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Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.1 by dl, Mon Jul 7 16:53:30 2008 UTC vs.
Revision 1.18 by jsr166, Thu Jul 23 23:07:57 2009 UTC

#	Line 5 | Line 5
5		*/
6
7		package jsr166y;
8	<	import jsr166y.forkjoin.*;
8	>
9		import java.util.concurrent.*;
10		import java.util.concurrent.atomic.*;
11		import java.util.concurrent.locks.LockSupport;
12	+	import sun.misc.Unsafe;
13	+	import java.lang.reflect.*;
14
15		/**
16		* A reusable synchronization barrier, similar in functionality to a
17	<	* {@link java.util.concurrent.CyclicBarrier}, but supporting more
18	<	* flexible usage.
17	>	* {@link java.util.concurrent.CyclicBarrier CyclicBarrier} and
18	>	* {@link java.util.concurrent.CountDownLatch CountDownLatch}
19	>	* but supporting more flexible usage.
20		*
21		* <ul>
22		*
23	<	* <li> The number of parties synchronizing on the barrier may vary
24	<	* over time.  A task may register to be a party in a barrier at any
25	<	* time, and may deregister upon arriving at the barrier.  As is the
26	<	* case with most basic synchronization constructs, registration
27	<	* and deregistration affect only internal counts; they do not
28	<	* establish any further internal bookkeeping, so tasks cannot query
29	<	* whether they are registered.
23	>	* <li> The number of parties synchronizing on a phaser may vary over
24	>	* time.  A task may register to be a party at any time, and may
25	>	* deregister upon arriving at the barrier.  As is the case with most
26	>	* basic synchronization constructs, registration and deregistration
27	>	* affect only internal counts; they do not establish any further
28	>	* internal bookkeeping, so tasks cannot query whether they are
29	>	* registered. (However, you can introduce such bookkeeping by
30	>	* subclassing this class.)
31		*
32		* <li> Each generation has an associated phase value, starting at
33		* zero, and advancing when all parties reach the barrier (wrapping
34	<	* around to zero after reaching <tt>Integer.MAX_VALUE</tt>).
35	<	*
34	>	* around to zero after reaching {@code Integer.MAX_VALUE}).
35	>	*
36		* <li> Like a CyclicBarrier, a Phaser may be repeatedly awaited.
37	<	* Method <tt>arriveAndAwaitAdvance</tt> has effect analogous to
38	<	* <tt>CyclicBarrier.await</tt>.  However, Phasers separate two
39	<	* aspects of coordination, that may be invoked independently:
37	>	* Method {@code arriveAndAwaitAdvance} has effect analogous to
38	>	* {@code CyclicBarrier.await}.  However, Phasers separate two
39	>	* aspects of coordination, that may also be invoked independently:
40		*
41		* <ul>
42		*
43	<	*   <li> Arriving at a barrier. Methods <tt>arrive</tt> and
44	<	*       <tt>arriveAndDeregister</tt> do not block, but return
45	<	*       the phase value on entry to the method.
43	>	*   <li> Arriving at a barrier. Methods {@code arrive} and
44	>	*       {@code arriveAndDeregister} do not block, but return
45	>	*       the phase value current upon entry to the method.
46		*
47	<	*   <li> Awaiting others. Method <tt>awaitAdvance</tt> requires an
47	>	*   <li> Awaiting others. Method {@code awaitAdvance} requires an
48		*       argument indicating the entry phase, and returns when the
49		*       barrier advances to a new phase.
50		* </ul>
#	Line 48 | Line 52 | import java.util.concurrent.locks.LockSu
52		*
53		* <li> Barrier actions, performed by the task triggering a phase
54		* advance while others may be waiting, are arranged by overriding
55	<	* method <tt>onAdvance</tt>, that also controls termination.
55	>	* method {@code onAdvance}, that also controls termination.
56	>	* Overriding this method may be used to similar but more flexible
57	>	* effect as providing a barrier action to a CyclicBarrier.
58		*
59		* <li> Phasers may enter a <em>termination</em> state in which all
60	<	* await actions immediately return, indicating (via a negative phase
61	<	* value) that execution is complete.  Termination is triggered by
62	<	* executing the overridable <tt>onAdvance</tt> method that is invoked
63	<	* each time the barrier is tripped. When a Phaser is controlling an
60	>	* actions immediately return without updating phaser state or waiting
61	>	* for advance, and indicating (via a negative phase value) that
62	>	* execution is complete.  Termination is triggered by executing the
63	>	* overridable {@code onAdvance} method that is invoked each time the
64	>	* barrier is about to be tripped. When a Phaser is controlling an
65		* action with a fixed number of iterations, it is often convenient to
66		* override this method to cause termination when the current phase
67	<	* number reaches a threshold.  Method <tt>forceTermination</tt> is
68	<	* also available to assist recovery actions upon failure.
67	>	* number reaches a threshold. Method {@code forceTermination} is also
68	>	* available to abruptly release waiting threads and allow them to
69	>	* terminate.
70	>	*
71	>	* <li> Phasers may be tiered to reduce contention. Phasers with large
72	>	* numbers of parties that would otherwise experience heavy
73	>	* synchronization contention costs may instead be arranged in trees.
74	>	* This will typically greatly increase throughput even though it
75	>	* incurs somewhat greater per-operation overhead.
76		*
77	<	* <li> Unlike most synchronizers, a Phaser may also be used with
78	<	* ForkJoinTasks (as well as plain threads).
65	<	*
66	<	* <li> By default, <tt>awaitAdvance</tt> continues to wait even if
67	<	* the current thread is interrupted. And unlike the case in
77	>	* <li> By default, {@code awaitAdvance} continues to wait even if
78	>	* the waiting thread is interrupted. And unlike the case in
79		* CyclicBarriers, exceptions encountered while tasks wait
80		* interruptibly or with timeout do not change the state of the
81		* barrier. If necessary, you can perform any associated recovery
82	<	* within handlers of those exceptions.
82	>	* within handlers of those exceptions, often after invoking
83	>	* {@code forceTermination}.
84	>	*
85	>	* <li>Phasers ensure lack of starvation when used by ForkJoinTasks.
86		*
87		* </ul>
88		*
89	<	* <p><b>Sample usage:</b>
89	>	* <p><b>Sample usages:</b>
90		*
91	<	* <p>[todo: non-FJ example]
91	>	* <p>A Phaser may be used instead of a {@code CountDownLatch} to control
92	>	* a one-shot action serving a variable number of parties. The typical
93	>	* idiom is for the method setting this up to first register, then
94	>	* start the actions, then deregister, as in:
95	>	*
96	>	*  <pre> {@code
97	>	* void runTasks(List<Runnable> list) {
98	>	*   final Phaser phaser = new Phaser(1); // "1" to register self
99	>	*   for (Runnable r : list) {
100	>	*     phaser.register();
101	>	*     new Thread() {
102	>	*       public void run() {
103	>	*         phaser.arriveAndAwaitAdvance(); // await all creation
104	>	*         r.run();
105	>	*         phaser.arriveAndDeregister();   // signal completion
106	>	*       }
107	>	*     }.start();
108	>	*   }
109		*
110	<	* <p> A Phaser may be used to support a style of programming in
111	<	* which a task waits for others to complete, without otherwise
112	<	* needing to keep track of which tasks it is waiting for. This is
113	<	* similar to the "sync" construct in Cilk and "clocks" in X10.
114	<	* Special constructions based on such barriers are available using
115	<	* the <tt>LinkedAsyncAction</tt> and <tt>CyclicAction</tt> classes,
116	<	* but they can be useful in other contexts as well.  For a simple
117	<	* (but not very useful) example, here is a variant of Fibonacci:
118	<	*
119	<	* <pre>
120	<	* class BarrierFibonacci extends RecursiveAction {
121	<	*   int argument, result;
122	<	*   final Phaser parentBarrier;
123	<	*   BarrierFibonacci(int n, Phaser parentBarrier) {
124	<	*     this.argument = n;
125	<	*     this.parentBarrier = parentBarrier;
126	<	*     parentBarrier.register();
110	>	*   doSomethingOnBehalfOfWorkers();
111	>	*   phaser.arrive(); // allow threads to start
112	>	*   int p = phaser.arriveAndDeregister(); // deregister self  ...
113	>	*   p = phaser.awaitAdvance(p); // ... and await arrival
114	>	*   otherActions(); // do other things while tasks execute
115	>	*   phaser.awaitAdvance(p); // await final completion
116	>	* }}</pre>
117	>	*
118	>	* <p>One way to cause a set of threads to repeatedly perform actions
119	>	* for a given number of iterations is to override {@code onAdvance}:
120	>	*
121	>	*  <pre> {@code
122	>	* void startTasks(List<Runnable> list, final int iterations) {
123	>	*   final Phaser phaser = new Phaser() {
124	>	*     public boolean onAdvance(int phase, int registeredParties) {
125	>	*       return phase >= iterations || registeredParties == 0;
126	>	*     }
127	>	*   };
128	>	*   phaser.register();
129	>	*   for (Runnable r : list) {
130	>	*     phaser.register();
131	>	*     new Thread() {
132	>	*       public void run() {
133	>	*         do {
134	>	*           r.run();
135	>	*           phaser.arriveAndAwaitAdvance();
136	>	*         } while(!phaser.isTerminated();
137	>	*       }
138	>	*     }.start();
139		*   }
140	<	*   protected void compute() {
141	<	*     int n = argument;
142	<	*     if (n &lt;= 1)
143	<	*        result = n;
144	<	*     else {
145	<	*        Phaser childBarrier = new Phaser(1);
146	<	*        BarrierFibonacci f1 = new BarrierFibonacci(n - 1, childBarrier);
147	<	*        BarrierFibonacci f2 = new BarrierFibonacci(n - 2, childBarrier);
148	<	*        f1.fork();
149	<	*        f2.fork();
150	<	*        childBarrier.arriveAndAwait();
151	<	*        result = f1.result + f2.result;
140	>	*   phaser.arriveAndDeregister(); // deregister self, don't wait
141	>	* }}</pre>
142	>	*
143	>	* <p> To create a set of tasks using a tree of Phasers,
144	>	* you could use code of the following form, assuming a
145	>	* Task class with a constructor accepting a Phaser that
146	>	* it registers for upon construction:
147	>	*  <pre> {@code
148	>	* void build(Task[] actions, int lo, int hi, Phaser b) {
149	>	*   int step = (hi - lo) / TASKS_PER_PHASER;
150	>	*   if (step > 1) {
151	>	*     int i = lo;
152	>	*     while (i < hi) {
153	>	*       int r = Math.min(i + step, hi);
154	>	*       build(actions, i, r, new Phaser(b));
155	>	*       i = r;
156		*     }
157	<	*     parentBarrier.arriveAndDeregister();
157	>	*   } else {
158	>	*     for (int i = lo; i < hi; ++i)
159	>	*       actions[i] = new Task(b);
160	>	*       // assumes new Task(b) performs b.register()
161		*   }
162		* }
163	+	* // .. initially called, for n tasks via
164	+	* build(new Task[n], 0, n, new Phaser());}</pre>
165	+	*
166	+	* The best value of {@code TASKS_PER_PHASER} depends mainly on
167	+	* expected barrier synchronization rates. A value as low as four may
168	+	* be appropriate for extremely small per-barrier task bodies (thus
169	+	* high rates), or up to hundreds for extremely large ones.
170	+	*
171		* </pre>
172		*
173		* <p><b>Implementation notes</b>: This implementation restricts the
174	<	* maximum number of parties to 65535. Attempts to register
175	<	* additional parties result in IllegalStateExceptions.
174	>	* maximum number of parties to 65535. Attempts to register additional
175	>	* parties result in IllegalStateExceptions. However, you can and
176	>	* should create tiered phasers to accommodate arbitrarily large sets
177	>	* of participants.
178	>	*
179	>	* @since 1.7
180	>	* @author Doug Lea
181		*/
182		public class Phaser {
183		/*
184		* This class implements an extension of X10 "clocks".  Thanks to
185	<	* Vijay Saraswat for the idea of applying it to ForkJoinTasks,
186	<	* and to Vivek Sarkar for enhancements to extend functionality.
185	>	* Vijay Saraswat for the idea, and to Vivek Sarkar for
186	>	* enhancements to extend functionality.
187		*/
188
189		/**
190		* Barrier state representation. Conceptually, a barrier contains
191		* four values:
192	<	*
192	>	*
193		* * parties -- the number of parties to wait (16 bits)
194		* * unarrived -- the number of parties yet to hit barrier (16 bits)
195		* * phase -- the generation of the barrier (31 bits)
196		* * terminated -- set if barrier is terminated (1 bit)
197		*
198		* However, to efficiently maintain atomicity, these values are
199	<	* packed into a single AtomicLong. Termination uses the sign bit
200	<	* of 32 bit representation of phase, so phase is set to -1 on
201	<	* termination.
202	<	*/
203	<	private final AtomicLong state;
204	<
205	<	/**
143	<	* Head of Treiber stack for waiting nonFJ threads.
199	>	* packed into a single (atomic) long. Termination uses the sign
200	>	* bit of 32 bit representation of phase, so phase is set to -1 on
201	>	* termination. Good performance relies on keeping state decoding
202	>	* and encoding simple, and keeping race windows short.
