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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 1.29 by jsr166, Wed Aug 12 04:02:45 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.*;
10	>
11	>	import java.util.concurrent.atomic.AtomicReference;
12		import java.util.concurrent.locks.LockSupport;
13
14		/**
15		* A reusable synchronization barrier, similar in functionality to a
16	<	* {@link java.util.concurrent.CyclicBarrier}, but supporting more
17	<	* flexible usage.
16	>	* {@link java.util.concurrent.CyclicBarrier CyclicBarrier} and
17	>	* {@link java.util.concurrent.CountDownLatch CountDownLatch}
18	>	* but supporting more flexible usage.
19		*
20		* <ul>
21		*
22	<	* <li> The number of parties synchronizing on the barrier may vary
23	<	* over time.  A task may register to be a party in a barrier at any
24	<	* time, and may deregister upon arriving at the barrier.  As is the
25	<	* case with most basic synchronization constructs, registration
26	<	* and deregistration affect only internal counts; they do not
27	<	* establish any further internal bookkeeping, so tasks cannot query
28	<	* whether they are registered.
22	>	* <li> The number of parties synchronizing on a phaser may vary over
23	>	* time.  A task may register to be a party at any time, and may
24	>	* deregister upon arriving at the barrier.  As is the case with most
25	>	* basic synchronization constructs, registration and deregistration
26	>	* affect only internal counts; they do not establish any further
27	>	* internal bookkeeping, so tasks cannot query whether they are
28	>	* registered. (However, you can introduce such bookkeeping by
29	>	* subclassing this class.)
30		*
31		* <li> Each generation has an associated phase value, starting at
32		* zero, and advancing when all parties reach the barrier (wrapping
33	<	* around to zero after reaching <tt>Integer.MAX_VALUE</tt>).
34	<	*
35	<	* <li> Like a CyclicBarrier, a Phaser may be repeatedly awaited.
36	<	* Method <tt>arriveAndAwaitAdvance</tt> has effect analogous to
37	<	* <tt>CyclicBarrier.await</tt>.  However, Phasers separate two
38	<	* aspects of coordination, that may be invoked independently:
33	>	* around to zero after reaching {@code Integer.MAX_VALUE}).
34	>	*
35	>	* <li> Like a {@code CyclicBarrier}, a phaser may be repeatedly
36	>	* awaited.  Method {@link #arriveAndAwaitAdvance} has effect
37	>	* analogous to {@link java.util.concurrent.CyclicBarrier#await
38	>	* CyclicBarrier.await}.  However, phasers separate two aspects of
39	>	* coordination, which 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 {@link #arrive} and
44	>	*       {@link #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 {@link #awaitAdvance} requires an
48		*       argument indicating the entry phase, and returns when the
49		*       barrier advances to a new phase.
50		* </ul>
51		*
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.
54	>	* advance, are arranged by overriding method {@link #onAdvance(int,
55	>	* int)}, which also controls termination. Overriding this method is
56	>	* similar to, but more flexible than, providing a barrier action to a
57	>	* {@code 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
64	<	* action with a fixed number of iterations, it is often convenient to
65	<	* override this method to cause termination when the current phase
66	<	* number reaches a threshold.  Method <tt>forceTermination</tt> is
67	<	* also available to assist recovery actions upon failure.
68	<	*
69	<	* <li> Unlike most synchronizers, a Phaser may also be used with
70	<	* ForkJoinTasks (as well as plain threads).
71	<	*
72	<	* <li> By default, <tt>awaitAdvance</tt> continues to wait even if
73	<	* the current thread is interrupted. And unlike the case in
74	<	* CyclicBarriers, exceptions encountered while tasks wait
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 when an invocation
63	>	* of {@code onAdvance} returns {@code true}.  When a phaser is
64	>	* controlling an action with a fixed number of iterations, it is
65	>	* often convenient to override this method to cause termination when
66	>	* the current phase number reaches a threshold. Method {@link
67	>	* #forceTermination} is also available to abruptly release waiting
68	>	* threads and allow them to terminate.
69	>	*
70	>	* <li> Phasers may be tiered to reduce contention. Phasers with large
71	>	* numbers of parties that would otherwise experience heavy
72	>	* synchronization contention costs may instead be arranged in trees.
73	>	* This will typically greatly increase throughput even though it
74	>	* incurs somewhat greater per-operation overhead.
75	>	*
76	>	* <li> By default, {@code awaitAdvance} continues to wait even if
77	>	* the waiting thread is interrupted. And unlike the case in
78	>	* {@code CyclicBarrier}, exceptions encountered while tasks wait
79		* interruptibly or with timeout do not change the state of the
80		* barrier. If necessary, you can perform any associated recovery
81	<	* within handlers of those exceptions.
81	>	* within handlers of those exceptions, often after invoking
82	>	* {@code forceTermination}.
83	>	*
84	>	* <li>Phasers may be used to coordinate tasks executing in a {@link
85	>	* ForkJoinPool}, which will ensure sufficient parallelism to execute
86	>	* tasks when others are blocked waiting for a phase to advance.
87		*
88		* </ul>
89		*
90	<	* <p><b>Sample usage:</b>
90	>	* <p><b>Sample usages:</b>
91		*
92	<	* <p>[todo: non-FJ example]
92	>	* <p>A {@code Phaser} may be used instead of a {@code CountDownLatch}
93	>	* to control a one-shot action serving a variable number of
94	>	* parties. The typical idiom is for the method setting this up to
95	>	* first register, then start the actions, then deregister, as in:
96	>	*
97	>	*  <pre> {@code
98	>	* void runTasks(List<Runnable> list) {
99	>	*   final Phaser phaser = new Phaser(1); // "1" to register self
100	>	*   // create and start threads
101	>	*   for (Runnable r : list) {
102	>	*     phaser.register();
103	>	*     new Thread() {
104	>	*       public void run() {
105	>	*         phaser.arriveAndAwaitAdvance(); // await all creation
106	>	*         r.run();
107	>	*       }
108	>	*     }.start();
109	>	*   }
110		*
111	<	* <p> A Phaser may be used to support a style of programming in
112	<	* which a task waits for others to complete, without otherwise
113	<	* needing to keep track of which tasks it is waiting for. This is
114	<	* similar to the "sync" construct in Cilk and "clocks" in X10.
