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Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.49 by dl, Fri Nov 5 23:01:47 2010 UTC vs.
Revision 1.76 by jsr166, Sat Oct 15 21:46:25 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;
8
9	<	import java.util.concurrent.*;
9	>	import java.util.concurrent.TimeUnit;
10	>	import java.util.concurrent.TimeoutException;
11		import java.util.concurrent.atomic.AtomicReference;
12		import java.util.concurrent.locks.LockSupport;
13
#	Line 33 | 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 73 | 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 116 | 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 180 | 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	<	* }
201	<	* // .. initially called, for n tasks via
202	<	* 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 223 | Line 237 | public class Phaser {
237		*/
238
239		/**
240	<	* Barrier state representation. Conceptually, a barrier contains
227	<	* four values:
228	<	*
229	<	* * parties -- the number of parties to wait (16 bits)
230	<	* * unarrived -- the number of parties yet to hit barrier (16 bits)
231	<	* * phase -- the generation of the barrier (31 bits)
232	<	* * terminated -- set if barrier is terminated (1 bit)
233	<	*
234	<	* However, to efficiently maintain atomicity, these values are
235	<	* packed into a single (atomic) long. Termination uses the sign
236	<	* bit of 32 bit representation of phase, so phase is set to -1 on
237	<	* termination. Good performance relies on keeping state decoding
238	<	* and encoding simple, and keeping race windows short.
240	>	* Primary state representation, holding four bit-fields:
241		*
242	<	* Note: there are some cheats in arrive() that rely on unarrived
243	<	* count being lowest 16 bits.
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 ushortMask = 0xffff;
269	<	private static final int phaseMask  = 0x7fffffff;
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 TERMINATION_BIT = 1L << 63;
275	>
276	>	// some special values
277	>	private static final int  ONE_ARRIVAL     = 1;
278	>	private static final int  ONE_PARTY       = 1 << PARTIES_SHIFT;
279	>	private static final int  ONE_DEREGISTER  = ONE_ARRIVAL|ONE_PARTY;
280	>	private static final int  EMPTY           = 1;
281	>
282	>	// The following unpacking methods are usually manually inlined
283
284		private static int unarrivedOf(long s) {
285	<	return (int) (s & ushortMask);
285	>	int counts = (int)s;
286	>	return (counts == EMPTY) ? 0 : (counts & UNARRIVED_MASK);
287		}
288
289		private static int partiesOf(long s) {
290	<	return ((int) s) >>> 16;
290	>	return (int)s >>> PARTIES_SHIFT;
291		}
292
293		private static int phaseOf(long s) {
294	<	return (int) (s >>> 32);
294	>	return (int)(s >>> PHASE_SHIFT);
295		}
296
297		private static int arrivedOf(long s) {
298	<	return partiesOf(s) - unarrivedOf(s);
299	<	}
300	<
264	<	private static long stateFor(int phase, int parties, int unarrived) {
265	<	return ((((long) phase) << 32) | (((long) parties) << 16) |
266	<	(long) unarrived);
267	<	}
268	<
269	<	private static long trippedStateFor(int phase, int parties) {
270	<	long lp = (long) parties;
271	<	return (((long) phase) << 32) | (lp << 16) | lp;
272	<	}
273	<
274	<	/**
275	<	* Returns message string for bad bounds exceptions.
276	<	*/
277	<	private static String badBounds(int parties, int unarrived) {
278	<	return ("Attempt to set " + unarrived +
279	<	" unarrived of " + parties + " parties");
298	>	int counts = (int)s;
299	>	return (counts == EMPTY) ? 0 :
300	>	(counts >>> PARTIES_SHIFT) - (counts & UNARRIVED_MASK);
301		}
302
303		/**
#	Line 285 | Line 306 | public class Phaser {
306		private final Phaser parent;
307
308		/**
309	<	* The root of phaser tree. Equals this if not in a tree.  Used to
289	<	* support faster state push-down.
309	>	* The root of phaser tree. Equals this if not in a tree.
310		*/
311		private final Phaser root;
312
293	–	// Wait queues
294	–
313		/**
314		* Heads of Treiber stacks for waiting threads. To eliminate
315		* contention when releasing some threads while adding others, we
316		* use two of them, alternating across even and odd phases.
317		* Subphasers share queues with root to speed up releases.
318		*/
319	<	private final AtomicReference<QNode> evenQ = new AtomicReference<QNode>();
320	<	private final AtomicReference<QNode> oddQ  = new AtomicReference<QNode>();
319	>	private final AtomicReference<QNode> evenQ;
320	>	private final AtomicReference<QNode> oddQ;
321
322		private AtomicReference<QNode> queueFor(int phase) {
323	<	Phaser r = root;
306	<	return ((phase & 1) == 0) ? r.evenQ : r.oddQ;
323	>	return ((phase & 1) == 0) ? evenQ : oddQ;
324		}
325
326		/**
327	<	* Returns current state, first resolving lagged propagation from
311	<	* root if necessary.
327	>	* Returns message string for bounds exceptions on arrival.
328		*/
329	<	private long getReconciledState() {
330	<	return (parent == null) ? state : reconcileState();
329	>	private String badArrive(long s) {
330	>	return "Attempted arrival of unregistered party for " +
331	>	stateToString(s);
332		}
333
334		/**
335	<	* Recursively resolves state.
335	>	* Returns message string for bounds exceptions on registration.
336	>	*/
337	>	private String badRegister(long s) {
338	>	return "Attempt to register more than " +
339	>	MAX_PARTIES + " parties for " + stateToString(s);
340	>	}
341	>
342	>	/**
343	>	* Main implementation for methods arrive and arriveAndDeregister.
344	>	* Manually tuned to speed up and minimize race windows for the
345	>	* common case of just decrementing unarrived field.
346	>	*
347	>	* @param adjust value to subtract from state;
348	>	*               ONE_ARRIVAL for arrive,
349	>	*               ONE_DEREGISTER for arriveAndDeregister
350	>	*/
351	>	private int doArrive(int adjust) {
352	>	final Phaser root = this.root;
353	>	for (;;) {
354	>	long s = (root == this) ? state : reconcileState();
355	>	int phase = (int)(s >>> PHASE_SHIFT);
356	>	if (phase < 0)
357	>	return phase;
358	>	int counts = (int)s;
359	>	int unarrived = (counts == EMPTY) ? 0 : (counts & UNARRIVED_MASK);
360	>	if (unarrived <= 0)
361	>	throw new IllegalStateException(badArrive(s));
362	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s-=adjust)) {
363	>	if (unarrived == 1) {
364	>	long n = s & PARTIES_MASK;  // base of next state
365	>	int nextUnarrived = (int)n >>> PARTIES_SHIFT;
366	>	if (root == this) {
367	>	if (onAdvance(phase, nextUnarrived))
368	>	n |= TERMINATION_BIT;
369	>	else if (nextUnarrived == 0)
370	>	n |= EMPTY;
371	>	else
372	>	n |= nextUnarrived;
373	>	int nextPhase = (phase + 1) & MAX_PHASE;
374	>	n |= (long)nextPhase << PHASE_SHIFT;
375	>	UNSAFE.compareAndSwapLong(this, stateOffset, s, n);
376	>	releaseWaiters(phase);
377	>	}
378	>	else if (nextUnarrived == 0) { // propagate deregistration
379	>	phase = parent.doArrive(ONE_DEREGISTER);
380	>	UNSAFE.compareAndSwapLong(this, stateOffset,
381	>	s, s | EMPTY);
382	>	}
383	>	else
384	>	phase = parent.doArrive(ONE_ARRIVAL);
385	>	}
386	>	return phase;
387	>	}
388	>	}
389	>	}
390	>
391	>	/**
392	>	* Implementation of register, bulkRegister
393	>	*
394	>	* @param registrations number to add to both parties and
395	>	* unarrived fields. Must be greater than zero.
396		*/
397	<	private long reconcileState() {
398	<	Phaser par = parent;
399	<	long s = state;
400	<	if (par != null) {
401	<	int phase, rootPhase;
402	<	while ((phase = phaseOf(s)) >= 0 &&
403	<	(rootPhase = phaseOf(root.state)) != phase &&
404	<	(rootPhase < 0 || unarrivedOf(s) == 0)) {
405	<	long parentState = par.getReconciledState();
406	<	int parentPhase = phaseOf(parentState);
407	<	int parties = partiesOf(s);
408	<	long next = trippedStateFor(parentPhase, parties);
409	<	if (phaseOf(root.state) == rootPhase &&
410	<	parentPhase != phase &&
411	<	state == s && casState(s, next)) {
412	<	releaseWaiters(phase);
413	<	if (parties == 0) // exit if the final deregistration
397	>	private int doRegister(int registrations) {
398	>	// adjustment to state
399	>	long adjust = ((long)registrations << PARTIES_SHIFT) | registrations;
400	>	final Phaser parent = this.parent;
401	>	int phase;
402	>	for (;;) {
403	>	long s = (parent == null) ? state : reconcileState();
404	>	int counts = (int)s;
405	>	int parties = counts >>> PARTIES_SHIFT;
406	>	int unarrived = counts & UNARRIVED_MASK;
407	>	if (registrations > MAX_PARTIES - parties)
408	>	throw new IllegalStateException(badRegister(s));
409	>	phase = (int)(s >>> PHASE_SHIFT);
410	>	if (phase < 0)
411	>	break;
412	>	if (counts != EMPTY) {                  // not 1st registration
413	>	if (parent == null || reconcileState() == s) {
414	>	if (unarrived == 0)             // wait out advance
415	>	root.internalAwaitAdvance(phase, null);
416	>	else if (UNSAFE.compareAndSwapLong(this, stateOffset,
417	>	s, s + adjust))
418		break;
419		}
420	<	s = state;
420	>	}
421	>	else if (parent == null) {              // 1st root registration
422	>	long next = ((long)phase << PHASE_SHIFT) | adjust;
423	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next))
424	>	break;
425	>	}
426	>	else {
427	>	synchronized (this) {               // 1st sub registration
428	>	if (state == s) {               // recheck under lock
429	>	phase = parent.doRegister(1);
430	>	if (phase < 0)
431	>	break;
432	>	// finish registration whenever parent registration
433	>	// succeeded, even when racing with termination,
434	>	// since these are part of the same "transaction".
435	>	while (!UNSAFE.compareAndSwapLong
436	>	(this, stateOffset, s,
437	>	((long)phase << PHASE_SHIFT) | adjust)) {
438	>	s = state;
439	>	phase = (int)(root.state >>> PHASE_SHIFT);
440	>	// assert (int)s == EMPTY;
441	>	}
442	>	break;
443	>	}
444	>	}
445		}
446		}
447	+	return phase;
448	+	}
449	+
450	+	/**
451	+	* Resolves lagged phase propagation from root if necessary.
452	+	* Reconciliation normally occurs when root has advanced but
453	+	* subphasers have not yet done so, in which case they must finish
454	+	* their own advance by setting unarrived to parties (or if
455	+	* parties is zero, resetting to unregistered EMPTY state).
456	+	* However, this method may also be called when "floating"
457	+	* subphasers with possibly some unarrived parties are merely
458	+	* catching up to current phase, in which case counts are
459	+	* unaffected.
460	+	*
461	+	* @return reconciled state
462	+	*/
463	+	private long reconcileState() {
464	+	final Phaser root = this.root;
465	+	long s = state;
466	+	if (root != this) {
467	+	int phase, u, p;
468	+	// CAS root phase with current parties; possibly trip unarrived
469	+	while ((phase = (int)(root.state >>> PHASE_SHIFT)) !=
470	+	(int)(s >>> PHASE_SHIFT) &&
471	+	!UNSAFE.compareAndSwapLong
472	+	(this, stateOffset, s,
473	+	s = (((long)phase << PHASE_SHIFT) |
474	+	(s & PARTIES_MASK) |
475	+	((p = (int)s >>> PARTIES_SHIFT) == 0 ? EMPTY :
476	+	((u = (int)s & UNARRIVED_MASK) == 0 && phase >= 0) ?
477	+	p : u))))
478	+	s = state;
479	+	}
480		return s;
481		}
482
483		/**
484	<	* Creates a new phaser without any initially registered parties,
485	<	* initial phase number 0, and no parent. Any thread using this
484	>	* Creates a new phaser with no initially registered parties, no
485	>	* parent, and initial phase number 0. Any thread using this
486		* phaser will need to first register for it.
487		*/
488		public Phaser() {
489	<	this(null);
489	>	this(null, 0);
490		}
491
492		/**
493		* Creates a new phaser with the given number of registered
494	<	* unarrived parties, initial phase number 0, and no parent.
494	>	* unarrived parties, no parent, and initial phase number 0.
495		*
496	<	* @param parties the number of parties required to trip barrier
496	>	* @param parties the number of parties required to advance to the
497	>	* next phase
498		* @throws IllegalArgumentException if parties less than zero
499		* or greater than the maximum number of parties supported
500		*/
#	Line 364 | Line 503 | public class Phaser {
503		}
504
505		/**
506	<	* Creates a new phaser with the given parent, without any
368	<	* initially registered parties. If parent is non-null this phaser
369	<	* is registered with the parent and its initial phase number is
370	<	* the same as that of parent phaser.
