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Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.3 by jsr166, Fri Jul 25 18:11:53 2008 UTC vs.
Revision 1.35 by dl, Sun Aug 23 13:37:08 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 <em>registered</em> to synchronize on a
23	>	* phaser may vary over time.  Tasks may be registered at any time
24	>	* (using methods {@link #register}, {@link #bulkRegister}, or forms
25	>	* of constructors establishing initial numbers of parties), and may
26	>	* optionally be deregistered upon any arrival (using {@link
27	>	* #arriveAndDeregister}).  As is the case with most basic
28	>	* synchronization constructs, registration and deregistration affect
29	>	* only internal counts; they do not establish any further internal
30	>	* bookkeeping, so tasks cannot query whether they are
31	>	* registered. (However, you can introduce such bookkeeping by
32	>	* subclassing this class.)
33		*
34		* <li> Each generation has an associated phase value, starting at
35	<	* zero, and advancing when all parties reach the barrier (wrapping
36	<	* around to zero after reaching <tt>Integer.MAX_VALUE</tt>).
35	>	* zero, and advancing when all parties arrive at the barrier
36	>	* (wrapping around to zero after reaching {@code Integer.MAX_VALUE}).
37		*
38	<	* <li> Like a CyclicBarrier, a Phaser may be repeatedly awaited.
39	<	* Method <tt>arriveAndAwaitAdvance</tt> has effect analogous to
40	<	* <tt>CyclicBarrier.await</tt>.  However, Phasers separate two
41	<	* aspects of coordination, that may be invoked independently:
38	>	* <li> Like a {@code CyclicBarrier}, a phaser may be repeatedly
39	>	* awaited.  Method {@link #arriveAndAwaitAdvance} has effect
40	>	* analogous to {@link java.util.concurrent.CyclicBarrier#await
41	>	* CyclicBarrier.await}.  However, phasers separate two aspects of
42	>	* coordination, which may also be invoked independently:
43		*
44		* <ul>
45		*
46	<	*   <li> Arriving at a barrier. Methods <tt>arrive</tt> and
47	<	*       <tt>arriveAndDeregister</tt> do not block, but return
48	<	*       the phase value on entry to the method.
49	<	*
50	<	*   <li> Awaiting others. Method <tt>awaitAdvance</tt> requires an
51	<	*       argument indicating the entry phase, and returns when the
52	<	*       barrier advances to a new phase.
46	>	*   <li> Arriving at a barrier. Methods {@link #arrive} and
47	>	*       {@link #arriveAndDeregister} do not block, but return
48	>	*       an associated <em>arrival phase number</em>;
49	>	*       that is, the phase number of the barrier to which the
50	>	*       arrival applied.
51	>	*
52	>	*   <li> Awaiting others. Method {@link #awaitAdvance} requires an
53	>	*       argument indicating an arrival phase number, and returns
54	>	*       when the barrier advances to a new phase.
55		* </ul>
56		*
57		*
58		* <li> Barrier actions, performed by the task triggering a phase
59	<	* advance while others may be waiting, are arranged by overriding
60	<	* method <tt>onAdvance</tt>, that also controls termination.
59	>	* advance, are arranged by overriding method {@link #onAdvance(int,
60	>	* int)}, which also controls termination. Overriding this method is
61	>	* similar to, but more flexible than, providing a barrier action to a
62	>	* {@code CyclicBarrier}.
63		*
64		* <li> Phasers may enter a <em>termination</em> state in which all
65	<	* await actions immediately return, indicating (via a negative phase
66	<	* value) that execution is complete.  Termination is triggered by
67	<	* executing the overridable <tt>onAdvance</tt> method that is invoked
68	<	* each time the barrier is tripped. When a Phaser is controlling an
69	<	* action with a fixed number of iterations, it is often convenient to
70	<	* override this method to cause termination when the current phase
71	<	* number reaches a threshold.  Method <tt>forceTermination</tt> is
72	<	* also available to assist recovery actions upon failure.
73	<	*
74	<	* <li> Unlike most synchronizers, a Phaser may also be used with
75	<	* ForkJoinTasks (as well as plain threads).
76	<	*
77	<	* <li> By default, <tt>awaitAdvance</tt> continues to wait even if
78	<	* the current thread is interrupted. And unlike the case in
79	<	* CyclicBarriers, exceptions encountered while tasks wait
65	>	* actions immediately return without updating phaser state or waiting
66	>	* for advance, and indicating (via a negative phase value) that
67	>	* execution is complete.  Termination is triggered when an invocation
68	>	* of {@code onAdvance} returns {@code true}.  When a phaser is
69	>	* controlling an action with a fixed number of iterations, it is
70	>	* often convenient to override this method to cause termination when
71	>	* the current phase number reaches a threshold. Method {@link
72	>	* #forceTermination} is also available to abruptly release waiting
73	>	* threads and allow them to terminate.
74	>	*
75	>	* <li> Phasers may be tiered to reduce contention. Phasers with large
76	>	* numbers of parties that would otherwise experience heavy
77	>	* synchronization contention costs may instead be arranged in trees.
78	>	* This will typically greatly increase throughput even though it
79	>	* incurs somewhat greater per-operation overhead.
80	>	*
81	>	* <li> By default, {@code awaitAdvance} continues to wait even if
82	>	* the waiting thread is interrupted. And unlike the case in
83	>	* {@code CyclicBarrier}, exceptions encountered while tasks wait
84		* interruptibly or with timeout do not change the state of the
85		* barrier. If necessary, you can perform any associated recovery
86	<	* within handlers of those exceptions.
86	>	* within handlers of those exceptions, often after invoking
87	>	* {@code forceTermination}.
88	>	*
89	>	* <li>Phasers may be used to coordinate tasks executing in a {@link
90	>	* ForkJoinPool}, which will ensure sufficient parallelism to execute
91	>	* tasks when others are blocked waiting for a phase to advance.
