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Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.2 by jsr166, Fri Jul 25 18:10:41 2008 UTC vs.
Revision 1.36 by dl, Sun Aug 23 20:12:24 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.
29	<	*
30	<	* <li> Each generation has an associated phase value, starting at
31	<	* zero, and advancing when all parties reach the barrier (wrapping
32	<	* around to zero after reaching <tt>Integer.MAX_VALUE</tt>).
33	<	*
34	<	* <li> Like a CyclicBarrier, a Phaser may be repeatedly awaited.
35	<	* Method <tt>arriveAndAwaitAdvance</tt> has effect analogous to
36	<	* <tt>CyclicBarrier.await</tt>.  However, Phasers separate two
37	<	* aspects of coordination, that may be invoked independently:
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 number. The phase
35	>	* number starts at zero, amd advances when all parties arrive at the
36	>	* barrier, wrapping around to zero after reaching {@code
37	>	* Integer.MAX_VALUE}.
38	>	*
39	>	* <li> Like a {@code CyclicBarrier}, a phaser may be repeatedly
40	>	* awaited.  Method {@link #arriveAndAwaitAdvance} has effect
41	>	* analogous to {@link java.util.concurrent.CyclicBarrier#await
42	>	* CyclicBarrier.await}.  However, phasers separate two aspects of
43	>	* coordination, which may also be invoked independently:
44		*
45		* <ul>
46		*
47	<	*   <li> Arriving at a barrier. Methods <tt>arrive</tt> and
48	<	*       <tt>arriveAndDeregister</tt> do not block, but return
49	<	*       the phase value on entry to the method.
50	<	*
51	<	*   <li> Awaiting others. Method <tt>awaitAdvance</tt> requires an
52	<	*       argument indicating the entry phase, and returns when the
53	<	*       barrier advances to a new phase.
47	>	*   <li> Arriving at a barrier. Methods {@link #arrive} and
48	>	*       {@link #arriveAndDeregister} do not block, but return
49	>	*       an associated <em>arrival phase number</em>;
50	>	*       that is, the phase number of the barrier to which the
51	>	*       arrival applied.
52	>	*
53	>	*   <li> Awaiting others. Method {@link #awaitAdvance} requires an
54	>	*       argument indicating an arrival phase number, and returns
55	>	*       when the barrier advances to a new phase.
56		* </ul>
57		*
48	–	*
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	>	* <li>The current state of a phaser may be monitored.  At any given
94	>	* moment there are {@link #getRegisteredParties}, where {@link
95	>	* #getArrivedParties} have arrived at the current phase ({@link
96	>	* #getPhase}). When the remaining {@link #getUnarrivedParties})
97	>	* arrive, the phase advances. Method {@link #toString} returns
98	>	* snapshots of these state queries in a form convenient for
99	>	* informal monitoring.
100		*
101		* </ul>
102		*
103	<	* <p><b>Sample usage:</b>
103	>	* <p><b>Sample usages:</b>
104		*
105	<	* <p>[todo: non-FJ example]
105	>	* <p>A {@code Phaser} may be used instead of a {@code CountDownLatch}
106	>	* to control a one-shot action serving a variable number of
107	>	* parties. The typical idiom is for the method setting this up to
108	>	* first register, then start the actions, then deregister, as in:
109	>	*
110	>	*  <pre> {@code
111	>	* void runTasks(List<Runnable> tasks) {
112	>	*   final Phaser phaser = new Phaser(1); // "1" to register self
113	>	*   // create and start threads
114	>	*   for (Runnable task : tasks) {
115	>	*     phaser.register();
116	>	*     new Thread() {
117	>	*       public void run() {
118	>	*         phaser.arriveAndAwaitAdvance(); // await all creation
119	>	*         task.run();
120	>	*       }
121	>	*     }.start();
122	>	*   }
123		*
124	<	* <p> A Phaser may be used to support a style of programming in
125	<	* which a task waits for others to complete, without otherwise
126	<	* needing to keep track of which tasks it is waiting for. This is
127	<	* similar to the "sync" construct in Cilk and "clocks" in X10.
128	<	* Special constructions based on such barriers are available using
129	<	* the <tt>LinkedAsyncAction</tt> and <tt>CyclicAction</tt> classes,
130	<	* but they can be useful in other contexts as well.  For a simple
131	<	* (but not very useful) example, here is a variant of Fibonacci:
132	<	*
133	<	* <pre>
134	<	* class BarrierFibonacci extends RecursiveAction {
135	<	*   int argument, result;
136	<	*   final Phaser parentBarrier;
137	<	*   BarrierFibonacci(int n, Phaser parentBarrier) {
138	<	*     this.argument = n;
139	<	*     this.parentBarrier = parentBarrier;
140	<	*     parentBarrier.register();
124	>	*   // allow threads to start and deregister self
125	>	*   phaser.arriveAndDeregister();
126	>	* }}</pre>
127	>	*
128	>	* <p>One way to cause a set of threads to repeatedly perform actions
129	>	* for a given number of iterations is to override {@code onAdvance}:
130	>	*
131	>	*  <pre> {@code
132	>	* void startTasks(List<Runnable> tasks, final int iterations) {
133	>	*   final Phaser phaser = new Phaser() {
134	>	*     public boolean onAdvance(int phase, int registeredParties) {
135	>	*       return phase >= iterations || registeredParties == 0;
136	>	*     }
137	>	*   };
138	>	*   phaser.register();
139	>	*   for (Runnable task : tasks) {
140	>	*     phaser.register();
141	>	*     new Thread() {
142	>	*       public void run() {
143	>	*         do {
144	>	*           task.run();
145	>	*           phaser.arriveAndAwaitAdvance();
146	>	*         } while(!phaser.isTerminated();
147	>	*       }
148	>	*     }.start();
149		*   }
150	<	*   protected void compute() {
151	<	*     int n = argument;
152	<	*     if (n &lt;= 1)
153	<	*        result = n;
154	<	*     else {
155	<	*        Phaser childBarrier = new Phaser(1);
156	<	*        BarrierFibonacci f1 = new BarrierFibonacci(n - 1, childBarrier);
157	<	*        BarrierFibonacci f2 = new BarrierFibonacci(n - 2, childBarrier);
158	<	*        f1.fork();
159	<	*        f2.fork();
160	<	*        childBarrier.arriveAndAwait();
161	<	*        result = f1.result + f2.result;
150	>	*   phaser.arriveAndDeregister(); // deregister self, don't wait
151	>	* }}</pre>
152	>	*
153	>	* <p>To create a set of tasks using a tree of phasers,
154	>	* you could use code of the following form, assuming a
155	>	* Task class with a constructor accepting a phaser that
156	>	* it registers for upon construction:
157	>	*  <pre> {@code
158	>	* void build(Task[] actions, int lo, int hi, Phaser b) {
159	>	*   int step = (hi - lo) / TASKS_PER_PHASER;
160	>	*   if (step > 1) {
161	>	*     int i = lo;
162	>	*     while (i < hi) {
163	>	*       int r = Math.min(i + step, hi);
164	>	*       build(actions, i, r, new Phaser(b));
165	>	*       i = r;
166		*     }
167	<	*     parentBarrier.arriveAndDeregister();
167	>	*   } else {
168	>	*     for (int i = lo; i < hi; ++i)
169	>	*       actions[i] = new Task(b);
170	>	*       // assumes new Task(b) performs b.register()
171		*   }
172		* }
173	+	* // .. initially called, for n tasks via
174	+	* build(new Task[n], 0, n, new Phaser());}</pre>
175	+	*
176	+	* The best value of {@code TASKS_PER_PHASER} depends mainly on
177	+	* expected barrier synchronization rates. A value as low as four may
178	+	* be appropriate for extremely small per-barrier task bodies (thus
179	+	* high rates), or up to hundreds for extremely large ones.
180	+	*
181		* </pre>
182		*
183		* <p><b>Implementation notes</b>: This implementation restricts the
184	<	* maximum number of parties to 65535. Attempts to register
185	<	* additional parties result in IllegalStateExceptions.
184	>	* maximum number of parties to 65535. Attempts to register additional
185	>	* parties result in {@code IllegalStateException}. However, you can and
186	>	* should create tiered phasers to accommodate arbitrarily large sets
187	>	* of participants.
188	>	*
189	>	* @since 1.7
190	>	* @author Doug Lea
191		*/
192		public class Phaser {
193		/*
194		* This class implements an extension of X10 "clocks".  Thanks to
195	<	* Vijay Saraswat for the idea of applying it to ForkJoinTasks,
196	<	* and to Vivek Sarkar for enhancements to extend functionality.
195	>	* Vijay Saraswat for the idea, and to Vivek Sarkar for
196	>	* enhancements to extend functionality.
197		*/
198
199		/**
200		* Barrier state representation. Conceptually, a barrier contains
201		* four values:
202	<	*
202	>	*
203		* * parties -- the number of parties to wait (16 bits)
204		* * unarrived -- the number of parties yet to hit barrier (16 bits)
205		* * phase -- the generation of the barrier (31 bits)
206		* * terminated -- set if barrier is terminated (1 bit)
207		*
208		* However, to efficiently maintain atomicity, these values are
209	<	* packed into a single AtomicLong. Termination uses the sign bit
210	<	* of 32 bit representation of phase, so phase is set to -1 on
211	<	* termination.
212	<	*/
213	<	private final AtomicLong state;
214	<
215	<	/**
143	<	* Head of Treiber stack for waiting nonFJ threads.
209	>	* packed into a single (atomic) long. Termination uses the sign
210	>	* bit of 32 bit representation of phase, so phase is set to -1 on
211	>	* termination. Good performance relies on keeping state decoding
212	>	* and encoding simple, and keeping race windows short.
213	>	*
214	>	* Note: there are some cheats in arrive() that rely on unarrived
215	>	* count being lowest 16 bits.
216		*/
217	<	private final AtomicReference<QNode> head = new AtomicReference<QNode>();
217	>	private volatile long state;
218
219		private static final int ushortBits = 16;
220	<	private static final int ushortMask =  (1 << ushortBits) - 1;
221	<	private static final int phaseMask = 0x7fffffff;
220	>	private static final int ushortMask = 0xffff;
221	>	private static final int phaseMask  = 0x7fffffff;
222
223		private static int unarrivedOf(long s) {
224	<	return (int)(s & ushortMask);
224	>	return (int) (s & ushortMask);
225		}
226
227		private static int partiesOf(long s) {
228	<	return (int)(s & (ushortMask << 16)) >>> 16;
228	>	return ((int) s) >>> 16;
229		}
230
231		private static int phaseOf(long s) {
232	<	return (int)(s >>> 32);
232	>	return (int) (s >>> 32);
233		}
234
235		private static int arrivedOf(long s) {
#	Line 165 | Line 237 | public class Phaser {
237		}
238
239		private static long stateFor(int phase, int parties, int unarrived) {
240	<	return (((long)phase) << 32) | ((parties << 16) | unarrived);
240	>	return ((((long) phase) << 32) | (((long) parties) << 16) |
241	>	(long) unarrived);
242	>	}
243	>
244	>	private static long trippedStateFor(int phase, int parties) {
245	>	long lp = (long) parties;
246	>	return (((long) phase) << 32) | (lp << 16) | lp;
247	>	}
248	>
249	>	/**
250	>	* Returns message string for bad bounds exceptions.
251	>	*/
252	>	private static String badBounds(int parties, int unarrived) {
253	>	return ("Attempt to set " + unarrived +
254	>	" unarrived of " + parties + " parties");
255	>	}
256	>
257	>	/**
258	>	* The parent of this phaser, or null if none
259	>	*/
260	>	private final Phaser parent;
261	>
262	>	/**
263	>	* The root of phaser tree. Equals this if not in a tree.  Used to
264	>	* support faster state push-down.
265	>	*/
266	>	private final Phaser root;
267	>
268	>	// Wait queues
269	>
270	>	/**
271	>	* Heads of Treiber stacks for waiting threads. To eliminate
272	>	* contention while releasing some threads while adding others, we
273	>	* use two of them, alternating across even and odd phases.
274	>	*/
275	>	private final AtomicReference<QNode> evenQ = new AtomicReference<QNode>();
276	>	private final AtomicReference<QNode> oddQ  = new AtomicReference<QNode>();
277	>
278	>	private AtomicReference<QNode> queueFor(int phase) {
279	>	return ((phase & 1) == 0) ? evenQ : oddQ;
280		}
281
282	<	private static IllegalStateException badBounds(int parties, int unarrived) {
283	<	return new IllegalStateException("Attempt to set " + unarrived +
284	<	" unarrived of " + parties + " parties");
282	>	/**
283	>	* Returns current state, first resolving lagged propagation from
284	>	* root if necessary.
285	>	*/
286	>	private long getReconciledState() {
287	>	return (parent == null) ? state : reconcileState();
288	>	}
289	>
290	>	/**
291	>	* Recursively resolves state.
292	>	*/
293	>	private long reconcileState() {
294	>	Phaser p = parent;
295	>	long s = state;
296	>	if (p != null) {
297	>	while (unarrivedOf(s) == 0 && phaseOf(s) != phaseOf(root.state)) {
298	>	long parentState = p.getReconciledState();
299	>	int parentPhase = phaseOf(parentState);
300	>	int phase = phaseOf(s = state);
301	>	if (phase != parentPhase) {
302	>	long next = trippedStateFor(parentPhase, partiesOf(s));
303	>	if (casState(s, next)) {
304	>	releaseWaiters(phase);
305	>	s = next;
306	>	}
307	>	}
308	>	}
309	>	}
310	>	return s;
311		}
312
313		/**
314	<	* Creates a new Phaser without any initially registered parties,
315	<	* and initial phase number 0.
314	>	* Creates a new phaser without any initially registered parties,
315	>	* initial phase number 0, and no parent. Any thread using this
316	>	* phaser will need to first register for it.
317		*/
318		public Phaser() {
319	<	state = new AtomicLong(stateFor(0, 0, 0));
319	>	this(null);
320		}
321
322		/**
323	<	* Creates a new Phaser with the given numbers of registered
324	<	* unarrived parties and initial phase number 0.
325	<	* @param parties the number of parties required to trip barrier.
323	>	* Creates a new phaser with the given numbers of registered
324	>	* unarrived parties, initial phase number 0, and no parent.
325	>	*
326	>	* @param parties the number of parties required to trip barrier
327		* @throws IllegalArgumentException if parties less than zero
328	<	* or greater than the maximum number of parties supported.
328	>	* or greater than the maximum number of parties supported
329		*/
330		public Phaser(int parties) {
331	+	this(null, parties);
332	+	}
333	+
334	+	/**
335	+	* Creates a new phaser with the given parent, without any
336	+	* initially registered parties. If parent is non-null this phaser
337	+	* is registered with the parent and its initial phase number is
338	+	* the same as that of parent phaser.
339	+	*
340	+	* @param parent the parent phaser
341	+	*/
342	+	public Phaser(Phaser parent) {
343	+	int phase = 0;
344	+	this.parent = parent;
345	+	if (parent != null) {
346	+	this.root = parent.root;
347	+	phase = parent.register();
348	+	}
349	+	else
350	+	this.root = this;
351	+	this.state = trippedStateFor(phase, 0);
352	+	}
353	+
354	+	/**
355	+	* Creates a new phaser with the given parent and numbers of
356	+	* registered unarrived parties. If parent is non-null, this phaser
357	+	* is registered with the parent and its initial phase number is
358	+	* the same as that of parent phaser.
359	+	*
360	+	* @param parent the parent phaser
361	+	* @param parties the number of parties required to trip barrier
362	+	* @throws IllegalArgumentException if parties less than zero
363	+	* or greater than the maximum number of parties supported
364	+	*/
365	+	public Phaser(Phaser parent, int parties) {
366		if (parties < 0 || parties > ushortMask)
367		throw new IllegalArgumentException("Illegal number of parties");
368	<	state = new AtomicLong(stateFor(0, parties, parties));
368	>	int phase = 0;
369	>	this.parent = parent;
370	>	if (parent != null) {
371	>	this.root = parent.root;
372	>	phase = parent.register();
373	>	}
374	>	else
375	>	this.root = this;
376	>	this.state = trippedStateFor(phase, parties);
377		}
378
379		/**
380		* Adds a new unarrived party to this phaser.
381	<	* @return the current barrier phase number upon registration
381	>	*
382	>	* @return the arrival phase number to which this registration applied
383	>	* @throws IllegalStateException if attempting to register more
384	>	* than the maximum supported number of parties
385	>	*/
386	>	public int register() {
387	>	return doRegister(1);
388	>	}
389	>
390	>	/**
391	>	* Adds the given number of new unarrived parties to this phaser.
392	>	*
393	>	* @param parties the number of parties required to trip barrier
394	>	* @return the arrival phase number to which this registration applied
395		* @throws IllegalStateException if attempting to register more
396	<	* than the maximum supported number of parties.
