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Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.1 by dl, Mon Jul 7 16:53:30 2008 UTC vs.
Revision 1.49 by dl, Fri Nov 5 23:01:47 2010 UTC

#	Line 5 | Line 5
5		*/
6
7		package jsr166y;
8	<	import jsr166y.forkjoin.*;
8	>
9		import java.util.concurrent.*;
10	<	import java.util.concurrent.atomic.*;
10	>	import java.util.concurrent.atomic.AtomicReference;
11		import java.util.concurrent.locks.LockSupport;
12
13		/**
14	<	* A reusable synchronization barrier, similar in functionality to a
15	<	* {@link java.util.concurrent.CyclicBarrier}, but supporting more
16	<	* flexible usage.
14	>	* A reusable synchronization barrier, similar in functionality to
15	>	* {@link java.util.concurrent.CyclicBarrier CyclicBarrier} and
16	>	* {@link java.util.concurrent.CountDownLatch CountDownLatch}
17	>	* but supporting more flexible usage.
18	>	*
19	>	* <p> <b>Registration.</b> Unlike the case for other barriers, the
20	>	* number of parties <em>registered</em> to synchronize on a phaser
21	>	* may vary over time.  Tasks may be registered at any time (using
22	>	* methods {@link #register}, {@link #bulkRegister}, or forms of
23	>	* constructors establishing initial numbers of parties), and
24	>	* optionally deregistered upon any arrival (using {@link
25	>	* #arriveAndDeregister}).  As is the case with most basic
26	>	* synchronization constructs, registration and deregistration affect
27	>	* only internal counts; they do not establish any further internal
28	>	* bookkeeping, so tasks cannot query whether they are registered.
29	>	* (However, you can introduce such bookkeeping by subclassing this
30	>	* class.)
31	>	*
32	>	* <p> <b>Synchronization.</b> Like a {@code CyclicBarrier}, a {@code
33	>	* Phaser} may be repeatedly awaited.  Method {@link
34	>	* #arriveAndAwaitAdvance} has effect analogous to {@link
35	>	* java.util.concurrent.CyclicBarrier#await CyclicBarrier.await}. Each
36	>	* generation of a {@code Phaser} has an associated phase number. The
37	>	* phase number starts at zero, and advances when all parties arrive
38	>	* at the barrier, wrapping around to zero after reaching {@code
39	>	* Integer.MAX_VALUE}. The use of phase numbers enables independent
40	>	* control of actions upon arrival at a barrier and upon awaiting
41	>	* others, via two kinds of methods that may be invoked by any
42	>	* registered party:
43		*
44		* <ul>
45		*
46	<	* <li> The number of parties synchronizing on the barrier may vary
47	<	* over time.  A task may register to be a party in a barrier at any
48	<	* time, and may deregister upon arriving at the barrier.  As is the
49	<	* case with most basic synchronization constructs, registration
50	<	* and deregistration affect only internal counts; they do not
51	<	* establish any further internal bookkeeping, so tasks cannot query
52	<	* whether they are registered.
53	<	*
54	<	* <li> Each generation has an associated phase value, starting at
55	<	* zero, and advancing when all parties reach the barrier (wrapping
56	<	* around to zero after reaching <tt>Integer.MAX_VALUE</tt>).
57	<	*
58	<	* <li> Like a CyclicBarrier, a Phaser may be repeatedly awaited.
59	<	* Method <tt>arriveAndAwaitAdvance</tt> has effect analogous to
60	<	* <tt>CyclicBarrier.await</tt>.  However, Phasers separate two
61	<	* aspects of coordination, that may be invoked independently:
62	<	*
63	<	* <ul>
46	>	*   <li> <b>Arrival.</b> Methods {@link #arrive} and
47	>	*       {@link #arriveAndDeregister} record arrival at a
48	>	*       barrier. These methods do not block, but return an associated
49	>	*       <em>arrival phase number</em>; that is, the phase number of
50	>	*       the barrier to which the arrival applied. When the final
51	>	*       party for a given phase arrives, an optional barrier action
52	>	*       is performed and the phase advances.  Barrier actions,
53	>	*       performed by the party triggering a phase advance, are
54	>	*       arranged by overriding method {@link #onAdvance(int, int)},
55	>	*       which also controls termination. Overriding this method is
56	>	*       similar to, but more flexible than, providing a barrier
57	>	*       action to a {@code CyclicBarrier}.
58	>	*
59	>	*   <li> <b>Waiting.</b> Method {@link #awaitAdvance} requires an
60	>	*       argument indicating an arrival phase number, and returns when
61	>	*       the barrier advances to (or is already at) a different phase.
62	>	*       Unlike similar constructions using {@code CyclicBarrier},
63	>	*       method {@code awaitAdvance} continues to wait even if the
64	>	*       waiting thread is interrupted. Interruptible and timeout
65	>	*       versions are also available, but exceptions encountered while
66	>	*       tasks wait interruptibly or with timeout do not change the
67	>	*       state of the barrier. If necessary, you can perform any
68	>	*       associated recovery within handlers of those exceptions,
69	>	*       often after invoking {@code forceTermination}.  Phasers may
70	>	*       also be used by tasks executing in a {@link ForkJoinPool},
71	>	*       which will ensure sufficient parallelism to execute tasks
72	>	*       when others are blocked waiting for a phase to advance.
73		*
39	–	*   <li> Arriving at a barrier. Methods <tt>arrive</tt> and
40	–	*       <tt>arriveAndDeregister</tt> do not block, but return
41	–	*       the phase value on entry to the method.
42	–	*
43	–	*   <li> Awaiting others. Method <tt>awaitAdvance</tt> requires an
44	–	*       argument indicating the entry phase, and returns when the
45	–	*       barrier advances to a new phase.
74		* </ul>
75		*
76	+	* <p> <b>Termination.</b> A {@code Phaser} may enter a
77	+	* <em>termination</em> state in which all synchronization methods
78	+	* immediately return without updating phaser state or waiting for
79	+	* advance, and indicating (via a negative phase value) that execution
80	+	* is complete.  Termination is triggered when an invocation of {@code
81	+	* onAdvance} returns {@code true}.  As illustrated below, when
82	+	* phasers control actions with a fixed number of iterations, it is
83	+	* often convenient to override this method to cause termination when
84	+	* the current phase number reaches a threshold. Method {@link
85	+	* #forceTermination} is also available to abruptly release waiting
86	+	* threads and allow them to terminate.
87	+	*
88	+	* <p> <b>Tiering.</b> Phasers may be <em>tiered</em> (i.e., arranged
89	+	* in tree structures) to reduce contention. Phasers with large
90	+	* numbers of parties that would otherwise experience heavy
91	+	* synchronization contention costs may instead be set up so that
92	+	* groups of sub-phasers share a common parent.  This may greatly
93	+	* increase throughput even though it incurs greater per-operation
94	+	* overhead.