506	>	* Equivalent to {@link #Phaser(Phaser, int) Phaser(parent, 0)}.
507		*
508		* @param parent the parent phaser
509		*/
510		public Phaser(Phaser parent) {
511	<	int phase = 0;
376	<	this.parent = parent;
377	<	if (parent != null) {
378	<	this.root = parent.root;
379	<	phase = parent.register();
380	<	}
381	<	else
382	<	this.root = this;
383	<	this.state = trippedStateFor(phase, 0);
511	>	this(parent, 0);
512		}
513
514		/**
515		* Creates a new phaser with the given parent and number of
516	<	* registered unarrived parties. If parent is non-null, this phaser
517	<	* is registered with the parent and its initial phase number is
518	<	* the same as that of parent phaser.
516	>	* registered unarrived parties.  When the given parent is non-null
517	>	* and the given number of parties is greater than zero, this
518	>	* child phaser is registered with its parent.
519		*
520		* @param parent the parent phaser
521	<	* @param parties the number of parties required to trip barrier
521	>	* @param parties the number of parties required to advance to the
522	>	* next phase
523		* @throws IllegalArgumentException if parties less than zero
524		* or greater than the maximum number of parties supported
525		*/
526		public Phaser(Phaser parent, int parties) {
527	<	if (parties < 0 || parties > ushortMask)
527	>	if (parties >>> PARTIES_SHIFT != 0)
528		throw new IllegalArgumentException("Illegal number of parties");
529		int phase = 0;
530		this.parent = parent;
531		if (parent != null) {
532	<	this.root = parent.root;
533	<	phase = parent.register();
532	>	final Phaser root = parent.root;
533	>	this.root = root;
534	>	this.evenQ = root.evenQ;
535	>	this.oddQ = root.oddQ;
536	>	if (parties != 0)
537	>	phase = parent.doRegister(1);
538		}
539	<	else
539	>	else {
540		this.root = this;
541	<	this.state = trippedStateFor(phase, parties);
541	>	this.evenQ = new AtomicReference<QNode>();
542	>	this.oddQ = new AtomicReference<QNode>();
543	>	}
544	>	this.state = (parties == 0) ? (long)EMPTY :
545	>	((long)phase << PHASE_SHIFT) |
546	>	((long)parties << PARTIES_SHIFT) |
547	>	((long)parties);
548		}
549
550		/**
551	<	* Adds a new unarrived party to this phaser.
552	<	* If an ongoing invocation of {@link #onAdvance} is in progress,
553	<	* this method waits until its completion before registering.
554	<	*
555	<	* @return the arrival phase number to which this registration applied
551	>	* Adds a new unarrived party to this phaser.  If an ongoing
552	>	* invocation of {@link #onAdvance} is in progress, this method
553	>	* may await its completion before returning.  If this phaser has
554	>	* a parent, and this phaser previously had no registered parties,
555	>	* this child phaser is also registered with its parent. If
556	>	* this phaser is terminated, the attempt to register has
557	>	* no effect, and a negative value is returned.
558	>	*
559	>	* @return the arrival phase number to which this registration
560	>	* applied.  If this value is negative, then this phaser has
561	>	* terminated, in which case registration has no effect.
562		* @throws IllegalStateException if attempting to register more
563		* than the maximum supported number of parties
564		*/
#	Line 424 | Line 569 | public class Phaser {
569		/**
570		* Adds the given number of new unarrived parties to this phaser.
571		* If an ongoing invocation of {@link #onAdvance} is in progress,
572	<	* this method waits until its completion before registering.
573	<	*
574	<	* @param parties the number of additional parties required to trip barrier
575	<	* @return the arrival phase number to which this registration applied
572	>	* this method may await its completion before returning.  If this
573	>	* phaser has a parent, and the given number of parties is greater
574	>	* than zero, and this phaser previously had no registered
575	>	* parties, this child phaser is also registered with its parent.
576	>	* If this phaser is terminated, the attempt to register has no
577	>	* effect, and a negative value is returned.
578	>	*
579	>	* @param parties the number of additional parties required to
580	>	* advance to the next phase
581	>	* @return the arrival phase number to which this registration
582	>	* applied.  If this value is negative, then this phaser has
583	>	* terminated, in which case registration has no effect.
584		* @throws IllegalStateException if attempting to register more
585		* than the maximum supported number of parties
586		* @throws IllegalArgumentException if {@code parties < 0}
#	Line 441 | Line 594 | public class Phaser {
594		}
595
596		/**
597	<	* Shared code for register, bulkRegister
598	<	*/
599	<	private int doRegister(int registrations) {
600	<	Phaser par = parent;
601	<	long s;
602	<	int phase;
450	<	while ((phase = phaseOf(s = par==null? state:reconcileState())) >= 0) {
451	<	int p = partiesOf(s);
452	<	int u = unarrivedOf(s);
453	<	int unarrived = u + registrations;
454	<	int parties = p + registrations;
455	<	if (par == null || phase == phaseOf(root.state)) {
456	<	if (parties > ushortMask || unarrived > ushortMask)
457	<	throw new IllegalStateException(badBounds(parties,
458	<	unarrived));
459	<	else if (p != 0 && u == 0)       // back off if advancing
460	<	Thread.yield();              // not worth actually blocking
461	<	else if (casState(s, stateFor(phase, parties, unarrived)))
462	<	break;
463	<	}
464	<	}
465	<	return phase;
466	<	}
467	<
468	<	/**
469	<	* Arrives at the barrier, but does not wait for others.  (You can
470	<	* in turn wait for others via {@link #awaitAdvance}).  It is an
471	<	* unenforced usage error for an unregistered party to invoke this
472	<	* method.
597	>	* Arrives at this phaser, without waiting for others to arrive.
598	>	*
599	>	* <p>It is a usage error for an unregistered party to invoke this
600	>	* method.  However, this error may result in an {@code
601	>	* IllegalStateException} only upon some subsequent operation on
602	>	* this phaser, if ever.
