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Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.4 by dl, Sat Sep 6 13:19:17 2008 UTC vs.
Revision 1.40 by dl, Mon Aug 24 12:49:39 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 <tt>Integer.MAX_VALUE</tt>).
59	<	*
60	<	* <li> Like a CyclicBarrier, a Phaser may be repeatedly awaited.
61	<	* Method <tt>arriveAndAwaitAdvance</tt> has effect analogous to
62	<	* <tt>CyclicBarrier.await</tt>.  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 <tt>arrive</tt> and
43	–	*       <tt>arriveAndDeregister</tt> do not block, but return
44	–	*       the phase value current upon entry to the method.
45	–	*
46	–	*   <li> Awaiting others. Method <tt>awaitAdvance</tt> 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 <tt>onAdvance</tt>, that also controls termination.
81	<	* Overriding this method may be used to similar but more flecible
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 <tt>onAdvance</tt> 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	<	* <tt>forceTermination</tt> 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, <tt>awaitAdvance</tt> 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	<	* <tt>forceTermination</tt>.
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; thus, this value is always
104	>	* greater than zero if there are any registered parties.  The values
105	>	* returned by these methods may reflect transient states and so are
106	>	* not in general useful for synchronization control.  Method {@link
107	>	* #toString} returns snapshots of these state queries in a form
108	>	* convenient for informal monitoring.
109		*
110		* <p><b>Sample usages:</b>
111		*
112	<	* <p>A Phaser may be used instead of a <tt>CountdownLatch</tt> to control
113	<	* a one-shot action serving a variable number of parties. The typical
114	<	* idiom is for the method setting this up to first register, then
115	<	* start the actions, then deregister, as in:
116	<	*
117	<	* <pre>
118	<	*  void runTasks(List&lt;Runnable&gt; list) {
119	<	*    final Phaser phaser = new Phaser(1); // "1" to register self
120	<	*    for (Runnable r : list) {
121	<	*      phaser.register();
122	<	*      new Thread() {
123	<	*        public void run() {
124	<	*          phaser.arriveAndAwaitAdvance(); // await all creation
125	<	*          r.run();
126	<	*          phaser.arriveAndDeregister();   // signal completion
127	<	*        }
128	<	*      }.start();
112	>	* <p>A {@code Phaser} may be used instead of a {@code CountDownLatch}
113	>	* to control a one-shot action serving a variable number of
114	>	* parties. The typical idiom is for the method setting this up to
115	>	* first register, then start the actions, then deregister, as in:
116	>	*
117	>	*  <pre> {@code
118	>	* void runTasks(List<Runnable> tasks) {
119	>	*   final Phaser phaser = new Phaser(1); // "1" to register self
120	>	*   // create and start threads
121	>	*   for (Runnable task : tasks) {
122	>	*     phaser.register();
123	>	*     new Thread() {
124	>	*       public void run() {
125	>	*         phaser.arriveAndAwaitAdvance(); // await all creation
126	>	*         task.run();
127	>	*       }
128	>	*     }.start();
129		*   }
130	<	*   phaser.arrive(); // allow threads to start
131	<	*   int p = phaser.arriveAndDeregister(); // deregister self
132	<	*   otherActions(); // do other things while tasks execute
133	<	*   phaser.awaitAdvance(p); // wait for all tasks to arrive
109	<	* }
110	<	* </pre>
130	>	*
131	>	*   // allow threads to start and deregister self
132	>	*   phaser.arriveAndDeregister();
133	>	* }}</pre>
134		*
135		* <p>One way to cause a set of threads to repeatedly perform actions
136	<	* for a given number of iterations is to override <tt>onAdvance</tt>:
136	>	* for a given number of iterations is to override {@code onAdvance}:
137		*
138	<	* <pre>
139	<	*  void startTasks(List&lt;Runnable&gt; list, final int iterations) {
140	<	*    final Phaser phaser = new Phaser() {
141	<	*       public boolean onAdvance(int phase, int registeredParties) {
142	<	*         return phase &gt;= iterations || registeredParties == 0;
138	>	*  <pre> {@code
139	>	* void startTasks(List<Runnable> tasks, final int iterations) {
140	>	*   final Phaser phaser = new Phaser() {
141	>	*     protected boolean onAdvance(int phase, int registeredParties) {
142	>	*       return phase >= iterations || registeredParties == 0;
143	>	*     }
144	>	*   };
145	>	*   phaser.register();
146	>	*   for (Runnable task : tasks) {
147	>	*     phaser.register();
148	>	*     new Thread() {
149	>	*       public void run() {
150	>	*         do {
151	>	*           task.run();
152	>	*           phaser.arriveAndAwaitAdvance();
153	>	*         } while(!phaser.isTerminated();
154		*       }
155	<	*    };
122	<	*    phaser.register();
123	<	*    for (Runnable r : list) {
124	<	*      phaser.register();
125	<	*      new Thread() {
126	<	*        public void run() {
127	<	*           do {
128	<	*             r.run();
129	<	*             phaser.arriveAndAwaitAdvance();
130	<	*           } while(!phaser.isTerminated();
131	<	*        }
132	<	*      }.start();
155	>	*     }.start();
156		*   }
157		*   phaser.arriveAndDeregister(); // deregister self, don't wait
158	<	* }
159	<	* </pre>
158	>	* }}</pre>
159	>	*
160	>	* If the main task must later await termination, it
161	>	* may re-register and then execute a similar loop:
162	>	* <pre> {@code
163	>	*   // ...
164	>	*   phaser.register();
165	>	*   while (!phaser.isTerminated())
166	>	*     phaser.arriveAndAwaitAdvance();
167	>	* }</pre>
168	>	*
169	>	* Related constructions may be used to await particular phase numbers
170	>	* in contexts where you are sure that the phase will never wrap around
171	>	* {@code Integer.MAX_VALUE}. For example:
172	>	*
173	>	* <pre> {@code
174	>	*   void awaitPhase(Phaser phaser, int phase) {
175	>	*     int p = phaser.register(); // assumes caller not already registered
176	>	*     while (p < phase) {
177	>	*       if (phaser.isTerminated())
178	>	*         // ... deal with unexpected termination
179	>	*       else
180	>	*         p = phaser.arriveAndAwaitAdvance();
181	>	*     }
182	>	*     phaser.arriveAndDeregister();
183	>	*   }
184	>	* }</pre>
185		*
186	<	* <p> To create a set of tasks using a tree of Phasers,
186	>	*
187	>	* <p>To create a set of tasks using a tree of phasers,
188		* you could use code of the following form, assuming a
189	<	* Task class with a constructor accepting a Phaser that
189	>	* Task class with a constructor accepting a phaser that
190		* it registers for upon construction:
191	<	* <pre>
192	<	*  void build(Task[] actions, int lo, int hi, Phaser b) {
193	<	*    int step = (hi - lo) / TASKS_PER_PHASER;
194	<	*    if (step &gt; 1) {
195	<	*       int i = lo;
196	<	*       while (i &lt; hi) {
197	<	*         int r = Math.min(i + step, hi);
198	<	*         build(actions, i, r, new Phaser(b));
199	<	*         i = r;
200	<	*       }
201	<	*    }
202	<	*    else {
203	<	*      for (int i = lo; i &lt; hi; ++i)
204	<	*        actions[i] = new Task(b);
205	<	*        // assumes new Task(b) performs b.register()
206	<	*    }
207	<	*  }
208	<	*  // .. initially called, for n tasks via
160	<	*  build(new Task[n], 0, n, new Phaser());
161	<	* </pre>
191	>	*  <pre> {@code
192	>	* void build(Task[] actions, int lo, int hi, Phaser b) {
193	>	*   int step = (hi - lo) / TASKS_PER_PHASER;
194	>	*   if (step > 1) {
195	>	*     int i = lo;
196	>	*     while (i < hi) {
197	>	*       int r = Math.min(i + step, hi);
198	>	*       build(actions, i, r, new Phaser(b));
199	>	*       i = r;
200	>	*     }
201	>	*   } else {
202	>	*     for (int i = lo; i < 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
208	>	* build(new Task[n], 0, n, new Phaser());}</pre>
209		*
210	<	* The best value of <tt>TASKS_PER_PHASER</tt> depends mainly on
210	>	* The best value of {@code TASKS_PER_PHASER} depends mainly on
211		* expected barrier synchronization rates. A value as low as four may
212		* be appropriate for extremely small per-barrier task bodies (thus
213		* high rates), or up to hundreds for extremely large ones.