115	<	* Special constructions based on such barriers are available using
116	<	* the <tt>LinkedAsyncAction</tt> and <tt>CyclicAction</tt> classes,
117	<	* but they can be useful in other contexts as well.  For a simple
118	<	* (but not very useful) example, here is a variant of Fibonacci:
119	<	*
120	<	* <pre>
121	<	* class BarrierFibonacci extends RecursiveAction {
122	<	*   int argument, result;
123	<	*   final Phaser parentBarrier;
124	<	*   BarrierFibonacci(int n, Phaser parentBarrier) {
125	<	*     this.argument = n;
126	<	*     this.parentBarrier = parentBarrier;
127	<	*     parentBarrier.register();
111	>	*   // allow threads to start and deregister self
112	>	*   phaser.arriveAndDeregister();
113	>	* }}</pre>
114	>	*
115	>	* <p>One way to cause a set of threads to repeatedly perform actions
116	>	* for a given number of iterations is to override {@code onAdvance}:
117	>	*
118	>	*  <pre> {@code
119	>	* void startTasks(List<Runnable> list, final int iterations) {
120	>	*   final Phaser phaser = new Phaser() {
121	>	*     public boolean onAdvance(int phase, int registeredParties) {
122	>	*       return phase >= iterations || registeredParties == 0;
123	>	*     }
124	>	*   };
125	>	*   phaser.register();
126	>	*   for (Runnable r : list) {
127	>	*     phaser.register();
128	>	*     new Thread() {
129	>	*       public void run() {
130	>	*         do {
131	>	*           r.run();
132	>	*           phaser.arriveAndAwaitAdvance();
133	>	*         } while(!phaser.isTerminated();
134	>	*       }
135	>	*     }.start();
136		*   }
137	<	*   protected void compute() {
138	<	*     int n = argument;
139	<	*     if (n &lt;= 1)
140	<	*        result = n;
141	<	*     else {
142	<	*        Phaser childBarrier = new Phaser(1);
143	<	*        BarrierFibonacci f1 = new BarrierFibonacci(n - 1, childBarrier);
144	<	*        BarrierFibonacci f2 = new BarrierFibonacci(n - 2, childBarrier);
145	<	*        f1.fork();
146	<	*        f2.fork();
147	<	*        childBarrier.arriveAndAwait();
148	<	*        result = f1.result + f2.result;
137	>	*   phaser.arriveAndDeregister(); // deregister self, don't wait
138	>	* }}</pre>
139	>	*
140	>	* <p>To create a set of tasks using a tree of phasers,
141	>	* you could use code of the following form, assuming a
142	>	* Task class with a constructor accepting a phaser that
143	>	* it registers for upon construction:
144	>	*  <pre> {@code
145	>	* void build(Task[] actions, int lo, int hi, Phaser b) {
146	>	*   int step = (hi - lo) / TASKS_PER_PHASER;
147	>	*   if (step > 1) {
148	>	*     int i = lo;
149	>	*     while (i < hi) {
150	>	*       int r = Math.min(i + step, hi);
151	>	*       build(actions, i, r, new Phaser(b));
152	>	*       i = r;
153		*     }
154	<	*     parentBarrier.arriveAndDeregister();
154	>	*   } else {
155	>	*     for (int i = lo; i < hi; ++i)
156	>	*       actions[i] = new Task(b);
157	>	*       // assumes new Task(b) performs b.register()
158		*   }
159		* }
160	+	* // .. initially called, for n tasks via
161	+	* build(new Task[n], 0, n, new Phaser());}</pre>
162	+	*
163	+	* The best value of {@code TASKS_PER_PHASER} depends mainly on
164	+	* expected barrier synchronization rates. A value as low as four may
165	+	* be appropriate for extremely small per-barrier task bodies (thus
166	+	* high rates), or up to hundreds for extremely large ones.
167	+	*
168		* </pre>
169		*
170		* <p><b>Implementation notes</b>: This implementation restricts the
171	<	* maximum number of parties to 65535. Attempts to register
172	<	* additional parties result in IllegalStateExceptions.
171	>	* maximum number of parties to 65535. Attempts to register additional
172	>	* parties result in IllegalStateExceptions. However, you can and
173	>	* should create tiered phasers to accommodate arbitrarily large sets
174	>	* of participants.
175	>	*
176	>	* @since 1.7
177	>	* @author Doug Lea
178		*/
179		public class Phaser {
180		/*
181		* This class implements an extension of X10 "clocks".  Thanks to
182	<	* Vijay Saraswat for the idea of applying it to ForkJoinTasks,
183	<	* and to Vivek Sarkar for enhancements to extend functionality.
182	>	* Vijay Saraswat for the idea, and to Vivek Sarkar for
183	>	* enhancements to extend functionality.
184		*/
185
186		/**
187		* Barrier state representation. Conceptually, a barrier contains
188		* four values:
189	<	*
189	>	*
190		* * parties -- the number of parties to wait (16 bits)
191		* * unarrived -- the number of parties yet to hit barrier (16 bits)
192		* * phase -- the generation of the barrier (31 bits)
193		* * terminated -- set if barrier is terminated (1 bit)
194		*
195		* However, to efficiently maintain atomicity, these values are
196	<	* packed into a single AtomicLong. Termination uses the sign bit
197	<	* of 32 bit representation of phase, so phase is set to -1 on
198	<	* termination.
199	<	*/
200	<	private final AtomicLong state;
201	<
202	<	/**
143	<	* Head of Treiber stack for waiting nonFJ threads.