95	+	*
96	+	* <p><b>Monitoring.</b> While synchronization methods may be invoked
97	+	* only by registered parties, the current state of a phaser may be
98	+	* monitored by any caller.  At any given moment there are {@link
99	+	* #getRegisteredParties} parties in total, of which {@link
100	+	* #getArrivedParties} have arrived at the current phase ({@link
101	+	* #getPhase}).  When the remaining ({@link #getUnarrivedParties})
102	+	* parties arrive, the phase advances.  The values returned by these
103	+	* methods may reflect transient states and so are not in general
104	+	* useful for synchronization control.  Method {@link #toString}
105	+	* returns snapshots of these state queries in a form convenient for
106	+	* informal monitoring.
107	+	*
108	+	* <p><b>Sample usages:</b>
109	+	*
110	+	* <p>A {@code Phaser} may be used instead of a {@code CountDownLatch}
111	+	* to control a one-shot action serving a variable number of parties.
112	+	* The typical idiom is for the method setting this up to first
113	+	* register, then start the actions, then deregister, as in:
114	+	*
115	+	*  <pre> {@code
116	+	* void runTasks(List<Runnable> tasks) {
117	+	*   final Phaser phaser = new Phaser(1); // "1" to register self
118	+	*   // create and start threads
119	+	*   for (Runnable task : tasks) {
120	+	*     phaser.register();
121	+	*     new Thread() {
122	+	*       public void run() {
123	+	*         phaser.arriveAndAwaitAdvance(); // await all creation
124	+	*         task.run();
125	+	*       }
126	+	*     }.start();
127	+	*   }
128		*
129	<	* <li> Barrier actions, performed by the task triggering a phase
130	<	* advance while others may be waiting, are arranged by overriding
131	<	* method <tt>onAdvance</tt>, that also controls termination.
132	<	*
133	<	* <li> Phasers may enter a <em>termination</em> state in which all
134	<	* await actions immediately return, indicating (via a negative phase
135	<	* value) that execution is complete.  Termination is triggered by
136	<	* executing the overridable <tt>onAdvance</tt> method that is invoked
137	<	* each time the barrier is tripped. When a Phaser is controlling an
138	<	* action with a fixed number of iterations, it is often convenient to
139	<	* override this method to cause termination when the current phase
140	<	* number reaches a threshold.  Method <tt>forceTermination</tt> is
141	<	* also available to assist recovery actions upon failure.
142	<	*
143	<	* <li> Unlike most synchronizers, a Phaser may also be used with
144	<	* ForkJoinTasks (as well as plain threads).
145	<	*
146	<	* <li> By default, <tt>awaitAdvance</tt> continues to wait even if
147	<	* the current thread is interrupted. And unlike the case in
148	<	* CyclicBarriers, exceptions encountered while tasks wait
149	<	* interruptibly or with timeout do not change the state of the
150	<	* barrier. If necessary, you can perform any associated recovery
151	<	* within handlers of those exceptions.
152	<	*
153	<	* </ul>
129	>	*   // allow threads to start and deregister self
130	>	*   phaser.arriveAndDeregister();
131	>	* }}</pre>
132	>	*
133	>	* <p>One way to cause a set of threads to repeatedly perform actions
134	>	* for a given number of iterations is to override {@code onAdvance}:
135	>	*
136	>	*  <pre> {@code
137	>	* void startTasks(List<Runnable> tasks, final int iterations) {
138	>	*   final Phaser phaser = new Phaser() {
139	>	*     protected boolean onAdvance(int phase, int registeredParties) {
140	>	*       return phase >= iterations || registeredParties == 0;
141	>	*     }
142	>	*   };
143	>	*   phaser.register();
144	>	*   for (final Runnable task : tasks) {
145	>	*     phaser.register();
146	>	*     new Thread() {
147	>	*       public void run() {
148	>	*         do {
149	>	*           task.run();
150	>	*           phaser.arriveAndAwaitAdvance();
151	>	*         } while (!phaser.isTerminated());
152	>	*       }
153	>	*     }.start();
154	>	*   }
155	>	*   phaser.arriveAndDeregister(); // deregister self, don't wait
156	>	* }}</pre>
157		*
158	<	* <p><b>Sample usage:</b>
158	>	* If the main task must later await termination, it
159	>	* may re-register and then execute a similar loop:
160	>	*  <pre> {@code
161	>	*   // ...
162	>	*   phaser.register();
163	>	*   while (!phaser.isTerminated())
164	>	*     phaser.arriveAndAwaitAdvance();}</pre>
165	>	*
166	>	* <p>Related constructions may be used to await particular phase numbers
167	>	* in contexts where you are sure that the phase will never wrap around
168	>	* {@code Integer.MAX_VALUE}. For example:
169	>	*
170	>	*  <pre> {@code
171	>	* void awaitPhase(Phaser phaser, int phase) {
172	>	*   int p = phaser.register(); // assumes caller not already registered
173	>	*   while (p < phase) {
174	>	*     if (phaser.isTerminated())
175	>	*       // ... deal with unexpected termination
176	>	*     else
177	>	*       p = phaser.arriveAndAwaitAdvance();
178	>	*   }
179	>	*   phaser.arriveAndDeregister();
180	>	* }}</pre>
181		*
77	–	* <p>[todo: non-FJ example]
182		*
183	<	* <p> A Phaser may be used to support a style of programming in
184	<	* which a task waits for others to complete, without otherwise
185	<	* needing to keep track of which tasks it is waiting for. This is
186	<	* similar to the "sync" construct in Cilk and "clocks" in X10.
187	<	* Special constructions based on such barriers are available using
188	<	* the <tt>LinkedAsyncAction</tt> and <tt>CyclicAction</tt> classes,
189	<	* but they can be useful in other contexts as well.  For a simple
190	<	* (but not very useful) example, here is a variant of Fibonacci:
191	<	*
192	<	* <pre>
193	<	* class BarrierFibonacci extends RecursiveAction {
90	<	*   int argument, result;
91	<	*   final Phaser parentBarrier;
92	<	*   BarrierFibonacci(int n, Phaser parentBarrier) {
93	<	*     this.argument = n;
94	<	*     this.parentBarrier = parentBarrier;
95	<	*     parentBarrier.register();
96	<	*   }
97	<	*   protected void compute() {
98	<	*     int n = argument;
99	<	*     if (n &lt;= 1)
100	<	*        result = n;
101	<	*     else {
102	<	*        Phaser childBarrier = new Phaser(1);
103	<	*        BarrierFibonacci f1 = new BarrierFibonacci(n - 1, childBarrier);
104	<	*        BarrierFibonacci f2 = new BarrierFibonacci(n - 2, childBarrier);
105	<	*        f1.fork();
106	<	*        f2.fork();
107	<	*        childBarrier.arriveAndAwait();
108	<	*        result = f1.result + f2.result;
183	>	* <p>To create a set of tasks using a tree of phasers,
184	>	* you could use code of the following form, assuming a
185	>	* Task class with a constructor accepting a phaser that
186	>	* it registers with upon construction:
187	>	*
188	>	*  <pre> {@code
189	>	* void build(Task[] actions, int lo, int hi, Phaser ph) {
190	>	*   if (hi - lo > TASKS_PER_PHASER) {
191	>	*     for (int i = lo; i < hi; i += TASKS_PER_PHASER) {
192	>	*       int j = Math.min(i + TASKS_PER_PHASER, hi);
193	>	*       build(actions, i, j, new Phaser(ph));
194		*     }
195	<	*     parentBarrier.arriveAndDeregister();
195	>	*   } else {
196	>	*     for (int i = lo; i < hi; ++i)
197	>	*       actions[i] = new Task(ph);
198	>	*       // assumes new Task(ph) performs ph.register()
199		*   }
200		* }
201	<	* </pre>
201	>	* // .. initially called, for n tasks via
202	>	* build(new Task[n], 0, n, new Phaser());}</pre>
203	>	*
204	>	* The best value of {@code TASKS_PER_PHASER} depends mainly on
205	>	* expected barrier synchronization rates. A value as low as four may
206	>	* be appropriate for extremely small per-barrier task bodies (thus
207	>	* high rates), or up to hundreds for extremely large ones.