603		*
604		* @return the arrival phase number, or a negative value if terminated
605		* @throws IllegalStateException if not terminated and the number
606		* of unarrived parties would become negative
607		*/
608		public int arrive() {
609	<	Phaser par = parent;
480	<	long s;
481	<	int phase;
482	<	while ((phase = phaseOf(s = par==null? state:reconcileState())) >= 0) {
483	<	int parties = partiesOf(s);
484	<	int unarrived = unarrivedOf(s) - 1;
485	<	if (parties == 0 || unarrived < 0)
486	<	throw new IllegalStateException(badBounds(parties,
487	<	unarrived));
488	<	else if (unarrived > 0) {           // Not the last arrival
489	<	if (casState(s, s - 1))         // s-1 adds one arrival
490	<	break;
491	<	}
492	<	else if (par == null) {             // directly trip
493	<	if (casState(s, trippedStateFor(onAdvance(phase, parties) ? -1 :
494	<	((phase + 1) & phaseMask),
495	<	parties))) {
496	<	releaseWaiters(phase);
497	<	break;
498	<	}
499	<	}
500	<	else if (phaseOf(root.state) == phase && casState(s, s - 1)) {
501	<	par.arrive();                   // cascade to parent
502	<	reconcileState();
503	<	break;
504	<	}
505	<	}
506	<	return phase;
609	>	return doArrive(ONE_ARRIVAL);
610		}
611
612		/**
613	<	* Arrives at the barrier and deregisters from it without waiting
614	<	* for others. Deregistration reduces the number of parties
615	<	* required to trip the barrier in future phases.  If this phaser
613	>	* Arrives at this phaser and deregisters from it without waiting
614	>	* for others to arrive. Deregistration reduces the number of
615	>	* parties required to advance in future phases.  If this phaser
616		* has a parent, and deregistration causes this phaser to have
617	<	* zero parties, this phaser also arrives at and is deregistered
618	<	* from its parent.  It is an unenforced usage error for an
619	<	* unregistered party to invoke this method.
617	>	* zero parties, this phaser is also deregistered from its parent.
618	>	*
619	>	* <p>It is a usage error for an unregistered party to invoke this
620	>	* method.  However, this error may result in an {@code
621	>	* IllegalStateException} only upon some subsequent operation on
622	>	* this phaser, if ever.
623		*
624		* @return the arrival phase number, or a negative value if terminated
625		* @throws IllegalStateException if not terminated and the number
626		* of registered or unarrived parties would become negative
627		*/
628		public int arriveAndDeregister() {
629	<	// similar to arrive, but too different to merge
524	<	Phaser par = parent;
525	<	long s;
526	<	int phase;
527	<	while ((phase = phaseOf(s = par==null? state:reconcileState())) >= 0) {
528	<	int parties = partiesOf(s) - 1;
529	<	int unarrived = unarrivedOf(s) - 1;
530	<	if (parties < 0 || unarrived < 0)
531	<	throw new IllegalStateException(badBounds(parties,
532	<	unarrived));
533	<	else if (unarrived > 0) {
534	<	if (casState(s, stateFor(phase, parties, unarrived)))
535	<	break;
536	<	}
537	<	else if (par == null) {
538	<	if (casState(s, trippedStateFor(onAdvance(phase, parties)? -1:
539	<	(phase + 1) & phaseMask,
540	<	parties))) {
541	<	releaseWaiters(phase);
542	<	break;
543	<	}
544	<	}
545	<	else if (phaseOf(root.state) == phase &&
546	<	casState(s, stateFor(phase, parties, 0))) {
547	<	if (parties == 0)
548	<	par.arriveAndDeregister();
549	<	else
550	<	par.arrive();
551	<	reconcileState();
552	<	break;
553	<	}
554	<	}
555	<	return phase;
629	>	return doArrive(ONE_DEREGISTER);
630		}
631
632		/**
633	<	* Arrives at the barrier and awaits others. Equivalent in effect
633	>	* Arrives at this phaser and awaits others. Equivalent in effect
634		* to {@code awaitAdvance(arrive())}.  If you need to await with
635		* interruption or timeout, you can arrange this with an analogous
636		* construction using one of the other forms of the {@code
637		* awaitAdvance} method.  If instead you need to deregister upon
638	<	* arrival, use {@link #arriveAndDeregister}. It is an unenforced
639	<	* usage error for an unregistered party to invoke this method.
638	>	* arrival, use {@code awaitAdvance(arriveAndDeregister())}.
639	>	*
640	>	* <p>It is a usage error for an unregistered party to invoke this
641	>	* method.  However, this error may result in an {@code
642	>	* IllegalStateException} only upon some subsequent operation on
643	>	* this phaser, if ever.
644		*
645	<	* @return the arrival phase number, or a negative number if terminated
645	>	* @return the arrival phase number, or the (negative)
646	>	* {@linkplain #getPhase() current phase} if terminated
647		* @throws IllegalStateException if not terminated and the number
648		* of unarrived parties would become negative
649		*/
650		public int arriveAndAwaitAdvance() {
651	<	return awaitAdvance(arrive());
651	>	// Specialization of doArrive+awaitAdvance eliminating some reads/paths
652	>	final Phaser root = this.root;
653	>	for (;;) {
654	>	long s = (root == this) ? state : reconcileState();
655	>	int phase = (int)(s >>> PHASE_SHIFT);
656	>	if (phase < 0)
657	>	return phase;
658	>	int counts = (int)s;
659	>	int unarrived = (counts == EMPTY) ? 0 : (counts & UNARRIVED_MASK);
660	>	if (unarrived <= 0)
661	>	throw new IllegalStateException(badArrive(s));
662	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s,
663	>	s -= ONE_ARRIVAL)) {
664	>	if (unarrived > 1)
665	>	return root.internalAwaitAdvance(phase, null);
666	>	if (root != this)
667	>	return parent.arriveAndAwaitAdvance();
668	>	long n = s & PARTIES_MASK;  // base of next state
669	>	int nextUnarrived = (int)n >>> PARTIES_SHIFT;
670	>	if (onAdvance(phase, nextUnarrived))
671	>	n |= TERMINATION_BIT;
672	>	else if (nextUnarrived == 0)
673	>	n |= EMPTY;
674	>	else
675	>	n |= nextUnarrived;
676	>	int nextPhase = (phase + 1) & MAX_PHASE;
677	>	n |= (long)nextPhase << PHASE_SHIFT;
678	>	if (!UNSAFE.compareAndSwapLong(this, stateOffset, s, n))
679	>	return (int)(state >>> PHASE_SHIFT); // terminated
680	>	releaseWaiters(phase);
681	>	return nextPhase;
682	>	}
683	>	}
684		}
685
686		/**
687	<	* Awaits the phase of the barrier to advance from the given phase
688	<	* value, returning immediately if the current phase of the
689	<	* barrier is not equal to the given phase value or this barrier
579	<	* is terminated.  It is an unenforced usage error for an
580	<	* unregistered party to invoke this method.
687	>	* Awaits the phase of this phaser to advance from the given phase
688	>	* value, returning immediately if the current phase is not equal
689	>	* to the given phase value or this phaser is terminated.
690		*
691		* @param phase an arrival phase number, or negative value if
692		* terminated; this argument is normally the value returned by a
693	<	* previous call to {@code arrive} or its variants
694	<	* @return the next arrival phase number, or a negative value
695	<	* if terminated or argument is negative
693	>	* previous call to {@code arrive} or {@code arriveAndDeregister}.
694	>	* @return the next arrival phase number, or the argument if it is
695	>	* negative, or the (negative) {@linkplain #getPhase() current phase}
696	>	* if terminated
697		*/
698		public int awaitAdvance(int phase) {
699	+	final Phaser root = this.root;
700	+	long s = (root == this) ? state : reconcileState();
701	+	int p = (int)(s >>> PHASE_SHIFT);
702		if (phase < 0)
703		return phase;
704	<	int p = getPhase();
705	<	if (p != phase)
706	<	return p;
594	<	return untimedWait(phase);
704	>	if (p == phase)
705	>	return root.internalAwaitAdvance(phase, null);
706	>	return p;
707		}
708
709		/**
710	<	* Awaits the phase of the barrier to advance from the given phase
710	>	* Awaits the phase of this phaser to advance from the given phase
711		* value, throwing {@code InterruptedException} if interrupted
712	<	* while waiting, or returning immediately if the current phase of
713	<	* the barrier is not equal to the given phase value or this
714	<	* barrier is terminated. It is an unenforced usage error for an
603	<	* unregistered party to invoke this method.
712	>	* while waiting, or returning immediately if the current phase is
713	>	* not equal to the given phase value or this phaser is
714	>	* terminated.
715		*
716		* @param phase an arrival phase number, or negative value if
717		* terminated; this argument is normally the value returned by a
718	<	* previous call to {@code arrive} or its variants
719	<	* @return the next arrival phase number, or a negative value
720	<	* if terminated or argument is negative
718	>	* previous call to {@code arrive} or {@code arriveAndDeregister}.
719	>	* @return the next arrival phase number, or the argument if it is
720	>	* negative, or the (negative) {@linkplain #getPhase() current phase}
721	>	* if terminated
722		* @throws InterruptedException if thread interrupted while waiting
723		*/
724		public int awaitAdvanceInterruptibly(int phase)
725		throws InterruptedException {
726	+	final Phaser root = this.root;
727	+	long s = (root == this) ? state : reconcileState();
728	+	int p = (int)(s >>> PHASE_SHIFT);
729		if (phase < 0)
730		return phase;
731	<	int p = getPhase();
732	<	if (p != phase)
733	<	return p;
734	<	return interruptibleWait(phase);
731	>	if (p == phase) {
732	>	QNode node = new QNode(this, phase, true, false, 0L);
733	>	p = root.internalAwaitAdvance(phase, node);
734	>	if (node.wasInterrupted)
735	>	throw new InterruptedException();
736	>	}
737	>	return p;
738		}
739
740		/**
741	<	* Awaits the phase of the barrier to advance from the given phase
741	>	* Awaits the phase of this phaser to advance from the given phase
742		* value or the given timeout to elapse, throwing {@code
743		* InterruptedException} if interrupted while waiting, or
744	<	* returning immediately if the current phase of the barrier is
745	<	* not equal to the given phase value or this barrier is
628	<	* terminated.  It is an unenforced usage error for an
629	<	* unregistered party to invoke this method.
744	>	* returning immediately if the current phase is not equal to the
745	>	* given phase value or this phaser is terminated.
746		*
747		* @param phase an arrival phase number, or negative value if
748		* terminated; this argument is normally the value returned by a
749	<	* previous call to {@code arrive} or its variants
749	>	* previous call to {@code arrive} or {@code arriveAndDeregister}.
750		* @param timeout how long to wait before giving up, in units of
751		*        {@code unit}
752		* @param unit a {@code TimeUnit} determining how to interpret the
753		*        {@code timeout} parameter
754	<	* @return the next arrival phase number, or a negative value
755	<	* if terminated or argument is negative
754	>	* @return the next arrival phase number, or the argument if it is
755	>	* negative, or the (negative) {@linkplain #getPhase() current phase}
756	>	* if terminated
757		* @throws InterruptedException if thread interrupted while waiting
758		* @throws TimeoutException if timed out while waiting
759		*/
#	Line 644 | Line 761 | public class Phaser {
761		long timeout, TimeUnit unit)
762		throws InterruptedException, TimeoutException {
763		long nanos = unit.toNanos(timeout);
764	+	final Phaser root = this.root;
765	+	long s = (root == this) ? state : reconcileState();
766	+	int p = (int)(s >>> PHASE_SHIFT);
767		if (phase < 0)
768		return phase;
769	<	int p = getPhase();
770	<	if (p != phase)
771	<	return p;
772	<	return timedWait(phase, nanos);
769	>	if (p == phase) {
770	>	QNode node = new QNode(this, phase, true, true, nanos);
771	>	p = root.internalAwaitAdvance(phase, node);
772	>	if (node.wasInterrupted)
773	>	throw new InterruptedException();
774	>	else if (p == phase)
775	>	throw new TimeoutException();
776	>	}
777	>	return p;
778		}
779
780		/**
781	<	* Forces this barrier to enter termination state. Counts of
782	<	* arrived and registered parties are unaffected. If this phaser
783	<	* has a parent, it too is terminated. This method may be useful
784	<	* for coordinating recovery after one or more tasks encounter
781	>	* Forces this phaser to enter termination state.  Counts of
782	>	* registered parties are unaffected.  If this phaser is a member
783	>	* of a tiered set of phasers, then all of the phasers in the set
784	>	* are terminated.  If this phaser is already terminated, this
785	>	* method has no effect.  This method may be useful for
786	>	* coordinating recovery after one or more tasks encounter
787		* unexpected exceptions.
788		*/
789		public void forceTermination() {
790	<	Phaser r = root;    // force at root then reconcile
790	>	// Only need to change root state
791	>	final Phaser root = this.root;
792		long s;
793	<	while (phaseOf(s = r.state) >= 0)
794	<	r.casState(s, stateFor(-1, partiesOf(s), unarrivedOf(s)));
795	<	reconcileState();
796	<	releaseWaiters(0);  // ensure wakeups on both queues
797	<	releaseWaiters(1);
793	>	while ((s = root.state) >= 0) {
794	>	if (UNSAFE.compareAndSwapLong(root, stateOffset,
795	>	s, s | TERMINATION_BIT)) {
796	>	// signal all threads
797	>	releaseWaiters(0); // Waiters on evenQ
798	>	releaseWaiters(1); // Waiters on oddQ
799	>	return;
800	>	}
801	>	}
802		}
803
804		/**
805		* Returns the current phase number. The maximum phase number is
806		* {@code Integer.MAX_VALUE}, after which it restarts at
807	<	* zero. Upon termination, the phase number is negative.