396	>	* than the maximum supported number of parties
397		*/
398	<	public int register() { // increment both parties and unarrived
399	<	final AtomicLong state = this.state;
398	>	public int bulkRegister(int parties) {
399	>	if (parties < 0)
400	>	throw new IllegalArgumentException();
401	>	if (parties == 0)
402	>	return getPhase();
403	>	return doRegister(parties);
404	>	}
405	>
406	>	/**
407	>	* Shared code for register, bulkRegister
408	>	*/
409	>	private int doRegister(int registrations) {
410	>	int phase;
411		for (;;) {
412	<	long s = state.get();
413	<	int phase = phaseOf(s);
414	<	int parties = partiesOf(s) + 1;
415	<	int unarrived = unarrivedOf(s) + 1;
412	>	long s = getReconciledState();
413	>	phase = phaseOf(s);
414	>	int unarrived = unarrivedOf(s) + registrations;
415	>	int parties = partiesOf(s) + registrations;
416	>	if (phase < 0)
417	>	break;
418		if (parties > ushortMask || unarrived > ushortMask)
419	<	throw badBounds(parties, unarrived);
420	<	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
421	<	return phase;
419	>	throw new IllegalStateException(badBounds(parties, unarrived));
420	>	if (phase == phaseOf(root.state) &&
421	>	casState(s, stateFor(phase, parties, unarrived)))
422	>	break;
423		}
424	+	return phase;
425		}
426
427		/**
428		* Arrives at the barrier, but does not wait for others.  (You can
429		* in turn wait for others via {@link #awaitAdvance}).
430		*
431	<	* @return the current barrier phase number upon entry to
432	<	* this method, or a negative value if terminated;
433	<	* @throws IllegalStateException if the number of unarrived
224	<	* parties would become negative.
431	>	* @return the arrival phase number, or a negative value if terminated
432	>	* @throws IllegalStateException if not terminated and the number
433	>	* of unarrived parties would become negative
434		*/
435	<	public int arrive() { // decrement unarrived. If zero, trip
436	<	final AtomicLong state = this.state;
435	>	public int arrive() {
436	>	int phase;
437		for (;;) {
438	<	long s = state.get();
439	<	int phase = phaseOf(s);
438	>	long s = state;
439	>	phase = phaseOf(s);
440	>	if (phase < 0)
441	>	break;
442		int parties = partiesOf(s);
443		int unarrived = unarrivedOf(s) - 1;
444	<	if (unarrived < 0)
445	<	throw badBounds(parties, unarrived);
446	<	if (unarrived == 0 && phase >= 0) {
447	<	trip(phase, parties);
448	<	return phase;
444	>	if (unarrived > 0) {        // Not the last arrival
445	>	if (casState(s, s - 1)) // s-1 adds one arrival
446	>	break;
447	>	}
448	>	else if (unarrived == 0) {  // the last arrival
449	>	Phaser par = parent;
450	>	if (par == null) {      // directly trip
451	>	if (casState
452	>	(s,
453	>	trippedStateFor(onAdvance(phase, parties) ? -1 :
454	>	((phase + 1) & phaseMask), parties))) {
455	>	releaseWaiters(phase);
456	>	break;
457	>	}
458	>	}
459	>	else {                  // cascade to parent
460	>	if (casState(s, s - 1)) { // zeroes unarrived
461	>	par.arrive();
462	>	reconcileState();
463	>	break;
464	>	}
465	>	}
466		}
467	<	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
468	<	return phase;
467	>	else if (phase != phaseOf(root.state)) // or if unreconciled
468	>	reconcileState();
469	>	else
470	>	throw new IllegalStateException(badBounds(parties, unarrived));
471		}
472	+	return phase;
473		}
474
475		/**
476	<	* Arrives at the barrier, and deregisters from it, without
477	<	* waiting for others.
476	>	* Arrives at the barrier and deregisters from it without waiting
477	>	* for others. Deregistration reduces the number of parties
478	>	* required to trip the barrier in future phases.  If this phaser
479	>	* has a parent, and deregistration causes this phaser to have
480	>	* zero parties, this phaser also arrives at and is deregistered
481	>	* from its parent.
482		*
483	<	* @return the current barrier phase number upon entry to
484	<	* this method, or a negative value if terminated;
485	<	* @throws IllegalStateException if the number of registered or
486	<	* unarrived parties would become negative.
487	<	*/
488	<	public int arriveAndDeregister() { // Same as arrive, plus decrement parties
489	<	final AtomicLong state = this.state;
483	>	* @return the arrival phase number, or a negative value if terminated
484	>	* @throws IllegalStateException if not terminated and the number
485	>	* of registered or unarrived parties would become negative
486	>	*/
487	>	public int arriveAndDeregister() {
488	>	// similar code to arrive, but too different to merge
489	>	Phaser par = parent;
490	>	int phase;
491		for (;;) {
492	<	long s = state.get();
493	<	int phase = phaseOf(s);
492	>	long s = state;
493	>	phase = phaseOf(s);
494	>	if (phase < 0)
495	>	break;
496		int parties = partiesOf(s) - 1;
497		int unarrived = unarrivedOf(s) - 1;
498	<	if (parties < 0 || unarrived < 0)
499	<	throw badBounds(parties, unarrived);
500	<	if (unarrived == 0 && phase >= 0) {
501	<	trip(phase, parties);
502	<	return phase;
498	>	if (parties >= 0) {
499	>	if (unarrived > 0 || (unarrived == 0 && par != null)) {
500	>	if (casState
501	>	(s,
502	>	stateFor(phase, parties, unarrived))) {
503	>	if (unarrived == 0) {
504	>	par.arriveAndDeregister();
505	>	reconcileState();
506	>	}
507	>	break;
508	>	}
509	>	continue;
510	>	}
511	>	if (unarrived == 0) {
512	>	if (casState
513	>	(s,
514	>	trippedStateFor(onAdvance(phase, parties) ? -1 :
515	>	((phase + 1) & phaseMask), parties))) {
516	>	releaseWaiters(phase);
517	>	break;
518	>	}
519	>	continue;
520	>	}
521	>	if (par != null && phase != phaseOf(root.state)) {
522	>	reconcileState();
523	>	continue;
524	>	}
525		}
526	<	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
267	<	return phase;
526	>	throw new IllegalStateException(badBounds(parties, unarrived));
527		}
528	+	return phase;
529		}
530
531		/**
532	<	* Arrives at the barrier and awaits others. Unlike other arrival
533	<	* methods, this method returns the arrival index of the
534	<	* caller. The caller tripping the barrier returns zero, the
535	<	* previous caller 1, and so on.
