ViewVC Help

View File | Revision Log | Show Annotations | Download File | Root Listing

root/jsr166/jsr166/src/jsr166y/Phaser.java

Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.1 by dl, Mon Jul 7 16:53:30 2008 UTC vs.
Revision 1.15 by jsr166, Tue Jul 21 18:11:44 2009 UTC

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

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines