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Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.11 by jsr166, Thu Mar 19 04:49:44 2009 UTC vs.
Revision 1.50 by dl, Sat Nov 6 16:12:10 2010 UTC

#	Line 7 | Line 7
7		package jsr166y;
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	–	import sun.misc.Unsafe;
13	–	import java.lang.reflect.*;
12
13		/**
14	<	* A reusable synchronization barrier, similar in functionality to a
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	<	* <ul>
20	<	*
21	<	* <li> The number of parties synchronizing on a phaser may vary over
22	<	* time.  A task may register to be a party at any time, and may
23	<	* deregister upon arriving at the barrier.  As is the case with most
24	<	* basic synchronization constructs, registration and deregistration
25	<	* affect only internal counts; they do not establish any further
26	<	* internal bookkeeping, so tasks cannot query whether they are
27	<	* registered. (However, you can introduce such bookkeeping by
28	<	* subclassing this class.)
29	<	*
30	<	* <li> Each generation has an associated phase value, starting at
31	<	* zero, and advancing when all parties reach the barrier (wrapping
32	<	* around to zero after reaching {@code Integer.MAX_VALUE}).
33	<	*
34	<	* <li> Like a CyclicBarrier, a Phaser may be repeatedly awaited.
35	<	* Method {@code arriveAndAwaitAdvance} has effect analogous to
36	<	* {@code CyclicBarrier.await}.  However, Phasers separate two
37	<	* aspects of coordination, that may also be invoked independently:
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> Arriving at a barrier. Methods {@code arrive} and
47	<	*       {@code arriveAndDeregister} do not block, but return
48	<	*       the phase value current upon entry to the method.
49	<	*
50	<	*   <li> Awaiting others. Method {@code awaitAdvance} requires an
51	<	*       argument indicating the entry phase, and returns when the
52	<	*       barrier advances to a new phase.
53	<	* </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		*
74	+	* </ul>
75		*
76	<	* <li> Barrier actions, performed by the task triggering a phase
77	<	* advance while others may be waiting, are arranged by overriding
78	<	* method {@code onAdvance}, that also controls termination.
79	<	* Overriding this method may be used to similar but more flexible
80	<	* effect as providing a barrier action to a CyclicBarrier.
81	<	*
82	<	* <li> Phasers may enter a <em>termination</em> state in which all
83	<	* actions immediately return without updating phaser state or waiting
84	<	* for advance, and indicating (via a negative phase value) that
85	<	* execution is complete.  Termination is triggered by executing the
86	<	* 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 {@code forceTermination} is also
68	<	* available to abruptly release waiting threads and allow them to
69	<	* terminate.
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	<	* <li> Phasers may be tiered to reduce contention. Phasers with large
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 arranged in trees.
92	<	* This will typically greatly increase throughput even though it
93	<	* incurs somewhat greater per-operation overhead.
94	<	*
95	<	* <li> By default, {@code awaitAdvance} continues to wait even if
96	<	* the waiting thread is interrupted. And unlike the case in
97	<	* CyclicBarriers, exceptions encountered while tasks wait
98	<	* interruptibly or with timeout do not change the state of the
99	<	* barrier. If necessary, you can perform any associated recovery
100	<	* within handlers of those exceptions, often after invoking
101	<	* {@code forceTermination}.
102	<	*
103	<	* <li>Phasers ensure lack of starvation when used by ForkJoinTasks.
104	<	*
105	<	* </ul>
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 Phaser may be used instead of a {@code CountDownLatch} to control
111	<	* a one-shot action serving a variable number of parties. The typical
112	<	* idiom is for the method setting this up to first register, then
113	<	* start the actions, then deregister, as in:
114	<	*
115	<	* <pre>
116	<	*  void runTasks(List&lt;Runnable&gt; list) {
117	<	*    final Phaser phaser = new Phaser(1); // "1" to register self
118	<	*    for (Runnable r : list) {
119	<	*      phaser.register();
120	<	*      new Thread() {
121	<	*        public void run() {
122	<	*          phaser.arriveAndAwaitAdvance(); // await all creation
123	<	*          r.run();
124	<	*          phaser.arriveAndDeregister();   // signal completion
125	<	*        }
126	<	*      }.start();
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	<	*   doSomethingOnBehalfOfWorkers();
130	<	*   phaser.arrive(); // allow threads to start
131	<	*   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	<	* }
117	<	* </pre>
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>
137	<	*  void startTasks(List&lt;Runnable&gt; list, final int iterations) {
138	<	*    final Phaser phaser = new Phaser() {
139	<	*       public boolean onAdvance(int phase, int registeredParties) {
140	<	*         return phase &gt;= iterations || registeredParties == 0;
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	<	*    };
129	<	*    phaser.register();
130	<	*    for (Runnable r : list) {
131	<	*      phaser.register();
132	<	*      new Thread() {
133	<	*        public void run() {
134	<	*           do {
135	<	*             r.run();
136	<	*             phaser.arriveAndAwaitAdvance();
137	<	*           } while(!phaser.isTerminated();
138	<	*        }
139	<	*      }.start();
153	>	*     }.start();
154		*   }
155		*   phaser.arriveAndDeregister(); // deregister self, don't wait
156	<	* }
157	<	* </pre>
156	>	* }}</pre>
157	>	*
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		*
182	<	* <p> To create a set of tasks using a tree of Phasers,
182	>	*
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 for upon construction:
187	<	* <pre>
188	<	*  void build(Task[] actions, int lo, int hi, Phaser b) {
189	<	*    int step = (hi - lo) / TASKS_PER_PHASER;
190	<	*    if (step &gt; 1) {
191	<	*       int i = lo;
192	<	*       while (i &lt; hi) {
193	<	*         int r = Math.min(i + step, hi);
194	<	*         build(actions, i, r, new Phaser(b));
195	<	*         i = r;
196	<	*       }
197	<	*    }
198	<	*    else {
199	<	*      for (int i = lo; i &lt; hi; ++i)
200	<	*        actions[i] = new Task(b);
201	<	*        // assumes new Task(b) performs b.register()
202	<	*    }
165	<	*  }
166	<	*  // .. initially called, for n tasks via
167	<	*  build(new Task[n], 0, n, new Phaser());
168	<	* </pre>
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	>	*   } 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	>	* // .. 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		*
175	–	* </pre>
176	–	*
209		* <p><b>Implementation notes</b>: This implementation restricts the
210		* maximum number of parties to 65535. Attempts to register additional
211	<	* parties result in IllegalStateExceptions. However, you can and
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		/*
#	Line 207 | Line 242 | public class Phaser {
242		*/
243		private volatile long state;
244
210	–	private static final int ushortBits = 16;
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) >>> 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 228 | Line 262 | public class Phaser {
262		}
263
264		private static long stateFor(int phase, int parties, int unarrived) {
265	<	return ((((long)phase) << 32) | (((long)parties) << 16) |
266	<	(long)unarrived);
265	>	return ((((long) phase) << 32) | (((long) parties) << 16) |
266	>	(long) unarrived);
267		}
268
269		private static long trippedStateFor(int phase, int parties) {
270	<	long lp = (long)parties;
271	<	return (((long)phase) << 32) | (lp << 16) | lp;
270	>	long lp = (long) parties;
271	>	return (((long) phase) << 32) | (lp << 16) | lp;
272		}
273
274		/**
275	<	* Returns message string for bad bounds exceptions
275	>	* Returns message string for bad bounds exceptions.
276		*/
277		private static String badBounds(int parties, int unarrived) {
278		return ("Attempt to set " + unarrived +
#	Line 251 | Line 285 | public class Phaser {
285		private final Phaser parent;
286
287		/**
288	<	* The root of Phaser tree. Equals this if not in a tree.  Used to
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;
#	Line 260 | Line 294 | public class Phaser {
294
295		/**
296		* Heads of Treiber stacks for waiting threads. To eliminate
297	<	* contention while releasing some threads while adding others, we
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>();
301	>	private final AtomicReference<QNode> evenQ;
302	>	private final AtomicReference<QNode> oddQ;
303
304		private AtomicReference<QNode> queueFor(int phase) {
305	<	return (phase & 1) == 0? evenQ : oddQ;
305	>	return ((phase & 1) == 0) ? evenQ : oddQ;
306		}
307
308		/**
#	Line 275 | Line 310 | public class Phaser {
310		* root if necessary.
311		*/
312		private long getReconciledState() {
313	<	return parent == null? state : reconcileState();
313	>	return (parent == null) ? state : reconcileState();
314		}
315
316		/**
317		* Recursively resolves state.
318		*/
319		private long reconcileState() {
320	<	Phaser p = parent;
320	>	Phaser par = parent;
321		long s = state;
322	<	if (p != null) {
323	<	while (unarrivedOf(s) == 0 && phaseOf(s) != phaseOf(root.state)) {
324	<	long parentState = p.getReconciledState();
325	<	int parentPhase = phaseOf(parentState);
326	<	int phase = phaseOf(s = state);
327	<	if (phase != parentPhase) {
322	>	if (par != null) {
323	>	int phase, rootPhase;
324	>	while ((phase = phaseOf(s)) >= 0 &&
325	>	(rootPhase = phaseOf(root.state)) != phase &&
326	>	(rootPhase < 0 || unarrivedOf(s) == 0)) {
327	>	int parentPhase = phaseOf(par.getReconciledState());
328	>	if (parentPhase != phase) {
329		long next = trippedStateFor(parentPhase, partiesOf(s));
330	<	if (casState(s, next)) {
331	<	releaseWaiters(phase);
296	<	s = next;
297	<	}
330	>	if (state == s)
331	>	UNSAFE.compareAndSwapLong(this, stateOffset, s, next);
332		}
333	+	s = state;
334		}
335		}
336		return s;
337		}
338
339		/**
340	<	* Creates a new Phaser without any initially registered parties,
340	>	* Creates a new phaser without any initially registered parties,
341		* initial phase number 0, and no parent. Any thread using this
342	<	* Phaser will need to first register for it.
342	>	* phaser will need to first register for it.
343		*/
344		public Phaser() {
345	<	this(null);
345	>	this(null, 0);
346		}
347
348		/**
349	<	* Creates a new Phaser with the given numbers of registered
349	>	* Creates a new phaser with the given number of registered
350		* unarrived parties, initial phase number 0, and no parent.
351	<	* @param parties the number of parties required to trip barrier.
351	>	*
352	>	* @param parties the number of parties required to trip barrier
353		* @throws IllegalArgumentException if parties less than zero
354	<	* or greater than the maximum number of parties supported.
354	>	* or greater than the maximum number of parties supported
355		*/
356		public Phaser(int parties) {
357		this(null, parties);
358		}
359
360		/**
361	<	* Creates a new Phaser with the given parent, without any
361	>	* Creates a new phaser with the given parent, without any
362		* initially registered parties. If parent is non-null this phaser
363		* is registered with the parent and its initial phase number is
364		* the same as that of parent phaser.
365	<	* @param parent the parent phaser.
365	>	*
366	>	* @param parent the parent phaser
367		*/
368		public Phaser(Phaser parent) {
369	<	int phase = 0;
333	<	this.parent = parent;
334	<	if (parent != null) {
335	<	this.root = parent.root;
336	<	phase = parent.register();
337	<	}
338	<	else
339	<	this.root = this;
340	<	this.state = trippedStateFor(phase, 0);
369	>	this(parent, 0);
370		}
371
372		/**
373	<	* Creates a new Phaser with the given parent and numbers of
374	<	* registered unarrived parties. If parent is non-null this phaser
373	>	* Creates a new phaser with the given parent and number of
374	>	* registered unarrived parties. If parent is non-null, this phaser
375		* is registered with the parent and its initial phase number is
376		* the same as that of parent phaser.
377	<	* @param parent the parent phaser.
378	<	* @param parties the number of parties required to trip barrier.
377	>	*
378	>	* @param parent the parent phaser
379	>	* @param parties the number of parties required to trip barrier
380		* @throws IllegalArgumentException if parties less than zero
381	<	* or greater than the maximum number of parties supported.
381	>	* or greater than the maximum number of parties supported
382		*/
383		public Phaser(Phaser parent, int parties) {
384		if (parties < 0 || parties > ushortMask)
385		throw new IllegalArgumentException("Illegal number of parties");
386	<	int phase = 0;
386	>	int phase;
387		this.parent = parent;
388		if (parent != null) {
389	<	this.root = parent.root;
389	>	Phaser r = parent.root;
390	>	this.root = r;
391	>	this.evenQ = r.evenQ;
392	>	this.oddQ = r.oddQ;
393		phase = parent.register();
394		}
395	<	else
395	>	else {
396		this.root = this;
397	+	this.evenQ = new AtomicReference<QNode>();
398	+	this.oddQ = new AtomicReference<QNode>();
399	+	phase = 0;
400	+	}
401		this.state = trippedStateFor(phase, parties);
402		}
403
404		/**
405		* Adds a new unarrived party to this phaser.
406	<	* @return the current barrier phase number upon registration
406	>	* If an ongoing invocation of {@link #onAdvance} is in progress,
407	>	* this method may wait until its completion before registering.
408	>	*
409	>	* @return the arrival phase number to which this registration applied
410		* @throws IllegalStateException if attempting to register more
411	<	* than the maximum supported number of parties.
411	>	* than the maximum supported number of parties
412		*/
413		public int register() {
414		return doRegister(1);
#	Line 376 | Line 416 | public class Phaser {
416
417		/**
418		* Adds the given number of new unarrived parties to this phaser.
419	<	* @param parties the number of parties required to trip barrier.
420	<	* @return the current barrier phase number upon registration
419	>	* If an ongoing invocation of {@link #onAdvance} is in progress,
420	>	* this method may wait until its completion before registering.
421	>	*
422	>	* @param parties the number of additional parties required to trip barrier
423	>	* @return the arrival phase number to which this registration applied
424		* @throws IllegalStateException if attempting to register more
425	<	* than the maximum supported number of parties.
425	>	* than the maximum supported number of parties
426	>	* @throws IllegalArgumentException if {@code parties < 0}
427		*/
428		public int bulkRegister(int parties) {
429		if (parties < 0)
#	Line 393 | Line 437 | public class Phaser {
437		* Shared code for register, bulkRegister
438		*/
439		private int doRegister(int registrations) {
440	+	Phaser par = parent;
441	+	long s;
442		int phase;
443	<	for (;;) {
444	<	long s = getReconciledState();
445	<	phase = phaseOf(s);
446	<	int unarrived = unarrivedOf(s) + registrations;
447	<	int parties = partiesOf(s) + registrations;
448	<	if (phase < 0)
449	<	break;
450	<	if (parties > ushortMask || unarrived > ushortMask)
443	>	while ((phase = phaseOf(s = par==null? state:reconcileState())) >= 0) {
444	>	int p = partiesOf(s);
445	>	int u = unarrivedOf(s);
446	>	int unarrived = u + registrations;
447	>	int parties = p + registrations;
448	>	if (u == 0 && p != 0)  // if tripped, wait for advance
449	>	untimedWait(phase);
450	>	else if (parties > ushortMask)
451		throw new IllegalStateException(badBounds(parties, unarrived));
452	<	if (phase == phaseOf(root.state) &&
453	<	casState(s, stateFor(phase, parties, unarrived)))
454	<	break;
452	>	else if (par == null || phaseOf(root.state) == phase) {
453	>	long next = stateFor(phase, parties, unarrived);
454	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next))
455	>	break;
456	>	}
457		}
458		return phase;
459		}
460
461		/**
462		* Arrives at the barrier, but does not wait for others.  (You can
463	<	* in turn wait for others via {@link #awaitAdvance}).