536	<	* @return the arrival index
537	<	* @throws IllegalStateException if the number of unarrived
538	<	* parties would become negative.
532	>	* Arrives at the barrier and awaits others. Equivalent in effect
533	>	* to {@code awaitAdvance(arrive())}.  If you need to await with
534	>	* interruption or timeout, you can arrange this with an analogous
535	>	* construction using one of the other forms of the awaitAdvance
536	>	* method.  If instead you need to deregister upon arrival use
537	>	* {@code arriveAndDeregister}.
538	>	*
539	>	* @return the arrival phase number, or a negative number if terminated
540	>	* @throws IllegalStateException if not terminated and the number
541	>	* of unarrived parties would become negative
542		*/
543		public int arriveAndAwaitAdvance() {
544	<	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	<	}
544	>	return awaitAdvance(arrive());
545		}
546
547		/**
548	<	* Awaits the phase of the barrier to advance from the given
549	<	* value, or returns immediately if this barrier is terminated.
550	<	* @param phase the phase on entry to this method
551	<	* @return the phase on exit from this method
548	>	* Awaits the phase of the barrier to advance from the given phase
549	>	* value, returning immediately if the current phase of the
550	>	* barrier is not equal to the given phase value or this barrier
551	>	* is terminated.
552	>	*
553	>	* @param phase an arrival phase number, or negative value if
554	>	* terminated; this argument is normally the value returned by a
555	>	* previous call to {@code arrive} or its variants
556	>	* @return the next arrival phase number, or a negative value
557	>	* if terminated or argument is negative
558		*/
559		public int awaitAdvance(int phase) {
560		if (phase < 0)
561		return phase;
562	<	Thread current = Thread.currentThread();
563	<	if (current instanceof ForkJoinWorkerThread)
564	<	return helpingWait(phase);
565	<	if (untimedWait(current, phase, false))
566	<	current.interrupt();
567	<	return phaseOf(state.get());
562	>	long s = getReconciledState();
563	>	int p = phaseOf(s);
564	>	if (p != phase)
565	>	return p;
566	>	if (unarrivedOf(s) == 0 && parent != null)
567	>	parent.awaitAdvance(phase);
568	>	// Fall here even if parent waited, to reconcile and help release
569	>	return untimedWait(phase);
570		}
571
572		/**
573	<	* Awaits the phase of the barrier to advance from the given
574	<	* value, or returns immediately if this barrier is terminated, or
575	<	* throws InterruptedException if interrupted while waiting.
576	<	* @param phase the phase on entry to this method
577	<	* @return the phase on exit from this method
573	>	* Awaits the phase of the barrier to advance from the given phase
574	>	* value, throwing {@code InterruptedException} if interrupted while
575	>	* waiting, or returning immediately if the current phase of the
576	>	* barrier is not equal to the given phase value or this barrier
577	>	* is terminated.
578	>	*
579	>	* @param phase an arrival phase number, or negative value if
580	>	* terminated; this argument is normally the value returned by a
581	>	* previous call to {@code arrive} or its variants
582	>	* @return the next arrival phase number, or a negative value
583	>	* if terminated or argument is negative
584		* @throws InterruptedException if thread interrupted while waiting
585		*/
586	<	public int awaitAdvanceInterruptibly(int phase) throws InterruptedException {
586	>	public int awaitAdvanceInterruptibly(int phase)
587	>	throws InterruptedException {
588		if (phase < 0)
589		return phase;
590	<	Thread current = Thread.currentThread();
591	<	if (current instanceof ForkJoinWorkerThread)
592	<	return helpingWait(phase);
593	<	else if (Thread.interrupted() || untimedWait(current, phase, true))
594	<	throw new InterruptedException();
595	<	else
596	<	return phaseOf(state.get());
590	>	long s = getReconciledState();
591	>	int p = phaseOf(s);
592	>	if (p != phase)
593	>	return p;
594	>	if (unarrivedOf(s) == 0 && parent != null)
595	>	parent.awaitAdvanceInterruptibly(phase);
596	>	return interruptibleWait(phase);
597		}
598
599		/**
600	<	* Awaits the phase of the barrier to advance from the given value
601	<	* or the given timeout elapses, or returns immediately if this
602	<	* barrier is terminated.
603	<	* @param phase the phase on entry to this method
604	<	* @return the phase on exit from this method
600	>	* Awaits the phase of the barrier to advance from the given phase
601	>	* value or the given timeout to elapse, throwing
602	>	* {@code InterruptedException} if interrupted while waiting, or
603	>	* returning immediately if the current phase of the barrier is not
604	>	* equal to the given phase value or this barrier is terminated.