203	>	*
204	>	* Note: there are some cheats in arrive() that rely on unarrived
205	>	* count being lowest 16 bits.
206		*/
207	<	private final AtomicReference<QNode> head = new AtomicReference<QNode>();
207	>	private volatile long state;
208
209		private static final int ushortBits = 16;
210	<	private static final int ushortMask =  (1 << ushortBits) - 1;
211	<	private static final int phaseMask = 0x7fffffff;
210	>	private static final int ushortMask = 0xffff;
211	>	private static final int phaseMask  = 0x7fffffff;
212
213		private static int unarrivedOf(long s) {
214	<	return (int)(s & ushortMask);
214	>	return (int) (s & ushortMask);
215		}
216
217		private static int partiesOf(long s) {
218	<	return (int)(s & (ushortMask << 16)) >>> 16;
218	>	return ((int) s) >>> 16;
219		}
220
221		private static int phaseOf(long s) {
222	<	return (int)(s >>> 32);
222	>	return (int) (s >>> 32);
223		}
224
225		private static int arrivedOf(long s) {
#	Line 165 | Line 227 | public class Phaser {
227		}
228
229		private static long stateFor(int phase, int parties, int unarrived) {
230	<	return (((long)phase) << 32) | ((parties << 16) | unarrived);
230	>	return ((((long) phase) << 32) | (((long) parties) << 16) |
231	>	(long) unarrived);
232		}
233
234	<	private static IllegalStateException badBounds(int parties, int unarrived) {
235	<	return new IllegalStateException("Attempt to set " + unarrived +
236	<	" unarrived of " + parties + " parties");
234	>	private static long trippedStateFor(int phase, int parties) {
235	>	long lp = (long) parties;
236	>	return (((long) phase) << 32) | (lp << 16) | lp;
237	>	}
238	>
239	>	/**
240	>	* Returns message string for bad bounds exceptions.
241	>	*/
242	>	private static String badBounds(int parties, int unarrived) {
243	>	return ("Attempt to set " + unarrived +
244	>	" unarrived of " + parties + " parties");
245	>	}
246	>
247	>	/**
248	>	* The parent of this phaser, or null if none
249	>	*/
250	>	private final Phaser parent;
251	>
252	>	/**
253	>	* The root of Phaser tree. Equals this if not in a tree.  Used to
254	>	* support faster state push-down.
255	>	*/
256	>	private final Phaser root;
257	>
258	>	// Wait queues
259	>
260	>	/**
261	>	* Heads of Treiber stacks for waiting threads. To eliminate
262	>	* contention while releasing some threads while adding others, we
263	>	* use two of them, alternating across even and odd phases.
264	>	*/
265	>	private final AtomicReference<QNode> evenQ = new AtomicReference<QNode>();
266	>	private final AtomicReference<QNode> oddQ  = new AtomicReference<QNode>();
267	>
268	>	private AtomicReference<QNode> queueFor(int phase) {
269	>	return ((phase & 1) == 0) ? evenQ : oddQ;
270	>	}
271	>
272	>	/**
273	>	* Returns current state, first resolving lagged propagation from
274	>	* root if necessary.
275	>	*/
276	>	private long getReconciledState() {
277	>	return (parent == null) ? state : reconcileState();
278	>	}
279	>
280	>	/**
281	>	* Recursively resolves state.
282	>	*/
283	>	private long reconcileState() {
284	>	Phaser p = parent;
285	>	long s = state;
286	>	if (p != null) {
287	>	while (unarrivedOf(s) == 0 && phaseOf(s) != phaseOf(root.state)) {
288	>	long parentState = p.getReconciledState();
289	>	int parentPhase = phaseOf(parentState);
290	>	int phase = phaseOf(s = state);
291	>	if (phase != parentPhase) {
292	>	long next = trippedStateFor(parentPhase, partiesOf(s));
293	>	if (casState(s, next)) {
294	>	releaseWaiters(phase);
295	>	s = next;
296	>	}
297	>	}
298	>	}
299	>	}
300	>	return s;
301		}
302
303		/**
304		* Creates a new Phaser without any initially registered parties,
305	<	* and initial phase number 0.
305	>	* initial phase number 0, and no parent. Any thread using this
306	>	* Phaser will need to first register for it.
307		*/
308		public Phaser() {
309	<	state = new AtomicLong(stateFor(0, 0, 0));
309	>	this(null);
310		}
311
312		/**
313		* Creates a new Phaser with the given numbers of registered
314	<	* unarrived parties and initial phase number 0.
315	<	* @param parties the number of parties required to trip barrier.
314	>	* unarrived parties, initial phase number 0, and no parent.
315	>	*
316	>	* @param parties the number of parties required to trip barrier
317		* @throws IllegalArgumentException if parties less than zero
318	<	* or greater than the maximum number of parties supported.
318	>	* or greater than the maximum number of parties supported
319		*/
320		public Phaser(int parties) {
321	+	this(null, parties);
322	+	}
323	+
324	+	/**
325	+	* Creates a new Phaser with the given parent, without any
326	+	* initially registered parties. If parent is non-null this phaser
327	+	* is registered with the parent and its initial phase number is
328	+	* the same as that of parent phaser.
329	+	*
330	+	* @param parent the parent phaser
331	+	*/
332	+	public Phaser(Phaser parent) {
333	+	int phase = 0;
334	+	this.parent = parent;
335	+	if (parent != null) {
336	+	this.root = parent.root;
337	+	phase = parent.register();
338	+	}
339	+	else
340	+	this.root = this;
341	+	this.state = trippedStateFor(phase, 0);
342	+	}
343	+
344	+	/**
345	+	* Creates a new Phaser with the given parent and numbers of
346	+	* registered unarrived parties. If parent is non-null, this phaser
347	+	* is registered with the parent and its initial phase number is
348	+	* the same as that of parent phaser.
349	+	*
350	+	* @param parent the parent phaser
351	+	* @param parties the number of parties required to trip barrier
352	+	* @throws IllegalArgumentException if parties less than zero
353	+	* or greater than the maximum number of parties supported
354	+	*/
355	+	public Phaser(Phaser parent, int parties) {
356		if (parties < 0 || parties > ushortMask)
357		throw new IllegalArgumentException("Illegal number of parties");
358	<	state = new AtomicLong(stateFor(0, parties, parties));
358	>	int phase = 0;
359	>	this.parent = parent;
360	>	if (parent != null) {
361	>	this.root = parent.root;
362	>	phase = parent.register();
363	>	}
364	>	else
365	>	this.root = this;
366	>	this.state = trippedStateFor(phase, parties);
367		}
368
369		/**
370		* Adds a new unarrived party to this phaser.