463	>	* in turn wait for others via {@link #awaitAdvance}).  It is an
464	>	* unenforced usage error for an unregistered party to invoke this
465	>	* method.
466		*
467	<	* @return the barrier phase number upon entry to this method, or a
418	<	* negative value if terminated;
467	>	* @return the arrival phase number, or a negative value if terminated
468		* @throws IllegalStateException if not terminated and the number
469	<	* of unarrived parties would become negative.
469	>	* of unarrived parties would become negative
470		*/
471		public int arrive() {
472	+	Phaser par = parent;
473	+	long s;
474		int phase;
475	<	for (;;) {
425	<	long s = state;
426	<	phase = phaseOf(s);
427	<	if (phase < 0)
428	<	break;
475	>	while ((phase = phaseOf(s = par==null? state:reconcileState())) >= 0) {
476		int parties = partiesOf(s);
477		int unarrived = unarrivedOf(s) - 1;
478	<	if (unarrived > 0) {        // Not the last arrival
479	<	if (casState(s, s - 1)) // s-1 adds one arrival
480	<	break;
478	>	if (unarrived > 0) {                // Not the last arrival
479	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s - 1))
480	>	break;                      // s-1 adds one arrival
481		}
482	<	else if (unarrived == 0) {  // the last arrival
483	<	Phaser par = parent;
484	<	if (par == null) {      // directly trip
485	<	if (casState
486	<	(s,
487	<	trippedStateFor(onAdvance(phase, parties)? -1 :
488	<	((phase + 1) & phaseMask), parties))) {
489	<	releaseWaiters(phase);
490	<	break;
444	<	}
445	<	}
446	<	else {                  // cascade to parent
447	<	if (casState(s, s - 1)) { // zeroes unarrived
448	<	par.arrive();
449	<	reconcileState();
450	<	break;
451	<	}
482	>	else if (unarrived < 0)
483	>	throw new IllegalStateException(badBounds(parties, unarrived));
484	>	else if (par == null) {             // directly trip
485	>	long next = trippedStateFor(onAdvance(phase, parties) ? -1 :
486	>	((phase + 1) & phaseMask),
487	>	parties);
488	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next)) {
489	>	releaseWaiters(phase);
490	>	break;
491		}
492		}
493	<	else if (phase != phaseOf(root.state)) // or if unreconciled
493	>	else if (phaseOf(root.state) == phase &&
494	>	UNSAFE.compareAndSwapLong(this, stateOffset, s, s - 1)) {
495	>	par.arrive();                   // cascade to parent
496		reconcileState();
497	<	else
498	<	throw new IllegalStateException(badBounds(parties, unarrived));
497	>	break;
498	>	}
499		}
500		return phase;
501		}
502
503		/**
504	<	* Arrives at the barrier, and deregisters from it, without
505	<	* waiting for others. Deregistration reduces number of parties
504	>	* Arrives at the barrier and deregisters from it without waiting
505	>	* for others. Deregistration reduces the number of parties
506		* required to trip the barrier in future phases.  If this phaser
507		* has a parent, and deregistration causes this phaser to have
508	<	* zero parties, this phaser is also deregistered from its parent.
508	>	* zero parties, this phaser also arrives at and is deregistered
509	>	* from its parent.  It is an unenforced usage error for an
510	>	* unregistered party to invoke this method.
511		*
512	<	* @return the current barrier phase number upon entry to
470	<	* this method, or a negative value if terminated;
512	>	* @return the arrival phase number, or a negative value if terminated
513		* @throws IllegalStateException if not terminated and the number
514	<	* of registered or unarrived parties would become negative.
514	>	* of registered or unarrived parties would become negative
515		*/
516		public int arriveAndDeregister() {
517	<	// similar code to arrive, but too different to merge
517	>	// similar to arrive, but too different to merge
518		Phaser par = parent;
519	+	long s;
520		int phase;
521	<	for (;;) {
479	<	long s = state;
480	<	phase = phaseOf(s);
481	<	if (phase < 0)
482	<	break;
521	>	while ((phase = phaseOf(s = par==null? state:reconcileState())) >= 0) {
522		int parties = partiesOf(s) - 1;
523		int unarrived = unarrivedOf(s) - 1;
524	<	if (parties >= 0) {
525	<	if (unarrived > 0 || (unarrived == 0 && par != null)) {
526	<	if (casState
527	<	(s,
528	<	stateFor(phase, parties, unarrived))) {
529	<	if (unarrived == 0) {
530	<	par.arriveAndDeregister();
531	<	reconcileState();
532	<	}
533	<	break;
534	<	}
535	<	continue;
536	<	}
537	<	if (unarrived == 0) {
499	<	if (casState
500	<	(s,
501	<	trippedStateFor(onAdvance(phase, parties)? -1 :
502	<	((phase + 1) & phaseMask), parties))) {
503	<	releaseWaiters(phase);
504	<	break;
505	<	}
506	<	continue;
524	>	if (unarrived > 0) {
525	>	long next = stateFor(phase, parties, unarrived);
526	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next))
527	>	break;
528	>	}
529	>	else if (unarrived < 0)
530	>	throw new IllegalStateException(badBounds(parties, unarrived));
531	>	else if (par == null) {
532	>	long next = trippedStateFor(onAdvance(phase, parties)? -1:
533	>	(phase + 1) & phaseMask,
534	>	parties);
535	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next)) {
536	>	releaseWaiters(phase);
537	>	break;
538		}
539	<	if (par != null && phase != phaseOf(root.state)) {
539	>	}
540	>	else if (phaseOf(root.state) == phase) {
541	>	long next = stateFor(phase, parties, 0);
542	>	if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next)) {
543	>	if (parties == 0)
544	>	par.arriveAndDeregister();
545	>	else
546	>	par.arrive();
547		reconcileState();
548	<	continue;
548	>	break;
549		}
550		}
513	–	throw new IllegalStateException(badBounds(parties, unarrived));
551		}
552		return phase;
553		}
554
555		/**
556		* Arrives at the barrier and awaits others. Equivalent in effect
557	<	* to {@code awaitAdvance(arrive())}.  If you instead need to
558	<	* await with interruption of timeout, and/or deregister upon
559	<	* arrival, you can arrange them using analogous constructions.