605	>	*
606	>	* @param phase an arrival phase number, or negative value if
607	>	* terminated; this argument is normally the value returned by a
608	>	* previous call to {@code arrive} or its variants
609	>	* @param timeout how long to wait before giving up, in units of
610	>	*        {@code unit}
611	>	* @param unit a {@code TimeUnit} determining how to interpret the
612	>	*        {@code timeout} parameter
613	>	* @return the next arrival phase number, or a negative value
614	>	* if terminated or argument is negative
615		* @throws InterruptedException if thread interrupted while waiting
616		* @throws TimeoutException if timed out while waiting
617		*/
618	<	public int awaitAdvanceInterruptibly(int phase, long timeout, TimeUnit unit)
618	>	public int awaitAdvanceInterruptibly(int phase,
619	>	long timeout, TimeUnit unit)
620		throws InterruptedException, TimeoutException {
621		if (phase < 0)
622		return phase;
623	<	long nanos = unit.toNanos(timeout);
624	<	Thread current = Thread.currentThread();
625	<	if (current instanceof ForkJoinWorkerThread)
626	<	return timedHelpingWait(phase, nanos);
627	<	timedWait(current, phase, nanos);
628	<	return phaseOf(state.get());
623	>	long s = getReconciledState();
624	>	int p = phaseOf(s);
625	>	if (p != phase)
626	>	return p;
627	>	if (unarrivedOf(s) == 0 && parent != null)
628	>	parent.awaitAdvanceInterruptibly(phase, timeout, unit);
629	>	return timedWait(phase, unit.toNanos(timeout));
630		}
631
632		/**
633		* Forces this barrier to enter termination state. Counts of
634	<	* arrived and registered parties are unaffected. This method may
635	<	* be useful for coordinating recovery after one or more tasks
636	<	* encounter unexpected exceptions.
634	>	* arrived and registered parties are unaffected. If this phaser
635	>	* has a parent, it too is terminated. This method may be useful
636	>	* for coordinating recovery after one or more tasks encounter
637	>	* unexpected exceptions.
638		*/
639		public void forceTermination() {
365	–	final AtomicLong state = this.state;
640		for (;;) {
641	<	long s = state.get();
641	>	long s = getReconciledState();
642		int phase = phaseOf(s);
643		int parties = partiesOf(s);
644		int unarrived = unarrivedOf(s);
645		if (phase < 0 ||
646	<	state.compareAndSet(s, stateFor(-1, parties, unarrived))) {
647	<	if (head.get() != null)
648	<	releaseWaiters(-1);
646	>	casState(s, stateFor(-1, parties, unarrived))) {
647	>	releaseWaiters(0);
648	>	releaseWaiters(1);
649	>	if (parent != null)
650	>	parent.forceTermination();
651		return;
652		}
653		}
654		}
655
656		/**
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	–	/**
657		* Returns the current phase number. The maximum phase number is
658	<	* <tt>Integer.MAX_VALUE</tt>, after which it restarts at
658	>	* {@code Integer.MAX_VALUE}, after which it restarts at
659		* zero. Upon termination, the phase number is negative.
660	+	*
661		* @return the phase number, or a negative value if terminated
662		*/
663	<	public int getPhase() {
664	<	return phaseOf(state.get());
663	>	public final int getPhase() {
664	>	return phaseOf(getReconciledState());
665		}
666
667		/**
668		* Returns the number of parties registered at this barrier.
669	+	*
670		* @return the number of parties
671		*/
672		public int getRegisteredParties() {
673	<	return partiesOf(state.get());
673	>	return partiesOf(state);
674		}
675
676		/**
677	<	* Returns the number of parties that have arrived at the current
678	<	* phase of this barrier.
677	>	* Returns the number of registered parties that have arrived at
678	>	* the current phase of this barrier.
679	>	*
680		* @return the number of arrived parties
681		*/
682		public int getArrivedParties() {
683	<	return arrivedOf(state.get());
683	>	return arrivedOf(state);
684		}
685
686		/**
687		* Returns the number of registered parties that have not yet
688		* arrived at the current phase of this barrier.
689	+	*
690		* @return the number of unarrived parties
691		*/
692		public int getUnarrivedParties() {
693	<	return unarrivedOf(state.get());
693	>	return unarrivedOf(state);
694	>	}
695	>
696	>	/**
697	>	* Returns the parent of this phaser, or {@code null} if none.
698	>	*
699	>	* @return the parent of this phaser, or {@code null} if none
700	>	*/
701	>	public Phaser getParent() {
702	>	return parent;
703	>	}
704	>
705	>	/**
706	>	* Returns the root ancestor of this phaser, which is the same as
707	>	* this phaser if it has no parent.
708	>	*
709	>	* @return the root ancestor of this phaser
710	>	*/
711	>	public Phaser getRoot() {
712	>	return root;
713		}
714
715		/**
716	<	* Returns true if this barrier has been terminated.
717	<	* @return true if this barrier has been terminated
716	>	* Returns {@code true} if this barrier has been terminated.
717	>	*
718	>	* @return {@code true} if this barrier has been terminated
719		*/
720		public boolean isTerminated() {
721	<	return phaseOf(state.get()) < 0;
721	>	return getPhase() < 0;
722		}
723
724		/**
725		* Overridable method to perform an action upon phase advance, and
726		* to control termination. This method is invoked whenever the
727		* barrier is tripped (and thus all other waiting parties are
728	<	* dormant). If it returns true, then, rather than advance the
729	<	* phase number, this barrier will be set to a final termination
730	<	* state, and subsequent calls to <tt>isTerminated</tt> will
731	<	* return true.
732	<	*
733	<	* <p> The default version returns true when the number of
728	>	* dormant). If it returns {@code true}, then, rather than advance
729	>	* the phase number, this barrier will be set to a final
730	>	* termination state, and subsequent calls to {@link #isTerminated}
731	>	* will return true.
732	>	*
733	>	* <p>The default version returns {@code true} when the number of
734		* registered parties is zero. Normally, overrides that arrange
735		* termination for other reasons should also preserve this
736		* property.
737		*
738	+	* <p>You may override this method to perform an action with side
739	+	* effects visible to participating tasks, but it is in general
740	+	* only sensible to do so in designs where all parties register
741	+	* before any arrive, and all {@link #awaitAdvance} at each phase.
742	+	* Otherwise, you cannot ensure lack of interference from other
743	+	* parties during the invocation of this method.
744	+	*
745		* @param phase the phase number on entering the barrier
746	<	* @param registeredParties the current number of registered
747	<	* parties.