196	>	* packed into a single (atomic) long. Termination uses the sign
197	>	* bit of 32 bit representation of phase, so phase is set to -1 on
198	>	* termination. Good performance relies on keeping state decoding
199	>	* and encoding simple, and keeping race windows short.
200	>	*
201	>	* Note: there are some cheats in arrive() that rely on unarrived
202	>	* count being lowest 16 bits.
203		*/
204	<	private final AtomicReference<QNode> head = new AtomicReference<QNode>();
204	>	private volatile long state;
205
206		private static final int ushortBits = 16;
207	<	private static final int ushortMask =  (1 << ushortBits) - 1;
208	<	private static final int phaseMask = 0x7fffffff;
207	>	private static final int ushortMask = 0xffff;
208	>	private static final int phaseMask  = 0x7fffffff;
209
210		private static int unarrivedOf(long s) {
211	<	return (int)(s & ushortMask);
211	>	return (int) (s & ushortMask);
212		}
213
214		private static int partiesOf(long s) {
215	<	return (int)(s & (ushortMask << 16)) >>> 16;
215	>	return ((int) s) >>> 16;
216		}
217
218		private static int phaseOf(long s) {
219	<	return (int)(s >>> 32);
219	>	return (int) (s >>> 32);
220		}
221
222		private static int arrivedOf(long s) {
#	Line 165 | Line 224 | public class Phaser {
224		}
225
226		private static long stateFor(int phase, int parties, int unarrived) {
227	<	return (((long)phase) << 32) | ((parties << 16) | unarrived);
227	>	return ((((long) phase) << 32) | (((long) parties) << 16) |
228	>	(long) unarrived);
229		}
230
231	<	private static IllegalStateException badBounds(int parties, int unarrived) {
232	<	return new IllegalStateException("Attempt to set " + unarrived +
233	<	" unarrived of " + parties + " parties");
231	>	private static long trippedStateFor(int phase, int parties) {
232	>	long lp = (long) parties;
233	>	return (((long) phase) << 32) | (lp << 16) | lp;
234		}
235
236		/**
237	<	* Creates a new Phaser without any initially registered parties,
238	<	* and initial phase number 0.
237	>	* Returns message string for bad bounds exceptions.
238	>	*/
239	>	private static String badBounds(int parties, int unarrived) {
240	>	return ("Attempt to set " + unarrived +
241	>	" unarrived of " + parties + " parties");
242	>	}
243	>
244	>	/**
245	>	* The parent of this phaser, or null if none
246	>	*/
247	>	private final Phaser parent;
248	>
249	>	/**
250	>	* The root of phaser tree. Equals this if not in a tree.  Used to
251	>	* support faster state push-down.
252	>	*/
253	>	private final Phaser root;
254	>
255	>	// Wait queues
256	>
257	>	/**
258	>	* Heads of Treiber stacks for waiting threads. To eliminate
259	>	* contention while releasing some threads while adding others, we
260	>	* use two of them, alternating across even and odd phases.
261	>	*/
262	>	private final AtomicReference<QNode> evenQ = new AtomicReference<QNode>();
263	>	private final AtomicReference<QNode> oddQ  = new AtomicReference<QNode>();
264	>
265	>	private AtomicReference<QNode> queueFor(int phase) {
266	>	return ((phase & 1) == 0) ? evenQ : oddQ;
267	>	}
268	>
269	>	/**
270	>	* Returns current state, first resolving lagged propagation from
271	>	* root if necessary.
272	>	*/
273	>	private long getReconciledState() {
274	>	return (parent == null) ? state : reconcileState();
275	>	}
276	>
277	>	/**
278	>	* Recursively resolves state.
279	>	*/
280	>	private long reconcileState() {
281	>	Phaser p = parent;
282	>	long s = state;
283	>	if (p != null) {
284	>	while (unarrivedOf(s) == 0 && phaseOf(s) != phaseOf(root.state)) {
285	>	long parentState = p.getReconciledState();
286	>	int parentPhase = phaseOf(parentState);
287	>	int phase = phaseOf(s = state);
288	>	if (phase != parentPhase) {
289	>	long next = trippedStateFor(parentPhase, partiesOf(s));
290	>	if (casState(s, next)) {
291	>	releaseWaiters(phase);
292	>	s = next;
293	>	}
294	>	}
295	>	}
296	>	}
297	>	return s;
298	>	}
299	>
300	>	/**
301	>	* Creates a new phaser without any initially registered parties,
302	>	* initial phase number 0, and no parent. Any thread using this
303	>	* phaser will need to first register for it.
304		*/
305		public Phaser() {
306	<	state = new AtomicLong(stateFor(0, 0, 0));
306	>	this(null);
307		}
308
309		/**
310	<	* Creates a new Phaser with the given numbers of registered
311	<	* unarrived parties and initial phase number 0.
312	<	* @param parties the number of parties required to trip barrier.
310	>	* Creates a new phaser with the given numbers of registered
311	>	* unarrived parties, initial phase number 0, and no parent.
312	>	*
313	>	* @param parties the number of parties required to trip barrier
314		* @throws IllegalArgumentException if parties less than zero
315	<	* or greater than the maximum number of parties supported.
315	>	* or greater than the maximum number of parties supported
316		*/
317		public Phaser(int parties) {
318	+	this(null, parties);
319	+	}
320	+
321	+	/**
322	+	* Creates a new phaser with the given parent, without any
323	+	* initially registered parties. If parent is non-null this phaser
324	+	* is registered with the parent and its initial phase number is
325	+	* the same as that of parent phaser.
326	+	*
327	+	* @param parent the parent phaser
328	+	*/
329	+	public Phaser(Phaser parent) {
330	+	int phase = 0;
331	+	this.parent = parent;
332	+	if (parent != null) {
333	+	this.root = parent.root;
334	+	phase = parent.register();
335	+	}
336	+	else
337	+	this.root = this;
338	+	this.state = trippedStateFor(phase, 0);
339	+	}
340	+
341	+	/**
342	+	* Creates a new phaser with the given parent and numbers of
343	+	* registered unarrived parties. If parent is non-null, this phaser
344	+	* is registered with the parent and its initial phase number is
345	+	* the same as that of parent phaser.