92		*
93		* </ul>
94		*
95	<	* <p><b>Sample usage:</b>
95	>	* <p><b>Sample usages:</b>
96		*
97	<	* <p>[todo: non-FJ example]
97	>	* <p>A {@code Phaser} may be used instead of a {@code CountDownLatch}
98	>	* to control a one-shot action serving a variable number of
99	>	* parties. The typical idiom is for the method setting this up to
100	>	* first register, then start the actions, then deregister, as in:
101	>	*
102	>	*  <pre> {@code
103	>	* void runTasks(List<Runnable> tasks) {
104	>	*   final Phaser phaser = new Phaser(1); // "1" to register self
105	>	*   // create and start threads
106	>	*   for (Runnable task : tasks) {
107	>	*     phaser.register();
108	>	*     new Thread() {
109	>	*       public void run() {
110	>	*         phaser.arriveAndAwaitAdvance(); // await all creation
111	>	*         task.run();
112	>	*       }
113	>	*     }.start();
114	>	*   }
115		*
116	<	* <p> A Phaser may be used to support a style of programming in
117	<	* which a task waits for others to complete, without otherwise
118	<	* needing to keep track of which tasks it is waiting for. This is
119	<	* similar to the "sync" construct in Cilk and "clocks" in X10.
120	<	* Special constructions based on such barriers are available using
121	<	* the <tt>LinkedAsyncAction</tt> and <tt>CyclicAction</tt> classes,
122	<	* but they can be useful in other contexts as well.  For a simple
123	<	* (but not very useful) example, here is a variant of Fibonacci:
124	<	*
125	<	* <pre>
126	<	* class BarrierFibonacci extends RecursiveAction {
127	<	*   int argument, result;
128	<	*   final Phaser parentBarrier;
129	<	*   BarrierFibonacci(int n, Phaser parentBarrier) {
130	<	*     this.argument = n;
131	<	*     this.parentBarrier = parentBarrier;
132	<	*     parentBarrier.register();
116	>	*   // allow threads to start and deregister self
117	>	*   phaser.arriveAndDeregister();
118	>	* }}</pre>
119	>	*
120	>	* <p>One way to cause a set of threads to repeatedly perform actions
121	>	* for a given number of iterations is to override {@code onAdvance}:
122	>	*
123	>	*  <pre> {@code
124	>	* void startTasks(List<Runnable> tasks, final int iterations) {
125	>	*   final Phaser phaser = new Phaser() {
126	>	*     public boolean onAdvance(int phase, int registeredParties) {
127	>	*       return phase >= iterations || registeredParties == 0;
128	>	*     }
129	>	*   };
130	>	*   phaser.register();
131	>	*   for (Runnable task : tasks) {
132	>	*     phaser.register();
133	>	*     new Thread() {
134	>	*       public void run() {
135	>	*         do {
136	>	*           task.run();
137	>	*           phaser.arriveAndAwaitAdvance();
138	>	*         } while(!phaser.isTerminated();
139	>	*       }
140	>	*     }.start();
141		*   }
142	<	*   protected void compute() {
143	<	*     int n = argument;
144	<	*     if (n &lt;= 1)
145	<	*        result = n;
146	<	*     else {
147	<	*        Phaser childBarrier = new Phaser(1);
148	<	*        BarrierFibonacci f1 = new BarrierFibonacci(n - 1, childBarrier);
149	<	*        BarrierFibonacci f2 = new BarrierFibonacci(n - 2, childBarrier);
150	<	*        f1.fork();
151	<	*        f2.fork();
152	<	*        childBarrier.arriveAndAwait();
153	<	*        result = f1.result + f2.result;
142	>	*   phaser.arriveAndDeregister(); // deregister self, don't wait
143	>	* }}</pre>
144	>	*
145	>	* <p>To create a set of tasks using a tree of phasers,
146	>	* you could use code of the following form, assuming a
147	>	* Task class with a constructor accepting a phaser that
148	>	* it registers for upon construction:
149	>	*  <pre> {@code
150	>	* void build(Task[] actions, int lo, int hi, Phaser b) {
151	>	*   int step = (hi - lo) / TASKS_PER_PHASER;
152	>	*   if (step > 1) {
153	>	*     int i = lo;
154	>	*     while (i < hi) {
155	>	*       int r = Math.min(i + step, hi);
156	>	*       build(actions, i, r, new Phaser(b));
157	>	*       i = r;
158		*     }
159	<	*     parentBarrier.arriveAndDeregister();
159	>	*   } else {
160	>	*     for (int i = lo; i < hi; ++i)
161	>	*       actions[i] = new Task(b);
162	>	*       // assumes new Task(b) performs b.register()
163		*   }
164		* }
165	+	* // .. initially called, for n tasks via
166	+	* build(new Task[n], 0, n, new Phaser());}</pre>
167	+	*
168	+	* The best value of {@code TASKS_PER_PHASER} depends mainly on
169	+	* expected barrier synchronization rates. A value as low as four may
170	+	* be appropriate for extremely small per-barrier task bodies (thus
171	+	* high rates), or up to hundreds for extremely large ones.
172	+	*
173		* </pre>
174		*
175		* <p><b>Implementation notes</b>: This implementation restricts the
176	<	* maximum number of parties to 65535. Attempts to register
177	<	* additional parties result in IllegalStateExceptions.
176	>	* maximum number of parties to 65535. Attempts to register additional
177	>	* parties result in {@code IllegalStateException}. However, you can and
178	>	* should create tiered phasers to accommodate arbitrarily large sets
179	>	* of participants.
180	>	*
181	>	* @since 1.7
182	>	* @author Doug Lea
183		*/
184		public class Phaser {
185		/*
186		* This class implements an extension of X10 "clocks".  Thanks to
187	<	* Vijay Saraswat for the idea of applying it to ForkJoinTasks,
188	<	* and to Vivek Sarkar for enhancements to extend functionality.
187	>	* Vijay Saraswat for the idea, and to Vivek Sarkar for
188	>	* enhancements to extend functionality.
189		*/
190
191		/**
#	Line 133 | Line 198 | public class Phaser {
198		* * terminated -- set if barrier is terminated (1 bit)
199		*
200		* However, to efficiently maintain atomicity, these values are
201	<	* packed into a single AtomicLong. Termination uses the sign bit
202	<	* of 32 bit representation of phase, so phase is set to -1 on
203	<	* termination.
204	<	*/
205	<	private final AtomicLong state;
206	<
207	<	/**
143	<	* Head of Treiber stack for waiting nonFJ threads.
