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Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.8 by jsr166, Mon Jan 5 05:50:47 2009 UTC vs.
Revision 1.43 by dl, Mon Aug 24 23:08:18 2009 UTC

#	Line 5 | Line 5
5		*/
6
7		package jsr166y;
8	+
9		import java.util.concurrent.*;
10	<	import java.util.concurrent.atomic.*;
10	>
11	>	import java.util.concurrent.atomic.AtomicReference;
12		import java.util.concurrent.locks.LockSupport;
11	–	import sun.misc.Unsafe;
12	–	import java.lang.reflect.*;
13
14		/**
15	<	* A reusable synchronization barrier, similar in functionality to a
16	<	* {@link java.util.concurrent.CyclicBarrier} and {@link
17	<	* java.util.concurrent.CountDownLatch} but supporting more flexible
18	<	* usage.
15	>	* A reusable synchronization barrier, similar in functionality to
16	>	* {@link java.util.concurrent.CyclicBarrier CyclicBarrier} and
17	>	* {@link java.util.concurrent.CountDownLatch CountDownLatch}
18	>	* but supporting more flexible usage.
19	>	*
20	>	* <p> <b>Registration.</b> Unlike the case for other barriers, the
21	>	* number of parties <em>registered</em> to synchronize on a phaser
22	>	* may vary over time.  Tasks may be registered at any time (using
23	>	* methods {@link #register}, {@link #bulkRegister}, or forms of
24	>	* constructors establishing initial numbers of parties), and
25	>	* optionally deregistered upon any arrival (using {@link
26	>	* #arriveAndDeregister}).  As is the case with most basic
27	>	* synchronization constructs, registration and deregistration affect
28	>	* only internal counts; they do not establish any further internal
29	>	* bookkeeping, so tasks cannot query whether they are registered.
30	>	* (However, you can introduce such bookkeeping by subclassing this
31	>	* class.)
32	>	*
33	>	* <p> <b>Synchronization.</b> Like a {@code CyclicBarrier}, a {@code
34	>	* Phaser} may be repeatedly awaited.  Method {@link
35	>	* #arriveAndAwaitAdvance} has effect analogous to {@link
36	>	* java.util.concurrent.CyclicBarrier#await CyclicBarrier.await}. Each
37	>	* generation of a {@code Phaser} has an associated phase number. The
38	>	* phase number starts at zero, and advances when all parties arrive
39	>	* at the barrier, wrapping around to zero after reaching {@code
40	>	* Integer.MAX_VALUE}. The use of phase numbers enables independent
41	>	* control of actions upon arrival at a barrier and upon awaiting
42	>	* others, via two kinds of methods that may be invoked by any
43	>	* registered party:
44		*
45		* <ul>
46		*
47	<	* <li> The number of parties synchronizing on a phaser may vary over
48	<	* time.  A task may register to be a party at any time, and may
49	<	* deregister upon arriving at the barrier.  As is the case with most
50	<	* basic synchronization constructs, registration and deregistration
51	<	* affect only internal counts; they do not establish any further
52	<	* internal bookkeeping, so tasks cannot query whether they are
53	<	* registered. (However, you can introduce such bookkeeping in by
54	<	* subclassing this class.)
55	<	*
56	<	* <li> Each generation has an associated phase value, starting at
57	<	* zero, and advancing when all parties reach the barrier (wrapping
58	<	* around to zero after reaching {@code Integer.MAX_VALUE}).
59	<	*
60	<	* <li> Like a CyclicBarrier, a Phaser may be repeatedly awaited.
61	<	* Method {@code arriveAndAwaitAdvance} has effect analogous to
62	<	* {@code CyclicBarrier.await}.  However, Phasers separate two
63	<	* aspects of coordination, that may also be invoked independently:
64	<	*
65	<	* <ul>
47	>	*   <li> <b>Arrival.</b> Methods {@link #arrive} and
48	>	*       {@link #arriveAndDeregister} record arrival at a
49	>	*       barrier. These methods do not block, but return an associated
50	>	*       <em>arrival phase number</em>; that is, the phase number of
51	>	*       the barrier to which the arrival applied. When the final
52	>	*       party for a given phase arrives, an optional barrier action
53	>	*       is performed and the phase advances.  Barrier actions,
54	>	*       performed by the party triggering a phase advance, are
55	>	*       arranged by overriding method {@link #onAdvance(int, int)},
56	>	*       which also controls termination. Overriding this method is
57	>	*       similar to, but more flexible than, providing a barrier
58	>	*       action to a {@code CyclicBarrier}.
59	>	*
60	>	*   <li> <b>Waiting.</b> Method {@link #awaitAdvance} requires an
61	>	*       argument indicating an arrival phase number, and returns when
62	>	*       the barrier advances to (or is already at) a different phase.
63	>	*       Unlike similar constructions using {@code CyclicBarrier},
64	>	*       method {@code awaitAdvance} continues to wait even if the
65	>	*       waiting thread is interrupted. Interruptible and timeout
66	>	*       versions are also available, but exceptions encountered while
67	>	*       tasks wait interruptibly or with timeout do not change the
68	>	*       state of the barrier. If necessary, you can perform any
69	>	*       associated recovery within handlers of those exceptions,
70	>	*       often after invoking {@code forceTermination}.  Phasers may
71	>	*       also be used by tasks executing in a {@link ForkJoinPool},
72	>	*       which will ensure sufficient parallelism to execute tasks
73	>	*       when others are blocked waiting for a phase to advance.
74		*
42	–	*   <li> Arriving at a barrier. Methods {@code arrive} and
43	–	*       {@code arriveAndDeregister} do not block, but return
44	–	*       the phase value current upon entry to the method.
45	–	*
46	–	*   <li> Awaiting others. Method {@code awaitAdvance} requires an
47	–	*       argument indicating the entry phase, and returns when the
48	–	*       barrier advances to a new phase.
75		* </ul>
76		*
77	<	*
78	<	* <li> Barrier actions, performed by the task triggering a phase
79	<	* advance while others may be waiting, are arranged by overriding
80	<	* method {@code onAdvance}, that also controls termination.
81	<	* Overriding this method may be used to similar but more flexible
82	<	* effect as providing a barrier action to a CyclicBarrier.