371	+	*
372	+	* @return the current barrier phase number upon registration
373	+	* @throws IllegalStateException if attempting to register more
374	+	* than the maximum supported number of parties
375	+	*/
376	+	public int register() {
377	+	return doRegister(1);
378	+	}
379	+
380	+	/**
381	+	* Adds the given number of new unarrived parties to this phaser.
382	+	*
383	+	* @param parties the number of parties required to trip barrier
384		* @return the current barrier phase number upon registration
385		* @throws IllegalStateException if attempting to register more
386	<	* than the maximum supported number of parties.
386	>	* than the maximum supported number of parties
387		*/
388	<	public int register() { // increment both parties and unarrived
389	<	final AtomicLong state = this.state;
388	>	public int bulkRegister(int parties) {
389	>	if (parties < 0)
390	>	throw new IllegalArgumentException();
391	>	if (parties == 0)
392	>	return getPhase();
393	>	return doRegister(parties);
394	>	}
395	>
396	>	/**
397	>	* Shared code for register, bulkRegister
398	>	*/
399	>	private int doRegister(int registrations) {
400	>	int phase;
401		for (;;) {
402	<	long s = state.get();
403	<	int phase = phaseOf(s);
404	<	int parties = partiesOf(s) + 1;
405	<	int unarrived = unarrivedOf(s) + 1;
402	>	long s = getReconciledState();
403	>	phase = phaseOf(s);
404	>	int unarrived = unarrivedOf(s) + registrations;
405	>	int parties = partiesOf(s) + registrations;
406	>	if (phase < 0)
407	>	break;
408		if (parties > ushortMask || unarrived > ushortMask)
409	<	throw badBounds(parties, unarrived);
410	<	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
411	<	return phase;
409	>	throw new IllegalStateException(badBounds(parties, unarrived));
410	>	if (phase == phaseOf(root.state) &&
411	>	casState(s, stateFor(phase, parties, unarrived)))
412	>	break;
413		}
414	+	return phase;
415		}
416
417		/**
418		* Arrives at the barrier, but does not wait for others.  (You can
419		* in turn wait for others via {@link #awaitAdvance}).
420		*
421	<	* @return the current barrier phase number upon entry to
422	<	* this method, or a negative value if terminated;
423	<	* @throws IllegalStateException if the number of unarrived
424	<	* parties would become negative.
421	>	* @return the barrier phase number upon entry to this method, or a
422	>	* negative value if terminated
423	>	* @throws IllegalStateException if not terminated and the number
424	>	* of unarrived parties would become negative
425		*/
426	<	public int arrive() { // decrement unarrived. If zero, trip
427	<	final AtomicLong state = this.state;
426	>	public int arrive() {
427	>	int phase;
428		for (;;) {
429	<	long s = state.get();
430	<	int phase = phaseOf(s);
429	>	long s = state;
430	>	phase = phaseOf(s);
431	>	if (phase < 0)
432	>	break;
433		int parties = partiesOf(s);
434		int unarrived = unarrivedOf(s) - 1;
435	<	if (unarrived < 0)
436	<	throw badBounds(parties, unarrived);
437	<	if (unarrived == 0 && phase >= 0) {
236	<	trip(phase, parties);
237	<	return phase;
435	>	if (unarrived > 0) {        // Not the last arrival
436	>	if (casState(s, s - 1)) // s-1 adds one arrival
437	>	break;
438		}
439	<	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
440	<	return phase;
439	>	else if (unarrived == 0) {  // the last arrival
440	>	Phaser par = parent;
441	>	if (par == null) {      // directly trip
442	>	if (casState
443	>	(s,
444	>	trippedStateFor(onAdvance(phase, parties) ? -1 :
445	>	((phase + 1) & phaseMask), parties))) {
446	>	releaseWaiters(phase);
447	>	break;
448	>	}
449	>	}
450	>	else {                  // cascade to parent
451	>	if (casState(s, s - 1)) { // zeroes unarrived
452	>	par.arrive();
453	>	reconcileState();
454	>	break;
455	>	}
456	>	}
457	>	}
458	>	else if (phase != phaseOf(root.state)) // or if unreconciled
459	>	reconcileState();
460	>	else
461	>	throw new IllegalStateException(badBounds(parties, unarrived));
462		}
463	+	return phase;
464		}
465
466		/**
467		* Arrives at the barrier, and deregisters from it, without
468	<	* waiting for others.
468	>	* waiting for others. Deregistration reduces number of parties
469	>	* required to trip the barrier in future phases.  If this phaser
470	>	* has a parent, and deregistration causes this phaser to have
471	>	* zero parties, this phaser is also deregistered from its parent.
472		*
473		* @return the current barrier phase number upon entry to
474	<	* this method, or a negative value if terminated;
475	<	* @throws IllegalStateException if the number of registered or
476	<	* unarrived parties would become negative.
477	<	*/
478	<	public int arriveAndDeregister() { // Same as arrive, plus decrement parties
479	<	final AtomicLong state = this.state;
474	>	* this method, or a negative value if terminated
475	>	* @throws IllegalStateException if not terminated and the number
476	>	* of registered or unarrived parties would become negative
477	>	*/
478	>	public int arriveAndDeregister() {
479	>	// similar code to arrive, but too different to merge
480	>	Phaser par = parent;
481	>	int phase;
482		for (;;) {
483	<	long s = state.get();
484	<	int phase = phaseOf(s);
483	>	long s = state;
484	>	phase = phaseOf(s);
485	>	if (phase < 0)
486	>	break;
487		int parties = partiesOf(s) - 1;
488		int unarrived = unarrivedOf(s) - 1;
489	<	if (parties < 0 || unarrived < 0)
490	<	throw badBounds(parties, unarrived);
491	<	if (unarrived == 0 && phase >= 0) {
492	<	trip(phase, parties);
493	<	return phase;
489	>	if (parties >= 0) {
490	>	if (unarrived > 0 || (unarrived == 0 && par != null)) {
491	>	if (casState
492	>	(s,
493	>	stateFor(phase, parties, unarrived))) {
494	>	if (unarrived == 0) {
495	>	par.arriveAndDeregister();
496	>	reconcileState();
497	>	}
498	>	break;
499	>	}
500	>	continue;
501	>	}
502	>	if (unarrived == 0) {
503	>	if (casState
504	>	(s,
505	>	trippedStateFor(onAdvance(phase, parties) ? -1 :
506	>	((phase + 1) & phaseMask), parties))) {
507	>	releaseWaiters(phase);
508	>	break;
509	>	}
510	>	continue;
511	>	}
512	>	if (par != null && phase != phaseOf(root.state)) {
513	>	reconcileState();
514	>	continue;
515	>	}
516		}
517	<	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
267	<	return phase;
517	>	throw new IllegalStateException(badBounds(parties, unarrived));
518		}
519	+	return phase;
520		}
521
522		/**
523	<	* Arrives at the barrier and awaits others. Unlike other arrival
524	<	* methods, this method returns the arrival index of the
525	<	* caller. The caller tripping the barrier returns zero, the
526	<	* previous caller 1, and so on.