560	<	* @return the phase on entry to this method
557	>	* to {@code awaitAdvance(arrive())}.  If you need to await with
558	>	* interruption or timeout, you can arrange this with an analogous
559	>	* construction using one of the other forms of the {@code
560	>	* awaitAdvance} method.  If instead you need to deregister upon
561	>	* arrival, use {@link #arriveAndDeregister}. It is an unenforced
562	>	* usage error for an unregistered party to invoke this method.
563	>	*
564	>	* @return the arrival phase number, or a negative number if terminated
565		* @throws IllegalStateException if not terminated and the number
566	<	* of unarrived parties would become negative.
566	>	* of unarrived parties would become negative
567		*/
568		public int arriveAndAwaitAdvance() {
569		return awaitAdvance(arrive());
570		}
571
572		/**
573	<	* Awaits the phase of the barrier to advance from the given
574	<	* value, or returns immediately if argument is negative or this
575	<	* barrier is terminated.
576	<	* @param phase the phase on entry to this method
577	<	* @return the phase on exit from this method
573	>	* Awaits the phase of the barrier to advance from the given phase
574	>	* value, returning immediately if the current phase of the
575	>	* barrier is not equal to the given phase value or this barrier
576	>	* is terminated.
577	>	*
578	>	* @param phase an arrival phase number, or negative value if
579	>	* terminated; this argument is normally the value returned by a
580	>	* previous call to {@code arrive} or its variants
581	>	* @return the next arrival phase number, or a negative value
582	>	* if terminated or argument is negative
583		*/
584		public int awaitAdvance(int phase) {
585		if (phase < 0)
586		return phase;
587	<	long s = getReconciledState();
542	<	int p = phaseOf(s);
587	>	int p = getPhase();
588		if (p != phase)
589		return p;
545	–	if (unarrivedOf(s) == 0 && parent != null)
546	–	parent.awaitAdvance(phase);
547	–	// Fall here even if parent waited, to reconcile and help release
590		return untimedWait(phase);
591		}
592
593		/**
594	<	* Awaits the phase of the barrier to advance from the given
595	<	* value, or returns immediately if argument is negative or this
596	<	* barrier is terminated, or throws InterruptedException if
597	<	* interrupted while waiting.
598	<	* @param phase the phase on entry to this method
599	<	* @return the phase on exit from this method
594	>	* Awaits the phase of the barrier to advance from the given phase
595	>	* value, throwing {@code InterruptedException} if interrupted
596	>	* while waiting, or returning immediately if the current phase of
597	>	* the barrier is not equal to the given phase value or this
598	>	* barrier is terminated.
599	>	*
600	>	* @param phase an arrival phase number, or negative value if
601	>	* terminated; this argument is normally the value returned by a
602	>	* previous call to {@code arrive} or its variants
603	>	* @return the next arrival phase number, or a negative value
604	>	* if terminated or argument is negative
605		* @throws InterruptedException if thread interrupted while waiting
606		*/
607	<	public int awaitAdvanceInterruptibly(int phase)
607	>	public int awaitAdvanceInterruptibly(int phase)
608		throws InterruptedException {
609		if (phase < 0)
610		return phase;
611	<	long s = getReconciledState();
565	<	int p = phaseOf(s);
611	>	int p = getPhase();
612		if (p != phase)
613		return p;
568	–	if (unarrivedOf(s) == 0 && parent != null)
569	–	parent.awaitAdvanceInterruptibly(phase);
614		return interruptibleWait(phase);
615		}
616
617		/**
618	<	* Awaits the phase of the barrier to advance from the given value
619	<	* or the given timeout elapses, or returns immediately if
620	<	* argument is negative or this barrier is terminated.
621	<	* @param phase the phase on entry to this method
622	<	* @return the phase on exit from this method
618	>	* Awaits the phase of the barrier to advance from the given phase
619	>	* value or the given timeout to elapse, throwing {@code
620	>	* InterruptedException} if interrupted while waiting, or
621	>	* returning immediately if the current phase of the barrier is
622	>	* not equal to the given phase value or this barrier is
623	>	* terminated.