346	+	*
347	+	* @param parent the parent phaser
348	+	* @param parties the number of parties required to trip barrier
349	+	* @throws IllegalArgumentException if parties less than zero
350	+	* or greater than the maximum number of parties supported
351	+	*/
352	+	public Phaser(Phaser parent, int parties) {
353		if (parties < 0 || parties > ushortMask)
354		throw new IllegalArgumentException("Illegal number of parties");
355	<	state = new AtomicLong(stateFor(0, parties, parties));
355	>	int phase = 0;
356	>	this.parent = parent;
357	>	if (parent != null) {
358	>	this.root = parent.root;
359	>	phase = parent.register();
360	>	}
361	>	else
362	>	this.root = this;
363	>	this.state = trippedStateFor(phase, parties);
364		}
365
366		/**
367		* Adds a new unarrived party to this phaser.
368	+	*
369	+	* @return the current barrier phase number upon registration
370	+	* @throws IllegalStateException if attempting to register more
371	+	* than the maximum supported number of parties
372	+	*/
373	+	public int register() {
374	+	return doRegister(1);
375	+	}
376	+
377	+	/**
378	+	* Adds the given number of new unarrived parties to this phaser.
379	+	*
380	+	* @param parties the number of parties required to trip barrier
381		* @return the current barrier phase number upon registration
382		* @throws IllegalStateException if attempting to register more
383	<	* than the maximum supported number of parties.
383	>	* than the maximum supported number of parties
384		*/
385	<	public int register() { // increment both parties and unarrived
386	<	final AtomicLong state = this.state;
385	>	public int bulkRegister(int parties) {
386	>	if (parties < 0)
387	>	throw new IllegalArgumentException();
388	>	if (parties == 0)
389	>	return getPhase();
390	>	return doRegister(parties);
391	>	}
392	>
393	>	/**
394	>	* Shared code for register, bulkRegister
395	>	*/
396	>	private int doRegister(int registrations) {
397	>	int phase;
398		for (;;) {
399	<	long s = state.get();
400	<	int phase = phaseOf(s);
401	<	int parties = partiesOf(s) + 1;
402	<	int unarrived = unarrivedOf(s) + 1;
399	>	long s = getReconciledState();
400	>	phase = phaseOf(s);
401	>	int unarrived = unarrivedOf(s) + registrations;
402	>	int parties = partiesOf(s) + registrations;
403	>	if (phase < 0)
404	>	break;
405		if (parties > ushortMask || unarrived > ushortMask)
406	<	throw badBounds(parties, unarrived);
407	<	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
408	<	return phase;
406	>	throw new IllegalStateException(badBounds(parties, unarrived));
407	>	if (phase == phaseOf(root.state) &&
408	>	casState(s, stateFor(phase, parties, unarrived)))
409	>	break;
410		}
411	+	return phase;
412		}
413
414		/**
415		* Arrives at the barrier, but does not wait for others.  (You can
416		* in turn wait for others via {@link #awaitAdvance}).
417		*
418	<	* @return the current barrier phase number upon entry to
419	<	* this method, or a negative value if terminated;
420	<	* @throws IllegalStateException if the number of unarrived
421	<	* parties would become negative.
418	>	* @return the barrier phase number upon entry to this method, or a
419	>	* negative value if terminated
420	>	* @throws IllegalStateException if not terminated and the number
421	>	* of unarrived parties would become negative
422		*/
423	<	public int arrive() { // decrement unarrived. If zero, trip
424	<	final AtomicLong state = this.state;
423	>	public int arrive() {
424	>	int phase;
425		for (;;) {
426	<	long s = state.get();
427	<	int phase = phaseOf(s);
426	>	long s = state;
427	>	phase = phaseOf(s);
428	>	if (phase < 0)
429	>	break;
430		int parties = partiesOf(s);
431		int unarrived = unarrivedOf(s) - 1;
432	<	if (unarrived < 0)
433	<	throw badBounds(parties, unarrived);
434	<	if (unarrived == 0 && phase >= 0) {
435	<	trip(phase, parties);
436	<	return phase;
432	>	if (unarrived > 0) {        // Not the last arrival
433	>	if (casState(s, s - 1)) // s-1 adds one arrival
434	>	break;
435	>	}
436	>	else if (unarrived == 0) {  // the last arrival
437	>	Phaser par = parent;
438	>	if (par == null) {      // directly trip
439	>	if (casState
440	>	(s,
441	>	trippedStateFor(onAdvance(phase, parties) ? -1 :
442	>	((phase + 1) & phaseMask), parties))) {
443	>	releaseWaiters(phase);
444	>	break;
445	>	}
446	>	}
447	>	else {                  // cascade to parent
448	>	if (casState(s, s - 1)) { // zeroes unarrived
449	>	par.arrive();
450	>	reconcileState();
451	>	break;
452	>	}
453	>	}
454		}
455	<	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
456	<	return phase;
455	>	else if (phase != phaseOf(root.state)) // or if unreconciled
456	>	reconcileState();
457	>	else
458	>	throw new IllegalStateException(badBounds(parties, unarrived));
459		}
460	+	return phase;
461		}
462
463		/**
464	<	* Arrives at the barrier, and deregisters from it, without
465	<	* waiting for others.
464	>	* Arrives at the barrier and deregisters from it without waiting
465	>	* for others. Deregistration reduces the number of parties
466	>	* required to trip the barrier in future phases.  If this phaser
467	>	* has a parent, and deregistration causes this phaser to have
468	>	* zero parties, this phaser also arrives at and is deregistered
469	>	* from its parent.
470		*
471		* @return the current barrier phase number upon entry to
472	<	* this method, or a negative value if terminated;
473	<	* @throws IllegalStateException if the number of registered or
474	<	* unarrived parties would become negative.