527	<	* @return the arrival index
528	<	* @throws IllegalStateException if the number of unarrived
529	<	* parties would become negative.
523	>	* Arrives at the barrier and awaits others. Equivalent in effect
524	>	* to {@code awaitAdvance(arrive())}.  If you instead need to
525	>	* await with interruption of timeout, and/or deregister upon
526	>	* arrival, you can arrange them using analogous constructions.
527	>	*
528	>	* @return the phase on entry to this method
529	>	* @throws IllegalStateException if not terminated and the number
530	>	* of unarrived parties would become negative
531		*/
532		public int arriveAndAwaitAdvance() {
533	<	final AtomicLong state = this.state;
282	<	for (;;) {
283	<	long s = state.get();
284	<	int phase = phaseOf(s);
285	<	int parties = partiesOf(s);
286	<	int unarrived = unarrivedOf(s) - 1;
287	<	if (unarrived < 0)
288	<	throw badBounds(parties, unarrived);
289	<	if (unarrived == 0 && phase >= 0) {
290	<	trip(phase, parties);
291	<	return 0;
292	<	}
293	<	if (state.compareAndSet(s, stateFor(phase, parties, unarrived))) {
294	<	awaitAdvance(phase);
295	<	return unarrived;
296	<	}
297	<	}
533	>	return awaitAdvance(arrive());
534		}
535
536		/**
537		* Awaits the phase of the barrier to advance from the given
538	<	* value, or returns immediately if this barrier is terminated
538	>	* value, or returns immediately if argument is negative or this
539	>	* barrier is terminated.
540	>	*
541		* @param phase the phase on entry to this method
542		* @return the phase on exit from this method
543		*/
544		public int awaitAdvance(int phase) {
545		if (phase < 0)
546		return phase;
547	<	Thread current = Thread.currentThread();
548	<	if (current instanceof ForkJoinWorkerThread)
549	<	return helpingWait(phase);
550	<	if (untimedWait(current, phase, false))
551	<	current.interrupt();
552	<	return phaseOf(state.get());
547	>	long s = getReconciledState();
548	>	int p = phaseOf(s);
549	>	if (p != phase)
550	>	return p;
551	>	if (unarrivedOf(s) == 0 && parent != null)
552	>	parent.awaitAdvance(phase);
553	>	// Fall here even if parent waited, to reconcile and help release
554	>	return untimedWait(phase);
555		}
556
557		/**
558		* Awaits the phase of the barrier to advance from the given
559	<	* value, or returns immediately if this barrier is terminated, or
560	<	* throws InterruptedException if interrupted while waiting.
559	>	* value, or returns immediately if argument is negative or this
560	>	* barrier is terminated, or throws InterruptedException if
561	>	* interrupted while waiting.
562	>	*
563		* @param phase the phase on entry to this method
564		* @return the phase on exit from this method
565		* @throws InterruptedException if thread interrupted while waiting
566		*/
567	<	public int awaitAdvanceInterruptibly(int phase) throws InterruptedException {
567	>	public int awaitAdvanceInterruptibly(int phase)
568	>	throws InterruptedException {
569		if (phase < 0)
570		return phase;
571	<	Thread current = Thread.currentThread();
572	<	if (current instanceof ForkJoinWorkerThread)
573	<	return helpingWait(phase);
574	<	else if (Thread.interrupted() || untimedWait(current, phase, true))
575	<	throw new InterruptedException();
576	<	else
577	<	return phaseOf(state.get());
571	>	long s = getReconciledState();
572	>	int p = phaseOf(s);
573	>	if (p != phase)
574	>	return p;
575	>	if (unarrivedOf(s) == 0 && parent != null)
576	>	parent.awaitAdvanceInterruptibly(phase);
577	>	return interruptibleWait(phase);
578		}
579
580		/**
581		* Awaits the phase of the barrier to advance from the given value
582	<	* or the given timeout elapses, or returns immediately if this
583	<	* barrier is terminated
582	>	* or the given timeout elapses, or returns immediately if
583	>	* argument is negative or this barrier is terminated.
584	>	*
585		* @param phase the phase on entry to this method
586		* @return the phase on exit from this method
587		* @throws InterruptedException if thread interrupted while waiting
588		* @throws TimeoutException if timed out while waiting
589		*/
590	<	public int awaitAdvanceInterruptibly(int phase, long timeout, TimeUnit unit)
590	>	public int awaitAdvanceInterruptibly(int phase,
591	>	long timeout, TimeUnit unit)
592		throws InterruptedException, TimeoutException {
593		if (phase < 0)
594		return phase;
595	<	long nanos = unit.toNanos(timeout);
596	<	Thread current = Thread.currentThread();
597	<	if (current instanceof ForkJoinWorkerThread)
598	<	return timedHelpingWait(phase, nanos);
599	<	timedWait(current, phase, nanos);
600	<	return phaseOf(state.get());
595	>	long s = getReconciledState();
596	>	int p = phaseOf(s);
597	>	if (p != phase)
598	>	return p;
599	>	if (unarrivedOf(s) == 0 && parent != null)
600	>	parent.awaitAdvanceInterruptibly(phase, timeout, unit);
601	>	return timedWait(phase, unit.toNanos(timeout));
602		}
603
604		/**
605		* Forces this barrier to enter termination state. Counts of
606	<	* arrived and registered parties are unaffected. This method may
607	<	* be useful for coordinating recovery after one or more tasks
608	<	* encounter unexpected exceptions.
606	>	* arrived and registered parties are unaffected. If this phaser
607	>	* has a parent, it too is terminated. This method may be useful
608	>	* for coordinating recovery after one or more tasks encounter
609	>	* unexpected exceptions.
610		*/
611		public void forceTermination() {
365	–	final AtomicLong state = this.state;
612		for (;;) {
613	<	long s = state.get();
613	>	long s = getReconciledState();
614		int phase = phaseOf(s);
615		int parties = partiesOf(s);
616		int unarrived = unarrivedOf(s);
617		if (phase < 0 ||
618	<	state.compareAndSet(s, stateFor(-1, parties, unarrived))) {
619	<	if (head.get() != null)
620	<	releaseWaiters(-1);
618	>	casState(s, stateFor(-1, parties, unarrived))) {
619	>	releaseWaiters(0);
620	>	releaseWaiters(1);
621	>	if (parent != null)
622	>	parent.forceTermination();
623		return;
624		}
625		}
626		}
627
628		/**
629	<	* Resets the barrier with the given numbers of registered unarrived
630	<	* parties and phase number 0. This method allows repeated reuse
631	<	* of this barrier, but only if it is somehow known not to be in
632	<	* use for other purposes.