#	Line 169 | Line 216 | import java.lang.reflect.*;
216		*
217		* <p><b>Implementation notes</b>: This implementation restricts the
218		* maximum number of parties to 65535. Attempts to register additional
219	<	* parties result in IllegalStateExceptions. However, you can and
219	>	* parties result in {@code IllegalStateException}. However, you can and
220		* should create tiered phasers to accommodate arbitrarily large sets
221		* of participants.
222	+	*
223	+	* @since 1.7
224	+	* @author Doug Lea
225		*/
226		public class Phaser {
227		/*
#	Line 192 | Line 242 | public class Phaser {
242		* However, to efficiently maintain atomicity, these values are
243		* packed into a single (atomic) long. Termination uses the sign
244		* bit of 32 bit representation of phase, so phase is set to -1 on
245	<	* termination. Good performace relies on keeping state decoding
245	>	* termination. Good performance relies on keeping state decoding
246		* and encoding simple, and keeping race windows short.
247		*
248		* Note: there are some cheats in arrive() that rely on unarrived
249	<	* being lowest 16 bits.
249	>	* count being lowest 16 bits.
250		*/
251		private volatile long state;
252
253		private static final int ushortBits = 16;
254	<	private static final int ushortMask =  (1 << ushortBits) - 1;
255	<	private static final int phaseMask = 0x7fffffff;
254	>	private static final int ushortMask = 0xffff;
255	>	private static final int phaseMask  = 0x7fffffff;
256
257		private static int unarrivedOf(long s) {
258	<	return (int)(s & ushortMask);
258	>	return (int) (s & ushortMask);
259		}
260
261		private static int partiesOf(long s) {
262	<	return (int)(s & (ushortMask << 16)) >>> 16;
262	>	return ((int) s) >>> 16;
263		}
264
265		private static int phaseOf(long s) {
266	<	return (int)(s >>> 32);
266	>	return (int) (s >>> 32);
267		}
268
269		private static int arrivedOf(long s) {
#	Line 221 | Line 271 | public class Phaser {
271		}
272
273		private static long stateFor(int phase, int parties, int unarrived) {
274	<	return (((long)phase) << 32) | ((parties << 16) | unarrived);
274	>	return ((((long) phase) << 32) | (((long) parties) << 16) |
275	>	(long) unarrived);
276		}
277
278		private static long trippedStateFor(int phase, int parties) {
279	<	return (((long)phase) << 32) | ((parties << 16) | parties);
279	>	long lp = (long) parties;
280	>	return (((long) phase) << 32) | (lp << 16) | lp;
281		}
282
283	<	private static IllegalStateException badBounds(int parties, int unarrived) {
284	<	return new IllegalStateException
285	<	("Attempt to set " + unarrived +
286	<	" unarrived of " + parties + " parties");
283	>	/**
284	>	* Returns message string for bad bounds exceptions.
285	>	*/
286	>	private static String badBounds(int parties, int unarrived) {
287	>	return ("Attempt to set " + unarrived +
288	>	" unarrived of " + parties + " parties");
289		}
290
291		/**
#	Line 240 | Line 294 | public class Phaser {
294		private final Phaser parent;
295
296		/**
297	<	* The root of Phaser tree. Equals this if not in a tree.  Used to
297	>	* The root of phaser tree. Equals this if not in a tree.  Used to
298		* support faster state push-down.