201	>	* packed into a single (atomic) long. Termination uses the sign
202	>	* bit of 32 bit representation of phase, so phase is set to -1 on
203	>	* termination. Good performance relies on keeping state decoding
204	>	* and encoding simple, and keeping race windows short.
205	>	*
206	>	* Note: there are some cheats in arrive() that rely on unarrived
207	>	* count being lowest 16 bits.
208		*/
209	<	private final AtomicReference<QNode> head = new AtomicReference<QNode>();
209	>	private volatile long state;
210
211		private static final int ushortBits = 16;
212	<	private static final int ushortMask =  (1 << ushortBits) - 1;
213	<	private static final int phaseMask = 0x7fffffff;
212	>	private static final int ushortMask = 0xffff;
213	>	private static final int phaseMask  = 0x7fffffff;
214
215		private static int unarrivedOf(long s) {
216	<	return (int)(s & ushortMask);
216	>	return (int) (s & ushortMask);
217		}
218
219		private static int partiesOf(long s) {
220	<	return (int)(s & (ushortMask << 16)) >>> 16;
220	>	return ((int) s) >>> 16;
221		}
222
223		private static int phaseOf(long s) {
224	<	return (int)(s >>> 32);
224	>	return (int) (s >>> 32);
225		}
226
227		private static int arrivedOf(long s) {
#	Line 165 | Line 229 | public class Phaser {
229		}
230
231		private static long stateFor(int phase, int parties, int unarrived) {
232	<	return (((long)phase) << 32) | ((parties << 16) | unarrived);
232	>	return ((((long) phase) << 32) | (((long) parties) << 16) |
233	>	(long) unarrived);
234		}
235
236	<	private static IllegalStateException badBounds(int parties, int unarrived) {
237	<	return new IllegalStateException("Attempt to set " + unarrived +
238	<	" unarrived of " + parties + " parties");
236	>	private static long trippedStateFor(int phase, int parties) {
237	>	long lp = (long) parties;
238	>	return (((long) phase) << 32) | (lp << 16) | lp;
239		}
240
241		/**
242	<	* Creates a new Phaser without any initially registered parties,
243	<	* and initial phase number 0.
242	>	* Returns message string for bad bounds exceptions.
243	>	*/
244	>	private static String badBounds(int parties, int unarrived) {
245	>	return ("Attempt to set " + unarrived +
246	>	" unarrived of " + parties + " parties");
247	>	}
248	>
249	>	/**
250	>	* The parent of this phaser, or null if none
251	>	*/
252	>	private final Phaser parent;
253	>
254	>	/**
255	>	* The root of phaser tree. Equals this if not in a tree.  Used to
256	>	* support faster state push-down.
257	>	*/
258	>	private final Phaser root;
259	>
260	>	// Wait queues
261	>
262	>	/**
263	>	* Heads of Treiber stacks for waiting threads. To eliminate
264	>	* contention while releasing some threads while adding others, we
265	>	* use two of them, alternating across even and odd phases.
266	>	*/
267	>	private final AtomicReference<QNode> evenQ = new AtomicReference<QNode>();
268	>	private final AtomicReference<QNode> oddQ  = new AtomicReference<QNode>();
269	>
270	>	private AtomicReference<QNode> queueFor(int phase) {
271	>	return ((phase & 1) == 0) ? evenQ : oddQ;
272	>	}
273	>
274	>	/**
275	>	* Returns current state, first resolving lagged propagation from
276	>	* root if necessary.
277	>	*/
278	>	private long getReconciledState() {
279	>	return (parent == null) ? state : reconcileState();
280	>	}
281	>
282	>	/**
283	>	* Recursively resolves state.
284	>	*/
285	>	private long reconcileState() {
286	>	Phaser p = parent;
287	>	long s = state;
288	>	if (p != null) {
289	>	while (unarrivedOf(s) == 0 && phaseOf(s) != phaseOf(root.state)) {
290	>	long parentState = p.getReconciledState();
291	>	int parentPhase = phaseOf(parentState);
292	>	int phase = phaseOf(s = state);
293	>	if (phase != parentPhase) {
294	>	long next = trippedStateFor(parentPhase, partiesOf(s));
295	>	if (casState(s, next)) {
296	>	releaseWaiters(phase);
297	>	s = next;
298	>	}
299	>	}
300	>	}
301	>	}
302	>	return s;
303	>	}
304	>
305	>	/**
306	>	* Creates a new phaser without any initially registered parties,
307	>	* initial phase number 0, and no parent. Any thread using this
308	>	* phaser will need to first register for it.
309		*/
310		public Phaser() {
311	<	state = new AtomicLong(stateFor(0, 0, 0));
311	>	this(null);
312		}
313
314		/**
315	<	* Creates a new Phaser with the given numbers of registered
316	<	* unarrived parties and initial phase number 0.
317	<	* @param parties the number of parties required to trip barrier.
315	>	* Creates a new phaser with the given numbers of registered
316	>	* unarrived parties, initial phase number 0, and no parent.
317	>	*
318	>	* @param parties the number of parties required to trip barrier
319		* @throws IllegalArgumentException if parties less than zero
320	<	* or greater than the maximum number of parties supported.
320	>	* or greater than the maximum number of parties supported
321		*/
322		public Phaser(int parties) {
323	+	this(null, parties);
324	+	}
325	+
326	+	/**
327	+	* Creates a new phaser with the given parent, without any
328	+	* initially registered parties. If parent is non-null this phaser
329	+	* is registered with the parent and its initial phase number is
330	+	* the same as that of parent phaser.
331	+	*
332	+	* @param parent the parent phaser
333	+	*/
334	+	public Phaser(Phaser parent) {
335	+	int phase = 0;
336	+	this.parent = parent;
337	+	if (parent != null) {
338	+	this.root = parent.root;
339	+	phase = parent.register();
340	+	}
341	+	else
342	+	this.root = this;
343	+	this.state = trippedStateFor(phase, 0);
344	+	}
345	+
346	+	/**
347	+	* Creates a new phaser with the given parent and numbers of
348	+	* registered unarrived parties. If parent is non-null, this phaser
349	+	* is registered with the parent and its initial phase number is
350	+	* the same as that of parent phaser.