475	<	*/
476	<	public int arriveAndDeregister() { // Same as arrive, plus decrement parties
477	<	final AtomicLong state = this.state;
472	>	* this method, or a negative value if terminated
473	>	* @throws IllegalStateException if not terminated and the number
474	>	* of registered or unarrived parties would become negative
475	>	*/
476	>	public int arriveAndDeregister() {
477	>	// similar code to arrive, but too different to merge
478	>	Phaser par = parent;
479	>	int phase;
480		for (;;) {
481	<	long s = state.get();
482	<	int phase = phaseOf(s);
481	>	long s = state;
482	>	phase = phaseOf(s);
483	>	if (phase < 0)
484	>	break;
485		int parties = partiesOf(s) - 1;
486		int unarrived = unarrivedOf(s) - 1;
487	<	if (parties < 0 || unarrived < 0)
488	<	throw badBounds(parties, unarrived);
489	<	if (unarrived == 0 && phase >= 0) {
490	<	trip(phase, parties);
491	<	return phase;
487	>	if (parties >= 0) {
488	>	if (unarrived > 0 || (unarrived == 0 && par != null)) {
489	>	if (casState
490	>	(s,
491	>	stateFor(phase, parties, unarrived))) {
492	>	if (unarrived == 0) {
493	>	par.arriveAndDeregister();
494	>	reconcileState();
495	>	}
496	>	break;
497	>	}
498	>	continue;
499	>	}
500	>	if (unarrived == 0) {
501	>	if (casState
502	>	(s,
503	>	trippedStateFor(onAdvance(phase, parties) ? -1 :
504	>	((phase + 1) & phaseMask), parties))) {
505	>	releaseWaiters(phase);
506	>	break;
507	>	}
508	>	continue;
509	>	}
510	>	if (par != null && phase != phaseOf(root.state)) {
511	>	reconcileState();
512	>	continue;
513	>	}
514		}
515	<	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
267	<	return phase;
515	>	throw new IllegalStateException(badBounds(parties, unarrived));
516		}
517	+	return phase;
518		}
519
520		/**
521	<	* Arrives at the barrier and awaits others. Unlike other arrival
522	<	* methods, this method returns the arrival index of the
523	<	* caller. The caller tripping the barrier returns zero, the
524	<	* previous caller 1, and so on.
525	<	* @return the arrival index
526	<	* @throws IllegalStateException if the number of unarrived
527	<	* parties would become negative.
521	>	* Arrives at the barrier and awaits others. Equivalent in effect
522	>	* to {@code awaitAdvance(arrive())}.  If you need to await with
523	>	* interruption or timeout, you can arrange this with an analogous
524	>	* construction using one of the other forms of the awaitAdvance
525	>	* method.  If instead you need to deregister upon arrival use
526	>	* {@code arriveAndDeregister}.
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
537	>	* Awaits the phase of the barrier to advance from the given phase
538	>	* value, or returns immediately if the current phase of the barrier
539	>	* is not equal to the given phase value or this barrier is
540	>	* terminated.
541	>	*
542		* @param phase the phase on entry to this method
543		* @return the phase on exit from this method
544		*/
545		public int awaitAdvance(int phase) {
546		if (phase < 0)
547		return phase;
548	<	Thread current = Thread.currentThread();
549	<	if (current instanceof ForkJoinWorkerThread)
550	<	return helpingWait(phase);
551	<	if (untimedWait(current, phase, false))
552	<	current.interrupt();
553	<	return phaseOf(state.get());
548	>	long s = getReconciledState();
549	>	int p = phaseOf(s);
550	>	if (p != phase)
551	>	return p;
552	>	if (unarrivedOf(s) == 0 && parent != null)
553	>	parent.awaitAdvance(phase);
554	>	// Fall here even if parent waited, to reconcile and help release
555	>	return untimedWait(phase);
556		}
557
558		/**
559		* Awaits the phase of the barrier to advance from the given
560	<	* value, or returns immediately if this barrier is terminated, or
561	<	* throws InterruptedException if interrupted while waiting.
560	>	* value, or returns immediately if argument is negative or this
561	>	* barrier is terminated, or throws InterruptedException if
562	>	* interrupted while waiting.
563	>	*
564		* @param phase the phase on entry to this method
565		* @return the phase on exit from this method
566		* @throws InterruptedException if thread interrupted while waiting
567		*/
568	<	public int awaitAdvanceInterruptibly(int phase) throws InterruptedException {
568	>	public int awaitAdvanceInterruptibly(int phase)
569	>	throws InterruptedException {
570		if (phase < 0)
571		return phase;
572	<	Thread current = Thread.currentThread();
573	<	if (current instanceof ForkJoinWorkerThread)
574	<	return helpingWait(phase);
575	<	else if (Thread.interrupted() || untimedWait(current, phase, true))
576	<	throw new InterruptedException();
577	<	else
578	<	return phaseOf(state.get());
572	>	long s = getReconciledState();
573	>	int p = phaseOf(s);
574	>	if (p != phase)
575	>	return p;
576	>	if (unarrivedOf(s) == 0 && parent != null)
577	>	parent.awaitAdvanceInterruptibly(phase);
578	>	return interruptibleWait(phase);
579		}
580
581		/**
582		* Awaits the phase of the barrier to advance from the given value
583	<	* or the given timeout elapses, or returns immediately if this
584	<	* barrier is terminated
583	>	* or the given timeout elapses, or returns immediately if
584	>	* argument is negative or this barrier is terminated.
