<	if ((phase = (int)(s >>> PHASE_SHIFT)) < 0)
364	>	long s = (parent == null) ? state : reconcileState();
365	>	int phase = (int)(s >>> PHASE_SHIFT);
366	>	if (phase < 0)
367		return phase;
368	<	if ((parties = ((int)(s & PARTIES_MASK)) >>> PARTIES_SHIFT) != 0 &&
369	<	(s & UNARRIVED_MASK) == 0)
368	>	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 (parties + registrations > MAX_COUNT)
371	>	else if (registrations > MAX_PARTIES - parties)
372		throw new IllegalStateException(badRegister(s));
373		else if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s + adj))
374		return phase;
#	Line 374 | Line 376 | public class Phaser {
376		}
377
378		/**
379	<	* Returns message string for bounds exceptions on registration
379	>	* Returns message string for out of bounds exceptions on registration.
380		*/
381		private String badRegister(long s) {
382		return "Attempt to register more than " +
383	<	MAX_COUNT + " parties for " + stateToString(s);
383	>	MAX_PARTIES + " parties for " + stateToString(s);
384		}
385
386		/**
387	<	* Recursively resolves lagged phase propagation from root if
386	<	* necessary.
387	>	* Recursively resolves lagged phase propagation from root if necessary.
388		*/
389		private long reconcileState() {
390		Phaser par = parent;
391	<	if (par == null)
392	<	return state;
393	<	Phaser rt = root;
394	<	for (;;) {
395	<	long s, u;
396	<	int phase, rPhase, pPhase;
397	<	if ((phase = (int)((s = state)>>> PHASE_SHIFT)) < 0 ||
398	<	(rPhase = (int)(rt.state >>> PHASE_SHIFT)) == phase)
399	<	return s;
400	<	long pState = par.parent == null? par.state : par.reconcileState();
401	<	if (state == s) {
402	<	if ((rPhase < 0 || (s & UNARRIVED_MASK) == 0) &&
403	<	((pPhase = (int)(pState >>> PHASE_SHIFT)) < 0 ||
404	<	pPhase == ((phase + 1) & MAX_PHASE)))
405	<	UNSAFE.compareAndSwapLong
406	<	(this, stateOffset, s,
407	<	(((long) pPhase) << PHASE_SHIFT) |
408	<	(u = s & PARTIES_MASK) |
408	<	(u >>> PARTIES_SHIFT)); // reset unarrived to parties
409	<	else
410	<	releaseWaiters(phase); // help release others
391	>	long s = state;
392	>	if (par != null) {
393	>	Phaser rt = root;
394	>	int phase, rPhase;
395	>	while ((phase = (int)(s >>> PHASE_SHIFT)) >= 0 &&
396	>	(rPhase = (int)(rt.state >>> PHASE_SHIFT)) != phase) {
397	>	if ((int)(par.state >>> PHASE_SHIFT) != rPhase)
398	>	par.reconcileState();
399	>	else if (rPhase < 0 || ((int)s & UNARRIVED_MASK) == 0) {
400	>	long u = s & PARTIES_MASK; // reset unarrived to parties
401	>	long next = ((((long) rPhase) << PHASE_SHIFT) | u |
402	>	(u >>> PARTIES_SHIFT));
403	>	if (state == s &&
404	>	UNSAFE.compareAndSwapLong(this, stateOffset,
405	>	s, s = next))
406	>	break;
407	>	}
408	>	s = state;
409		}
410		}
411	+	return s;
412		}
413
414		/**
#	Line 457 | Line 456 | public class Phaser {
456		* or greater than the maximum number of parties supported
457		*/
458		public Phaser(Phaser parent, int parties) {
459	<	if (parties < 0 || parties > MAX_COUNT)
459	>	if (parties >>> PARTIES_SHIFT != 0)
460		throw new IllegalArgumentException("Illegal number of parties");
461		int phase;
462		this.parent = parent;
#	Line 475 | Line 474 | public class Phaser {
474		phase = 0;
475		}
476		long p = (long)parties;
477	<	this.state = (((long) phase) << PHASE_SHIFT) | p | (p << PARTIES_SHIFT);
477	>	this.state = (((long)phase) << PHASE_SHIFT) | p | (p << PARTIES_SHIFT);
478		}
479
480		/**
#	Line 505 | Line 504 | public class Phaser {
504		public int bulkRegister(int parties) {
505		if (parties < 0)
506		throw new IllegalArgumentException();
508	–	if (parties > MAX_COUNT)
509	–	throw new IllegalStateException(badRegister(state));
507		if (parties == 0)
508		return getPhase();
509		return doRegister(parties);
#	Line 575 | Line 572 | public class Phaser {
572		public int awaitAdvance(int phase) {
573		if (phase < 0)
574		return phase;
575	<	int p = (int)((parent==null? state : reconcileState()) >>> PHASE_SHIFT);
576	<	if (p != phase)
577	<	return p;
581	<	return internalAwaitAdvance(phase, null);
575	>	long s = (parent == null) ? state : reconcileState();
576	>	int p = (int)(s >>> PHASE_SHIFT);
577	>	return (p != phase) ? p : internalAwaitAdvance(phase, null);
578		}
579
580		/**
#	Line 599 | Line 595 | public class Phaser {
595		throws InterruptedException {