807	>	* zero. Upon termination, the phase number is negative,
808	>	* in which case the prevailing phase prior to termination
809	>	* may be obtained via {@code getPhase() + Integer.MIN_VALUE}.
810		*
811		* @return the phase number, or a negative value if terminated
812		*/
813		public final int getPhase() {
814	<	return phaseOf(getReconciledState());
814	>	return (int)(root.state >>> PHASE_SHIFT);
815		}
816
817		/**
818	<	* Returns the number of parties registered at this barrier.
818	>	* Returns the number of parties registered at this phaser.
819		*
820		* @return the number of parties
821		*/
822		public int getRegisteredParties() {
823	<	return partiesOf(getReconciledState());
823	>	return partiesOf(state);
824		}
825
826		/**
827		* Returns the number of registered parties that have arrived at
828	<	* the current phase of this barrier.
828	>	* the current phase of this phaser. If this phaser has terminated,
829	>	* the returned value is meaningless and arbitrary.
830		*
831		* @return the number of arrived parties
832		*/
833		public int getArrivedParties() {
834	<	return arrivedOf(getReconciledState());
834	>	return arrivedOf(reconcileState());
835		}
836
837		/**
838		* Returns the number of registered parties that have not yet
839	<	* arrived at the current phase of this barrier.
839	>	* arrived at the current phase of this phaser. If this phaser has
840	>	* terminated, the returned value is meaningless and arbitrary.
841		*
842		* @return the number of unarrived parties
843		*/
844		public int getUnarrivedParties() {
845	<	return unarrivedOf(getReconciledState());
845	>	return unarrivedOf(reconcileState());
846		}
847
848		/**
#	Line 729 | Line 865 | public class Phaser {
865		}
866
867		/**
868	<	* Returns {@code true} if this barrier has been terminated.
868	>	* Returns {@code true} if this phaser has been terminated.
869		*
870	<	* @return {@code true} if this barrier has been terminated
870	>	* @return {@code true} if this phaser has been terminated
871		*/
872		public boolean isTerminated() {
873	<	return getPhase() < 0;
873	>	return root.state < 0L;
874		}
875
876		/**
877		* Overridable method to perform an action upon impending phase
878		* advance, and to control termination. This method is invoked
879	<	* upon arrival of the party tripping the barrier (when all other
879	>	* upon arrival of the party advancing this phaser (when all other
880		* waiting parties are dormant).  If this method returns {@code
881	<	* true}, then, rather than advance the phase number, this barrier
882	<	* will be set to a final termination state, and subsequent calls
883	<	* to {@link #isTerminated} will return true. Any (unchecked)
884	<	* Exception or Error thrown by an invocation of this method is
885	<	* propagated to the party attempting to trip the barrier, in
886	<	* which case no advance occurs.
881	>	* true}, this phaser will be set to a final termination state
882	>	* upon advance, and subsequent calls to {@link #isTerminated}
883	>	* will return true. Any (unchecked) Exception or Error thrown by
884	>	* an invocation of this method is propagated to the party
885	>	* attempting to advance this phaser, in which case no advance
886	>	* occurs.
887		*
888		* <p>The arguments to this method provide the state of the phaser
889	<	* prevailing for the current transition. (When called from within
890	<	* an implementation of {@code onAdvance} the values returned by
891	<	* methods such as {@code getPhase} may or may not reliably
892	<	* indicate the state to which this transition applies.)
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.
889	>	* prevailing for the current transition.  The effects of invoking
890	>	* arrival, registration, and waiting methods on this phaser from
891	>	* within {@code onAdvance} are unspecified and should not be
892	>	* relied on.
893	>	*
894	>	* <p>If this phaser is a member of a tiered set of phasers, then
895	>	* {@code onAdvance} is invoked only for its root phaser on each
896	>	* advance.
897	>	*
898	>	* <p>To support the most common use cases, the default
899	>	* implementation of this method returns {@code true} when the
900	>	* number of registered parties has become zero as the result of a
901	>	* party invoking {@code arriveAndDeregister}.  You can disable
902	>	* this behavior, thus enabling continuation upon future
903	>	* registrations, by overriding this method to always return
904	>	* {@code false}:
905	>	*
906	>	* <pre> {@code
907	>	* Phaser phaser = new Phaser() {
908	>	*   protected boolean onAdvance(int phase, int parties) { return false; }
909	>	* }}</pre>
910		*
911	<	* @param phase the phase number on entering the barrier
911	>	* @param phase the current phase number on entry to this method,
912	>	* before this phaser is advanced
913		* @param registeredParties the current number of registered parties
914	<	* @return {@code true} if this barrier should terminate
914	>	* @return {@code true} if this phaser should terminate
915		*/
916		protected boolean onAdvance(int phase, int registeredParties) {
917	<	return registeredParties <= 0;
917	>	return registeredParties == 0;
918		}
919
920		/**
#	Line 775 | Line 924 | public class Phaser {
924		* followed by the number of registered parties, and {@code
925		* "arrived = "} followed by the number of arrived parties.
926		*
927	<	* @return a string identifying this barrier, as well as its state
927	>	* @return a string identifying this phaser, as well as its state
928		*/
929		public String toString() {
930	<	long s = getReconciledState();
930	>	return stateToString(reconcileState());
931	>	}
932	>
933	>	/**
934	>	* Implementation of toString and string-based error messages
935	>	*/
936	>	private String stateToString(long s) {
937		return super.toString() +
938		"[phase = " + phaseOf(s) +
939		" parties = " + partiesOf(s) +
940		" arrived = " + arrivedOf(s) + "]";
941		}
942
943	<	// methods for waiting
943	>	// Waiting mechanics
944
945		/**
946	<	* Wait nodes for Treiber stack representing wait queue
946	>	* Removes and signals threads from queue for phase.