585	>	*
586		* @param phase the phase on entry to this method
587		* @return the phase on exit from this method
588		* @throws InterruptedException if thread interrupted while waiting
589		* @throws TimeoutException if timed out while waiting
590		*/
591	<	public int awaitAdvanceInterruptibly(int phase, long timeout, TimeUnit unit)
591	>	public int awaitAdvanceInterruptibly(int phase,
592	>	long timeout, TimeUnit unit)
593		throws InterruptedException, TimeoutException {
594		if (phase < 0)
595		return phase;
596	<	long nanos = unit.toNanos(timeout);
597	<	Thread current = Thread.currentThread();
598	<	if (current instanceof ForkJoinWorkerThread)
599	<	return timedHelpingWait(phase, nanos);
600	<	timedWait(current, phase, nanos);
601	<	return phaseOf(state.get());
596	>	long s = getReconciledState();
597	>	int p = phaseOf(s);
598	>	if (p != phase)
599	>	return p;
600	>	if (unarrivedOf(s) == 0 && parent != null)
601	>	parent.awaitAdvanceInterruptibly(phase, timeout, unit);
602	>	return timedWait(phase, unit.toNanos(timeout));
603		}
604
605		/**
606		* Forces this barrier to enter termination state. Counts of
607	<	* arrived and registered parties are unaffected. This method may
608	<	* be useful for coordinating recovery after one or more tasks
609	<	* encounter unexpected exceptions.
607	>	* arrived and registered parties are unaffected. If this phaser
608	>	* has a parent, it too is terminated. This method may be useful
609	>	* for coordinating recovery after one or more tasks encounter
610	>	* unexpected exceptions.
611		*/
612		public void forceTermination() {
365	–	final AtomicLong state = this.state;
613		for (;;) {
614	<	long s = state.get();
614	>	long s = getReconciledState();
615		int phase = phaseOf(s);
616		int parties = partiesOf(s);
617		int unarrived = unarrivedOf(s);
618		if (phase < 0 ||
619	<	state.compareAndSet(s, stateFor(-1, parties, unarrived))) {
620	<	if (head.get() != null)
621	<	releaseWaiters(-1);
619	>	casState(s, stateFor(-1, parties, unarrived))) {
620	>	releaseWaiters(0);
621	>	releaseWaiters(1);
622	>	if (parent != null)
623	>	parent.forceTermination();
624		return;
625		}
626		}
627		}
628
629		/**
381	–	* Resets the barrier with the given numbers of registered unarrived
382	–	* parties and phase number 0. This method allows repeated reuse
383	–	* of this barrier, but only if it is somehow known not to be in
384	–	* use for other purposes.
385	–	* @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.
388	–	*/
389	–	public void reset(int parties) {
390	–	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);
395	–	}
396	–
397	–	/**
630		* Returns the current phase number. The maximum phase number is
631	<	* <tt>Integer.MAX_VALUE</tt>, after which it restarts at
631	>	* {@code Integer.MAX_VALUE}, after which it restarts at
632		* zero. Upon termination, the phase number is negative.
633	+	*
634		* @return the phase number, or a negative value if terminated
635		*/
636	<	public int getPhase() {
637	<	return phaseOf(state.get());
636	>	public final int getPhase() {
637	>	return phaseOf(getReconciledState());
638		}
639
640		/**
641		* Returns the number of parties registered at this barrier.
642	+	*
643		* @return the number of parties
644		*/
645		public int getRegisteredParties() {
646	<	return partiesOf(state.get());
646	>	return partiesOf(state);
647		}
648
649		/**
650		* Returns the number of parties that have arrived at the current
651		* phase of this barrier.
652	+	*
653		* @return the number of arrived parties
654		*/
655		public int getArrivedParties() {
656	<	return arrivedOf(state.get());
656	>	return arrivedOf(state);
657		}
658
659		/**
660		* Returns the number of registered parties that have not yet
661		* arrived at the current phase of this barrier.
662	+	*
663		* @return the number of unarrived parties
664		*/
665		public int getUnarrivedParties() {
666	<	return unarrivedOf(state.get());
666	>	return unarrivedOf(state);
667		}
668
669		/**
670	<	* Returns true if this barrier has been terminated
671	<	* @return true if this barrier has been terminated
670	>	* Returns the parent of this phaser, or {@code null} if none.
671	>	*
672	>	* @return the parent of this phaser, or {@code null} if none
673	>	*/
674	>	public Phaser getParent() {
675	>	return parent;
676	>	}
677	>
678	>	/**
679	>	* Returns the root ancestor of this phaser, which is the same as
680	>	* this phaser if it has no parent.
681	>	*
682	>	* @return the root ancestor of this phaser
683	>	*/
684	>	public Phaser getRoot() {
685	>	return root;
686	>	}
687	>
688	>	/**
689	>	* Returns {@code true} if this barrier has been terminated.
690	>	*
691	>	* @return {@code true} if this barrier has been terminated
692		*/
693		public boolean isTerminated() {
694	<	return phaseOf(state.get()) < 0;
694	>	return getPhase() < 0;
695		}
696
697		/**
698		* Overridable method to perform an action upon phase advance, and
699		* to control termination. This method is invoked whenever the
700		* barrier is tripped (and thus all other waiting parties are
701	<	* dormant). If it returns true, then, rather than advance the
702	<	* phase number, this barrier will be set to a final termination
703	<	* state, and subsequent calls to <tt>isTerminated</tt> will
704	<	* return true.
705	<	*
706	<	* <p> The default version returns true when the number of
701	>	* dormant). If it returns {@code true}, then, rather than advance
702	>	* the phase number, this barrier will be set to a final
703	>	* termination state, and subsequent calls to {@link #isTerminated}
704	>	* will return true.
705	>	*
706	>	* <p>The default version returns {@code true} when the number of
707		* registered parties is zero. Normally, overrides that arrange
708		* termination for other reasons should also preserve this
709		* property.
710		*
711	+	* <p>You may override this method to perform an action with side
712	+	* effects visible to participating tasks, but it is in general
713	+	* only sensible to do so in designs where all parties register
714	+	* before any arrive, and all {@link #awaitAdvance} at each phase.
715	+	* Otherwise, you cannot ensure lack of interference from other
716	+	* parties during the invocation of this method.
717	+	*
718		* @param phase the phase number on entering the barrier
719	<	* @param registeredParties the current number of registered
720	<	* parties.