624	>	*
625	>	* @param phase an arrival phase number, or negative value if
626	>	* terminated; this argument is normally the value returned by a
627	>	* previous call to {@code arrive} or its variants
628	>	* @param timeout how long to wait before giving up, in units of
629	>	*        {@code unit}
630	>	* @param unit a {@code TimeUnit} determining how to interpret the
631	>	*        {@code timeout} parameter
632	>	* @return the next arrival phase number, or a negative value
633	>	* if terminated or argument is negative
634		* @throws InterruptedException if thread interrupted while waiting
635		* @throws TimeoutException if timed out while waiting
636		*/
637	<	public int awaitAdvanceInterruptibly(int phase, long timeout, TimeUnit unit)
637	>	public int awaitAdvanceInterruptibly(int phase,
638	>	long timeout, TimeUnit unit)
639		throws InterruptedException, TimeoutException {
640	+	long nanos = unit.toNanos(timeout);
641		if (phase < 0)
642		return phase;
643	<	long s = getReconciledState();
587	<	int p = phaseOf(s);
643	>	int p = getPhase();
644		if (p != phase)
645		return p;
646	<	if (unarrivedOf(s) == 0 && parent != null)
591	<	parent.awaitAdvanceInterruptibly(phase, timeout, unit);
592	<	return timedWait(phase, unit.toNanos(timeout));
646	>	return timedWait(phase, nanos);
647		}
648
649		/**
#	Line 600 | Line 654 | public class Phaser {
654		* unexpected exceptions.
655		*/
656		public void forceTermination() {
657	<	for (;;) {
658	<	long s = getReconciledState();
659	<	int phase = phaseOf(s);
660	<	int parties = partiesOf(s);
661	<	int unarrived = unarrivedOf(s);
662	<	if (phase < 0 ||
663	<	casState(s, stateFor(-1, parties, unarrived))) {
664	<	releaseWaiters(0);
665	<	releaseWaiters(1);
612	<	if (parent != null)
613	<	parent.forceTermination();
614	<	return;
615	<	}
616	<	}
657	>	Phaser r = root;    // force at root then reconcile
658	>	long s;
659	>	while (phaseOf(s = r.state) >= 0)
660	>	UNSAFE.compareAndSwapLong(r, stateOffset, s,
661	>	stateFor(-1, partiesOf(s),
662	>	unarrivedOf(s)));
663	>	reconcileState();
664	>	releaseWaiters(0);  // ensure wakeups on both queues
665	>	releaseWaiters(1);
666		}
667
668		/**
669		* Returns the current phase number. The maximum phase number is
670		* {@code Integer.MAX_VALUE}, after which it restarts at
671		* zero. Upon termination, the phase number is negative.
672	+	*
673		* @return the phase number, or a negative value if terminated
674		*/
675		public final int getPhase() {
#	Line 627 | Line 677 | public class Phaser {
677		}
678
679		/**
630	–	* Returns {@code true} if the current phase number equals the given phase.
631	–	* @param phase the phase
632	–	* @return {@code true} if the current phase number equals the given phase
633	–	*/
634	–	public final boolean hasPhase(int phase) {
635	–	return phaseOf(getReconciledState()) == phase;
636	–	}
637	–
638	–	/**
680		* Returns the number of parties registered at this barrier.
681	+	*
682		* @return the number of parties
683		*/
684		public int getRegisteredParties() {
685	<	return partiesOf(state);
685	>	return partiesOf(getReconciledState());
686		}
687
688		/**
689	<	* Returns the number of parties that have arrived at the current
690	<	* phase of this barrier.
689	>	* Returns the number of registered parties that have arrived at
690	>	* the current phase of this barrier.
691	>	*
692		* @return the number of arrived parties
693		*/
694		public int getArrivedParties() {
695	<	return arrivedOf(state);
695	>	return arrivedOf(getReconciledState());
696		}
697
698		/**
699		* Returns the number of registered parties that have not yet
700		* arrived at the current phase of this barrier.
701	+	*
702		* @return the number of unarrived parties
703		*/
704		public int getUnarrivedParties() {
705	<	return unarrivedOf(state);
705	>	return unarrivedOf(getReconciledState());
706		}
707
708		/**
709	<	* Returns the parent of this phaser, or null if none.
710	<	* @return the parent of this phaser, or null if none
709	>	* Returns the parent of this phaser, or {@code null} if none.
710	>	*
711	>	* @return the parent of this phaser, or {@code null} if none
712		*/
713		public Phaser getParent() {
714		return parent;
#	Line 672 | Line 717 | public class Phaser {
717		/**
718		* Returns the root ancestor of this phaser, which is the same as
719		* this phaser if it has no parent.
720	+	*
721		* @return the root ancestor of this phaser
722		*/
723		public Phaser getRoot() {
#	Line 680 | Line 726 | public class Phaser {
726
727		/**
728		* Returns {@code true} if this barrier has been terminated.