208		*
209		* <p><b>Implementation notes</b>: This implementation restricts the
210	<	* maximum number of parties to 65535. Attempts to register
211	<	* additional parties result in IllegalStateExceptions.
210	>	* maximum number of parties to 65535. Attempts to register additional
211	>	* parties result in {@code IllegalStateException}. However, you can and
212	>	* should create tiered phasers to accommodate arbitrarily large sets
213	>	* of participants.
214	>	*
215	>	* @since 1.7
216	>	* @author Doug Lea
217		*/
218		public class Phaser {
219		/*
220		* This class implements an extension of X10 "clocks".  Thanks to
221	<	* Vijay Saraswat for the idea of applying it to ForkJoinTasks,
222	<	* and to Vivek Sarkar for enhancements to extend functionality.
221	>	* Vijay Saraswat for the idea, and to Vivek Sarkar for
222	>	* enhancements to extend functionality.
223		*/
224
225		/**
226		* Barrier state representation. Conceptually, a barrier contains
227		* four values:
228	<	*
228	>	*
229		* * parties -- the number of parties to wait (16 bits)
230		* * unarrived -- the number of parties yet to hit barrier (16 bits)
231		* * phase -- the generation of the barrier (31 bits)
232		* * terminated -- set if barrier is terminated (1 bit)
233		*
234		* However, to efficiently maintain atomicity, these values are
235	<	* packed into a single AtomicLong. Termination uses the sign bit
236	<	* of 32 bit representation of phase, so phase is set to -1 on
237	<	* termination.
238	<	*/
239	<	private final AtomicLong state;
240	<
241	<	/**
143	<	* Head of Treiber stack for waiting nonFJ threads.
235	>	* packed into a single (atomic) long. Termination uses the sign
236	>	* bit of 32 bit representation of phase, so phase is set to -1 on
237	>	* termination. Good performance relies on keeping state decoding
238	>	* and encoding simple, and keeping race windows short.
239	>	*
240	>	* Note: there are some cheats in arrive() that rely on unarrived
241	>	* count being lowest 16 bits.
242		*/
243	<	private final AtomicReference<QNode> head = new AtomicReference<QNode>();
243	>	private volatile long state;
244
245	<	private static final int ushortBits = 16;
246	<	private static final int ushortMask =  (1 << ushortBits) - 1;
149	<	private static final int phaseMask = 0x7fffffff;
245	>	private static final int ushortMask = 0xffff;
246	>	private static final int phaseMask  = 0x7fffffff;
247
248		private static int unarrivedOf(long s) {
249	<	return (int)(s & ushortMask);
249	>	return (int) (s & ushortMask);
250		}
251
252		private static int partiesOf(long s) {
253	<	return (int)(s & (ushortMask << 16)) >>> 16;
253	>	return ((int) s) >>> 16;
254		}
255
256		private static int phaseOf(long s) {
257	<	return (int)(s >>> 32);
257	>	return (int) (s >>> 32);
258		}
259
260		private static int arrivedOf(long s) {
#	Line 165 | Line 262 | public class Phaser {
262		}
263
264		private static long stateFor(int phase, int parties, int unarrived) {
265	<	return (((long)phase) << 32) | ((parties << 16) | unarrived);
265	>	return ((((long) phase) << 32) | (((long) parties) << 16) |
266	>	(long) unarrived);
267		}
268
269	<	private static IllegalStateException badBounds(int parties, int unarrived) {
270	<	return new IllegalStateException("Attempt to set " + unarrived +
271	<	" unarrived of " + parties + " parties");
269	>	private static long trippedStateFor(int phase, int parties) {
270	>	long lp = (long) parties;
271	>	return (((long) phase) << 32) | (lp << 16) | lp;
272		}
273
274		/**
275	<	* Creates a new Phaser without any initially registered parties,
276	<	* and initial phase number 0.
275	>	* Returns message string for bad bounds exceptions.
276	>	*/
277	>	private static String badBounds(int parties, int unarrived) {
278	>	return ("Attempt to set " + unarrived +
279	>	" unarrived of " + parties + " parties");
280	>	}
281	>
282	>	/**
283	>	* The parent of this phaser, or null if none
284	>	*/
285	>	private final Phaser parent;
286	>
287	>	/**
288	>	* The root of phaser tree. Equals this if not in a tree.  Used to
289	>	* support faster state push-down.
290	>	*/
291	>	private final Phaser root;
292	>
293	>	// Wait queues
294	>
295	>	/**
296	>	* Heads of Treiber stacks for waiting threads. To eliminate
297	>	* contention when releasing some threads while adding others, we
298	>	* use two of them, alternating across even and odd phases.
299	>	* Subphasers share queues with root to speed up releases.
300	>	*/
301	>	private final AtomicReference<QNode> evenQ = new AtomicReference<QNode>();
302	>	private final AtomicReference<QNode> oddQ  = new AtomicReference<QNode>();
303	>
304	>	private AtomicReference<QNode> queueFor(int phase) {
305	>	Phaser r = root;
306	>	return ((phase & 1) == 0) ? r.evenQ : r.oddQ;
307	>	}
308	>
309	>	/**
310	>	* Returns current state, first resolving lagged propagation from
311	>	* root if necessary.
312	>	*/
313	>	private long getReconciledState() {
314	>	return (parent == null) ? state : reconcileState();
315	>	}
316	>
317	>	/**
318	>	* Recursively resolves state.
319	>	*/
320	>	private long reconcileState() {
321	>	Phaser par = parent;
322	>	long s = state;
323	>	if (par != null) {
324	>	int phase, rootPhase;
325	>	while ((phase = phaseOf(s)) >= 0 &&
326	>	(rootPhase = phaseOf(root.state)) != phase &&
327	>	(rootPhase < 0 || unarrivedOf(s) == 0)) {
328	>	long parentState = par.getReconciledState();
329	>	int parentPhase = phaseOf(parentState);
330	>	int parties = partiesOf(s);
331	>	long next = trippedStateFor(parentPhase, parties);
332	>	if (phaseOf(root.state) == rootPhase &&
333	>	parentPhase != phase &&
334	>	state == s && casState(s, next)) {
335	>	releaseWaiters(phase);
336	>	if (parties == 0) // exit if the final deregistration
337	>	break;
338	>	}
339	>	s = state;
340	>	}
341	>	}
342	>	return s;
343	>	}
344	>
345	>	/**
346	>	* Creates a new phaser without any initially registered parties,
347	>	* initial phase number 0, and no parent. Any thread using this
348	>	* phaser will need to first register for it.