458	<	* @return true if this barrier should terminate
719	>	* @param registeredParties the current number of registered parties
720	>	* @return {@code true} if this barrier should terminate
721		*/
722		protected boolean onAdvance(int phase, int registeredParties) {
723		return registeredParties <= 0;
724		}
725
726		/**
727	<	* Returns a string identifying this barrier, as well as its
727	>	* Returns a string identifying this phaser, as well as its
728		* state.  The state, in brackets, includes the String {@code
729	<	* "phase ="} followed by the phase number, {@code "parties ="}
729	>	* "phase = "} followed by the phase number, {@code "parties = "}
730		* followed by the number of registered parties, and {@code
731	<	* "arrived ="} followed by the number of arrived parties
731	>	* "arrived = "} followed by the number of arrived parties.
732		*
733		* @return a string identifying this barrier, as well as its state
734		*/
735		public String toString() {
736	<	long s = state.get();
737	<	return super.toString() + "[phase = " + phaseOf(s) + " parties = " + partiesOf(s) + " arrived = " + arrivedOf(s) + "]";
736	>	long s = getReconciledState();
737	>	return super.toString() +
738	>	"[phase = " + phaseOf(s) +
739	>	" parties = " + partiesOf(s) +
740	>	" arrived = " + arrivedOf(s) + "]";
741		}
742
743	<	// methods for tripping and waiting
743	>	// methods for waiting
744
745		/**
746	<	* Advance the current phase (or terminate)
746	>	* Wait nodes for Treiber stack representing wait queue
747		*/
748	<	private void trip(int phase, int parties) {
749	<	int next = onAdvance(phase, parties)? -1 : ((phase + 1) & phaseMask);
750	<	state.set(stateFor(next, parties, parties));
751	<	if (head.get() != null)
752	<	releaseWaiters(next);
753	<	}
754	<
755	<	private int helpingWait(int phase) {
756	<	final AtomicLong state = this.state;
757	<	int p;
758	<	while ((p = phaseOf(state.get())) == phase) {
759	<	ForkJoinTask<?> t = ForkJoinWorkerThread.pollTask();
760	<	if (t != null) {
761	<	if ((p = phaseOf(state.get())) == phase)
762	<	t.exec();
763	<	else {   // push task and exit if barrier advanced
764	<	t.fork();
765	<	break;
766	<	}
748	>	static final class QNode implements ForkJoinPool.ManagedBlocker {
749	>	final Phaser phaser;
750	>	final int phase;
751	>	final long startTime;
752	>	final long nanos;
753	>	final boolean timed;
754	>	final boolean interruptible;
755	>	volatile boolean wasInterrupted = false;
756	>	volatile Thread thread; // nulled to cancel wait
757	>	QNode next;
758	>	QNode(Phaser phaser, int phase, boolean interruptible,
759	>	boolean timed, long startTime, long nanos) {
760	>	this.phaser = phaser;
761	>	this.phase = phase;
762	>	this.timed = timed;
763	>	this.interruptible = interruptible;
764	>	this.startTime = startTime;
765	>	this.nanos = nanos;
766	>	thread = Thread.currentThread();
767	>	}
768	>	public boolean isReleasable() {
769	>	return (thread == null ||
770	>	phaser.getPhase() != phase ||
771	>	(interruptible && wasInterrupted) ||
772	>	(timed && (nanos - (System.nanoTime() - startTime)) <= 0));
773	>	}
774	>	public boolean block() {
775	>	if (Thread.interrupted()) {
776	>	wasInterrupted = true;
777	>	if (interruptible)
778	>	return true;
779	>	}
780	>	if (!timed)
781	>	LockSupport.park(this);
782	>	else {
783	>	long waitTime = nanos - (System.nanoTime() - startTime);
784	>	if (waitTime <= 0)
785	>	return true;
786	>	LockSupport.parkNanos(this, waitTime);
787		}
788	+	return isReleasable();
789		}
790	<	return p;
791	<	}
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();
790	>	void signal() {
791	>	Thread t = thread;
792		if (t != null) {
793	<	if ((p = phaseOf(state.get())) == phase)
794	<	t.exec();
795	<	else {   // push task and exit if barrier advanced
796	<	t.fork();
797	<	break;
793	>	thread = null;
794	>	LockSupport.unpark(t);
795	>	}
796	>	}
797	>	boolean doWait() {
798	>	if (thread != null) {
799	>	try {
800	>	ForkJoinPool.managedBlock(this, false);
801	>	} catch (InterruptedException ie) {
802		}
803		}
804	+	return wasInterrupted;
805		}
806	<	return p;
806	>
807		}
808
809		/**
810	<	* 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.
810	>	* Removes and signals waiting threads from wait queue.
811		*/
812	<	static final class QNode {
813	<	QNode next;
814	<	volatile Thread thread; // nulled to cancel wait
815	<	final int phase;
816	<	QNode(Thread t, int c) {
817	<	thread = t;
545	<	phase = c;
812	>	private void releaseWaiters(int phase) {
813	>	AtomicReference<QNode> head = queueFor(phase);
814	>	QNode q;
815	>	while ((q = head.get()) != null) {
816	>	if (head.compareAndSet(q, q.next))
817	>	q.signal();
818		}
819		}
820
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	–
821		/**
822	<	* The number of times to spin before blocking in untimed waits.
823	<	* This is greater than timed value because untimed waits spin
824	<	* faster since they don't need to check times on each spin.
822	>	* Tries to enqueue given node in the appropriate wait queue.
823	>	*
824	>	* @return true if successful
825		*/
826	<	static final int maxUntimedSpins = maxTimedSpins * 32;
826	>	private boolean tryEnqueue(QNode node) {
827	>	AtomicReference<QNode> head = queueFor(node.phase);
828	>	return head.compareAndSet(node.next = head.get(), node);
829	>	}
830
831		/**
832	<	* The number of nanoseconds for which it is faster to spin
833	<	* rather than to use timed park. A rough estimate suffices.