633	<	* @param parties the number of parties required to trip barrier.
386	<	* @throws IllegalArgumentException if parties less than zero
387	<	* or greater than the maximum number of parties supported.
629	>	* Returns the current phase number. The maximum phase number is
630	>	* {@code Integer.MAX_VALUE}, after which it restarts at
631	>	* zero. Upon termination, the phase number is negative.
632	>	*
633	>	* @return the phase number, or a negative value if terminated
634		*/
635	<	public void reset(int parties) {
636	<	if (parties < 0 || parties > ushortMask)
391	<	throw new IllegalArgumentException("Illegal number of parties");
392	<	state.set(stateFor(0, parties, parties));
393	<	if (head.get() != null)
394	<	releaseWaiters(0);
635	>	public final int getPhase() {
636	>	return phaseOf(getReconciledState());
637		}
638
639		/**
640	<	* Returns the current phase number. The maximum phase number is
641	<	* <tt>Integer.MAX_VALUE</tt>, after which it restarts at
642	<	* zero. Upon termination, the phase number is negative.
643	<	* @return the phase number, or a negative value if terminated
640	>	* Returns {@code true} if the current phase number equals the given phase.
641	>	*
642	>	* @param phase the phase
643	>	* @return {@code true} if the current phase number equals the given phase
644		*/
645	<	public int getPhase() {
646	<	return phaseOf(state.get());
645	>	public final boolean hasPhase(int phase) {
646	>	return phaseOf(getReconciledState()) == phase;
647		}
648
649		/**
650		* Returns the number of parties registered at this barrier.
651	+	*
652		* @return the number of parties
653		*/
654		public int getRegisteredParties() {
655	<	return partiesOf(state.get());
655	>	return partiesOf(state);
656		}
657
658		/**
659		* Returns the number of parties that have arrived at the current
660		* phase of this barrier.
661	+	*
662		* @return the number of arrived parties
663		*/
664		public int getArrivedParties() {
665	<	return arrivedOf(state.get());
665	>	return arrivedOf(state);
666		}
667
668		/**
669		* Returns the number of registered parties that have not yet
670		* arrived at the current phase of this barrier.
671	+	*
672		* @return the number of unarrived parties
673		*/
674		public int getUnarrivedParties() {
675	<	return unarrivedOf(state.get());
675	>	return unarrivedOf(state);
676		}
677
678		/**
679	<	* Returns true if this barrier has been terminated
680	<	* @return true if this barrier has been terminated
679	>	* Returns the parent of this phaser, or null if none.
680	>	*
681	>	* @return the parent of this phaser, or null if none
682	>	*/
683	>	public Phaser getParent() {
684	>	return parent;
685	>	}
686	>
687	>	/**
688	>	* Returns the root ancestor of this phaser, which is the same as
689	>	* this phaser if it has no parent.
690	>	*
691	>	* @return the root ancestor of this phaser
692	>	*/
693	>	public Phaser getRoot() {
694	>	return root;
695	>	}
696	>
697	>	/**
698	>	* Returns {@code true} if this barrier has been terminated.
699	>	*
700	>	* @return {@code true} if this barrier has been terminated
701		*/
702		public boolean isTerminated() {
703	<	return phaseOf(state.get()) < 0;
703	>	return getPhase() < 0;
704		}
705
706		/**
#	Line 444 | Line 709 | public class Phaser {
709		* barrier is tripped (and thus all other waiting parties are
710		* dormant). If it returns true, then, rather than advance the
711		* phase number, this barrier will be set to a final termination
712	<	* state, and subsequent calls to <tt>isTerminated</tt> will
712	>	* state, and subsequent calls to {@code isTerminated} will
713		* return true.
714	<	*
714	>	*
715		* <p> The default version returns true when the number of
716		* registered parties is zero. Normally, overrides that arrange
717		* termination for other reasons should also preserve this
718		* property.
719		*
720	+	* <p> You may override this method to perform an action with side
721	+	* effects visible to participating tasks, but it is in general
722	+	* only sensible to do so in designs where all parties register
723	+	* before any arrive, and all {@code awaitAdvance} at each phase.
724	+	* Otherwise, you cannot ensure lack of interference. In
725	+	* particular, this method may be invoked more than once per
726	+	* transition if other parties successfully register while the
727	+	* invocation of this method is in progress, thus postponing the
728	+	* transition until those parties also arrive, re-triggering this
729	+	* method.
730	+	*
731		* @param phase the phase number on entering the barrier
732	<	* @param registeredParties the current number of registered
733	<	* parties.
458	<	* @return true if this barrier should terminate
732	>	* @param registeredParties the current number of registered parties
733	>	* @return {@code true} if this barrier should terminate
734		*/
735		protected boolean onAdvance(int phase, int registeredParties) {
736		return registeredParties <= 0;
737		}
738
739		/**
740	<	* Returns a string identifying this barrier, as well as its
740	>	* Returns a string identifying this phaser, as well as its
741		* state.  The state, in brackets, includes the String {@code
742	<	* "phase ="} followed by the phase number, {@code "parties ="}
742	>	* "phase = "} followed by the phase number, {@code "parties = "}
743		* followed by the number of registered parties, and {@code
744	<	* "arrived ="} followed by the number of arrived parties
744	>	* "arrived = "} followed by the number of arrived parties.