349		*/
350		public Phaser() {
351	<	state = new AtomicLong(stateFor(0, 0, 0));
351	>	this(null);
352		}
353
354		/**
355	<	* Creates a new Phaser with the given numbers of registered
356	<	* unarrived parties and initial phase number 0.
357	<	* @param parties the number of parties required to trip barrier.
355	>	* Creates a new phaser with the given number of registered
356	>	* unarrived parties, initial phase number 0, and no parent.
357	>	*
358	>	* @param parties the number of parties required to trip barrier
359		* @throws IllegalArgumentException if parties less than zero
360	<	* or greater than the maximum number of parties supported.
360	>	* or greater than the maximum number of parties supported
361		*/
362		public Phaser(int parties) {
363	+	this(null, parties);
364	+	}
365	+
366	+	/**
367	+	* Creates a new phaser with the given parent, without any
368	+	* initially registered parties. If parent is non-null this phaser
369	+	* is registered with the parent and its initial phase number is
370	+	* the same as that of parent phaser.
371	+	*
372	+	* @param parent the parent phaser
373	+	*/
374	+	public Phaser(Phaser parent) {
375	+	int phase = 0;
376	+	this.parent = parent;
377	+	if (parent != null) {
378	+	this.root = parent.root;
379	+	phase = parent.register();
380	+	}
381	+	else
382	+	this.root = this;
383	+	this.state = trippedStateFor(phase, 0);
384	+	}
385	+
386	+	/**
387	+	* Creates a new phaser with the given parent and number of
388	+	* registered unarrived parties. If parent is non-null, this phaser
389	+	* is registered with the parent and its initial phase number is
390	+	* the same as that of parent phaser.
391	+	*
392	+	* @param parent the parent phaser
393	+	* @param parties the number of parties required to trip barrier
394	+	* @throws IllegalArgumentException if parties less than zero
395	+	* or greater than the maximum number of parties supported
396	+	*/
397	+	public Phaser(Phaser parent, int parties) {
398		if (parties < 0 || parties > ushortMask)
399		throw new IllegalArgumentException("Illegal number of parties");
400	<	state = new AtomicLong(stateFor(0, parties, parties));
400	>	int phase = 0;
401	>	this.parent = parent;
402	>	if (parent != null) {
403	>	this.root = parent.root;
404	>	phase = parent.register();
405	>	}
406	>	else
407	>	this.root = this;
408	>	this.state = trippedStateFor(phase, parties);
409		}
410
411		/**
412		* Adds a new unarrived party to this phaser.
413	<	* @return the current barrier phase number upon registration
413	>	* If an ongoing invocation of {@link #onAdvance} is in progress,
414	>	* this method waits until its completion before registering.
415	>	*
416	>	* @return the arrival phase number to which this registration applied
417		* @throws IllegalStateException if attempting to register more
418	<	* than the maximum supported number of parties.
418	>	* than the maximum supported number of parties
419		*/
420	<	public int register() { // increment both parties and unarrived
421	<	final AtomicLong state = this.state;
422	<	for (;;) {
423	<	long s = state.get();
424	<	int phase = phaseOf(s);
425	<	int parties = partiesOf(s) + 1;
426	<	int unarrived = unarrivedOf(s) + 1;
427	<	if (parties > ushortMask || unarrived > ushortMask)
428	<	throw badBounds(parties, unarrived);
429	<	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
430	<	return phase;
420	>	public int register() {
421	>	return doRegister(1);
422	>	}
423	>
424	>	/**
425	>	* Adds the given number of new unarrived parties to this phaser.
426	>	* If an ongoing invocation of {@link #onAdvance} is in progress,
427	>	* this method waits until its completion before registering.
428	>	*
429	>	* @param parties the number of additional parties required to trip barrier
430	>	* @return the arrival phase number to which this registration applied
431	>	* @throws IllegalStateException if attempting to register more
432	>	* than the maximum supported number of parties
433	>	* @throws IllegalArgumentException if {@code parties < 0}
434	>	*/
435	>	public int bulkRegister(int parties) {
436	>	if (parties < 0)
437	>	throw new IllegalArgumentException();
438	>	if (parties == 0)
439	>	return getPhase();
440	>	return doRegister(parties);
441	>	}
442	>
443	>	/**
444	>	* Shared code for register, bulkRegister
445	>	*/
446	>	private int doRegister(int registrations) {
447	>	Phaser par = parent;
448	>	long s;
449	>	int phase;
450	>	while ((phase = phaseOf(s = par==null? state:reconcileState())) >= 0) {
451	>	int p = partiesOf(s);
452	>	int u = unarrivedOf(s);
453	>	int unarrived = u + registrations;
454	>	int parties = p + registrations;
455	>	if (par == null || phase == phaseOf(root.state)) {
456	>	if (parties > ushortMask || unarrived > ushortMask)
457	>	throw new IllegalStateException(badBounds(parties,
458	>	unarrived));
459	>	else if (p != 0 && u == 0)       // back off if advancing
460	>	Thread.yield();              // not worth actually blocking
461	>	else if (casState(s, stateFor(phase, parties, unarrived)))
462	>	break;
463	>	}
464		}
465	+	return phase;
466		}
467
468		/**
469		* Arrives at the barrier, but does not wait for others.  (You can
470	<	* in turn wait for others via {@link #awaitAdvance}).
470	>	* in turn wait for others via {@link #awaitAdvance}).  It is an
471	>	* unenforced usage error for an unregistered party to invoke this
472	>	* method.
473		*
474	<	* @return the current barrier phase number upon entry to
475	<	* this method, or a negative value if terminated;
476	<	* @throws IllegalStateException if the number of unarrived
477	<	* parties would become negative.
478	<	*/
479	<	public int arrive() { // decrement unarrived. If zero, trip
480	<	final AtomicLong state = this.state;
481	<	for (;;) {
482	<	long s = state.get();
230	<	int phase = phaseOf(s);
474	>	* @return the arrival phase number, or a negative value if terminated
475	>	* @throws IllegalStateException if not terminated and the number
476	>	* of unarrived parties would become negative
477	>	*/
478	>	public int arrive() {
479	>	Phaser par = parent;
480	>	long s;
481	>	int phase;
482	>	while ((phase = phaseOf(s = par==null? state:reconcileState())) >= 0) {
483		int parties = partiesOf(s);
484		int unarrived = unarrivedOf(s) - 1;
485	<	if (unarrived < 0)
486	<	throw badBounds(parties, unarrived);
487	<	if (unarrived == 0 && phase >= 0) {
488	<	trip(phase, parties);
489	<	return phase;
485	>	if (parties == 0 || unarrived < 0)
486	>	throw new IllegalStateException(badBounds(parties,
487	>	unarrived));
488	>	else if (unarrived > 0) {           // Not the last arrival
489	>	if (casState(s, s - 1))         // s-1 adds one arrival
490	>	break;
491	>	}
492	>	else if (par == null) {             // directly trip
493	>	if (casState(s, trippedStateFor(onAdvance(phase, parties) ? -1 :
494	>	((phase + 1) & phaseMask),
495	>	parties))) {
496	>	releaseWaiters(phase);
497	>	break;
498	>	}
499	>	}
500	>	else if (phaseOf(root.state) == phase && casState(s, s - 1)) {
501	>	par.arrive();                   // cascade to parent
502	>	reconcileState();
503	>	break;
504		}
239	–	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
240	–	return phase;
505		}
506	+	return phase;
507		}
508
509		/**
510	<	* Arrives at the barrier, and deregisters from it, without
511	<	* waiting for others.
