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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 1.13 by jsr166, Mon Jul 20 22:40:09 2009 UTC

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

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