83	<	*
58	<	* <li> Phasers may enter a <em>termination</em> state in which all
59	<	* await actions immediately return, indicating (via a negative phase
60	<	* value) that execution is complete.  Termination is triggered by
61	<	* executing the overridable {@code onAdvance} method that is invoked
62	<	* each time the barrier is about to be tripped. When a Phaser is
63	<	* controlling an action with a fixed number of iterations, it is
77	>	* <p> <b>Termination.</b> A {@code Phaser} may enter a
78	>	* <em>termination</em> state in which all synchronization methods
79	>	* immediately return without updating phaser state or waiting for
80	>	* advance, and indicating (via a negative phase value) that execution
81	>	* is complete.  Termination is triggered when an invocation of {@code
82	>	* onAdvance} returns {@code true}.  As illustrated below, when
83	>	* phasers control actions with a fixed number of iterations, it is
84		* often convenient to override this method to cause termination when
85	<	* the current phase number reaches a threshold. Method
86	<	* {@code forceTermination} is also available to abruptly release
87	<	* waiting threads and allow them to terminate.
85	>	* the current phase number reaches a threshold. Method {@link
86	>	* #forceTermination} is also available to abruptly release waiting
87	>	* threads and allow them to terminate.
88		*
89	<	* <li> Phasers may be tiered to reduce contention. Phasers with large
89	>	* <p> <b>Tiering.</b> Phasers may be <em>tiered</em> (i.e., arranged
90	>	* in tree structures) to reduce contention. Phasers with large
91		* numbers of parties that would otherwise experience heavy
92	<	* synchronization contention costs may instead be arranged in trees.
93	<	* This will typically greatly increase throughput even though it
94	<	* incurs somewhat greater per-operation overhead.
95	<	*
96	<	* <li> By default, {@code awaitAdvance} continues to wait even if
97	<	* the waiting thread is interrupted. And unlike the case in
98	<	* CyclicBarriers, exceptions encountered while tasks wait
99	<	* interruptibly or with timeout do not change the state of the
100	<	* barrier. If necessary, you can perform any associated recovery
101	<	* within handlers of those exceptions, often after invoking
102	<	* {@code forceTermination}.
103	<	*
104	<	* </ul>
92	>	* synchronization contention costs may instead be set up so that
93	>	* groups of sub-phasers share a common parent.  This may greatly
94	>	* increase throughput even though it incurs greater per-operation
95	>	* overhead.
96	>	*
97	>	* <p><b>Monitoring.</b> While synchronization methods may be invoked
98	>	* only by registered parties, the current state of a phaser may be
99	>	* monitored by any caller.  At any given moment there are {@link
100	>	* #getRegisteredParties} parties in total, of which {@link
101	>	* #getArrivedParties} have arrived at the current phase ({@link
102	>	* #getPhase}).  When the remaining ({@link #getUnarrivedParties})
103	>	* parties arrive, the phase advances.  The values returned by these
104	>	* methods may reflect transient states and so are not in general
105	>	* useful for synchronization control.  Method {@link #toString}
106	>	* returns snapshots of these state queries in a form convenient for
107	>	* informal monitoring.
108		*
109		* <p><b>Sample usages:</b>
110		*
111	<	* <p>A Phaser may be used instead of a {@code CountDownLatch} to control
112	<	* a one-shot action serving a variable number of parties. The typical
113	<	* idiom is for the method setting this up to first register, then
114	<	* start the actions, then deregister, as in:
115	<	*
116	<	* <pre>
117	<	*  void runTasks(List&lt;Runnable&gt; list) {
118	<	*    final Phaser phaser = new Phaser(1); // "1" to register self
119	<	*    for (Runnable r : list) {
120	<	*      phaser.register();
121	<	*      new Thread() {
122	<	*        public void run() {
123	<	*          phaser.arriveAndAwaitAdvance(); // await all creation
124	<	*          r.run();
125	<	*          phaser.arriveAndDeregister();   // signal completion
126	<	*        }
127	<	*      }.start();
111	>	* <p>A {@code Phaser} may be used instead of a {@code CountDownLatch}
112	>	* to control a one-shot action serving a variable number of
113	>	* parties. The typical idiom is for the method setting this up to
114	>	* first register, then start the actions, then deregister, as in:
115	>	*
116	>	*  <pre> {@code
117	>	* void runTasks(List<Runnable> tasks) {
118	>	*   final Phaser phaser = new Phaser(1); // "1" to register self
119	>	*   // create and start threads
120	>	*   for (Runnable task : tasks) {
121	>	*     phaser.register();
122	>	*     new Thread() {
123	>	*       public void run() {
124	>	*         phaser.arriveAndAwaitAdvance(); // await all creation
125	>	*         task.run();
126	>	*       }
127	>	*     }.start();
128		*   }
129		*
130	<	*   doSomethingOnBehalfOfWorkers();
131	<	*   phaser.arrive(); // allow threads to start
132	<	*   int p = phaser.arriveAndDeregister(); // deregister self  ...
109	<	*   p = phaser.awaitAdvance(p); // ... and await arrival
110	<	*   otherActions(); // do other things while tasks execute
111	<	*   phaser.awaitAdvance(p); // await final completion
112	<	* }
113	<	* </pre>
130	>	*   // allow threads to start and deregister self
131	>	*   phaser.arriveAndDeregister();
132	>	* }}</pre>
133		*
134		* <p>One way to cause a set of threads to repeatedly perform actions
135		* for a given number of iterations is to override {@code onAdvance}:
136		*
137	<	* <pre>
138	<	*  void startTasks(List&lt;Runnable&gt; list, final int iterations) {
139	<	*    final Phaser phaser = new Phaser() {
140	<	*       public boolean onAdvance(int phase, int registeredParties) {
141	<	*         return phase &gt;= iterations || registeredParties == 0;
137	>	*  <pre> {@code
138	>	* void startTasks(List<Runnable> tasks, final int iterations) {
139	>	*   final Phaser phaser = new Phaser() {
140	>	*     protected boolean onAdvance(int phase, int registeredParties) {
141	>	*       return phase >= iterations || registeredParties == 0;
142	>	*     }
143	>	*   };
144	>	*   phaser.register();
145	>	*   for (Runnable task : tasks) {
146	>	*     phaser.register();
147	>	*     new Thread() {
148	>	*       public void run() {
149	>	*         do {
150	>	*           task.run();
151	>	*           phaser.arriveAndAwaitAdvance();
152	>	*         } while(!phaser.isTerminated();
153		*       }
154	<	*    };
125	<	*    phaser.register();
126	<	*    for (Runnable r : list) {
127	<	*      phaser.register();
128	<	*      new Thread() {
129	<	*        public void run() {
130	<	*           do {
131	<	*             r.run();
132	<	*             phaser.arriveAndAwaitAdvance();
133	<	*           } while(!phaser.isTerminated();
134	<	*        }
135	<	*      }.start();
154	>	*     }.start();
155		*   }
156		*   phaser.arriveAndDeregister(); // deregister self, don't wait
157	<	* }
158	<	* </pre>
157	>	* }}</pre>
158	>	*
159	>	* If the main task must later await termination, it
160	>	* may re-register and then execute a similar loop:
161	>	* <pre> {@code
162	>	*   // ...
163	>	*   phaser.register();
164	>	*   while (!phaser.isTerminated())
165	>	*     phaser.arriveAndAwaitAdvance();
166	>	* }</pre>
167	>	*
168	>	* Related constructions may be used to await particular phase numbers
169	>	* in contexts where you are sure that the phase will never wrap around
170	>	* {@code Integer.MAX_VALUE}. For example:
171	>	*
172	>	* <pre> {@code
173	>	*   void awaitPhase(Phaser phaser, int phase) {
174	>	*     int p = phaser.register(); // assumes caller not already registered
175	>	*     while (p < phase) {
176	>	*       if (phaser.isTerminated())
177	>	*         // ... deal with unexpected termination
178	>	*       else
179	>	*         p = phaser.arriveAndAwaitAdvance();
180	>	*     }
181	>	*     phaser.arriveAndDeregister();
182	>	*   }
183	>	* }</pre>
184	>	*
185		*
186	<	* <p> To create a set of tasks using a tree of Phasers,
186	>	* <p>To create a set of tasks using a tree of phasers,
187		* you could use code of the following form, assuming a
188	<	* Task class with a constructor accepting a Phaser that
188	>	* Task class with a constructor accepting a phaser that
189		* it registers for upon construction:
190	<	* <pre>
191	<	*  void build(Task[] actions, int lo, int hi, Phaser b) {
192	<	*    int step = (hi - lo) / TASKS_PER_PHASER;
193	<	*    if (step &gt; 1) {
194	<	*       int i = lo;
195	<	*       while (i &lt; hi) {
196	<	*         int r = Math.min(i + step, hi);
197	<	*         build(actions, i, r, new Phaser(b));
198	<	*         i = r;
199	<	*       }
200	<	*    }
201	<	*    else {
202	<	*      for (int i = lo; i &lt; hi; ++i)
203	<	*        actions[i] = new Task(b);
204	<	*        // assumes new Task(b) performs b.register()
205	<	*    }
206	<	*  }
207	<	*  // .. initially called, for n tasks via
163	<	*  build(new Task[n], 0, n, new Phaser());
164	<	* </pre>
190	>	*  <pre> {@code
191	>	* void build(Task[] actions, int lo, int hi, Phaser b) {
192	>	*   int step = (hi - lo) / TASKS_PER_PHASER;
193	>	*   if (step > 1) {
194	>	*     int i = lo;
195	>	*     while (i < hi) {
196	>	*       int r = Math.min(i + step, hi);
197	>	*       build(actions, i, r, new Phaser(b));
198	>	*       i = r;
199	>	*     }
200	>	*   } else {
201	>	*     for (int i = lo; i < hi; ++i)
202	>	*       actions[i] = new Task(b);
203	>	*       // assumes new Task(b) performs b.register()
204	>	*   }
205	>	* }
206	>	* // .. initially called, for n tasks via
207	>	* build(new Task[n], 0, n, new Phaser());}</pre>
208		*
209		* The best value of {@code TASKS_PER_PHASER} depends mainly on
210		* expected barrier synchronization rates. A value as low as four may
#	Line 172 | Line 215 | import java.lang.reflect.*;
215		*
216		* <p><b>Implementation notes</b>: This implementation restricts the
217		* maximum number of parties to 65535. Attempts to register additional
218	<	* parties result in IllegalStateExceptions. However, you can and
218	>	* parties result in {@code IllegalStateException}. However, you can and
219		* should create tiered phasers to accommodate arbitrarily large sets
220		* of participants.
221	+	*
222	+	* @since 1.7
223	+	* @author Doug Lea
224		*/
225		public class Phaser {
226		/*
#	Line 199 | Line 245 | public class Phaser {
245		* and encoding simple, and keeping race windows short.
246		*
247		* Note: there are some cheats in arrive() that rely on unarrived
248	<	* being lowest 16 bits.
248	>	* count being lowest 16 bits.
249		*/
250		private volatile long state;
251
252	<	private static final int ushortBits = 16;
253	<	private static final int ushortMask =  (1 << ushortBits) - 1;
208	<	private static final int phaseMask = 0x7fffffff;
252	>	private static final int ushortMask = 0xffff;
253	>	private static final int phaseMask  = 0x7fffffff;
254
255		private static int unarrivedOf(long s) {
256	<	return (int)(s & ushortMask);
256	>	return (int) (s & ushortMask);
257		}
258
259		private static int partiesOf(long s) {
260	<	return (int)(s & (ushortMask << 16)) >>> 16;
260	>	return ((int) s) >>> 16;
261		}
262
263		private static int phaseOf(long s) {
264	<	return (int)(s >>> 32);
264	>	return (int) (s >>> 32);
265		}
266
267		private static int arrivedOf(long s) {
#	Line 224 | Line 269 | public class Phaser {
269		}
270
271		private static long stateFor(int phase, int parties, int unarrived) {
272	<	return (((long)phase) << 32) | ((parties << 16) | unarrived);
272	>	return ((((long) phase) << 32) | (((long) parties) << 16) |
273	>	(long) unarrived);
274		}
275
276		private static long trippedStateFor(int phase, int parties) {
277	<	return (((long)phase) << 32) | ((parties << 16) | parties);
277	>	long lp = (long) parties;
278	>	return (((long) phase) << 32) | (lp << 16) | lp;
279		}
280
281	<	private static IllegalStateException badBounds(int parties, int unarrived) {
282	<	return new IllegalStateException
283	<	("Attempt to set " + unarrived +
284	<	" unarrived of " + parties + " parties");
281	>	/**
282	>	* Returns message string for bad bounds exceptions.
283	>	*/
284	>	private static String badBounds(int parties, int unarrived) {
285	>	return ("Attempt to set " + unarrived +
286	>	" unarrived of " + parties + " parties");
287		}
288
289		/**
#	Line 243 | Line 292 | public class Phaser {
292		private final Phaser parent;
293
294		/**
295	<	* The root of Phaser tree. Equals this if not in a tree.  Used to
295	>	* The root of phaser tree. Equals this if not in a tree.  Used to
296		* support faster state push-down.
297		*/
298		private final Phaser root;
#	Line 251 | Line 300 | public class Phaser {
300		// Wait queues
301
302		/**
303	<	* Heads of Treiber stacks waiting for nonFJ threads. To eliminate
303	>	* Heads of Treiber stacks for waiting threads. To eliminate
304		* contention while releasing some threads while adding others, we
305		* use two of them, alternating across even and odd phases.
306		*/
#	Line 259 | Line 308 | public class Phaser {
308		private final AtomicReference<QNode> oddQ  = new AtomicReference<QNode>();
309
310		private AtomicReference<QNode> queueFor(int phase) {
311	<	return (phase & 1) == 0? evenQ : oddQ;
311	>	return ((phase & 1) == 0) ? evenQ : oddQ;
312		}
313
314		/**
#	Line 267 | Line 316 | public class Phaser {
316		* root if necessary.
317		*/
318		private long getReconciledState() {
319	<	return parent == null? state : reconcileState();
319	>	return (parent == null) ? state : reconcileState();
320		}
321
322		/**
#	Line 294 | Line 343 | public class Phaser {
343		}
344
345		/**
346	<	* Creates a new Phaser without any initially registered parties,
347	<	* initial phase number 0, and no parent.
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		this(null);
352		}
353
354		/**
355	<	* Creates a new Phaser with the given numbers of registered
355	>	* Creates a new phaser with the given numbers of registered
356		* unarrived parties, initial phase number 0, and no parent.
357	<	* @param parties the number of parties required to trip barrier.
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
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	<	* @param parent the parent phaser.
371	>	*
372	>	* @param parent the parent phaser
373		*/
374		public Phaser(Phaser parent) {
375		int phase = 0;
#	Line 332 | Line 384 | public class Phaser {
384		}
385
386		/**
387	<	* Creates a new Phaser with the given parent and numbers of
388	<	* registered unarrived parties. If parent is non-null this phaser
387	>	* Creates a new phaser with the given parent and numbers 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	<	* @param parent the parent phaser.
392	<	* @param parties the number of parties required to trip barrier.
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.
395	>	* or greater than the maximum number of parties supported
396		*/
397		public Phaser(Phaser parent, int parties) {
398		if (parties < 0 || parties > ushortMask)
#	Line 357 | Line 410 | public class Phaser {
410
411		/**
412		* Adds a new unarrived party to this phaser.
413	<	* @return the current barrier phase number upon registration
413	>	*
414	>	* @return the arrival phase number to which this registration applied
415		* @throws IllegalStateException if attempting to register more
416	<	* than the maximum supported number of parties.
416	>	* than the maximum supported number of parties
417		*/
418		public int register() {
419		return doRegister(1);
#	Line 367 | Line 421 | public class Phaser {
421
422		/**
423		* Adds the given number of new unarrived parties to this phaser.
424	<	* @param parties the number of parties required to trip barrier.
425	<	* @return the current barrier phase number upon registration
424	>	*
425	>	* @param parties the number of parties required to trip barrier
426	>	* @return the arrival phase number to which this registration applied
427		* @throws IllegalStateException if attempting to register more
428	<	* than the maximum supported number of parties.
428	>	* than the maximum supported number of parties
429		*/
430		public int bulkRegister(int parties) {
431		if (parties < 0)
#	Line 393 | Line 448 | public class Phaser {
448		if (phase < 0)
449		break;
450		if (parties > ushortMask || unarrived > ushortMask)
451	<	throw badBounds(parties, unarrived);
451	>	throw new IllegalStateException(badBounds(parties, unarrived));
452		if (phase == phaseOf(root.state) &&
453		casState(s, stateFor(phase, parties, unarrived)))
454		break;
#	Line 403 | Line 458 | public class Phaser {
458
459		/**
460		* Arrives at the barrier, but does not wait for others.  (You can
461	<	* in turn wait for others via {@link #awaitAdvance}).
461	>	* in turn wait for others via {@link #awaitAdvance}).  It is an
462	>	* unenforced usage error for an unregistered party to invoke this
463	>	* method.
464		*
465	<	* @return the barrier phase number upon entry to this method, or a
409	<	* negative value if terminated;
465	>	* @return the arrival phase number, or a negative value if terminated
466		* @throws IllegalStateException if not terminated and the number
467	<	* of unarrived parties would become negative.
467	>	* of unarrived parties would become negative
468		*/
469		public int arrive() {
470		int phase;
471		for (;;) {
472		long s = state;
473		phase = phaseOf(s);
474	+	if (phase < 0)
475	+	break;
476		int parties = partiesOf(s);
477		int unarrived = unarrivedOf(s) - 1;
478		if (unarrived > 0) {        // Not the last arrival
#	Line 426 | Line 484 | public class Phaser {
484		if (par == null) {      // directly trip
485		if (casState
486		(s,
487	<	trippedStateFor(onAdvance(phase, parties)? -1 :
487	>	trippedStateFor(onAdvance(phase, parties) ? -1 :
488		((phase + 1) & phaseMask), parties))) {
489		releaseWaiters(phase);
490		break;
#	Line 440 | Line 498 | public class Phaser {
498		}
499		}
500		}
443	–	else if (phase < 0) // Don't throw exception if terminated
444	–	break;
501		else if (phase != phaseOf(root.state)) // or if unreconciled
502		reconcileState();
503		else
504	<	throw badBounds(parties, unarrived);
504	>	throw new IllegalStateException(badBounds(parties, unarrived));
505		}
506		return phase;
507		}
508
509		/**
510	<	* Arrives at the barrier, and deregisters from it, without
511	<	* waiting for others. Deregistration reduces number of parties
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 is also deregistered from its parent.
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
461	<	* this method, or a negative value if terminated;
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.