510	>	* Arrives at the barrier and deregisters from it without waiting
511	>	* for others. Deregistration reduces the number of parties
512	>	* required to trip the barrier in future phases.  If this phaser
513	>	* has a parent, and deregistration causes this phaser to have
514	>	* zero parties, this phaser also arrives at and is deregistered
515	>	* from its parent.  It is an unenforced usage error for an
516	>	* unregistered party to invoke this method.
517		*
518	<	* @return the current barrier phase number upon entry to
519	<	* this method, or a negative value if terminated;
520	<	* @throws IllegalStateException if the number of registered or
521	<	* unarrived parties would become negative.
522	<	*/
523	<	public int arriveAndDeregister() { // Same as arrive, plus decrement parties
524	<	final AtomicLong state = this.state;
525	<	for (;;) {
526	<	long s = state.get();
527	<	int phase = phaseOf(s);
518	>	* @return the arrival phase number, or a negative value if terminated
519	>	* @throws IllegalStateException if not terminated and the number
520	>	* of registered or unarrived parties would become negative
521	>	*/
522	>	public int arriveAndDeregister() {
523	>	// similar to arrive, but too different to merge
524	>	Phaser par = parent;
525	>	long s;
526	>	int phase;
527	>	while ((phase = phaseOf(s = par==null? state:reconcileState())) >= 0) {
528		int parties = partiesOf(s) - 1;
529		int unarrived = unarrivedOf(s) - 1;
530		if (parties < 0 || unarrived < 0)
531	<	throw badBounds(parties, unarrived);
532	<	if (unarrived == 0 && phase >= 0) {
533	<	trip(phase, parties);
534	<	return phase;
531	>	throw new IllegalStateException(badBounds(parties,
532	>	unarrived));
533	>	else if (unarrived > 0) {
534	>	if (casState(s, stateFor(phase, parties, unarrived)))
535	>	break;
536	>	}
537	>	else if (par == null) {
538	>	if (casState(s, trippedStateFor(onAdvance(phase, parties)? -1:
539	>	(phase + 1) & phaseMask,
540	>	parties))) {
541	>	releaseWaiters(phase);
542	>	break;
543	>	}
544	>	}
545	>	else if (phaseOf(root.state) == phase &&
546	>	casState(s, stateFor(phase, parties, 0))) {
547	>	if (parties == 0)
548	>	par.arriveAndDeregister();
549	>	else
550	>	par.arrive();
551	>	reconcileState();
552	>	break;
553		}
266	–	if (state.compareAndSet(s, stateFor(phase, parties, unarrived)))
267	–	return phase;
554		}
555	+	return phase;
556		}
557
558		/**
559	<	* Arrives at the barrier and awaits others. Unlike other arrival
560	<	* methods, this method returns the arrival index of the
561	<	* caller. The caller tripping the barrier returns zero, the
562	<	* previous caller 1, and so on.
563	<	* @return the arrival index
564	<	* @throws IllegalStateException if the number of unarrived
565	<	* parties would become negative.
559	>	* Arrives at the barrier and awaits others. Equivalent in effect
560	>	* to {@code awaitAdvance(arrive())}.  If you need to await with
561	>	* interruption or timeout, you can arrange this with an analogous
562	>	* construction using one of the other forms of the {@code
563	>	* awaitAdvance} method.  If instead you need to deregister upon
564	>	* arrival, use {@link #arriveAndDeregister}. It is an unenforced
565	>	* usage error for an unregistered party to invoke this method.
566	>	*
567	>	* @return the arrival phase number, or a negative number if terminated
568	>	* @throws IllegalStateException if not terminated and the number
569	>	* of unarrived parties would become negative
570		*/
571		public int arriveAndAwaitAdvance() {
572	<	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	<	}
572	>	return awaitAdvance(arrive());
573		}
574
575		/**
576	<	* Awaits the phase of the barrier to advance from the given
577	<	* value, or returns immediately if this barrier is terminated
578	<	* @param phase the phase on entry to this method
579	<	* @return the phase on exit from this method
576	>	* Awaits the phase of the barrier to advance from the given phase
577	>	* value, returning immediately if the current phase of the
578	>	* barrier is not equal to the given phase value or this barrier
579	>	* is terminated.  It is an unenforced usage error for an
580	>	* unregistered party to invoke this method.
581	>	*
582	>	* @param phase an arrival phase number, or negative value if
583	>	* terminated; this argument is normally the value returned by a
584	>	* previous call to {@code arrive} or its variants
585	>	* @return the next arrival phase number, or a negative value
586	>	* if terminated or argument is negative
587		*/
588		public int awaitAdvance(int phase) {
589		if (phase < 0)
590		return phase;
591	<	Thread current = Thread.currentThread();
592	<	if (current instanceof ForkJoinWorkerThread)
593	<	return helpingWait(phase);
594	<	if (untimedWait(current, phase, false))
313	<	current.interrupt();
314	<	return phaseOf(state.get());
591	>	int p = getPhase();
592	>	if (p != phase)
593	>	return p;
594	>	return untimedWait(phase);
595		}
596
597		/**
598	<	* Awaits the phase of the barrier to advance from the given
599	<	* value, or returns immediately if this barrier is terminated, or
600	<	* throws InterruptedException if interrupted while waiting.
601	<	* @param phase the phase on entry to this method
602	<	* @return the phase on exit from this method
598	>	* Awaits the phase of the barrier to advance from the given phase
599	>	* value, throwing {@code InterruptedException} if interrupted
600	>	* while waiting, or returning immediately if the current phase of
601	>	* the barrier is not equal to the given phase value or this
602	>	* barrier is terminated. It is an unenforced usage error for an
603	>	* unregistered party to invoke this method.
604	>	*
605	>	* @param phase an arrival phase number, or negative value if
606	>	* terminated; this argument is normally the value returned by a
607	>	* previous call to {@code arrive} or its variants
608	>	* @return the next arrival phase number, or a negative value
609	>	* if terminated or argument is negative
610		* @throws InterruptedException if thread interrupted while waiting
611		*/
612	<	public int awaitAdvanceInterruptibly(int phase) throws InterruptedException {
612	>	public int awaitAdvanceInterruptibly(int phase)
613	>	throws InterruptedException {
614		if (phase < 0)
615		return phase;
616	<	Thread current = Thread.currentThread();
617	<	if (current instanceof ForkJoinWorkerThread)
618	<	return helpingWait(phase);
619	<	else if (Thread.interrupted() || untimedWait(current, phase, true))
332	<	throw new InterruptedException();
333	<	else
334	<	return phaseOf(state.get());
616	>	int p = getPhase();
617	>	if (p != phase)
618	>	return p;
619	>	return interruptibleWait(phase);
620		}
621
622		/**
623	<	* Awaits the phase of the barrier to advance from the given value
624	<	* or the given timeout elapses, or returns immediately if this
625	<	* barrier is terminated
626	<	* @param phase the phase on entry to this method
627	<	* @return the phase on exit from this method
623	>	* Awaits the phase of the barrier to advance from the given phase
624	>	* value or the given timeout to elapse, throwing {@code
625	>	* InterruptedException} if interrupted while waiting, or
626	>	* returning immediately if the current phase of the barrier is
627	>	* not equal to the given phase value or this barrier is
628	>	* terminated.  It is an unenforced usage error for an
629	>	* unregistered party to invoke this method.