947		*/
948	<	static final class QNode implements ForkJoinPool.ManagedBlocker {
949	<	final Phaser phaser;
950	<	final int phase;
951	<	final long startTime;
952	<	final long nanos;
953	<	final boolean timed;
954	<	final boolean interruptible;
955	<	volatile boolean wasInterrupted = false;
956	<	volatile Thread thread; // nulled to cancel wait
802	<	QNode next;
803	<
804	<	QNode(Phaser phaser, int phase, boolean interruptible,
805	<	boolean timed, long startTime, long nanos) {
806	<	this.phaser = phaser;
807	<	this.phase = phase;
808	<	this.timed = timed;
809	<	this.interruptible = interruptible;
810	<	this.startTime = startTime;
811	<	this.nanos = nanos;
812	<	thread = Thread.currentThread();
813	<	}
814	<
815	<	public boolean isReleasable() {
816	<	return (thread == null ||
817	<	phaser.getPhase() != phase ||
818	<	(interruptible && wasInterrupted) ||
819	<	(timed && (nanos - (System.nanoTime() - startTime)) <= 0));
820	<	}
821	<
822	<	public boolean block() {
823	<	if (Thread.interrupted()) {
824	<	wasInterrupted = true;
825	<	if (interruptible)
826	<	return true;
827	<	}
828	<	if (!timed)
829	<	LockSupport.park(this);
830	<	else {
831	<	long waitTime = nanos - (System.nanoTime() - startTime);
832	<	if (waitTime <= 0)
833	<	return true;
834	<	LockSupport.parkNanos(this, waitTime);
835	<	}
836	<	return isReleasable();
837	<	}
838	<
839	<	void signal() {
840	<	Thread t = thread;
841	<	if (t != null) {
842	<	thread = null;
948	>	private void releaseWaiters(int phase) {
949	>	QNode q;   // first element of queue
950	>	Thread t;  // its thread
951	>	AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ;
952	>	while ((q = head.get()) != null &&
953	>	q.phase != (int)(root.state >>> PHASE_SHIFT)) {
954	>	if (head.compareAndSet(q, q.next) &&
955	>	(t = q.thread) != null) {
956	>	q.thread = null;
957		LockSupport.unpark(t);
958		}
959		}
846	–
847	–	boolean doWait() {
848	–	if (thread != null) {
849	–	try {
850	–	ForkJoinPool.managedBlock(this);
851	–	} catch (InterruptedException ie) {
852	–	wasInterrupted = true; // can't currently happen
853	–	}
854	–	}
855	–	return wasInterrupted;
856	–	}
960		}
961
962		/**
963	<	* Removes and signals waiting threads from wait queue.
964	<	*/
965	<	private void releaseWaiters(int phase) {
966	<	AtomicReference<QNode> head = queueFor(phase);
967	<	QNode q;
968	<	while ((q = head.get()) != null) {
969	<	if (head.compareAndSet(q, q.next))
970	<	q.signal();
963	>	* Variant of releaseWaiters that additionally tries to remove any
964	>	* nodes no longer waiting for advance due to timeout or
965	>	* interrupt. Currently, nodes are removed only if they are at
966	>	* head of queue, which suffices to reduce memory footprint in
967	>	* most usages.
968	>	*
969	>	* @return current phase on exit
970	>	*/
971	>	private int abortWait(int phase) {
972	>	AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ;
973	>	for (;;) {
974	>	Thread t;
975	>	QNode q = head.get();
976	>	int p = (int)(root.state >>> PHASE_SHIFT);
977	>	if (q == null || ((t = q.thread) != null && q.phase == p))
978	>	return p;
979	>	if (head.compareAndSet(q, q.next) && t != null) {
980	>	q.thread = null;
981	>	LockSupport.unpark(t);
982	>	}
983		}
984		}
985
986	+	/** The number of CPUs, for spin control */
987	+	private static final int NCPU = Runtime.getRuntime().availableProcessors();
988	+
989		/**
990	<	* Tries to enqueue given node in the appropriate wait queue.
991	<	*
992	<	* @return true if successful
990	>	* The number of times to spin before blocking while waiting for
991	>	* advance, per arrival while waiting. On multiprocessors, fully
992	>	* blocking and waking up a large number of threads all at once is
993	>	* usually a very slow process, so we use rechargeable spins to
994	>	* avoid it when threads regularly arrive: When a thread in
995	>	* internalAwaitAdvance notices another arrival before blocking,
996	>	* and there appear to be enough CPUs available, it spins
997	>	* SPINS_PER_ARRIVAL more times before blocking. The value trades
998	>	* off good-citizenship vs big unnecessary slowdowns.
999		*/
1000	<	private boolean tryEnqueue(QNode node) {
877	<	AtomicReference<QNode> head = queueFor(node.phase);
878	<	return head.compareAndSet(node.next = head.get(), node);
879	<	}
1000	>	static final int SPINS_PER_ARRIVAL = (NCPU < 2) ? 1 : 1 << 8;
1001
1002		/**
1003	<	* Enqueues node and waits unless aborted or signalled.
1003	>	* Possibly blocks and waits for phase to advance unless aborted.
1004	>	* Call only on root phaser.