520	>	* of registered or unarrived parties would become negative
521		*/
522		public int arriveAndDeregister() {
523		// similar code to arrive, but too different to merge
#	Line 469 | Line 526 | public class Phaser {
526		for (;;) {
527		long s = state;
528		phase = phaseOf(s);
529	+	if (phase < 0)
530	+	break;
531		int parties = partiesOf(s) - 1;
532		int unarrived = unarrivedOf(s) - 1;
533		if (parties >= 0) {
#	Line 487 | Line 546 | public class Phaser {
546		if (unarrived == 0) {
547		if (casState
548		(s,
549	<	trippedStateFor(onAdvance(phase, parties)? -1 :
549	>	trippedStateFor(onAdvance(phase, parties) ? -1 :
550		((phase + 1) & phaseMask), parties))) {
551		releaseWaiters(phase);
552		break;
553		}
554		continue;
555		}
497	–	if (phase < 0)
498	–	break;
556		if (par != null && phase != phaseOf(root.state)) {
557		reconcileState();
558		continue;
559		}
560		}
561	<	throw badBounds(parties, unarrived);
561	>	throw new IllegalStateException(badBounds(parties, unarrived));
562		}
563		return phase;
564		}
565
566		/**
567		* Arrives at the barrier and awaits others. Equivalent in effect
568	<	* to {@code awaitAdvance(arrive())}.  If you instead need to
569	<	* await with interruption of timeout, and/or deregister upon
570	<	* arrival, you can arrange them using analogous constructions.
571	<	* @return the phase on entry to this method
568	>	* to {@code awaitAdvance(arrive())}.  If you need to await with
569	>	* interruption or timeout, you can arrange this with an analogous
570	>	* construction using one of the other forms of the awaitAdvance
571	>	* method.  If instead you need to deregister upon arrival use
572	>	* {@code arriveAndDeregister}. It is an unenforced usage error
573	>	* for an unregistered party to invoke this method.
574	>	*
575	>	* @return the arrival phase number, or a negative number if terminated
576		* @throws IllegalStateException if not terminated and the number
577	<	* of unarrived parties would become negative.
577	>	* of unarrived parties would become negative
578		*/
579		public int arriveAndAwaitAdvance() {
580		return awaitAdvance(arrive());
581		}
582
583		/**
584	<	* Awaits the phase of the barrier to advance from the given
585	<	* value, or returns immediately if argument is negative or this
586	<	* barrier is terminated.
587	<	* @param phase the phase on entry to this method
588	<	* @return the phase on exit from this method
584	>	* Awaits the phase of the barrier to advance from the given phase
585	>	* value, returning immediately if the current phase of the
586	>	* barrier is not equal to the given phase value or this barrier
587	>	* is terminated.  It is an unenforced usage error for an
588	>	* unregistered party to invoke this method.
589	>	*
590	>	* @param phase an arrival phase number, or negative value if
591	>	* terminated; this argument is normally the value returned by a
592	>	* previous call to {@code arrive} or its variants
593	>	* @return the next arrival phase number, or a negative value
594	>	* if terminated or argument is negative
595		*/
596		public int awaitAdvance(int phase) {
597		if (phase < 0)
#	Line 533 | Line 600 | public class Phaser {
600		int p = phaseOf(s);
601		if (p != phase)
602		return p;
603	<	if (unarrivedOf(s) == 0)
603	>	if (unarrivedOf(s) == 0 && parent != null)
604		parent.awaitAdvance(phase);
605		// Fall here even if parent waited, to reconcile and help release
606		return untimedWait(phase);
607		}
608
609		/**
610	<	* Awaits the phase of the barrier to advance from the given
611	<	* value, or returns immediately if argument is negative or this
612	<	* barrier is terminated, or throws InterruptedException if
613	<	* interrupted while waiting.
614	<	* @param phase the phase on entry to this method
615	<	* @return the phase on exit from this method
610	>	* Awaits the phase of the barrier to advance from the given phase
611	>	* value, throwing {@code InterruptedException} if interrupted
612	>	* while waiting, or returning immediately if the current phase of
613	>	* the barrier is not equal to the given phase value or this
614	>	* barrier is terminated. It is an unenforced usage error for an
615	>	* unregistered party to invoke this method.
616	>	*
617	>	* @param phase an arrival phase number, or negative value if
618	>	* terminated; this argument is normally the value returned by a
619	>	* previous call to {@code arrive} or its variants
620	>	* @return the next arrival phase number, or a negative value
621	>	* if terminated or argument is negative
622		* @throws InterruptedException if thread interrupted while waiting
623		*/
624	<	public int awaitAdvanceInterruptibly(int phase) throws InterruptedException {
624	>	public int awaitAdvanceInterruptibly(int phase)
625	>	throws InterruptedException {
626		if (phase < 0)
627		return phase;
628		long s = getReconciledState();
629		int p = phaseOf(s);
630		if (p != phase)
631		return p;
632	<	if (unarrivedOf(s) != 0)
632	>	if (unarrivedOf(s) == 0 && parent != null)
633		parent.awaitAdvanceInterruptibly(phase);
634		return interruptibleWait(phase);
635		}
636
637		/**
638	<	* Awaits the phase of the barrier to advance from the given value
639	<	* or the given timeout elapses, or returns immediately if
640	<	* argument is negative or this barrier is terminated.
641	<	* @param phase the phase on entry to this method
642	<	* @return the phase on exit from this method
638	>	* Awaits the phase of the barrier to advance from the given phase
639	>	* value or the given timeout to elapse, throwing {@code
640	>	* InterruptedException} if interrupted while waiting, or
641	>	* returning immediately if the current phase of the barrier is
642	>	* not equal to the given phase value or this barrier is
643	>	* terminated.  It is an unenforced usage error for an
644	>	* unregistered party to invoke this method.