630	>	*
631	>	* @param phase an arrival phase number, or negative value if
632	>	* terminated; this argument is normally the value returned by a
633	>	* previous call to {@code arrive} or its variants
634	>	* @param timeout how long to wait before giving up, in units of
635	>	*        {@code unit}
636	>	* @param unit a {@code TimeUnit} determining how to interpret the
637	>	*        {@code timeout} parameter
638	>	* @return the next arrival phase number, or a negative value
639	>	* if terminated or argument is negative
640		* @throws InterruptedException if thread interrupted while waiting
641		* @throws TimeoutException if timed out while waiting
642		*/
643	<	public int awaitAdvanceInterruptibly(int phase, long timeout, TimeUnit unit)
643	>	public int awaitAdvanceInterruptibly(int phase,
644	>	long timeout, TimeUnit unit)
645		throws InterruptedException, TimeoutException {
646	+	long nanos = unit.toNanos(timeout);
647		if (phase < 0)
648		return phase;
649	<	long nanos = unit.toNanos(timeout);
650	<	Thread current = Thread.currentThread();
651	<	if (current instanceof ForkJoinWorkerThread)
652	<	return timedHelpingWait(phase, nanos);
354	<	timedWait(current, phase, nanos);
355	<	return phaseOf(state.get());
649	>	int p = getPhase();
650	>	if (p != phase)
651	>	return p;
652	>	return timedWait(phase, nanos);
653		}
654
655		/**
656		* Forces this barrier to enter termination state. Counts of
657	<	* arrived and registered parties are unaffected. This method may
658	<	* be useful for coordinating recovery after one or more tasks
659	<	* encounter unexpected exceptions.
657	>	* arrived and registered parties are unaffected. If this phaser
658	>	* has a parent, it too is terminated. This method may be useful
659	>	* for coordinating recovery after one or more tasks encounter
660	>	* unexpected exceptions.
661		*/
662		public void forceTermination() {
663	<	final AtomicLong state = this.state;
664	<	for (;;) {
665	<	long s = state.get();
666	<	int phase = phaseOf(s);
667	<	int parties = partiesOf(s);
668	<	int unarrived = unarrivedOf(s);
669	<	if (phase < 0 ||
372	<	state.compareAndSet(s, stateFor(-1, parties, unarrived))) {
373	<	if (head.get() != null)
374	<	releaseWaiters(-1);
375	<	return;
376	<	}
377	<	}
378	<	}
379	<
380	<	/**
381	<	* Resets the barrier with the given numbers of registered unarrived
382	<	* parties and phase number 0. This method allows repeated reuse
383	<	* of this barrier, but only if it is somehow known not to be in
384	<	* use for other purposes.
385	<	* @param parties the number of parties required to trip barrier.
386	<	* @throws IllegalArgumentException if parties less than zero
387	<	* or greater than the maximum number of parties supported.
388	<	*/
389	<	public void reset(int parties) {
390	<	if (parties < 0 || parties > ushortMask)
391	<	throw new IllegalArgumentException("Illegal number of parties");
392	<	state.set(stateFor(0, parties, parties));
393	<	if (head.get() != null)
394	<	releaseWaiters(0);
663	>	Phaser r = root;    // force at root then reconcile
664	>	long s;
665	>	while (phaseOf(s = r.state) >= 0)
666	>	r.casState(s, stateFor(-1, partiesOf(s), unarrivedOf(s)));
667	>	reconcileState();
668	>	releaseWaiters(0);  // ensure wakeups on both queues
669	>	releaseWaiters(1);
670		}
671
672		/**
673		* Returns the current phase number. The maximum phase number is
674	<	* <tt>Integer.MAX_VALUE</tt>, after which it restarts at
674	>	* {@code Integer.MAX_VALUE}, after which it restarts at
675		* zero. Upon termination, the phase number is negative.
676	+	*
677		* @return the phase number, or a negative value if terminated
678		*/
679	<	public int getPhase() {
680	<	return phaseOf(state.get());
679	>	public final int getPhase() {
680	>	return phaseOf(getReconciledState());
681		}
682
683		/**
684		* Returns the number of parties registered at this barrier.
685	+	*
686		* @return the number of parties
687		*/
688		public int getRegisteredParties() {
689	<	return partiesOf(state.get());
689	>	return partiesOf(getReconciledState());
690		}
691
692		/**
693	<	* Returns the number of parties that have arrived at the current
694	<	* phase of this barrier.
693	>	* Returns the number of registered parties that have arrived at
694	>	* the current phase of this barrier.
695	>	*
696		* @return the number of arrived parties
697		*/
698		public int getArrivedParties() {
699	<	return arrivedOf(state.get());
699	>	return arrivedOf(getReconciledState());
700		}
701
702		/**
703		* Returns the number of registered parties that have not yet
704		* arrived at the current phase of this barrier.
705	+	*
706		* @return the number of unarrived parties
707		*/
708		public int getUnarrivedParties() {
709	<	return unarrivedOf(state.get());
709	>	return unarrivedOf(getReconciledState());
710	>	}
711	>
712	>	/**
713	>	* Returns the parent of this phaser, or {@code null} if none.
714	>	*
715	>	* @return the parent of this phaser, or {@code null} if none
716	>	*/
717	>	public Phaser getParent() {
718	>	return parent;
719		}
720
721		/**
722	<	* Returns true if this barrier has been terminated
723	<	* @return true if this barrier has been terminated
722	>	* Returns the root ancestor of this phaser, which is the same as
723	>	* this phaser if it has no parent.
724	>	*
725	>	* @return the root ancestor of this phaser
726	>	*/
727	>	public Phaser getRoot() {
728	>	return root;
729	>	}
730	>
731	>	/**
732	>	* Returns {@code true} if this barrier has been terminated.
733	>	*
734	>	* @return {@code true} if this barrier has been terminated
735		*/
736		public boolean isTerminated() {
737	<	return phaseOf(state.get()) < 0;
737	>	return getPhase() < 0;
738		}
739
740		/**
741	<	* Overridable method to perform an action upon phase advance, and
742	<	* to control termination. This method is invoked whenever the
743	<	* barrier is tripped (and thus all other waiting parties are
744	<	* dormant). If it returns true, then, rather than advance the
745	<	* phase number, this barrier will be set to a final termination
746	<	* state, and subsequent calls to <tt>isTerminated</tt> will
747	<	* return true.