351	+	*
352	+	* @param parent the parent phaser
353	+	* @param parties the number of parties required to trip barrier
354	+	* @throws IllegalArgumentException if parties less than zero
355	+	* or greater than the maximum number of parties supported
356	+	*/
357	+	public Phaser(Phaser parent, int parties) {
358		if (parties < 0 || parties > ushortMask)
359		throw new IllegalArgumentException("Illegal number of parties");
360	<	state = new AtomicLong(stateFor(0, parties, parties));
360	>	int phase = 0;
361	>	this.parent = parent;
362	>	if (parent != null) {
363	>	this.root = parent.root;
364	>	phase = parent.register();
365	>	}
366	>	else
367	>	this.root = this;
368	>	this.state = trippedStateFor(phase, parties);
369		}
370
371		/**
372		* Adds a new unarrived party to this phaser.
373	<	* @return the current barrier phase number upon registration
373	>	*
374	>	* @return the arrival phase number to which this registration applied
375	>	* @throws IllegalStateException if attempting to register more
376	>	* than the maximum supported number of parties
377	>	*/
378	>	public int register() {
379	>	return doRegister(1);
380	>	}
381	>
382	>	/**
383	>	* Adds the given number of new unarrived parties to this phaser.
384	>	*
385	>	* @param parties the number of parties required to trip barrier
386	>	* @return the arrival phase number to which this registration applied
387		* @throws IllegalStateException if attempting to register more
388	<	* than the maximum supported number of parties.
388	>	* than the maximum supported number of parties
389		*/
390	<	public int register() { // increment both parties and unarrived
391	<	final AtomicLong state = this.state;
390	>	public int bulkRegister(int parties) {
391	>	if (parties < 0)
392	>	throw new IllegalArgumentException();
393	>	if (parties == 0)
394	>	return getPhase();
395	>	return doRegister(parties);
396	>	}
397	>
398	>	/**
399	>	* Shared code for register, bulkRegister
400	>	*/
401	>	private int doRegister(int registrations) {
402	>	int phase;
403		for (;;) {
404	<	long s = state.get();
405	<	int phase = phaseOf(s);
406	<	int parties = partiesOf(s) + 1;
407	<	int unarrived = unarrivedOf(s) + 1;
404	>	long s = getReconciledState();
405	>	phase = phaseOf(s);
406	>	int unarrived = unarrivedOf(s) + registrations;
407	>	int parties = partiesOf(s) + registrations;
408	>	if (phase < 0)
409	>	break;
410		if (parties > ushortMask || unarrived > ushortMask)
411	<	throw badBounds(parties, unarrived);
412	<	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
413	<	return phase;
411	>	throw new IllegalStateException(badBounds(parties, unarrived));
412	>	if (phase == phaseOf(root.state) &&
413	>	casState(s, stateFor(phase, parties, unarrived)))
414	>	break;
415		}
416	+	return phase;
417		}
418
419		/**
420		* Arrives at the barrier, but does not wait for others.  (You can
421		* in turn wait for others via {@link #awaitAdvance}).
422		*
423	<	* @return the current barrier phase number upon entry to
424	<	* this method, or a negative value if terminated;
425	<	* @throws IllegalStateException if the number of unarrived
224	<	* parties would become negative.
423	>	* @return the arrival phase number, or a negative value if terminated
424	>	* @throws IllegalStateException if not terminated and the number
425	>	* of unarrived parties would become negative
426		*/
427	<	public int arrive() { // decrement unarrived. If zero, trip
428	<	final AtomicLong state = this.state;
427	>	public int arrive() {
428	>	int phase;
429		for (;;) {
430	<	long s = state.get();
431	<	int phase = phaseOf(s);
430	>	long s = state;
431	>	phase = phaseOf(s);
432	>	if (phase < 0)
433	>	break;
434		int parties = partiesOf(s);
435		int unarrived = unarrivedOf(s) - 1;
436	<	if (unarrived < 0)
437	<	throw badBounds(parties, unarrived);
438	<	if (unarrived == 0 && phase >= 0) {
236	<	trip(phase, parties);
237	<	return phase;
436	>	if (unarrived > 0) {        // Not the last arrival
437	>	if (casState(s, s - 1)) // s-1 adds one arrival
438	>	break;
439		}
440	<	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
441	<	return phase;
440	>	else if (unarrived == 0) {  // the last arrival
441	>	Phaser par = parent;
442	>	if (par == null) {      // directly trip
443	>	if (casState
444	>	(s,
445	>	trippedStateFor(onAdvance(phase, parties) ? -1 :
446	>	((phase + 1) & phaseMask), parties))) {
447	>	releaseWaiters(phase);
448	>	break;
449	>	}
450	>	}
451	>	else {                  // cascade to parent
452	>	if (casState(s, s - 1)) { // zeroes unarrived
453	>	par.arrive();
454	>	reconcileState();
455	>	break;
456	>	}
457	>	}
458	>	}
459	>	else if (phase != phaseOf(root.state)) // or if unreconciled
460	>	reconcileState();
461	>	else
462	>	throw new IllegalStateException(badBounds(parties, unarrived));
463		}
464	+	return phase;
465		}
466
467		/**
468	<	* Arrives at the barrier, and deregisters from it, without
469	<	* waiting for others.
468	>	* Arrives at the barrier and deregisters from it without waiting
469	>	* for others. Deregistration reduces the number of parties
470	>	* required to trip the barrier in future phases.  If this phaser
471	>	* has a parent, and deregistration causes this phaser to have
472	>	* zero parties, this phaser also arrives at and is deregistered
473	>	* from its parent.
474		*
475	<	* @return the current barrier phase number upon entry to
476	<	* this method, or a negative value if terminated;
477	<	* @throws IllegalStateException if the number of registered or
478	<	* unarrived parties would become negative.