645	>	*
646	>	* @param phase an arrival phase number, or negative value if
647	>	* terminated; this argument is normally the value returned by a
648	>	* previous call to {@code arrive} or its variants
649	>	* @param timeout how long to wait before giving up, in units of
650	>	*        {@code unit}
651	>	* @param unit a {@code TimeUnit} determining how to interpret the
652	>	*        {@code timeout} parameter
653	>	* @return the next arrival phase number, or a negative value
654	>	* if terminated or argument is negative
655		* @throws InterruptedException if thread interrupted while waiting
656		* @throws TimeoutException if timed out while waiting
657		*/
658	<	public int awaitAdvanceInterruptibly(int phase, long timeout, TimeUnit unit)
658	>	public int awaitAdvanceInterruptibly(int phase,
659	>	long timeout, TimeUnit unit)
660		throws InterruptedException, TimeoutException {
661		if (phase < 0)
662		return phase;
#	Line 577 | Line 664 | public class Phaser {
664		int p = phaseOf(s);
665		if (p != phase)
666		return p;
667	<	if (unarrivedOf(s) == 0)
667	>	if (unarrivedOf(s) == 0 && parent != null)
668		parent.awaitAdvanceInterruptibly(phase, timeout, unit);
669		return timedWait(phase, unit.toNanos(timeout));
670		}
#	Line 610 | Line 697 | public class Phaser {
697		* Returns the current phase number. The maximum phase number is
698		* {@code Integer.MAX_VALUE}, after which it restarts at
699		* zero. Upon termination, the phase number is negative.
700	+	*
701		* @return the phase number, or a negative value if terminated
702		*/
703		public final int getPhase() {
#	Line 617 | Line 705 | public class Phaser {
705		}
706
707		/**
620	–	* Returns true if the current phase number equals the given phase.
621	–	* @param phase the phase
622	–	* @return true if the current phase number equals the given phase.
623	–	*/
624	–	public final boolean hasPhase(int phase) {
625	–	return phaseOf(getReconciledState()) == phase;
626	–	}
627	–
628	–	/**
708		* Returns the number of parties registered at this barrier.
709	+	*
710		* @return the number of parties
711		*/
712		public int getRegisteredParties() {
#	Line 634 | Line 714 | public class Phaser {
714		}
715
716		/**
717	<	* Returns the number of parties that have arrived at the current
718	<	* phase of this barrier.
717	>	* Returns the number of registered parties that have arrived at
718	>	* the current phase of this barrier.
719	>	*
720		* @return the number of arrived parties
721		*/
722		public int getArrivedParties() {
#	Line 645 | Line 726 | public class Phaser {
726		/**
727		* Returns the number of registered parties that have not yet
728		* arrived at the current phase of this barrier.
729	+	*
730		* @return the number of unarrived parties
731		*/
732		public int getUnarrivedParties() {
#	Line 652 | Line 734 | public class Phaser {
734		}
735
736		/**
737	<	* Returns the parent of this phaser, or null if none.
738	<	* @return the parent of this phaser, or null if none.
737	>	* Returns the parent of this phaser, or {@code null} if none.
738	>	*
739	>	* @return the parent of this phaser, or {@code null} if none
740		*/
741		public Phaser getParent() {
742		return parent;
#	Line 662 | Line 745 | public class Phaser {
745		/**
746		* Returns the root ancestor of this phaser, which is the same as
747		* this phaser if it has no parent.
748	<	* @return the root ancestor of this phaser.
748	>	*
749	>	* @return the root ancestor of this phaser
750		*/
751		public Phaser getRoot() {
752		return root;
753		}
754
755		/**
756	<	* Returns true if this barrier has been terminated.
757	<	* @return true if this barrier has been terminated
756	>	* Returns {@code true} if this barrier has been terminated.
757	>	*
758	>	* @return {@code true} if this barrier has been terminated
759		*/
760		public boolean isTerminated() {
761		return getPhase() < 0;
762		}
763
764		/**
765	<	* Overridable method to perform an action upon phase advance, and
766	<	* to control termination. This method is invoked whenever the
767	<	* barrier is tripped (and thus all other waiting parties are
768	<	* dormant). If it returns true, then, rather than advance the
769	<	* phase number, this barrier will be set to a final termination
770	<	* state, and subsequent calls to {@code isTerminated} will
771	<	* return true.
765	>	* Overridable method to perform an action upon impending phase
766	>	* advance, and to control termination. This method is invoked
767	>	* upon arrival of the party tripping the barrier (when all other
768	>	* waiting parties are dormant).  If this method returns {@code
769	>	* true}, then, rather than advance the phase number, this barrier
770	>	* will be set to a final termination state, and subsequent calls
771	>	* to {@link #isTerminated} will return true. Any (unchecked)
772	>	* Exception or Error thrown by an invocation of this method is
773	>	* propagated to the party attempting to trip the barrier, in
774	>	* which case no advance occurs.
775	>	*
776	>	* <p>The arguments to this method provide the state of the phaser
777	>	* prevailing for the current transition. (When called from within
778	>	* an implementation of {@code onAdvance} the values returned by
779	>	* methods such as {@code getPhase} may or may not reliably
780	>	* indicate the state to which this transition applies.)
781		*
782	<	* <p> The default version returns true when the number of
782	>	* <p>The default version returns {@code true} when the number of
783		* registered parties is zero. Normally, overrides that arrange
784		* termination for other reasons should also preserve this
785		* property.
786		*
787	<	* <p> You may override this method to perform an action with side
788	<	* effects visible to participating tasks, but it is in general
789	<	* only sensible to do so in designs where all parties register
790	<	* before any arrive, and all {@code awaitAdvance} at each phase.
791	<	* Otherwise, you cannot ensure lack of interference. In
792	<	* particular, this method may be invoked more than once per
793	<	* transition if other parties successfully register while the
700	<	* invocation of this method is in progress, thus postponing the
701	<	* transition until those parties also arrive, re-triggering this
702	<	* method.
787	>	* <p>You may override this method to perform an action with side
788	>	* effects visible to participating tasks, but doing so requires
789	>	* care: Method {@code onAdvance} may be invoked more than once
790	>	* per transition.  Further, unless all parties register before
791	>	* any arrive, and all {@link #awaitAdvance} at each phase, then
792	>	* you cannot ensure lack of interference from other parties
793	>	* during the invocation of this method.
794		*
795		* @param phase the phase number on entering the barrier
796	<	* @param registeredParties the current number of registered
797	<	* parties.