458	<	* @return true if this barrier should terminate
746	>	* @param registeredParties the current number of registered parties
747	>	* @return {@code true} if this barrier should terminate
748		*/
749		protected boolean onAdvance(int phase, int registeredParties) {
750		return registeredParties <= 0;
751		}
752
753		/**
754	<	* Returns a string identifying this barrier, as well as its
754	>	* Returns a string identifying this phaser, as well as its
755		* state.  The state, in brackets, includes the String {@code
756	<	* "phase ="} followed by the phase number, {@code "parties ="}
756	>	* "phase = "} followed by the phase number, {@code "parties = "}
757		* followed by the number of registered parties, and {@code
758	<	* "arrived ="} followed by the number of arrived parties
758	>	* "arrived = "} followed by the number of arrived parties.
759		*
760		* @return a string identifying this barrier, as well as its state
761		*/
762		public String toString() {
763	<	long s = state.get();
764	<	return super.toString() + "[phase = " + phaseOf(s) + " parties = " + partiesOf(s) + " arrived = " + arrivedOf(s) + "]";
763	>	long s = getReconciledState();
764	>	return super.toString() +
765	>	"[phase = " + phaseOf(s) +
766	>	" parties = " + partiesOf(s) +
767	>	" arrived = " + arrivedOf(s) + "]";
768		}
769
770	<	// methods for tripping and waiting
770	>	// methods for waiting
771
772		/**
773	<	* Advance the current phase (or terminate)
773	>	* Wait nodes for Treiber stack representing wait queue
774		*/
775	<	private void trip(int phase, int parties) {
776	<	int next = onAdvance(phase, parties)? -1 : ((phase + 1) & phaseMask);
777	<	state.set(stateFor(next, parties, parties));
778	<	if (head.get() != null)
779	<	releaseWaiters(next);
780	<	}
781	<
782	<	private int helpingWait(int phase) {
783	<	final AtomicLong state = this.state;
784	<	int p;
785	<	while ((p = phaseOf(state.get())) == phase) {
786	<	ForkJoinTask<?> t = ForkJoinWorkerThread.pollTask();
787	<	if (t != null) {
788	<	if ((p = phaseOf(state.get())) == phase)
789	<	t.exec();
790	<	else {   // push task and exit if barrier advanced
791	<	t.fork();
792	<	break;
793	<	}
775	>	static final class QNode implements ForkJoinPool.ManagedBlocker {
776	>	final Phaser phaser;
777	>	final int phase;
778	>	final long startTime;
779	>	final long nanos;
780	>	final boolean timed;
781	>	final boolean interruptible;
782	>	volatile boolean wasInterrupted = false;
783	>	volatile Thread thread; // nulled to cancel wait
784	>	QNode next;
785	>	QNode(Phaser phaser, int phase, boolean interruptible,
786	>	boolean timed, long startTime, long nanos) {
787	>	this.phaser = phaser;
788	>	this.phase = phase;
789	>	this.timed = timed;
790	>	this.interruptible = interruptible;
791	>	this.startTime = startTime;
792	>	this.nanos = nanos;
793	>	thread = Thread.currentThread();
794	>	}
795	>	public boolean isReleasable() {
796	>	return (thread == null ||
797	>	phaser.getPhase() != phase ||
798	>	(interruptible && wasInterrupted) ||
799	>	(timed && (nanos - (System.nanoTime() - startTime)) <= 0));
800	>	}
801	>	public boolean block() {
802	>	if (Thread.interrupted()) {
803	>	wasInterrupted = true;
804	>	if (interruptible)
805	>	return true;
806	>	}
807	>	if (!timed)
808	>	LockSupport.park(this);
809	>	else {
810	>	long waitTime = nanos - (System.nanoTime() - startTime);
811	>	if (waitTime <= 0)
812	>	return true;
813	>	LockSupport.parkNanos(this, waitTime);
814		}
815	+	return isReleasable();
816		}
817	<	return p;
818	<	}
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();
817	>	void signal() {
818	>	Thread t = thread;
819		if (t != null) {
820	<	if ((p = phaseOf(state.get())) == phase)
821	<	t.exec();
822	<	else {   // push task and exit if barrier advanced
823	<	t.fork();
824	<	break;
820	>	thread = null;
821	>	LockSupport.unpark(t);
822	>	}
823	>	}
824	>	boolean doWait() {
825	>	if (thread != null) {
826	>	try {
827	>	ForkJoinPool.managedBlock(this, false);
828	>	} catch (InterruptedException ie) {
829		}
830		}
831	+	return wasInterrupted;
832		}
833	<	return p;
833	>
834		}
835
836		/**
837	<	* 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.
837	>	* Removes and signals waiting threads from wait queue.
838		*/
839	<	static final class QNode {
840	<	QNode next;
841	<	volatile Thread thread; // nulled to cancel wait
842	<	final int phase;
843	<	QNode(Thread t, int c) {
844	<	thread = t;
545	<	phase = c;
839	>	private void releaseWaiters(int phase) {
840	>	AtomicReference<QNode> head = queueFor(phase);
841	>	QNode q;
842	>	while ((q = head.get()) != null) {
843	>	if (head.compareAndSet(q, q.next))
844	>	q.signal();
845		}
846		}
847
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	–
848		/**
849	<	* The number of times to spin before blocking in untimed waits.
850	<	* This is greater than timed value because untimed waits spin
851	<	* faster since they don't need to check times on each spin.
849	>	* Tries to enqueue given node in the appropriate wait queue.
850	>	*
851	>	* @return true if successful
852		*/
853	<	static final int maxUntimedSpins = maxTimedSpins * 32;
853	>	private boolean tryEnqueue(QNode node) {
854	>	AtomicReference<QNode> head = queueFor(node.phase);
855	>	return head.compareAndSet(node.next = head.get(), node);
856	>	}
857
858		/**
859	<	* The number of nanoseconds for which it is faster to spin
860	<	* rather than to use timed park. A rough estimate suffices.