479	<	*/
480	<	public int arriveAndDeregister() { // Same as arrive, plus decrement parties
481	<	final AtomicLong state = this.state;
475	>	* @return the arrival phase number, or a negative value if terminated
476	>	* @throws IllegalStateException if not terminated and the number
477	>	* of registered or unarrived parties would become negative
478	>	*/
479	>	public int arriveAndDeregister() {
480	>	// similar code to arrive, but too different to merge
481	>	Phaser par = parent;
482	>	int phase;
483		for (;;) {
484	<	long s = state.get();
485	<	int phase = phaseOf(s);
484	>	long s = state;
485	>	phase = phaseOf(s);
486	>	if (phase < 0)
487	>	break;
488		int parties = partiesOf(s) - 1;
489		int unarrived = unarrivedOf(s) - 1;
490	<	if (parties < 0 || unarrived < 0)
491	<	throw badBounds(parties, unarrived);
492	<	if (unarrived == 0 && phase >= 0) {
493	<	trip(phase, parties);
494	<	return phase;
490	>	if (parties >= 0) {
491	>	if (unarrived > 0 || (unarrived == 0 && par != null)) {
492	>	if (casState
493	>	(s,
494	>	stateFor(phase, parties, unarrived))) {
495	>	if (unarrived == 0) {
496	>	par.arriveAndDeregister();
497	>	reconcileState();
498	>	}
499	>	break;
500	>	}
501	>	continue;
502	>	}
503	>	if (unarrived == 0) {
504	>	if (casState
505	>	(s,
506	>	trippedStateFor(onAdvance(phase, parties) ? -1 :
507	>	((phase + 1) & phaseMask), parties))) {
508	>	releaseWaiters(phase);
509	>	break;
510	>	}
511	>	continue;
512	>	}
513	>	if (par != null && phase != phaseOf(root.state)) {
514	>	reconcileState();
515	>	continue;
516	>	}
517		}
518	<	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
267	<	return phase;
518	>	throw new IllegalStateException(badBounds(parties, unarrived));
519		}
520	+	return phase;
521		}
522
523		/**
524	<	* Arrives at the barrier and awaits others. Unlike other arrival
525	<	* methods, this method returns the arrival index of the
526	<	* caller. The caller tripping the barrier returns zero, the
527	<	* previous caller 1, and so on.
528	<	* @return the arrival index
529	<	* @throws IllegalStateException if the number of unarrived
530	<	* parties would become negative.
524	>	* Arrives at the barrier and awaits others. Equivalent in effect
525	>	* to {@code awaitAdvance(arrive())}.  If you need to await with
526	>	* interruption or timeout, you can arrange this with an analogous
527	>	* construction using one of the other forms of the awaitAdvance
528	>	* method.  If instead you need to deregister upon arrival use
529	>	* {@code arriveAndDeregister}.
530	>	*
531	>	* @return the arrival phase number, or a negative number if terminated
532	>	* @throws IllegalStateException if not terminated and the number
533	>	* of unarrived parties would become negative
534		*/
535		public int arriveAndAwaitAdvance() {
536	<	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	<	}
536	>	return awaitAdvance(arrive());
537		}
538
539		/**
540	<	* Awaits the phase of the barrier to advance from the given
541	<	* value, or returns immediately if this barrier is terminated.
542	<	* @param phase the phase on entry to this method
543	<	* @return the phase on exit from this method
540	>	* Awaits the phase of the barrier to advance from the given phase
541	>	* value, returning immediately if the current phase of the
542	>	* barrier is not equal to the given phase value or this barrier
543	>	* is terminated.
544	>	*
545	>	* @param phase an arrival phase number, or negative value if
546	>	* terminated; this argument is normally the value returned by a
547	>	* previous call to {@code arrive} or its variants
548	>	* @return the next arrival phase number, or a negative value
549	>	* if terminated or argument is negative
550		*/
551		public int awaitAdvance(int phase) {
552		if (phase < 0)
553		return phase;
554	<	Thread current = Thread.currentThread();
555	<	if (current instanceof ForkJoinWorkerThread)
556	<	return helpingWait(phase);
557	<	if (untimedWait(current, phase, false))
558	<	current.interrupt();
559	<	return phaseOf(state.get());
554	>	long s = getReconciledState();
555	>	int p = phaseOf(s);
556	>	if (p != phase)
557	>	return p;
558	>	if (unarrivedOf(s) == 0 && parent != null)
559	>	parent.awaitAdvance(phase);
560	>	// Fall here even if parent waited, to reconcile and help release
561	>	return untimedWait(phase);
562		}
563
564		/**
565	<	* Awaits the phase of the barrier to advance from the given
566	<	* value, or returns immediately if this barrier is terminated, or
567	<	* throws InterruptedException if interrupted while waiting.
568	<	* @param phase the phase on entry to this method
569	<	* @return the phase on exit from this method
565	>	* Awaits the phase of the barrier to advance from the given phase
566	>	* value, throwing {@code InterruptedException} if interrupted while
567	>	* waiting, or returning immediately if the current phase of the
568	>	* barrier is not equal to the given phase value or this barrier
569	>	* is terminated.
570	>	*
571	>	* @param phase an arrival phase number, or negative value if
572	>	* terminated; this argument is normally the value returned by a
573	>	* previous call to {@code arrive} or its variants
574	>	* @return the next arrival phase number, or a negative value
575	>	* if terminated or argument is negative
576		* @throws InterruptedException if thread interrupted while waiting
577		*/
578	<	public int awaitAdvanceInterruptibly(int phase) throws InterruptedException {
578	>	public int awaitAdvanceInterruptibly(int phase)
579	>	throws InterruptedException {
580		if (phase < 0)
581		return phase;
582	<	Thread current = Thread.currentThread();
583	<	if (current instanceof ForkJoinWorkerThread)
584	<	return helpingWait(phase);
585	<	else if (Thread.interrupted() || untimedWait(current, phase, true))
586	<	throw new InterruptedException();
587	<	else
588	<	return phaseOf(state.get());
582	>	long s = getReconciledState();
583	>	int p = phaseOf(s);
584	>	if (p != phase)
585	>	return p;
586	>	if (unarrivedOf(s) == 0 && parent != null)
587	>	parent.awaitAdvanceInterruptibly(phase);
588	>	return interruptibleWait(phase);
589		}
590
591		/**
592	<	* Awaits the phase of the barrier to advance from the given value
593	<	* or the given timeout elapses, or returns immediately if this
594	<	* barrier is terminated.