707	<	* @return true if this barrier should terminate
796	>	* @param registeredParties the current number of registered parties
797	>	* @return {@code true} if this barrier should terminate
798		*/
799		protected boolean onAdvance(int phase, int registeredParties) {
800		return registeredParties <= 0;
#	Line 713 | Line 803 | public class Phaser {
803		/**
804		* Returns a string identifying this phaser, as well as its
805		* state.  The state, in brackets, includes the String {@code
806	<	* "phase ="} followed by the phase number, {@code "parties ="}
806	>	* "phase = "} followed by the phase number, {@code "parties = "}
807		* followed by the number of registered parties, and {@code
808	<	* "arrived ="} followed by the number of arrived parties
808	>	* "arrived = "} followed by the number of arrived parties.
809		*
810		* @return a string identifying this barrier, as well as its state
811		*/
812		public String toString() {
813		long s = getReconciledState();
814	<	return super.toString() + "[phase = " + phaseOf(s) + " parties = " + partiesOf(s) + " arrived = " + arrivedOf(s) + "]";
814	>	return super.toString() +
815	>	"[phase = " + phaseOf(s) +
816	>	" parties = " + partiesOf(s) +
817	>	" arrived = " + arrivedOf(s) + "]";
818		}
819
820		// methods for waiting
821
729	–	/** The number of CPUs, for spin control */
730	–	static final int NCPUS = Runtime.getRuntime().availableProcessors();
731	–
732	–	/**
733	–	* The number of times to spin before blocking in timed waits.
734	–	* The value is empirically derived.
735	–	*/
736	–	static final int maxTimedSpins = (NCPUS < 2)? 0 : 32;
737	–
738	–	/**
739	–	* The number of times to spin before blocking in untimed waits.
740	–	* This is greater than timed value because untimed waits spin
741	–	* faster since they don't need to check times on each spin.
742	–	*/
743	–	static final int maxUntimedSpins = maxTimedSpins * 32;
744	–
745	–	/**
746	–	* The number of nanoseconds for which it is faster to spin
747	–	* rather than to use timed park. A rough estimate suffices.
748	–	*/
749	–	static final long spinForTimeoutThreshold = 1000L;
750	–
822		/**
823	<	* Wait nodes for Treiber stack representing wait queue for non-FJ
753	<	* tasks.
823	>	* Wait nodes for Treiber stack representing wait queue
824		*/
825	<	static final class QNode {
826	<	QNode next;
825	>	static final class QNode implements ForkJoinPool.ManagedBlocker {
826	>	final Phaser phaser;
827	>	final int phase;
828	>	final long startTime;
829	>	final long nanos;
830	>	final boolean timed;
831	>	final boolean interruptible;
832	>	volatile boolean wasInterrupted = false;
833		volatile Thread thread; // nulled to cancel wait
834	<	QNode() {
834	>	QNode next;
835	>	QNode(Phaser phaser, int phase, boolean interruptible,
836	>	boolean timed, long startTime, long nanos) {
837	>	this.phaser = phaser;
838	>	this.phase = phase;
839	>	this.timed = timed;
840	>	this.interruptible = interruptible;
841	>	this.startTime = startTime;
842	>	this.nanos = nanos;
843		thread = Thread.currentThread();
844		}
845	+	public boolean isReleasable() {
846	+	return (thread == null ||
847	+	phaser.getPhase() != phase ||
848	+	(interruptible && wasInterrupted) ||
849	+	(timed && (nanos - (System.nanoTime() - startTime)) <= 0));
850	+	}
851	+	public boolean block() {
852	+	if (Thread.interrupted()) {
853	+	wasInterrupted = true;
854	+	if (interruptible)
855	+	return true;
856	+	}
857	+	if (!timed)
858	+	LockSupport.park(this);
859	+	else {
860	+	long waitTime = nanos - (System.nanoTime() - startTime);
861	+	if (waitTime <= 0)
862	+	return true;
863	+	LockSupport.parkNanos(this, waitTime);
864	+	}
865	+	return isReleasable();
866	+	}
867		void signal() {
868		Thread t = thread;
869		if (t != null) {
#	Line 765 | Line 871 | public class Phaser {
871		LockSupport.unpark(t);
872		}
873		}
874	+	boolean doWait() {
875	+	if (thread != null) {
876	+	try {
877	+	ForkJoinPool.managedBlock(this, false);
878	+	} catch (InterruptedException ie) {
879	+	}
880	+	}
881	+	return wasInterrupted;
882	+	}
883	+
884		}
885
886		/**
887	<	* Removes and signals waiting threads from wait queue
887	>	* Removes and signals waiting threads from wait queue.
888		*/
889		private void releaseWaiters(int phase) {
890		AtomicReference<QNode> head = queueFor(phase);
#	Line 780 | Line 896 | public class Phaser {
896		}
897
898		/**
899	+	* Tries to enqueue given node in the appropriate wait queue.
900	+	*
901	+	* @return true if successful
902	+	*/
903	+	private boolean tryEnqueue(QNode node) {
904	+	AtomicReference<QNode> head = queueFor(node.phase);
905	+	return head.compareAndSet(node.next = head.get(), node);
906	+	}
907	+
908	+	/**
909		* Enqueues node and waits unless aborted or signalled.
910	+	*
911	+	* @return current phase
912		*/
913		private int untimedWait(int phase) {
786	–	int spins = maxUntimedSpins;
914		QNode node = null;
788	–	boolean interrupted = false;
915		boolean queued = false;
916	+	boolean interrupted = false;
917		int p;
918		while ((p = getPhase()) == phase) {
919	<	interrupted = Thread.interrupted();
920	<	if (node != null) {
921	<	if (!queued) {
922	<	AtomicReference<QNode> head = queueFor(phase);
923	<	queued = head.compareAndSet(node.next = head.get(), node);
924	<	}
798	<	else if (node.thread != null)
799	<	LockSupport.park(this);
800	<	}
801	<	else if (spins <= 0)
802	<	node = new QNode();
919	>	if (Thread.interrupted())
920	>	interrupted = true;
921	>	else if (node == null)
922	>	node = new QNode(this, phase, false, false, 0, 0);
923	>	else if (!queued)
924	>	queued = tryEnqueue(node);
925		else
926	<	--spins;
926	>	interrupted = node.doWait();
927		}
928		if (node != null)
929		node.thread = null;
930	+	releaseWaiters(phase);
931		if (interrupted)
932		Thread.currentThread().interrupt();
810	–	releaseWaiters(phase);
933		return p;
934		}
935
936		/**
937	<	* Messier interruptible version
937	>	* Interruptible version
938	>	* @return current phase
939		*/
940		private int interruptibleWait(int phase) throws InterruptedException {
818	–	int spins = maxUntimedSpins;
941		QNode node = null;
942		boolean queued = false;
943		boolean interrupted = false;
944		int p;
945	<	while ((p = getPhase()) == phase) {
946	<	if (interrupted = Thread.interrupted())
947	<	break;
948	<	if (node != null) {
949	<	if (!queued) {
950	<	AtomicReference<QNode> head = queueFor(phase);
951	<	queued = head.compareAndSet(node.next = head.get(), node);
830	<	}
831	<	else if (node.thread != null)
832	<	LockSupport.park(this);
833	<	}
834	<	else if (spins <= 0)
835	<	node = new QNode();
945	>	while ((p = getPhase()) == phase && !interrupted) {
946	>	if (Thread.interrupted())
947	>	interrupted = true;
948	>	else if (node == null)
949	>	node = new QNode(this, phase, true, false, 0, 0);
950	>	else if (!queued)
951	>	queued = tryEnqueue(node);
952		else
953	<	--spins;
953	>	interrupted = node.doWait();
954		}
955		if (node != null)
956		node.thread = null;
957	+	if (p != phase || (p = getPhase()) != phase)
958	+	releaseWaiters(phase);
959		if (interrupted)
960		throw new InterruptedException();
843	–	releaseWaiters(phase);
961		return p;
962		}
963
964		/**
965	<	* Even messier timeout version.