859	>	* Enqueues node and waits unless aborted or signalled.
860	>	*
861	>	* @return current phase
862		*/
863	<	static final long spinForTimeoutThreshold = 1000L;
863	>	private int untimedWait(int phase) {
864	>	QNode node = null;
865	>	boolean queued = false;
866	>	boolean interrupted = false;
867	>	int p;
868	>	while ((p = getPhase()) == phase) {
869	>	if (Thread.interrupted())
870	>	interrupted = true;
871	>	else if (node == null)
872	>	node = new QNode(this, phase, false, false, 0, 0);
873	>	else if (!queued)
874	>	queued = tryEnqueue(node);
875	>	else
876	>	interrupted = node.doWait();
877	>	}
878	>	if (node != null)
879	>	node.thread = null;
880	>	releaseWaiters(phase);
881	>	if (interrupted)
882	>	Thread.currentThread().interrupt();
883	>	return p;
884	>	}
885
886		/**
887	<	* Enqueues node and waits unless aborted or signalled.
887	>	* Interruptible version
888	>	* @return current phase
889		*/
890	<	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;
890	>	private int interruptibleWait(int phase) throws InterruptedException {
891		QNode node = null;
892		boolean queued = false;
893	<	int spins = maxUntimedSpins;
894	<	while (phaseOf(state.get()) == currentPhase) {
895	<	QNode h;
896	<	if (node != null && queued) {
897	<	if (node.thread != null) {
898	<	LockSupport.park();
899	<	if (Thread.interrupted()) {
900	<	wasInterrupted = true;
901	<	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);
893	>	boolean interrupted = false;
894	>	int p;
895	>	while ((p = getPhase()) == phase && !interrupted) {
896	>	if (Thread.interrupted())
897	>	interrupted = true;
898	>	else if (node == null)
899	>	node = new QNode(this, phase, true, false, 0, 0);
900	>	else if (!queued)
901	>	queued = tryEnqueue(node);
902		else
903	<	--spins;
903	>	interrupted = node.doWait();
904		}
905		if (node != null)
906		node.thread = null;
907	<	return wasInterrupted;
907	>	if (p != phase || (p = getPhase()) != phase)
908	>	releaseWaiters(phase);
909	>	if (interrupted)
910	>	throw new InterruptedException();
911	>	return p;
912		}
913
914		/**
915	<	* Messier timeout version
915	>	* Timeout version.
916	>	* @return current phase
917		*/
918	<	private void timedWait(Thread thread, int currentPhase, long nanos)
918	>	private int timedWait(int phase, long nanos)
919		throws InterruptedException, TimeoutException {
920	<	final AtomicReference<QNode> head = this.head;
641	<	final AtomicLong state = this.state;
642	<	long lastTime = System.nanoTime();
920	>	long startTime = System.nanoTime();
921		QNode node = null;
922		boolean queued = false;
923	<	int spins = maxTimedSpins;
924	<	while (phaseOf(state.get()) == currentPhase) {
925	<	QNode h;
926	<	long now = System.nanoTime();
927	<	nanos -= now - lastTime;
928	<	lastTime = now;
929	<	if (nanos <= 0) {
930	<	if (node != null)
931	<	node.thread = null;
932	<	if (phaseOf(state.get()) == currentPhase)
933	<	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);
923	>	boolean interrupted = false;
924	>	int p;
925	>	while ((p = getPhase()) == phase && !interrupted) {
926	>	if (Thread.interrupted())
927	>	interrupted = true;
928	>	else if (nanos - (System.nanoTime() - startTime) <= 0)
929	>	break;
930	>	else if (node == null)
931	>	node = new QNode(this, phase, true, true, startTime, nanos);
932	>	else if (!queued)
933	>	queued = tryEnqueue(node);
934		else
935	<	--spins;
935	>	interrupted = node.doWait();
936		}
937		if (node != null)
938		node.thread = null;
939	+	if (p != phase || (p = getPhase()) != phase)
940	+	releaseWaiters(phase);
941	+	if (interrupted)
942	+	throw new InterruptedException();
943	+	if (p == phase)
944	+	throw new TimeoutException();
945	+	return p;
946		}
947
948	<	}
948	>	// Unsafe mechanics
949
950	+	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
951	+	private static final long stateOffset =
952	+	objectFieldOffset("state", Phaser.class);
953	+
954	+	private final boolean casState(long cmp, long val) {
955	+	return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val);
956	+	}
957	+
958	+	private static long objectFieldOffset(String field, Class<?> klazz) {
959	+	try {
960	+	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
961	+	} catch (NoSuchFieldException e) {
962	+	// Convert Exception to corresponding Error
963	+	NoSuchFieldError error = new NoSuchFieldError(field);
964	+	error.initCause(e);
965	+	throw error;
966	+	}
967	+	}
968	+
969	+	/**
970	+	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
971	+	* Replace with a simple call to Unsafe.getUnsafe when integrating
972	+	* into a jdk.
973	+	*
974	+	* @return a sun.misc.Unsafe
975	+	*/
976	+	private static sun.misc.Unsafe getUnsafe() {
977	+	try {
978	+	return sun.misc.Unsafe.getUnsafe();
979	+	} catch (SecurityException se) {
980	+	try {
981	+	return java.security.AccessController.doPrivileged
982	+	(new java.security
983	+	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
984	+	public sun.misc.Unsafe run() throws Exception {
985	+	java.lang.reflect.Field f = sun.misc
986	+	.Unsafe.class.getDeclaredField("theUnsafe");
987	+	f.setAccessible(true);
988	+	return (sun.misc.Unsafe) f.get(null);
989	+	}});
990	+	} catch (java.security.PrivilegedActionException e) {
991	+	throw new RuntimeException("Could not initialize intrinsics",
992	+	e.getCause());
993	+	}
994	+	}
995	+	}
996	+	}

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