745		*
746		* @return a string identifying this barrier, as well as its state
747		*/
748		public String toString() {
749	<	long s = state.get();
750	<	return super.toString() + "[phase = " + phaseOf(s) + " parties = " + partiesOf(s) + " arrived = " + arrivedOf(s) + "]";
749	>	long s = getReconciledState();
750	>	return super.toString() +
751	>	"[phase = " + phaseOf(s) +
752	>	" parties = " + partiesOf(s) +
753	>	" arrived = " + arrivedOf(s) + "]";
754		}
755
756	<	// methods for tripping and waiting
756	>	// methods for waiting
757
758		/**
759	<	* Advance the current phase (or terminate)
759	>	* Wait nodes for Treiber stack representing wait queue
760		*/
761	<	private void trip(int phase, int parties) {
762	<	int next = onAdvance(phase, parties)? -1 : ((phase + 1) & phaseMask);
763	<	state.set(stateFor(next, parties, parties));
764	<	if (head.get() != null)
765	<	releaseWaiters(next);
766	<	}
767	<
768	<	private int helpingWait(int phase) {
769	<	final AtomicLong state = this.state;
770	<	int p;
771	<	while ((p = phaseOf(state.get())) == phase) {
772	<	ForkJoinTask<?> t = ForkJoinWorkerThread.pollTask();
773	<	if (t != null) {
774	<	if ((p = phaseOf(state.get())) == phase)
775	<	t.exec();
776	<	else {   // push task and exit if barrier advanced
777	<	t.fork();
778	<	break;
779	<	}
761	>	static final class QNode implements ForkJoinPool.ManagedBlocker {
762	>	final Phaser phaser;
763	>	final int phase;
764	>	final long startTime;
765	>	final long nanos;
766	>	final boolean timed;
767	>	final boolean interruptible;
768	>	volatile boolean wasInterrupted = false;
769	>	volatile Thread thread; // nulled to cancel wait
770	>	QNode next;
771	>	QNode(Phaser phaser, int phase, boolean interruptible,
772	>	boolean timed, long startTime, long nanos) {
773	>	this.phaser = phaser;
774	>	this.phase = phase;
775	>	this.timed = timed;
776	>	this.interruptible = interruptible;
777	>	this.startTime = startTime;
778	>	this.nanos = nanos;
779	>	thread = Thread.currentThread();
780	>	}
781	>	public boolean isReleasable() {
782	>	return (thread == null ||
783	>	phaser.getPhase() != phase ||
784	>	(interruptible && wasInterrupted) ||
785	>	(timed && (nanos - (System.nanoTime() - startTime)) <= 0));
786	>	}
787	>	public boolean block() {
788	>	if (Thread.interrupted()) {
789	>	wasInterrupted = true;
790	>	if (interruptible)
791	>	return true;
792	>	}
793	>	if (!timed)
794	>	LockSupport.park(this);
795	>	else {
796	>	long waitTime = nanos - (System.nanoTime() - startTime);
797	>	if (waitTime <= 0)
798	>	return true;
799	>	LockSupport.parkNanos(this, waitTime);
800		}
801	+	return isReleasable();
802		}
803	<	return p;
804	<	}
506	<
507	<	private int timedHelpingWait(int phase, long nanos) throws TimeoutException {
508	<	final AtomicLong state = this.state;
509	<	long lastTime = System.nanoTime();
510	<	int p;
511	<	while ((p = phaseOf(state.get())) == phase) {
512	<	long now = System.nanoTime();
513	<	nanos -= now - lastTime;
514	<	lastTime = now;
515	<	if (nanos <= 0) {
516	<	if ((p = phaseOf(state.get())) == phase)
517	<	throw new TimeoutException();
518	<	else
519	<	break;
520	<	}
521	<	ForkJoinTask<?> t = ForkJoinWorkerThread.pollTask();
803	>	void signal() {
804	>	Thread t = thread;
805		if (t != null) {
806	<	if ((p = phaseOf(state.get())) == phase)
807	<	t.exec();
808	<	else {   // push task and exit if barrier advanced
809	<	t.fork();
810	<	break;
806	>	thread = null;
807	>	LockSupport.unpark(t);
808	>	}
809	>	}
810	>	boolean doWait() {
811	>	if (thread != null) {
812	>	try {
813	>	ForkJoinPool.managedBlock(this, false);
814	>	} catch (InterruptedException ie) {
815		}
816		}
817	+	return wasInterrupted;
818		}
819	<	return p;
819	>
820		}
821
822		/**
823	<	* Wait nodes for Treiber stack representing wait queue for non-FJ
536	<	* tasks. The waiting scheme is an adaptation of the one used in
537	<	* forkjoin.PoolBarrier.
823	>	* Removes and signals waiting threads from wait queue.
824		*/
825	<	static final class QNode {
826	<	QNode next;
827	<	volatile Thread thread; // nulled to cancel wait
828	<	final int phase;
829	<	QNode(Thread t, int c) {
830	<	thread = t;
545	<	phase = c;
825	>	private void releaseWaiters(int phase) {
826	>	AtomicReference<QNode> head = queueFor(phase);
827	>	QNode q;
828	>	while ((q = head.get()) != null) {
829	>	if (head.compareAndSet(q, q.next))
830	>	q.signal();
831		}
832		}
833
549	–	private void releaseWaiters(int currentPhase) {
550	–	final AtomicReference<QNode> head = this.head;
551	–	QNode p;
552	–	while ((p = head.get()) != null && p.phase != currentPhase) {
553	–	if (head.compareAndSet(p, null)) {
554	–	do {
555	–	Thread t = p.thread;
556	–	if (t != null) {
557	–	p.thread = null;
558	–	LockSupport.unpark(t);
559	–	}
560	–	} while ((p = p.next) != null);
561	–	}
562	–	}
563	–	}
564	–
565	–	/** The number of CPUs, for spin control */
566	–	static final int NCPUS = Runtime.getRuntime().availableProcessors();
567	–
568	–	/**
569	–	* The number of times to spin before blocking in timed waits.
570	–	* The value is empirically derived
571	–	*/
572	–	static final int maxTimedSpins = (NCPUS < 2)? 0 : 32;
573	–
834		/**
835	<	* The number of times to spin before blocking in untimed waits.
836	<	* This is greater than timed value because untimed waits spin
837	<	* faster since they don't need to check times on each spin.
835	>	* Tries to enqueue given node in the appropriate wait queue.
836	>	*
837	>	* @return true if successful
838		*/
839	<	static final int maxUntimedSpins = maxTimedSpins * 32;
839	>	private boolean tryEnqueue(QNode node) {
840	>	AtomicReference<QNode> head = queueFor(node.phase);
841	>	return head.compareAndSet(node.next = head.get(), node);
842	>	}
843
844		/**
845	<	* The number of nanoseconds for which it is faster to spin
846	<	* rather than to use timed park. A rough estimate suffices.
845	>	* Enqueues node and waits unless aborted or signalled.
846	>	*
847	>	* @return current phase
848		*/
849	<	static final long spinForTimeoutThreshold = 1000L;
849	>	private int untimedWait(int phase) {
850	>	QNode node = null;
851	>	boolean queued = false;
852	>	boolean interrupted = false;
853	>	int p;
854	>	while ((p = getPhase()) == phase) {
855	>	if (Thread.interrupted())
856	>	interrupted = true;
857	>	else if (node == null)
858	>	node = new QNode(this, phase, false, false, 0, 0);
859	>	else if (!queued)
860	>	queued = tryEnqueue(node);
861	>	else
862	>	interrupted = node.doWait();
863	>	}
864	>	if (node != null)
865	>	node.thread = null;
866	>	releaseWaiters(phase);
867	>	if (interrupted)
868	>	Thread.currentThread().interrupt();
869	>	return p;
870	>	}
871
872		/**
873	<	* Enqueues node and waits unless aborted or signalled.