965	>	* Timeout version.
966	>	* @return current phase
967		*/
968		private int timedWait(int phase, long nanos)
969		throws InterruptedException, TimeoutException {
970	+	long startTime = System.nanoTime();
971	+	QNode node = null;
972	+	boolean queued = false;
973	+	boolean interrupted = false;
974		int p;
975	<	if ((p = getPhase()) == phase) {
976	<	long lastTime = System.nanoTime();
977	<	int spins = maxTimedSpins;
978	<	QNode node = null;
979	<	boolean queued = false;
980	<	boolean interrupted = false;
981	<	while ((p = getPhase()) == phase) {
982	<	if (interrupted = Thread.interrupted())
983	<	break;
984	<	long now = System.nanoTime();
985	<	if ((nanos -= now - lastTime) <= 0)
864	<	break;
865	<	lastTime = now;
866	<	if (node != null) {
867	<	if (!queued) {
868	<	AtomicReference<QNode> head = queueFor(phase);
869	<	queued = head.compareAndSet(node.next = head.get(), node);
870	<	}
871	<	else if (node.thread != null &&
872	<	nanos > spinForTimeoutThreshold) {
873	<	LockSupport.parkNanos(this, nanos);
874	<	}
875	<	}
876	<	else if (spins <= 0)
877	<	node = new QNode();
878	<	else
879	<	--spins;
880	<	}
881	<	if (node != null)
882	<	node.thread = null;
883	<	if (interrupted)
884	<	throw new InterruptedException();
885	<	if (p == phase && (p = getPhase()) == phase)
886	<	throw new TimeoutException();
975	>	while ((p = getPhase()) == phase && !interrupted) {
976	>	if (Thread.interrupted())
977	>	interrupted = true;
978	>	else if (nanos - (System.nanoTime() - startTime) <= 0)
979	>	break;
980	>	else if (node == null)
981	>	node = new QNode(this, phase, true, true, startTime, nanos);
982	>	else if (!queued)
983	>	queued = tryEnqueue(node);
984	>	else
985	>	interrupted = node.doWait();
986		}
987	<	releaseWaiters(phase);
987	>	if (node != null)
988	>	node.thread = null;
989	>	if (p != phase || (p = getPhase()) != phase)
990	>	releaseWaiters(phase);
991	>	if (interrupted)
992	>	throw new InterruptedException();
993	>	if (p == phase)
994	>	throw new TimeoutException();
995		return p;
996		}
997
998	<	// Temporary Unsafe mechanics for preliminary release
998	>	// Unsafe mechanics
999
1000	<	static final Unsafe _unsafe;
1001	<	static final long stateOffset;
1000	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1001	>	private static final long stateOffset =
1002	>	objectFieldOffset("state", Phaser.class);
1003
1004	<	static {
1004	>	private final boolean casState(long cmp, long val) {
1005	>	return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val);
1006	>	}
1007	>
1008	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1009		try {
1010	<	if (Phaser.class.getClassLoader() != null) {
1011	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1012	<	f.setAccessible(true);
1013	<	_unsafe = (Unsafe)f.get(null);
1014	<	}
1015	<	else
905	<	_unsafe = Unsafe.getUnsafe();
906	<	stateOffset = _unsafe.objectFieldOffset
907	<	(Phaser.class.getDeclaredField("state"));
908	<	} catch (Exception e) {
909	<	throw new RuntimeException("Could not initialize intrinsics", e);
1010	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1011	>	} catch (NoSuchFieldException e) {
1012	>	// Convert Exception to corresponding Error
1013	>	NoSuchFieldError error = new NoSuchFieldError(field);
1014	>	error.initCause(e);
1015	>	throw error;
1016		}
1017		}
1018
1019	<	final boolean casState(long cmp, long val) {
1020	<	return _unsafe.compareAndSwapLong(this, stateOffset, cmp, val);
1019	>	/**
1020	>	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1021	>	* Replace with a simple call to Unsafe.getUnsafe when integrating
1022	>	* into a jdk.
1023	>	*
1024	>	* @return a sun.misc.Unsafe
1025	>	*/
1026	>	private static sun.misc.Unsafe getUnsafe() {
1027	>	try {
1028	>	return sun.misc.Unsafe.getUnsafe();
1029	>	} catch (SecurityException se) {
1030	>	try {
1031	>	return java.security.AccessController.doPrivileged
1032	>	(new java.security
1033	>	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1034	>	public sun.misc.Unsafe run() throws Exception {
1035	>	java.lang.reflect.Field f = sun.misc
1036	>	.Unsafe.class.getDeclaredField("theUnsafe");
1037	>	f.setAccessible(true);
1038	>	return (sun.misc.Unsafe) f.get(null);
1039	>	}});
1040	>	} catch (java.security.PrivilegedActionException e) {
1041	>	throw new RuntimeException("Could not initialize intrinsics",
1042	>	e.getCause());
1043	>	}
1044	>	}
1045		}
1046		}

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