729	+	*
730		* @return {@code true} if this barrier has been terminated
731		*/
732		public boolean isTerminated() {
#	Line 687 | Line 734 | public class Phaser {
734		}
735
736		/**
737	<	* Overridable method to perform an action upon phase advance, and
738	<	* to control termination. This method is invoked whenever the
739	<	* barrier is tripped (and thus all other waiting parties are
740	<	* dormant). If it returns true, then, rather than advance the
741	<	* phase number, this barrier will be set to a final termination
742	<	* state, and subsequent calls to {@code isTerminated} will
743	<	* return true.
737	>	* Overridable method to perform an action upon impending phase
738	>	* advance, and to control termination. This method is invoked
739	>	* upon arrival of the party tripping the barrier (when all other
740	>	* waiting parties are dormant).  If this method returns {@code
741	>	* true}, then, rather than advance the phase number, this barrier
742	>	* will be set to a final termination state, and subsequent calls
743	>	* to {@link #isTerminated} will return true. Any (unchecked)
744	>	* Exception or Error thrown by an invocation of this method is
745	>	* propagated to the party attempting to trip the barrier, in
746	>	* which case no advance occurs.
747		*
748	<	* <p> The default version returns true when the number of
748	>	* <p>The arguments to this method provide the state of the phaser
749	>	* prevailing for the current transition.  The results and effects
750	>	* of invoking phase-related methods (including {@code getPhase}
751	>	* as well as arrival, registration, and waiting methods) from
752	>	* within {@code onAdvance} are unspecified and should not be
753	>	* relied on. Similarly, while it is possible to override this
754	>	* method to produce side-effects visible to participating tasks,
755	>	* it is in general safe to do so only in designs in which all
756	>	* parties register before any arrive, and all {@link
757	>	* #awaitAdvance} at each phase.
758	>	*
759	>	* <p>The default version returns {@code true} when the number of
760		* registered parties is zero. Normally, overrides that arrange
761		* termination for other reasons should also preserve this
762		* property.
763		*
703	–	* <p> You may override this method to perform an action with side
704	–	* effects visible to participating tasks, but it is in general
705	–	* only sensible to do so in designs where all parties register
706	–	* before any arrive, and all {@code awaitAdvance} at each phase.
707	–	* Otherwise, you cannot ensure lack of interference. In
708	–	* particular, this method may be invoked more than once per
709	–	* transition if other parties successfully register while the
710	–	* invocation of this method is in progress, thus postponing the
711	–	* transition until those parties also arrive, re-triggering this
712	–	* method.
713	–	*
764		* @param phase the phase number on entering the barrier
765		* @param registeredParties the current number of registered parties
766		* @return {@code true} if this barrier should terminate
#	Line 751 | Line 801 | public class Phaser {
801		volatile boolean wasInterrupted = false;
802		volatile Thread thread; // nulled to cancel wait
803		QNode next;
804	+
805		QNode(Phaser phaser, int phase, boolean interruptible,
806		boolean timed, long startTime, long nanos) {
807		this.phaser = phaser;
#	Line 761 | Line 812 | public class Phaser {
812		this.nanos = nanos;
813		thread = Thread.currentThread();
814		}
815	+
816		public boolean isReleasable() {
817		return (thread == null ||
818		phaser.getPhase() != phase ||
819		(interruptible && wasInterrupted) ||
820		(timed && (nanos - (System.nanoTime() - startTime)) <= 0));
821		}
822	+
823		public boolean block() {
824		if (Thread.interrupted()) {
825		wasInterrupted = true;
#	Line 783 | Line 836 | public class Phaser {
836		}
837		return isReleasable();
838		}
839	+
840		void signal() {
841		Thread t = thread;
842		if (t != null) {
#	Line 790 | Line 844 | public class Phaser {
844		LockSupport.unpark(t);
845		}
846		}
847	+
848		boolean doWait() {
849		if (thread != null) {
850		try {
851	<	ForkJoinPool.managedBlock(this, false);
851	>	ForkJoinPool.managedBlock(this);
852		} catch (InterruptedException ie) {
853	<	}
853	>	wasInterrupted = true; // can't currently happen
854	>	}
855		}
856		return wasInterrupted;
857		}
802	–
858		}
859
860		/**
861	<	* Removes and signals waiting threads from wait queue
861	>	* Removes and signals waiting threads from wait queue.
862		*/
863		private void releaseWaiters(int phase) {
864		AtomicReference<QNode> head = queueFor(phase);
#	Line 815 | Line 870 | public class Phaser {
870		}
871
872		/**
873	<	* Tries to enqueue given node in the appropriate wait queue
873	>	* Tries to enqueue given node in the appropriate wait queue.
874	>	*
875		* @return true if successful
876		*/
877		private boolean tryEnqueue(QNode node) {
#	Line 824 | Line 880 | public class Phaser {
880		}
881
882		/**
883	+	* The number of times to spin before blocking waiting for advance.
884	+	*/
885	+	static final int MAX_SPINS =
886	+	Runtime.getRuntime().availableProcessors() == 1 ? 0 : 1 << 8;
887	+
888	+	/**
889		* Enqueues node and waits unless aborted or signalled.