595	<	* @param phase the phase on entry to this method
596	<	* @return the phase on exit from this method
592	>	* Awaits the phase of the barrier to advance from the given phase
593	>	* value or the given timeout to elapse, throwing
594	>	* {@code InterruptedException} if interrupted while waiting, or
595	>	* returning immediately if the current phase of the barrier is not
596	>	* equal to the given phase value or this barrier is terminated.
597	>	*
598	>	* @param phase an arrival phase number, or negative value if
599	>	* terminated; this argument is normally the value returned by a
600	>	* previous call to {@code arrive} or its variants
601	>	* @param timeout how long to wait before giving up, in units of
602	>	*        {@code unit}
603	>	* @param unit a {@code TimeUnit} determining how to interpret the
604	>	*        {@code timeout} parameter
605	>	* @return the next arrival phase number, or a negative value
606	>	* if terminated or argument is negative
607		* @throws InterruptedException if thread interrupted while waiting
608		* @throws TimeoutException if timed out while waiting
609		*/
610	<	public int awaitAdvanceInterruptibly(int phase, long timeout, TimeUnit unit)
610	>	public int awaitAdvanceInterruptibly(int phase,
611	>	long timeout, TimeUnit unit)
612		throws InterruptedException, TimeoutException {
613		if (phase < 0)
614		return phase;
615	<	long nanos = unit.toNanos(timeout);
616	<	Thread current = Thread.currentThread();
617	<	if (current instanceof ForkJoinWorkerThread)
618	<	return timedHelpingWait(phase, nanos);
619	<	timedWait(current, phase, nanos);
620	<	return phaseOf(state.get());
615	>	long s = getReconciledState();
616	>	int p = phaseOf(s);
617	>	if (p != phase)
618	>	return p;
619	>	if (unarrivedOf(s) == 0 && parent != null)
620	>	parent.awaitAdvanceInterruptibly(phase, timeout, unit);
621	>	return timedWait(phase, unit.toNanos(timeout));
622		}
623
624		/**
625		* Forces this barrier to enter termination state. Counts of
626	<	* arrived and registered parties are unaffected. This method may
627	<	* be useful for coordinating recovery after one or more tasks
628	<	* encounter unexpected exceptions.
626	>	* arrived and registered parties are unaffected. If this phaser
627	>	* has a parent, it too is terminated. This method may be useful
628	>	* for coordinating recovery after one or more tasks encounter
629	>	* unexpected exceptions.
630		*/
631		public void forceTermination() {
365	–	final AtomicLong state = this.state;
632		for (;;) {
633	<	long s = state.get();
633	>	long s = getReconciledState();
634		int phase = phaseOf(s);
635		int parties = partiesOf(s);
636		int unarrived = unarrivedOf(s);
637		if (phase < 0 ||
638	<	state.compareAndSet(s, stateFor(-1, parties, unarrived))) {
639	<	if (head.get() != null)
640	<	releaseWaiters(-1);
638	>	casState(s, stateFor(-1, parties, unarrived))) {
639	>	releaseWaiters(0);
640	>	releaseWaiters(1);
641	>	if (parent != null)
642	>	parent.forceTermination();
643		return;
644		}
645		}
646		}
647
648		/**
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	–	/**
649		* Returns the current phase number. The maximum phase number is
650	<	* <tt>Integer.MAX_VALUE</tt>, after which it restarts at
650	>	* {@code Integer.MAX_VALUE}, after which it restarts at
651		* zero. Upon termination, the phase number is negative.
652	+	*
653		* @return the phase number, or a negative value if terminated
654		*/
655	<	public int getPhase() {
656	<	return phaseOf(state.get());
655	>	public final int getPhase() {
656	>	return phaseOf(getReconciledState());
657		}
658
659		/**
660		* Returns the number of parties registered at this barrier.
661	+	*
662		* @return the number of parties
663		*/
664		public int getRegisteredParties() {
665	<	return partiesOf(state.get());
665	>	return partiesOf(state);
666		}
667
668		/**
669		* Returns the number of parties that have arrived at the current
670		* phase of this barrier.
671	+	*
672		* @return the number of arrived parties
673		*/
674		public int getArrivedParties() {
675	<	return arrivedOf(state.get());
675	>	return arrivedOf(state);
676		}
677
678		/**
679		* Returns the number of registered parties that have not yet
680		* arrived at the current phase of this barrier.
681	+	*
682		* @return the number of unarrived parties
683		*/
684		public int getUnarrivedParties() {
685	<	return unarrivedOf(state.get());
685	>	return unarrivedOf(state);
686	>	}
687	>
688	>	/**
689	>	* Returns the parent of this phaser, or {@code null} if none.
690	>	*
691	>	* @return the parent of this phaser, or {@code null} if none
692	>	*/
693	>	public Phaser getParent() {
694	>	return parent;
695	>	}
696	>
697	>	/**
698	>	* Returns the root ancestor of this phaser, which is the same as
699	>	* this phaser if it has no parent.
700	>	*
701	>	* @return the root ancestor of this phaser
702	>	*/
703	>	public Phaser getRoot() {
704	>	return root;
705		}
706
707		/**
708	<	* Returns true if this barrier has been terminated.
709	<	* @return true if this barrier has been terminated
708	>	* Returns {@code true} if this barrier has been terminated.
709	>	*
710	>	* @return {@code true} if this barrier has been terminated
711		*/
712		public boolean isTerminated() {
713	<	return phaseOf(state.get()) < 0;
713	>	return getPhase() < 0;
714		}
715
716		/**
717		* Overridable method to perform an action upon phase advance, and
718		* to control termination. This method is invoked whenever the
719		* barrier is tripped (and thus all other waiting parties are
720	<	* dormant). If it returns true, then, rather than advance the
721	<	* phase number, this barrier will be set to a final termination
722	<	* state, and subsequent calls to <tt>isTerminated</tt> will
723	<	* return true.
720	>	* dormant). If it returns {@code true}, then, rather than advance
721	>	* the phase number, this barrier will be set to a final
722	>	* termination state, and subsequent calls to {@link #isTerminated}
723	>	* will return true.
724		*
725	<	* <p> The default version returns true when the number of
725	>	* <p>The default version returns {@code true} when the number of
726		* registered parties is zero. Normally, overrides that arrange
727		* termination for other reasons should also preserve this
728		* property.