299		*/
300		private final Phaser root;
#	Line 248 | Line 302 | public class Phaser {
302		// Wait queues
303
304		/**
305	<	* Heads of Treiber stacks waiting for nonFJ threads. To eliminate
305	>	* Heads of Treiber stacks for waiting threads. To eliminate
306		* contention while releasing some threads while adding others, we
307		* use two of them, alternating across even and odd phases.
308		*/
#	Line 256 | Line 310 | public class Phaser {
310		private final AtomicReference<QNode> oddQ  = new AtomicReference<QNode>();
311
312		private AtomicReference<QNode> queueFor(int phase) {
313	<	return (phase & 1) == 0? evenQ : oddQ;
313	>	return ((phase & 1) == 0) ? evenQ : oddQ;
314		}
315
316		/**
#	Line 264 | Line 318 | public class Phaser {
318		* root if necessary.
319		*/
320		private long getReconciledState() {
321	<	return parent == null? state : reconcileState();
321	>	return (parent == null) ? state : reconcileState();
322		}
323
324		/**
#	Line 291 | Line 345 | public class Phaser {
345		}
346
347		/**
348	<	* Creates a new Phaser without any initially registered parties,
349	<	* initial phase number 0, and no parent.
348	>	* Creates a new phaser without any initially registered parties,
349	>	* initial phase number 0, and no parent. Any thread using this
350	>	* phaser will need to first register for it.
351		*/
352		public Phaser() {
353		this(null);
354		}
355
356		/**
357	<	* Creates a new Phaser with the given numbers of registered
357	>	* Creates a new phaser with the given numbers of registered
358		* unarrived parties, initial phase number 0, and no parent.
359	<	* @param parties the number of parties required to trip barrier.
359	>	*
360	>	* @param parties the number of parties required to trip barrier
361		* @throws IllegalArgumentException if parties less than zero
362	<	* or greater than the maximum number of parties supported.
362	>	* or greater than the maximum number of parties supported
363		*/
364		public Phaser(int parties) {
365		this(null, parties);
366		}
367
368		/**
369	<	* Creates a new Phaser with the given parent, without any
369	>	* Creates a new phaser with the given parent, without any
370		* initially registered parties. If parent is non-null this phaser
371		* is registered with the parent and its initial phase number is
372		* the same as that of parent phaser.
373	<	* @param parent the parent phaser.
373	>	*
374	>	* @param parent the parent phaser
375		*/
376		public Phaser(Phaser parent) {
377		int phase = 0;
#	Line 329 | Line 386 | public class Phaser {
386		}
387
388		/**
389	<	* Creates a new Phaser with the given parent and numbers of
390	<	* registered unarrived parties. If parent is non-null this phaser
389	>	* Creates a new phaser with the given parent and numbers of
390	>	* registered unarrived parties. If parent is non-null, this phaser
391		* is registered with the parent and its initial phase number is
392		* the same as that of parent phaser.
393	<	* @param parent the parent phaser.
394	<	* @param parties the number of parties required to trip barrier.
393	>	*
394	>	* @param parent the parent phaser
395	>	* @param parties the number of parties required to trip barrier
396		* @throws IllegalArgumentException if parties less than zero
397	<	* or greater than the maximum number of parties supported.
397	>	* or greater than the maximum number of parties supported
398		*/
399		public Phaser(Phaser parent, int parties) {
400		if (parties < 0 || parties > ushortMask)
#	Line 354 | Line 412 | public class Phaser {
412
413		/**
414		* Adds a new unarrived party to this phaser.
415	<	* @return the current barrier phase number upon registration
415	>	*
416	>	* @return the arrival phase number to which this registration applied
417		* @throws IllegalStateException if attempting to register more
418	<	* than the maximum supported number of parties.