832	>	* Enqueues node and waits unless aborted or signalled.
833	>	*
834	>	* @return current phase
835		*/
836	<	static final long spinForTimeoutThreshold = 1000L;
836	>	private int untimedWait(int phase) {
837	>	QNode node = null;
838	>	boolean queued = false;
839	>	boolean interrupted = false;
840	>	int p;
841	>	while ((p = getPhase()) == phase) {
842	>	if (Thread.interrupted())
843	>	interrupted = true;
844	>	else if (node == null)
845	>	node = new QNode(this, phase, false, false, 0, 0);
846	>	else if (!queued)
847	>	queued = tryEnqueue(node);
848	>	else
849	>	interrupted = node.doWait();
850	>	}
851	>	if (node != null)
852	>	node.thread = null;
853	>	releaseWaiters(phase);
854	>	if (interrupted)
855	>	Thread.currentThread().interrupt();
856	>	return p;
857	>	}
858
859		/**
860	<	* Enqueues node and waits unless aborted or signalled.
860	>	* Interruptible version
861	>	* @return current phase
862		*/
863	<	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;
863	>	private int interruptibleWait(int phase) throws InterruptedException {
864		QNode node = null;
865		boolean queued = false;
866	<	int spins = maxUntimedSpins;
867	<	while (phaseOf(state.get()) == currentPhase) {
868	<	QNode h;
869	<	if (node != null && queued) {
870	<	if (node.thread != null) {
871	<	LockSupport.park();
872	<	if (Thread.interrupted()) {
873	<	wasInterrupted = true;
874	<	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);
866	>	boolean interrupted = false;
867	>	int p;
868	>	while ((p = getPhase()) == phase && !interrupted) {
869	>	if (Thread.interrupted())
870	>	interrupted = true;
871	>	else if (node == null)
872	>	node = new QNode(this, phase, true, false, 0, 0);
873	>	else if (!queued)
874	>	queued = tryEnqueue(node);
875		else
876	<	--spins;
876	>	interrupted = node.doWait();
877		}
878		if (node != null)
879		node.thread = null;
880	<	return wasInterrupted;
880	>	if (p != phase || (p = getPhase()) != phase)
881	>	releaseWaiters(phase);
882	>	if (interrupted)
883	>	throw new InterruptedException();
884	>	return p;
885		}
886
887		/**
888	<	* Messier timeout version
888	>	* Timeout version.
889	>	* @return current phase
890		*/
891	<	private void timedWait(Thread thread, int currentPhase, long nanos)
891	>	private int timedWait(int phase, long nanos)
892		throws InterruptedException, TimeoutException {
893	<	final AtomicReference<QNode> head = this.head;
641	<	final AtomicLong state = this.state;
642	<	long lastTime = System.nanoTime();
893	>	long startTime = System.nanoTime();
894		QNode node = null;
895		boolean queued = false;
896	<	int spins = maxTimedSpins;
897	<	while (phaseOf(state.get()) == currentPhase) {
898	<	QNode h;
899	<	long now = System.nanoTime();
900	<	nanos -= now - lastTime;
901	<	lastTime = now;
902	<	if (nanos <= 0) {
903	<	if (node != null)
904	<	node.thread = null;
905	<	if (phaseOf(state.get()) == currentPhase)
906	<	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);
896	>	boolean interrupted = false;
897	>	int p;
898	>	while ((p = getPhase()) == phase && !interrupted) {
899	>	if (Thread.interrupted())
900	>	interrupted = true;
901	>	else if (nanos - (System.nanoTime() - startTime) <= 0)
902	>	break;
903	>	else if (node == null)
904	>	node = new QNode(this, phase, true, true, startTime, nanos);
905	>	else if (!queued)
906	>	queued = tryEnqueue(node);
907		else
908	<	--spins;
908	>	interrupted = node.doWait();
909		}
910		if (node != null)
911		node.thread = null;
912	+	if (p != phase || (p = getPhase()) != phase)
913	+	releaseWaiters(phase);
914	+	if (interrupted)
915	+	throw new InterruptedException();
916	+	if (p == phase)
917	+	throw new TimeoutException();
918	+	return p;
919		}
920
921	<	}
921	>	// Unsafe mechanics
922
923	+	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
924	+	private static final long stateOffset =
925	+	objectFieldOffset("state", Phaser.class);
926	+
927	+	private final boolean casState(long cmp, long val) {
928	+	return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val);
929	+	}
930	+
931	+	private static long objectFieldOffset(String field, Class<?> klazz) {
932	+	try {
933	+	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
934	+	} catch (NoSuchFieldException e) {
935	+	// Convert Exception to corresponding Error
936	+	NoSuchFieldError error = new NoSuchFieldError(field);
937	+	error.initCause(e);
938	+	throw error;
939	+	}
940	+	}
941	+
942	+	/**
943	+	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
944	+	* Replace with a simple call to Unsafe.getUnsafe when integrating
945	+	* into a jdk.
946	+	*
947	+	* @return a sun.misc.Unsafe
948	+	*/
949	+	private static sun.misc.Unsafe getUnsafe() {
950	+	try {
951	+	return sun.misc.Unsafe.getUnsafe();
952	+	} catch (SecurityException se) {
953	+	try {
954	+	return java.security.AccessController.doPrivileged
955	+	(new java.security
956	+	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
957	+	public sun.misc.Unsafe run() throws Exception {
958	+	java.lang.reflect.Field f = sun.misc
959	+	.Unsafe.class.getDeclaredField("theUnsafe");
960	+	f.setAccessible(true);
961	+	return (sun.misc.Unsafe) f.get(null);
962	+	}});
963	+	} catch (java.security.PrivilegedActionException e) {
964	+	throw new RuntimeException("Could not initialize intrinsics",
965	+	e.getCause());
966	+	}
967	+	}
968	+	}
969	+	}

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