729		*
730	+	* <p>You may override this method to perform an action with side
731	+	* effects visible to participating tasks, but it is in general
732	+	* only sensible to do so in designs where all parties register
733	+	* before any arrive, and all {@link #awaitAdvance} at each phase.
734	+	* Otherwise, you cannot ensure lack of interference from other
735	+	* parties during the invocation of this method.
736	+	*
737		* @param phase the phase number on entering the barrier
738	<	* @param registeredParties the current number of registered
739	<	* parties.
458	<	* @return true if this barrier should terminate
738	>	* @param registeredParties the current number of registered parties
739	>	* @return {@code true} if this barrier should terminate
740		*/
741		protected boolean onAdvance(int phase, int registeredParties) {
742		return registeredParties <= 0;
743		}
744
745		/**
746	<	* Returns a string identifying this barrier, as well as its
746	>	* Returns a string identifying this phaser, as well as its
747		* state.  The state, in brackets, includes the String {@code
748	<	* "phase ="} followed by the phase number, {@code "parties ="}
748	>	* "phase = "} followed by the phase number, {@code "parties = "}
749		* followed by the number of registered parties, and {@code
750	<	* "arrived ="} followed by the number of arrived parties
750	>	* "arrived = "} followed by the number of arrived parties.
751		*
752		* @return a string identifying this barrier, as well as its state
753		*/
754		public String toString() {
755	<	long s = state.get();
756	<	return super.toString() + "[phase = " + phaseOf(s) + " parties = " + partiesOf(s) + " arrived = " + arrivedOf(s) + "]";
755	>	long s = getReconciledState();
756	>	return super.toString() +
757	>	"[phase = " + phaseOf(s) +
758	>	" parties = " + partiesOf(s) +
759	>	" arrived = " + arrivedOf(s) + "]";
760		}
761
762	<	// methods for tripping and waiting
762	>	// methods for waiting
763
764		/**
765	<	* Advance the current phase (or terminate)
765	>	* Wait nodes for Treiber stack representing wait queue
766		*/
767	<	private void trip(int phase, int parties) {
768	<	int next = onAdvance(phase, parties)? -1 : ((phase + 1) & phaseMask);
769	<	state.set(stateFor(next, parties, parties));
770	<	if (head.get() != null)
771	<	releaseWaiters(next);
772	<	}
773	<
774	<	private int helpingWait(int phase) {
775	<	final AtomicLong state = this.state;
776	<	int p;
777	<	while ((p = phaseOf(state.get())) == phase) {
778	<	ForkJoinTask<?> t = ForkJoinWorkerThread.pollTask();
779	<	if (t != null) {
780	<	if ((p = phaseOf(state.get())) == phase)
781	<	t.exec();
782	<	else {   // push task and exit if barrier advanced
783	<	t.fork();
784	<	break;
785	<	}
767	>	static final class QNode implements ForkJoinPool.ManagedBlocker {
768	>	final Phaser phaser;
769	>	final int phase;
770	>	final long startTime;
771	>	final long nanos;
772	>	final boolean timed;
773	>	final boolean interruptible;
774	>	volatile boolean wasInterrupted = false;
775	>	volatile Thread thread; // nulled to cancel wait
776	>	QNode next;
777	>	QNode(Phaser phaser, int phase, boolean interruptible,
778	>	boolean timed, long startTime, long nanos) {
779	>	this.phaser = phaser;
780	>	this.phase = phase;
781	>	this.timed = timed;
782	>	this.interruptible = interruptible;
783	>	this.startTime = startTime;
784	>	this.nanos = nanos;
785	>	thread = Thread.currentThread();
786	>	}
787	>	public boolean isReleasable() {
788	>	return (thread == null ||
789	>	phaser.getPhase() != phase ||
790	>	(interruptible && wasInterrupted) ||
791	>	(timed && (nanos - (System.nanoTime() - startTime)) <= 0));
792	>	}
793	>	public boolean block() {
794	>	if (Thread.interrupted()) {
795	>	wasInterrupted = true;
796	>	if (interruptible)
797	>	return true;
798	>	}
799	>	if (!timed)
800	>	LockSupport.park(this);
801	>	else {
802	>	long waitTime = nanos - (System.nanoTime() - startTime);
803	>	if (waitTime <= 0)
804	>	return true;
805	>	LockSupport.parkNanos(this, waitTime);
806		}
807	+	return isReleasable();
808		}
809	<	return p;
810	<	}
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();
809	>	void signal() {
810	>	Thread t = thread;
811		if (t != null) {
812	<	if ((p = phaseOf(state.get())) == phase)
813	<	t.exec();
814	<	else {   // push task and exit if barrier advanced
815	<	t.fork();
816	<	break;
812	>	thread = null;
813	>	LockSupport.unpark(t);
814	>	}
815	>	}
816	>	boolean doWait() {
817	>	if (thread != null) {
818	>	try {
819	>	ForkJoinPool.managedBlock(this, false);
820	>	} catch (InterruptedException ie) {
821		}
822		}
823	+	return wasInterrupted;
824		}
825	<	return p;
825	>
826		}
827
828		/**
829	<	* 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.
829	>	* Removes and signals waiting threads from wait queue.
830		*/
831	<	static final class QNode {
832	<	QNode next;
833	<	volatile Thread thread; // nulled to cancel wait
834	<	final int phase;
835	<	QNode(Thread t, int c) {
836	<	thread = t;
545	<	phase = c;
546	<	}
547	<	}
548	<
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	<	}
831	>	private void releaseWaiters(int phase) {
832	>	AtomicReference<QNode> head = queueFor(phase);
833	>	QNode q;
834	>	while ((q = head.get()) != null) {
835	>	if (head.compareAndSet(q, q.next))
836	>	q.signal();
837		}
838		}
839
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	–
840		/**
841	<	* The number of times to spin before blocking in untimed waits.
842	<	* This is greater than timed value because untimed waits spin
843	<	* faster since they don't need to check times on each spin.
841	>	* Tries to enqueue given node in the appropriate wait queue.