596		if (phase < 0)
597		return phase;
598	<	int p = (int)((parent==null? state : reconcileState()) >>> PHASE_SHIFT);
599	<	if (p != phase)
600	<	return p;
601	<	QNode node = new QNode(this, phase, true, false, 0L);
602	<	p = internalAwaitAdvance(phase, node);
603	<	if (node.wasInterrupted)
604	<	throw new InterruptedException();
605	<	else
606	<	return p;
598	>	long s = (parent == null) ? state : reconcileState();
599	>	int p = (int)(s >>> PHASE_SHIFT);
600	>	if (p == phase) {
601	>	QNode node = new QNode(this, phase, true, false, 0L);
602	>	p = internalAwaitAdvance(phase, node);
603	>	if (node.wasInterrupted)
604	>	throw new InterruptedException();
605	>	}
606	>	return p;
607		}
608
609		/**
#	Line 633 | Line 629 | public class Phaser {
629		public int awaitAdvanceInterruptibly(int phase,
630		long timeout, TimeUnit unit)
631		throws InterruptedException, TimeoutException {
636	–	long nanos = unit.toNanos(timeout);
632		if (phase < 0)
633		return phase;
634	<	int p = (int)((parent==null? state : reconcileState()) >>> PHASE_SHIFT);
635	<	if (p != phase)
636	<	return p;
637	<	QNode node = new QNode(this, phase, true, true, nanos);
638	<	p = internalAwaitAdvance(phase, node);
639	<	if (node.wasInterrupted)
640	<	throw new InterruptedException();
641	<	else if (p == phase)
642	<	throw new TimeoutException();
643	<	else
644	<	return p;
634	>	long s = (parent == null) ? state : reconcileState();
635	>	int p = (int)(s >>> PHASE_SHIFT);
636	>	if (p == phase) {
637	>	long nanos = unit.toNanos(timeout);
638	>	QNode node = new QNode(this, phase, true, true, nanos);
639	>	p = internalAwaitAdvance(phase, node);
640	>	if (node.wasInterrupted)
641	>	throw new InterruptedException();
642	>	else if (p == phase)
643	>	throw new TimeoutException();
644	>	}
645	>	return p;
646		}
647
648		/**
649	<	* Forces this barrier to enter termination state. Counts of
650	<	* arrived and registered parties are unaffected. If this phaser
651	<	* has a parent, it too is terminated. This method may be useful
652	<	* for coordinating recovery after one or more tasks encounter
653	<	* unexpected exceptions.
649	>	* Forces this barrier to enter termination state.  Counts of
650	>	* arrived and registered parties are unaffected.  If this phaser
651	>	* is a member of a tiered set of phasers, then all of the phasers
652	>	* in the set are terminated.  If this phaser is already
653	>	* terminated, this method has no effect.  This method may be
654	>	* useful for coordinating recovery after one or more tasks
655	>	* encounter unexpected exceptions.
656		*/
657		public void forceTermination() {
658	<	Phaser r = root;    // force at root then reconcile
658	>	// Only need to change root state
659	>	final Phaser root = this.root;
660		long s;
661	<	while ((s = r.state) >= 0)
662	<	UNSAFE.compareAndSwapLong(r, stateOffset, s, s | TERMINATION_PHASE);
663	<	reconcileState();
664	<	releaseWaiters(0); // signal all threads
665	<	releaseWaiters(1);
661	>	while ((s = root.state) >= 0) {
662	>	if (UNSAFE.compareAndSwapLong(root, stateOffset,
663	>	s, s | TERMINATION_PHASE)) {
664	>	releaseWaiters(0); // signal all threads
665	>	releaseWaiters(1);
666	>	return;
667	>	}
668	>	}
669		}
670
671		/**
#	Line 674 | Line 676 | public class Phaser {
676		* @return the phase number, or a negative value if terminated
677		*/
678		public final int getPhase() {
679	<	return (int)((parent==null? state : reconcileState()) >>> PHASE_SHIFT);
679	>	return (int)(root.state >>> PHASE_SHIFT);
680		}
681
682		/**
#	Line 683 | Line 685 | public class Phaser {
685		* @return the number of parties
686		*/
687		public int getRegisteredParties() {
688	<	return partiesOf(parent==null? state : reconcileState());
688	>	return partiesOf(state);
689		}
690
691		/**
#	Line 731 | Line 733 | public class Phaser {
733		* @return {@code true} if this barrier has been terminated
734		*/
735		public boolean isTerminated() {
736	<	return (parent == null? state : reconcileState()) < 0;
736	>	return root.state < 0L;
737		}
738
739		/**
#	Line 795 | Line 797 | public class Phaser {
797		// Waiting mechanics
798
799		/**
800	<	* Removes and signals threads from queue for phase
800	>	* Removes and signals threads from queue for phase.