890	+	*
891		* @return current phase
892		*/
893		private int untimedWait(int phase) {
894		QNode node = null;
895		boolean queued = false;
896		boolean interrupted = false;
897	+	int spins = MAX_SPINS;
898		int p;
899		while ((p = getPhase()) == phase) {
900		if (Thread.interrupted())
901		interrupted = true;
902	+	else if (spins > 0) {
903	+	if (--spins == 0)
904	+	Thread.yield();
905	+	}
906		else if (node == null)
907		node = new QNode(this, phase, false, false, 0, 0);
908		else if (!queued)
909		queued = tryEnqueue(node);
910	<	else
911	<	interrupted = node.doWait();
910	>	else if (node.doWait())
911	>	interrupted = true;
912		}
913		if (node != null)
914		node.thread = null;
#	Line 858 | Line 926 | public class Phaser {
926		QNode node = null;
927		boolean queued = false;
928		boolean interrupted = false;
929	+	int spins = MAX_SPINS;
930		int p;
931		while ((p = getPhase()) == phase && !interrupted) {
932		if (Thread.interrupted())
933		interrupted = true;
934	+	else if (spins > 0) {
935	+	if (--spins == 0)
936	+	Thread.yield();
937	+	}
938		else if (node == null)
939		node = new QNode(this, phase, true, false, 0, 0);
940		else if (!queued)
941		queued = tryEnqueue(node);
942	<	else
943	<	interrupted = node.doWait();
942	>	else if (node.doWait())
943	>	interrupted = true;
944		}
945		if (node != null)
946		node.thread = null;
#	Line 888 | Line 961 | public class Phaser {
961		QNode node = null;
962		boolean queued = false;
963		boolean interrupted = false;
964	+	int spins = MAX_SPINS;
965		int p;
966		while ((p = getPhase()) == phase && !interrupted) {
967		if (Thread.interrupted())
968		interrupted = true;
969		else if (nanos - (System.nanoTime() - startTime) <= 0)
970		break;
971	+	else if (spins > 0) {
972	+	if (--spins == 0)
973	+	Thread.yield();
974	+	}
975		else if (node == null)
976		node = new QNode(this, phase, true, true, startTime, nanos);
977		else if (!queued)
978		queued = tryEnqueue(node);
979	<	else
980	<	interrupted = node.doWait();
979	>	else if (node.doWait())
980	>	interrupted = true;
981		}
982		if (node != null)
983		node.thread = null;
#	Line 912 | Line 990 | public class Phaser {
990		return p;
991		}
992
993	<	// Temporary Unsafe mechanics for preliminary release
994	<	private static Unsafe getUnsafe() throws Throwable {
993	>	// Unsafe mechanics
994	>
995	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
996	>	private static final long stateOffset =
997	>	objectFieldOffset("state", Phaser.class);
998	>
999	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1000	>	try {
1001	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1002	>	} catch (NoSuchFieldException e) {
1003	>	// Convert Exception to corresponding Error
1004	>	NoSuchFieldError error = new NoSuchFieldError(field);
1005	>	error.initCause(e);
1006	>	throw error;
1007	>	}
1008	>	}
1009	>
1010	>	/**
1011	>	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1012	>	* Replace with a simple call to Unsafe.getUnsafe when integrating
1013	>	* into a jdk.
1014	>	*
1015	>	* @return a sun.misc.Unsafe
1016	>	*/
1017	>	private static sun.misc.Unsafe getUnsafe() {
1018		try {
1019	<	return Unsafe.getUnsafe();
1019	>	return sun.misc.Unsafe.getUnsafe();
1020		} catch (SecurityException se) {
1021		try {
1022		return java.security.AccessController.doPrivileged
1023	<	(new java.security.PrivilegedExceptionAction<Unsafe>() {
1024	<	public Unsafe run() throws Exception {
1025	<	return getUnsafePrivileged();
1023	>	(new java.security
1024	>	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1025	>	public sun.misc.Unsafe run() throws Exception {
1026	>	java.lang.reflect.Field f = sun.misc
1027	>	.Unsafe.class.getDeclaredField("theUnsafe");
1028	>	f.setAccessible(true);
1029	>	return (sun.misc.Unsafe) f.get(null);
1030		}});
1031		} catch (java.security.PrivilegedActionException e) {
1032	<	throw e.getCause();
1032	>	throw new RuntimeException("Could not initialize intrinsics",
1033	>	e.getCause());
1034		}
1035		}
1036		}
931	–
932	–	private static Unsafe getUnsafePrivileged()
933	–	throws NoSuchFieldException, IllegalAccessException {
934	–	Field f = Unsafe.class.getDeclaredField("theUnsafe");
935	–	f.setAccessible(true);
936	–	return (Unsafe)f.get(null);
937	–	}
938	–
939	–	private static long fieldOffset(String fieldName)
940	–	throws NoSuchFieldException {
941	–	return _unsafe.objectFieldOffset
942	–	(Phaser.class.getDeclaredField(fieldName));
943	–	}
944	–
945	–	static final Unsafe _unsafe;
946	–	static final long stateOffset;
947	–
948	–	static {
949	–	try {
950	–	_unsafe = getUnsafe();
951	–	stateOffset = fieldOffset("state");
952	–	} catch (Exception e) {
953	–	throw new RuntimeException("Could not initialize intrinsics", e);
954	–	}
955	–	}
956	–
957	–	final boolean casState(long cmp, long val) {
958	–	return _unsafe.compareAndSwapLong(this, stateOffset, cmp, val);
959	–	}
1037		}

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