873	>	* Interruptible version
874	>	* @return current phase
875		*/
876	<	private boolean untimedWait(Thread thread, int currentPhase,
591	<	boolean abortOnInterrupt) {
592	<	final AtomicReference<QNode> head = this.head;
593	<	final AtomicLong state = this.state;
594	<	boolean wasInterrupted = false;
876	>	private int interruptibleWait(int phase) throws InterruptedException {
877		QNode node = null;
878		boolean queued = false;
879	<	int spins = maxUntimedSpins;
880	<	while (phaseOf(state.get()) == currentPhase) {
881	<	QNode h;
882	<	if (node != null && queued) {
883	<	if (node.thread != null) {
884	<	LockSupport.park();
885	<	if (Thread.interrupted()) {
886	<	wasInterrupted = true;
887	<	if (abortOnInterrupt)
606	<	break;
607	<	}
608	<	}
609	<	}
610	<	else if ((h = head.get()) != null && h.phase != currentPhase) {
611	<	if (phaseOf(state.get()) == currentPhase) { // must recheck
612	<	if (head.compareAndSet(h, h.next)) {
613	<	Thread t = h.thread; // help clear out old waiters
614	<	if (t != null) {
615	<	h.thread = null;
616	<	LockSupport.unpark(t);
617	<	}
618	<	}
619	<	}
620	<	else
621	<	break;
622	<	}
623	<	else if (node != null)
624	<	queued = head.compareAndSet(node.next = h, node);
625	<	else if (spins <= 0)
626	<	node = new QNode(thread, currentPhase);
879	>	boolean interrupted = false;
880	>	int p;
881	>	while ((p = getPhase()) == phase && !interrupted) {
882	>	if (Thread.interrupted())
883	>	interrupted = true;
884	>	else if (node == null)
885	>	node = new QNode(this, phase, true, false, 0, 0);
886	>	else if (!queued)
887	>	queued = tryEnqueue(node);
888		else
889	<	--spins;
889	>	interrupted = node.doWait();
890		}
891		if (node != null)
892		node.thread = null;
893	<	return wasInterrupted;
893	>	if (p != phase || (p = getPhase()) != phase)
894	>	releaseWaiters(phase);
895	>	if (interrupted)
896	>	throw new InterruptedException();
897	>	return p;
898		}
899
900		/**
901	<	* Messier timeout version
901	>	* Timeout version.
902	>	* @return current phase
903		*/
904	<	private void timedWait(Thread thread, int currentPhase, long nanos)
904	>	private int timedWait(int phase, long nanos)
905		throws InterruptedException, TimeoutException {
906	<	final AtomicReference<QNode> head = this.head;
641	<	final AtomicLong state = this.state;
642	<	long lastTime = System.nanoTime();
906	>	long startTime = System.nanoTime();
907		QNode node = null;
908		boolean queued = false;
909	<	int spins = maxTimedSpins;
910	<	while (phaseOf(state.get()) == currentPhase) {
911	<	QNode h;
912	<	long now = System.nanoTime();
913	<	nanos -= now - lastTime;
914	<	lastTime = now;
915	<	if (nanos <= 0) {
916	<	if (node != null)
917	<	node.thread = null;
918	<	if (phaseOf(state.get()) == currentPhase)
919	<	throw new TimeoutException();
656	<	else
657	<	break;
658	<	}
659	<	else if (node != null && queued) {
660	<	if (node.thread != null &&
661	<	nanos > spinForTimeoutThreshold) {
662	<	//                LockSupport.parkNanos(this, nanos);
663	<	LockSupport.parkNanos(nanos);
664	<	if (Thread.interrupted()) {
665	<	node.thread = null;
666	<	throw new InterruptedException();
667	<	}
668	<	}
669	<	}
670	<	else if ((h = head.get()) != null && h.phase != currentPhase) {
671	<	if (phaseOf(state.get()) == currentPhase) { // must recheck
672	<	if (head.compareAndSet(h, h.next)) {
673	<	Thread t = h.thread; // help clear out old waiters
674	<	if (t != null) {
675	<	h.thread = null;
676	<	LockSupport.unpark(t);
677	<	}
678	<	}
679	<	}
680	<	else
681	<	break;
682	<	}
683	<	else if (node != null)
684	<	queued = head.compareAndSet(node.next = h, node);
685	<	else if (spins <= 0)
686	<	node = new QNode(thread, currentPhase);
909	>	boolean interrupted = false;
910	>	int p;
911	>	while ((p = getPhase()) == phase && !interrupted) {
912	>	if (Thread.interrupted())
913	>	interrupted = true;
914	>	else if (nanos - (System.nanoTime() - startTime) <= 0)
915	>	break;
916	>	else if (node == null)
917	>	node = new QNode(this, phase, true, true, startTime, nanos);
918	>	else if (!queued)
919	>	queued = tryEnqueue(node);
920		else
921	<	--spins;
921	>	interrupted = node.doWait();
922		}
923		if (node != null)
924		node.thread = null;
925	+	if (p != phase || (p = getPhase()) != phase)
926	+	releaseWaiters(phase);
927	+	if (interrupted)
928	+	throw new InterruptedException();
929	+	if (p == phase)
930	+	throw new TimeoutException();
931	+	return p;
932		}
933
934	<	}
934	>	// Temporary Unsafe mechanics for preliminary release
935	>	private static Unsafe getUnsafe() throws Throwable {
936	>	try {
937	>	return Unsafe.getUnsafe();
938	>	} catch (SecurityException se) {
939	>	try {
940	>	return java.security.AccessController.doPrivileged
941	>	(new java.security.PrivilegedExceptionAction<Unsafe>() {
942	>	public Unsafe run() throws Exception {
943	>	return getUnsafePrivileged();
944	>	}});
945	>	} catch (java.security.PrivilegedActionException e) {
946	>	throw e.getCause();
947	>	}
948	>	}
949	>	}
950	>
951	>	private static Unsafe getUnsafePrivileged()
952	>	throws NoSuchFieldException, IllegalAccessException {
953	>	Field f = Unsafe.class.getDeclaredField("theUnsafe");
954	>	f.setAccessible(true);
955	>	return (Unsafe) f.get(null);
956	>	}
957	>
958	>	private static long fieldOffset(String fieldName)
959	>	throws NoSuchFieldException {
960	>	return UNSAFE.objectFieldOffset
961	>	(Phaser.class.getDeclaredField(fieldName));
962	>	}
963
964	+	static final Unsafe UNSAFE;
965	+	static final long stateOffset;
966	+
967	+	static {
968	+	try {
969	+	UNSAFE = getUnsafe();
970	+	stateOffset = fieldOffset("state");
971	+	} catch (Throwable e) {
972	+	throw new RuntimeException("Could not initialize intrinsics", e);
973	+	}
974	+	}
975	+
976	+	final boolean casState(long cmp, long val) {
977	+	return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val);
978	+	}
979	+	}

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