801		*/
802		private void releaseWaiters(int phase) {
803		AtomicReference<QNode> head = queueFor(phase);
#	Line 809 | Line 811 | public class Phaser {
811		}
812		}
813
812	–	/**
813	–	* Tries to enqueue given node in the appropriate wait queue.
814	–	*
815	–	* @return true if successful
816	–	*/
817	–	private boolean tryEnqueue(int phase, QNode node) {
818	–	releaseWaiters(phase-1); // ensure old queue clean
819	–	AtomicReference<QNode> head = queueFor(phase);
820	–	QNode q = head.get();
821	–	return ((q == null || q.phase == phase) &&
822	–	(int)(root.state >>> PHASE_SHIFT) == phase &&
823	–	head.compareAndSet(node.next = q, node));
824	–	}
825	–
814		/** The number of CPUs, for spin control */
815		private static final int NCPU = Runtime.getRuntime().availableProcessors();
816
#	Line 834 | Line 822 | public class Phaser {
822		* avoid it when threads regularly arrive: When a thread in
823		* internalAwaitAdvance notices another arrival before blocking,
824		* and there appear to be enough CPUs available, it spins
825	<	* SPINS_PER_ARRIVAL more times before continuing to try to
826	<	* block. The value trades off good-citizenship vs big unnecessary
827	<	* slowdowns.
825	>	* SPINS_PER_ARRIVAL more times before blocking. Plus, even on
826	>	* uniprocessors, there is at least one intervening Thread.yield
827	>	* before blocking. The value trades off good-citizenship vs big
828	>	* unnecessary slowdowns.
829		*/
830	<	static final int SPINS_PER_ARRIVAL = NCPU < 2? 1 : 1 << 8;
830	>	static final int SPINS_PER_ARRIVAL = (NCPU < 2) ? 1 : 1 << 8;
831
832		/**
833		* Possibly blocks and waits for phase to advance unless aborted.
#	Line 853 | Line 842 | public class Phaser {
842		boolean queued = false;      // true when node is enqueued
843		int lastUnarrived = -1;      // to increase spins upon change
844		int spins = SPINS_PER_ARRIVAL;
845	<	for (;;) {
846	<	int p, unarrived;
845	>	long s;
846	>	int p;
847	>	while ((p = (int)((s = current.state) >>> PHASE_SHIFT)) == phase) {
848		Phaser par;
849	<	long s = current.state;
850	<	if ((p = (int)(s >>> PHASE_SHIFT)) != phase) {
851	<	if (node != null)
852	<	node.onRelease();
863	<	releaseWaiters(phase);
864	<	return p;
865	<	}
866	<	else if ((unarrived = (int)(s & UNARRIVED_MASK)) != lastUnarrived) {
849	>	int unarrived = (int)s & UNARRIVED_MASK;
850	>	if (unarrived != lastUnarrived) {
851	>	if (lastUnarrived == -1) // ensure old queue clean
852	>	releaseWaiters(phase-1);
853		if ((lastUnarrived = unarrived) < NCPU)
854		spins += SPINS_PER_ARRIVAL;
855		}
#	Line 872 | Line 858 | public class Phaser {
858		par = par.parent;
859		lastUnarrived = -1;
860		}
861	<	else if (spins > 0)
862	<	--spins;
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 ((int)(reconcileState() >>> PHASE_SHIFT) == phase)
868	>	if ((p = (int)(root.state >>> PHASE_SHIFT)) != phase)
869	>	break;
870	>	else
871		return phase;    // aborted
872		}
873	<	else if (!queued)
874	<	queued = tryEnqueue(phase, node);
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);
882	>	}
883	>	}
884		else {
885		try {
886		ForkJoinPool.managedBlock(node);
#	Line 890 | Line 889 | public class Phaser {
889		}
890		}
891		}
892	+	releaseWaiters(phase);
893	+	if (node != null)
894	+	node.onRelease();
895	+	return p;
896		}
897
898		/**

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