1005		*
1006	+	* @param phase current phase
1007	+	* @param node if non-null, the wait node to track interrupt and timeout;
1008	+	* if null, denotes noninterruptible wait
1009		* @return current phase
1010		*/
1011	<	private int untimedWait(int phase) {
1012	<	QNode node = null;
1013	<	boolean queued = false;
1014	<	boolean interrupted = false;
1011	>	private int internalAwaitAdvance(int phase, QNode node) {
1012	>	// assert root == this;
1013	>	releaseWaiters(phase-1);          // ensure old queue clean
1014	>	boolean queued = false;           // true when node is enqueued
1015	>	int lastUnarrived = 0;            // to increase spins upon change
1016	>	int spins = SPINS_PER_ARRIVAL;
1017	>	long s;
1018		int p;
1019	<	while ((p = getPhase()) == phase) {
1020	<	if (Thread.interrupted())
1021	<	interrupted = true;
1022	<	else if (node == null)
1023	<	node = new QNode(this, phase, false, false, 0, 0);
1024	<	else if (!queued)
1025	<	queued = tryEnqueue(node);
1026	<	else if (node.doWait())
1027	<	interrupted = true;
1019	>	while ((p = (int)((s = state) >>> PHASE_SHIFT)) == phase) {
1020	>	if (node == null) {           // spinning in noninterruptible mode
1021	>	int unarrived = (int)s & UNARRIVED_MASK;
1022	>	if (unarrived != lastUnarrived &&
1023	>	(lastUnarrived = unarrived) < NCPU)
1024	>	spins += SPINS_PER_ARRIVAL;
1025	>	boolean interrupted = Thread.interrupted();
1026	>	if (interrupted || --spins < 0) { // need node to record intr
1027	>	node = new QNode(this, phase, false, false, 0L);
1028	>	node.wasInterrupted = interrupted;
1029	>	}
1030	>	}
1031	>	else if (node.isReleasable()) // done or aborted
1032	>	break;
1033	>	else if (!queued) {           // push onto queue
1034	>	AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ;
1035	>	QNode q = node.next = head.get();
1036	>	if ((q == null || q.phase == phase) &&
1037	>	(int)(state >>> PHASE_SHIFT) == phase) // avoid stale enq
1038	>	queued = head.compareAndSet(q, node);
1039	>	}
1040	>	else {
1041	>	try {
1042	>	ForkJoinPool.managedBlock(node);
1043	>	} catch (InterruptedException ie) {
1044	>	node.wasInterrupted = true;
1045	>	}
1046	>	}
1047	>	}
1048	>
1049	>	if (node != null) {
1050	>	if (node.thread != null)
1051	>	node.thread = null;       // avoid need for unpark()
1052	>	if (node.wasInterrupted && !node.interruptible)
1053	>	Thread.currentThread().interrupt();
1054	>	if (p == phase && (p = (int)(state >>> PHASE_SHIFT)) == phase)
1055	>	return abortWait(phase); // possibly clean up on abort
1056		}
901	–	if (node != null)
902	–	node.thread = null;
1057		releaseWaiters(phase);
904	–	if (interrupted)
905	–	Thread.currentThread().interrupt();
1058		return p;
1059		}
1060
1061		/**
1062	<	* Interruptible version
911	<	* @return current phase
1062	>	* Wait nodes for Treiber stack representing wait queue
1063		*/
1064	<	private int interruptibleWait(int phase) throws InterruptedException {
1065	<	QNode node = null;
1066	<	boolean queued = false;
1067	<	boolean interrupted = false;
1068	<	int p;
1069	<	while ((p = getPhase()) == phase && !interrupted) {
1070	<	if (Thread.interrupted())
1071	<	interrupted = true;
1072	<	else if (node == null)
1073	<	node = new QNode(this, phase, true, false, 0, 0);
923	<	else if (!queued)
924	<	queued = tryEnqueue(node);
925	<	else if (node.doWait())
926	<	interrupted = true;
927	<	}
928	<	if (node != null)
929	<	node.thread = null;
930	<	if (p != phase || (p = getPhase()) != phase)
931	<	releaseWaiters(phase);
932	<	if (interrupted)
933	<	throw new InterruptedException();
934	<	return p;
935	<	}
1064	>	static final class QNode implements ForkJoinPool.ManagedBlocker {
1065	>	final Phaser phaser;
1066	>	final int phase;
1067	>	final boolean interruptible;
1068	>	final boolean timed;
1069	>	boolean wasInterrupted;
1070	>	long nanos;
1071	>	long lastTime;
1072	>	volatile Thread thread; // nulled to cancel wait
1073	>	QNode next;
1074
1075	<	/**
1076	<	* Timeout version.
1077	<	* @return current phase
1078	<	*/
1079	<	private int timedWait(int phase, long nanos)
1080	<	throws InterruptedException, TimeoutException {
1081	<	long startTime = System.nanoTime();
1082	<	QNode node = null;
1083	<	boolean queued = false;
1084	<	boolean interrupted = false;
1085	<	int p;
1086	<	while ((p = getPhase()) == phase && !interrupted) {
1075	>	QNode(Phaser phaser, int phase, boolean interruptible,
1076	>	boolean timed, long nanos) {
1077	>	this.phaser = phaser;
1078	>	this.phase = phase;
1079	>	this.interruptible = interruptible;
1080	>	this.nanos = nanos;
1081	>	this.timed = timed;
1082	>	this.lastTime = timed ? System.nanoTime() : 0L;
1083	>	thread = Thread.currentThread();
1084	>	}
1085	>
1086	>	public boolean isReleasable() {
1087	>	if (thread == null)
1088	>	return true;
1089	>	if (phaser.getPhase() != phase) {
1090	>	thread = null;
1091	>	return true;
1092	>	}
1093		if (Thread.interrupted())
1094	<	interrupted = true;
1095	<	else if (nanos - (System.nanoTime() - startTime) <= 0)
1096	<	break;
1097	<	else if (node == null)
1098	<	node = new QNode(this, phase, true, true, startTime, nanos);
1099	<	else if (!queued)
1100	<	queued = tryEnqueue(node);
1101	<	else if (node.doWait())
1102	<	interrupted = true;
1103	<	}
1104	<	if (node != null)
1105	<	node.thread = null;
1106	<	if (p != phase || (p = getPhase()) != phase)
1107	<	releaseWaiters(phase);
1108	<	if (interrupted)
1109	<	throw new InterruptedException();
1110	<	if (p == phase)
1111	<	throw new TimeoutException();
1112	<	return p;
1094	>	wasInterrupted = true;
1095	>	if (wasInterrupted && interruptible) {
1096	>	thread = null;
1097	>	return true;
1098	>	}
1099	>	if (timed) {
1100	>	if (nanos > 0L) {
1101	>	long now = System.nanoTime();
1102	>	nanos -= now - lastTime;
1103	>	lastTime = now;
1104	>	}
1105	>	if (nanos <= 0L) {
1106	>	thread = null;
1107	>	return true;
1108	>	}
1109	>	}
1110	>	return false;
1111	>	}
1112	>
1113	>	public boolean block() {
1114	>	if (isReleasable())
1115	>	return true;
1116	>	else if (!timed)
1117	>	LockSupport.park(this);
1118	>	else if (nanos > 0)
1119	>	LockSupport.parkNanos(this, nanos);
1120	>	return isReleasable();
1121	>	}
1122		}
1123
1124		// Unsafe mechanics
1125
1126	<	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1127	<	private static final long stateOffset =
1128	<	objectFieldOffset("state", Phaser.class);
976	<
977	<	private final boolean casState(long cmp, long val) {
978	<	return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val);
979	<	}
980	<
981	<	private static long objectFieldOffset(String field, Class<?> klazz) {
1126	>	private static final sun.misc.Unsafe UNSAFE;
1127	>	private static final long stateOffset;
1128	>	static {
1129		try {
1130	<	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1131	<	} catch (NoSuchFieldException e) {
1132	<	// Convert Exception to corresponding Error
1133	<	NoSuchFieldError error = new NoSuchFieldError(field);
1134	<	error.initCause(e);
1135	<	throw error;
1130	>	UNSAFE = getUnsafe();
1131	>	Class<?> k = Phaser.class;
1132	>	stateOffset = UNSAFE.objectFieldOffset
1133	>	(k.getDeclaredField("state"));
1134	>	} catch (Exception e) {
1135	>	throw new Error(e);
1136		}
1137		}
1138

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