842	>	*
843	>	* @return true if successful
844		*/
845	<	static final int maxUntimedSpins = maxTimedSpins * 32;
845	>	private boolean tryEnqueue(QNode node) {
846	>	AtomicReference<QNode> head = queueFor(node.phase);
847	>	return head.compareAndSet(node.next = head.get(), node);
848	>	}
849
850		/**
851	<	* The number of nanoseconds for which it is faster to spin
852	<	* rather than to use timed park. A rough estimate suffices.
851	>	* Enqueues node and waits unless aborted or signalled.
852	>	*
853	>	* @return current phase
854		*/
855	<	static final long spinForTimeoutThreshold = 1000L;
855	>	private int untimedWait(int phase) {
856	>	QNode node = null;
857	>	boolean queued = false;
858	>	boolean interrupted = false;
859	>	int p;
860	>	while ((p = getPhase()) == phase) {
861	>	if (Thread.interrupted())
862	>	interrupted = true;
863	>	else if (node == null)
864	>	node = new QNode(this, phase, false, false, 0, 0);
865	>	else if (!queued)
866	>	queued = tryEnqueue(node);
867	>	else
868	>	interrupted = node.doWait();
869	>	}
870	>	if (node != null)
871	>	node.thread = null;
872	>	releaseWaiters(phase);
873	>	if (interrupted)
874	>	Thread.currentThread().interrupt();
875	>	return p;
876	>	}
877
878		/**
879	<	* Enqueues node and waits unless aborted or signalled.
879	>	* Interruptible version
880	>	* @return current phase
881		*/
882	<	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;
882	>	private int interruptibleWait(int phase) throws InterruptedException {
883		QNode node = null;
884		boolean queued = false;
885	<	int spins = maxUntimedSpins;
886	<	while (phaseOf(state.get()) == currentPhase) {
887	<	QNode h;
888	<	if (node != null && queued) {
889	<	if (node.thread != null) {
890	<	LockSupport.park();
891	<	if (Thread.interrupted()) {
892	<	wasInterrupted = true;
893	<	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);
885	>	boolean interrupted = false;
886	>	int p;
887	>	while ((p = getPhase()) == phase && !interrupted) {
888	>	if (Thread.interrupted())
889	>	interrupted = true;
890	>	else if (node == null)
891	>	node = new QNode(this, phase, true, false, 0, 0);
892	>	else if (!queued)
893	>	queued = tryEnqueue(node);
894		else
895	<	--spins;
895	>	interrupted = node.doWait();
896		}
897		if (node != null)
898		node.thread = null;
899	<	return wasInterrupted;
899	>	if (p != phase || (p = getPhase()) != phase)
900	>	releaseWaiters(phase);
901	>	if (interrupted)
902	>	throw new InterruptedException();
903	>	return p;
904		}
905
906		/**
907	<	* Messier timeout version
907	>	* Timeout version.
908	>	* @return current phase
909		*/
910	<	private void timedWait(Thread thread, int currentPhase, long nanos)
910	>	private int timedWait(int phase, long nanos)
911		throws InterruptedException, TimeoutException {
912	<	final AtomicReference<QNode> head = this.head;
641	<	final AtomicLong state = this.state;
642	<	long lastTime = System.nanoTime();
912	>	long startTime = System.nanoTime();
913		QNode node = null;
914		boolean queued = false;
915	<	int spins = maxTimedSpins;
916	<	while (phaseOf(state.get()) == currentPhase) {
917	<	QNode h;
918	<	long now = System.nanoTime();
919	<	nanos -= now - lastTime;
920	<	lastTime = now;
921	<	if (nanos <= 0) {
922	<	if (node != null)
923	<	node.thread = null;
924	<	if (phaseOf(state.get()) == currentPhase)
925	<	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);
915	>	boolean interrupted = false;
916	>	int p;
917	>	while ((p = getPhase()) == phase && !interrupted) {
918	>	if (Thread.interrupted())
919	>	interrupted = true;
920	>	else if (nanos - (System.nanoTime() - startTime) <= 0)
921	>	break;
922	>	else if (node == null)
923	>	node = new QNode(this, phase, true, true, startTime, nanos);
924	>	else if (!queued)
925	>	queued = tryEnqueue(node);
926		else
927	<	--spins;
927	>	interrupted = node.doWait();
928		}
929		if (node != null)
930		node.thread = null;
931	+	if (p != phase || (p = getPhase()) != phase)
932	+	releaseWaiters(phase);
933	+	if (interrupted)
934	+	throw new InterruptedException();
935	+	if (p == phase)
936	+	throw new TimeoutException();
937	+	return p;
938		}
939
940	+	// Unsafe mechanics
941	+
942	+	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
943	+	private static final long stateOffset =
944	+	objectFieldOffset("state", Phaser.class);
945	+
946	+	private final boolean casState(long cmp, long val) {
947	+	return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val);
948	+	}
949	+
950	+	private static long objectFieldOffset(String field, Class<?> klazz) {
951	+	try {
952	+	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
953	+	} catch (NoSuchFieldException e) {
954	+	// Convert Exception to corresponding Error
955	+	NoSuchFieldError error = new NoSuchFieldError(field);
956	+	error.initCause(e);
957	+	throw error;
958	+	}
959	+	}
960	+
961	+	/**
962	+	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
963	+	* Replace with a simple call to Unsafe.getUnsafe when integrating
964	+	* into a jdk.
965	+	*
966	+	* @return a sun.misc.Unsafe
967	+	*/
968	+	private static sun.misc.Unsafe getUnsafe() {
969	+	try {
970	+	return sun.misc.Unsafe.getUnsafe();
971	+	} catch (SecurityException se) {
972	+	try {
973	+	return java.security.AccessController.doPrivileged
974	+	(new java.security
975	+	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
976	+	public sun.misc.Unsafe run() throws Exception {
977	+	java.lang.reflect.Field f = sun.misc
978	+	.Unsafe.class.getDeclaredField("theUnsafe");
979	+	f.setAccessible(true);
980	+	return (sun.misc.Unsafe) f.get(null);
981	+	}});
982	+	} catch (java.security.PrivilegedActionException e) {
983	+	throw new RuntimeException("Could not initialize intrinsics",
984	+	e.getCause());
985	+	}
986	+	}
987	+	}
988		}

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