748	<	*
749	<	* <p> The default version returns true when the number of
741	>	* Overridable method to perform an action upon impending phase
742	>	* advance, and to control termination. This method is invoked
743	>	* upon arrival of the party tripping the barrier (when all other
744	>	* waiting parties are dormant).  If this method returns {@code
745	>	* true}, then, rather than advance the phase number, this barrier
746	>	* will be set to a final termination state, and subsequent calls
747	>	* to {@link #isTerminated} will return true. Any (unchecked)
748	>	* Exception or Error thrown by an invocation of this method is
749	>	* propagated to the party attempting to trip the barrier, in
750	>	* which case no advance occurs.
751	>	*
752	>	* <p>The arguments to this method provide the state of the phaser
753	>	* prevailing for the current transition. (When called from within
754	>	* an implementation of {@code onAdvance} the values returned by
755	>	* methods such as {@code getPhase} may or may not reliably
756	>	* indicate the state to which this transition applies.)
757	>	*
758	>	* <p>The default version returns {@code true} when the number of
759		* registered parties is zero. Normally, overrides that arrange
760		* termination for other reasons should also preserve this
761		* property.
762		*
763		* @param phase the phase number on entering the barrier
764	<	* @param registeredParties the current number of registered
765	<	* parties.
458	<	* @return true if this barrier should terminate
764	>	* @param registeredParties the current number of registered parties
765	>	* @return {@code true} if this barrier should terminate
766		*/
767		protected boolean onAdvance(int phase, int registeredParties) {
768		return registeredParties <= 0;
769		}
770
771		/**
772	<	* Returns a string identifying this barrier, as well as its
772	>	* Returns a string identifying this phaser, as well as its
773		* state.  The state, in brackets, includes the String {@code
774	<	* "phase ="} followed by the phase number, {@code "parties ="}
774	>	* "phase = "} followed by the phase number, {@code "parties = "}
775		* followed by the number of registered parties, and {@code
776	<	* "arrived ="} followed by the number of arrived parties
776	>	* "arrived = "} followed by the number of arrived parties.
777		*
778		* @return a string identifying this barrier, as well as its state
779		*/
780		public String toString() {
781	<	long s = state.get();
782	<	return super.toString() + "[phase = " + phaseOf(s) + " parties = " + partiesOf(s) + " arrived = " + arrivedOf(s) + "]";
781	>	long s = getReconciledState();
782	>	return super.toString() +
783	>	"[phase = " + phaseOf(s) +
784	>	" parties = " + partiesOf(s) +
785	>	" arrived = " + arrivedOf(s) + "]";
786		}
787
788	<	// methods for tripping and waiting
788	>	// methods for waiting
789
790		/**
791	<	* Advance the current phase (or terminate)
791	>	* Wait nodes for Treiber stack representing wait queue
792		*/
793	<	private void trip(int phase, int parties) {
794	<	int next = onAdvance(phase, parties)? -1 : ((phase + 1) & phaseMask);
795	<	state.set(stateFor(next, parties, parties));
796	<	if (head.get() != null)
797	<	releaseWaiters(next);
798	<	}
793	>	static final class QNode implements ForkJoinPool.ManagedBlocker {
794	>	final Phaser phaser;
795	>	final int phase;
796	>	final long startTime;
797	>	final long nanos;
798	>	final boolean timed;
799	>	final boolean interruptible;
800	>	volatile boolean wasInterrupted = false;
801	>	volatile Thread thread; // nulled to cancel wait
802	>	QNode next;
803
804	<	private int helpingWait(int phase) {
805	<	final AtomicLong state = this.state;
806	<	int p;
807	<	while ((p = phaseOf(state.get())) == phase) {
808	<	ForkJoinTask<?> t = ForkJoinWorkerThread.pollTask();
809	<	if (t != null) {
810	<	if ((p = phaseOf(state.get())) == phase)
811	<	t.exec();
812	<	else {   // push task and exit if barrier advanced
813	<	t.fork();
814	<	break;
815	<	}
804	>	QNode(Phaser phaser, int phase, boolean interruptible,
805	>	boolean timed, long startTime, long nanos) {
806	>	this.phaser = phaser;
807	>	this.phase = phase;
808	>	this.timed = timed;
809	>	this.interruptible = interruptible;
810	>	this.startTime = startTime;
811	>	this.nanos = nanos;
812	>	thread = Thread.currentThread();
813	>	}
814	>
815	>	public boolean isReleasable() {
816	>	return (thread == null ||
817	>	phaser.getPhase() != phase ||
818	>	(interruptible && wasInterrupted) ||
819	>	(timed && (nanos - (System.nanoTime() - startTime)) <= 0));
820	>	}
821	>
822	>	public boolean block() {
823	>	if (Thread.interrupted()) {
824	>	wasInterrupted = true;
825	>	if (interruptible)
826	>	return true;
827	>	}
828	>	if (!timed)
829	>	LockSupport.park(this);
830	>	else {
831	>	long waitTime = nanos - (System.nanoTime() - startTime);
832	>	if (waitTime <= 0)
833	>	return true;
834	>	LockSupport.parkNanos(this, waitTime);
835		}
836	+	return isReleasable();
837		}
504	–	return p;
505	–	}
838
839	<	private int timedHelpingWait(int phase, long nanos) throws TimeoutException {
840	<	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();
839	>	void signal() {
840	>	Thread t = thread;
841		if (t != null) {
842	<	if ((p = phaseOf(state.get())) == phase)
843	<	t.exec();
525	<	else {   // push task and exit if barrier advanced
526	<	t.fork();
527	<	break;
528	<	}
842	>	thread = null;
843	>	LockSupport.unpark(t);
844		}
845		}
531	–	return p;
532	–	}
533	–
534	–	/**
535	–	* 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.
538	–	*/
539	–	static final class QNode {
540	–	QNode next;
541	–	volatile Thread thread; // nulled to cancel wait
542	–	final int phase;
543	–	QNode(Thread t, int c) {
544	–	thread = t;
545	–	phase = c;
546	–	}
547	–	}
846
847	<	private void releaseWaiters(int currentPhase) {
848	<	final AtomicReference<QNode> head = this.head;
849	<	QNode p;
850	<	while ((p = head.get()) != null && p.phase != currentPhase) {
851	<	if (head.compareAndSet(p, null)) {
852	<	do {
853	<	Thread t = p.thread;
556	<	if (t != null) {
557	<	p.thread = null;
558	<	LockSupport.unpark(t);
559	<	}
560	<	} while ((p = p.next) != null);
847	>	boolean doWait() {
848	>	if (thread != null) {
849	>	try {
850	>	ForkJoinPool.managedBlock(this);
851	>	} catch (InterruptedException ie) {
852	>	wasInterrupted = true; // can't currently happen
853	>	}
854		}
855	+	return wasInterrupted;
856		}
857		}
858
565	–	/** The number of CPUs, for spin control */
566	–	static final int NCPUS = Runtime.getRuntime().availableProcessors();
567	–
859		/**
860	<	* The number of times to spin before blocking in timed waits.
570	<	* The value is empirically derived
860	>	* Removes and signals waiting threads from wait queue.
861		*/
862	<	static final int maxTimedSpins = (NCPUS < 2)? 0 : 32;
862	>	private void releaseWaiters(int phase) {
863	>	AtomicReference<QNode> head = queueFor(phase);
864	>	QNode q;
865	>	while ((q = head.get()) != null) {
866	>	if (head.compareAndSet(q, q.next))
867	>	q.signal();
868	>	}
869	>	}
870
871		/**
872	<	* The number of times to spin before blocking in untimed waits.
873	<	* This is greater than timed value because untimed waits spin
874	<	* faster since they don't need to check times on each spin.
872	>	* Tries to enqueue given node in the appropriate wait queue.
873	>	*
874	>	* @return true if successful
875		*/
876	<	static final int maxUntimedSpins = maxTimedSpins * 32;
876	>	private boolean tryEnqueue(QNode node) {
877	>	AtomicReference<QNode> head = queueFor(node.phase);
878	>	return head.compareAndSet(node.next = head.get(), node);
879	>	}
880
881		/**
882	<	* The number of nanoseconds for which it is faster to spin
883	<	* rather than to use timed park. A rough estimate suffices.
882	>	* Enqueues node and waits unless aborted or signalled.
883	>	*
884	>	* @return current phase
885		*/
886	<	static final long spinForTimeoutThreshold = 1000L;
886	>	private int untimedWait(int phase) {
887	>	QNode node = null;
888	>	boolean queued = false;
889	>	boolean interrupted = false;
890	>	int p;
891	>	while ((p = getPhase()) == phase) {
892	>	if (Thread.interrupted())
893	>	interrupted = true;
894	>	else if (node == null)
895	>	node = new QNode(this, phase, false, false, 0, 0);
896	>	else if (!queued)
897	>	queued = tryEnqueue(node);
898	>	else if (node.doWait())
899	>	interrupted = true;
900	>	}
901	>	if (node != null)
902	>	node.thread = null;
903	>	releaseWaiters(phase);
904	>	if (interrupted)
905	>	Thread.currentThread().interrupt();
906	>	return p;
907	>	}
908
909		/**
910	<	* Enqueues node and waits unless aborted or signalled.
910	>	* Interruptible version
911	>	* @return current phase
912		*/
913	<	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;
913	>	private int interruptibleWait(int phase) throws InterruptedException {
914		QNode node = null;
915		boolean queued = false;
916	<	int spins = maxUntimedSpins;
917	<	while (phaseOf(state.get()) == currentPhase) {
918	<	QNode h;
919	<	if (node != null && queued) {
920	<	if (node.thread != null) {
921	<	LockSupport.park();
922	<	if (Thread.interrupted()) {
923	<	wasInterrupted = true;
924	<	if (abortOnInterrupt)
925	<	break;
926	<	}
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);
627	<	else
628	<	--spins;
916	>	boolean interrupted = false;
917	>	int p;
918	>	while ((p = getPhase()) == phase && !interrupted) {
919	>	if (Thread.interrupted())
920	>	interrupted = true;
921	>	else if (node == null)
922	>	node = new QNode(this, phase, true, false, 0, 0);
923	>	else if (!queued)
924	>	queued = tryEnqueue(node);
925	>	else if (node.doWait())
926	>	interrupted = true;
927		}
928		if (node != null)
929		node.thread = null;
930	<	return wasInterrupted;
930	>	if (p != phase || (p = getPhase()) != phase)
931	>	releaseWaiters(phase);
932	>	if (interrupted)
933	>	throw new InterruptedException();
934	>	return p;
935		}
936
937		/**
938	<	* Messier timeout version
938	>	* Timeout version.
939	>	* @return current phase
940		*/
941	<	private void timedWait(Thread thread, int currentPhase, long nanos)
941	>	private int timedWait(int phase, long nanos)
942		throws InterruptedException, TimeoutException {
943	<	final AtomicReference<QNode> head = this.head;
641	<	final AtomicLong state = this.state;
642	<	long lastTime = System.nanoTime();
943	>	long startTime = System.nanoTime();
944		QNode node = null;
945		boolean queued = false;
946	<	int spins = maxTimedSpins;
947	<	while (phaseOf(state.get()) == currentPhase) {
948	<	QNode h;
949	<	long now = System.nanoTime();
950	<	nanos -= now - lastTime;
951	<	lastTime = now;
952	<	if (nanos <= 0) {
953	<	if (node != null)
954	<	node.thread = null;
955	<	if (phaseOf(state.get()) == currentPhase)
956	<	throw new TimeoutException();
957	<	else
958	<	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);
687	<	else
688	<	--spins;
946	>	boolean interrupted = false;
947	>	int p;
948	>	while ((p = getPhase()) == phase && !interrupted) {
949	>	if (Thread.interrupted())
950	>	interrupted = true;
951	>	else if (nanos - (System.nanoTime() - startTime) <= 0)
952	>	break;
953	>	else if (node == null)
954	>	node = new QNode(this, phase, true, true, startTime, nanos);
955	>	else if (!queued)
956	>	queued = tryEnqueue(node);
957	>	else if (node.doWait())
958	>	interrupted = true;
959		}
960		if (node != null)
961		node.thread = null;
962	+	if (p != phase || (p = getPhase()) != phase)
963	+	releaseWaiters(phase);
964	+	if (interrupted)
965	+	throw new InterruptedException();
966	+	if (p == phase)
967	+	throw new TimeoutException();
968	+	return p;
969		}
970
971	<	}
971	>	// Unsafe mechanics
972	>
973	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
974	>	private static final long stateOffset =
975	>	objectFieldOffset("state", Phaser.class);
976
977	+	private final boolean casState(long cmp, long val) {
978	+	return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val);
979	+	}
980	+
981	+	private static long objectFieldOffset(String field, Class<?> klazz) {
982	+	try {
983	+	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
984	+	} catch (NoSuchFieldException e) {
985	+	// Convert Exception to corresponding Error
986	+	NoSuchFieldError error = new NoSuchFieldError(field);
987	+	error.initCause(e);
988	+	throw error;
989	+	}
990	+	}
991	+
992	+	/**
993	+	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
994	+	* Replace with a simple call to Unsafe.getUnsafe when integrating
995	+	* into a jdk.
996	+	*
997	+	* @return a sun.misc.Unsafe
998	+	*/
999	+	private static sun.misc.Unsafe getUnsafe() {
1000	+	try {
1001	+	return sun.misc.Unsafe.getUnsafe();
1002	+	} catch (SecurityException se) {
1003	+	try {
1004	+	return java.security.AccessController.doPrivileged
1005	+	(new java.security
1006	+	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1007	+	public sun.misc.Unsafe run() throws Exception {
1008	+	java.lang.reflect.Field f = sun.misc
1009	+	.Unsafe.class.getDeclaredField("theUnsafe");
1010	+	f.setAccessible(true);
1011	+	return (sun.misc.Unsafe) f.get(null);
1012	+	}});
1013	+	} catch (java.security.PrivilegedActionException e) {
1014	+	throw new RuntimeException("Could not initialize intrinsics",
1015	+	e.getCause());
1016	+	}
1017	+	}
1018	+	}
1019	+	}

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