418	>	* than the maximum supported number of parties
419		*/
420		public int register() {
421		return doRegister(1);
#	Line 364 | Line 423 | public class Phaser {
423
424		/**
425		* Adds the given number of new unarrived parties to this phaser.
426	<	* @param parties the number of parties required to trip barrier.
427	<	* @return the current barrier phase number upon registration
426	>	*
427	>	* @param parties the number of parties required to trip barrier
428	>	* @return the arrival phase number to which this registration applied
429		* @throws IllegalStateException if attempting to register more
430	<	* than the maximum supported number of parties.
430	>	* than the maximum supported number of parties
431		*/
432		public int bulkRegister(int parties) {
433		if (parties < 0)
#	Line 390 | Line 450 | public class Phaser {
450		if (phase < 0)
451		break;
452		if (parties > ushortMask || unarrived > ushortMask)
453	<	throw badBounds(parties, unarrived);
453	>	throw new IllegalStateException(badBounds(parties, unarrived));
454		if (phase == phaseOf(root.state) &&
455		casState(s, stateFor(phase, parties, unarrived)))
456		break;
#	Line 400 | Line 460 | public class Phaser {
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
406	<	* 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		int phase;
473		for (;;) {
474		long s = state;
475		phase = phaseOf(s);
476	+	if (phase < 0)
477	+	break;
478		int parties = partiesOf(s);
479		int unarrived = unarrivedOf(s) - 1;
480		if (unarrived > 0) {        // Not the last arrival
#	Line 423 | Line 486 | public class Phaser {
486		if (par == null) {      // directly trip
487		if (casState
488		(s,
489	<	trippedStateFor(onAdvance(phase, parties)? -1 :
489	>	trippedStateFor(onAdvance(phase, parties) ? -1 :
490		((phase + 1) & phaseMask), parties))) {
491		releaseWaiters(phase);
492		break;
#	Line 437 | Line 500 | public class Phaser {
500		}
501		}
502		}
440	–	else if (phase < 0) // Don't throw exception if terminated
441	–	break;
503		else if (phase != phaseOf(root.state)) // or if unreconciled
504		reconcileState();
505		else
506	<	throw badBounds(parties, unarrived);
506	>	throw new IllegalStateException(badBounds(parties, unarrived));
507		}
508		return phase;
509		}
510
511		/**
512	<	* Arrives at the barrier, and deregisters from it, without
513	<	* waiting for others. Deregistration reduces number of parties
512	>	* Arrives at the barrier and deregisters from it without waiting
513	>	* for others. Deregistration reduces the number of parties
514		* required to trip the barrier in future phases.  If this phaser
515		* has a parent, and deregistration causes this phaser to have
516	<	* zero parties, this phaser is also deregistered from its parent.
516	>	* zero parties, this phaser also arrives at and is deregistered
517	>	* from its parent.  It is an unenforced usage error for an
518	>	* unregistered party to invoke this method.
519		*
520	<	* @return the current barrier phase number upon entry to
458	<	* this method, or a negative value if terminated;
520	>	* @return the arrival phase number, or a negative value if terminated
521		* @throws IllegalStateException if not terminated and the number
522	<	* of registered or unarrived parties would become negative.
522	>	* of registered or unarrived parties would become negative
523		*/
524		public int arriveAndDeregister() {
525		// similar code to arrive, but too different to merge
#	Line 466 | Line 528 | public class Phaser {
528		for (;;) {
529		long s = state;
530		phase = phaseOf(s);
531	+	if (phase < 0)
532	+	break;
533		int parties = partiesOf(s) - 1;
534		int unarrived = unarrivedOf(s) - 1;
535		if (parties >= 0) {
#	Line 484 | Line 548 | public class Phaser {
548		if (unarrived == 0) {
549		if (casState
550		(s,
551	<	trippedStateFor(onAdvance(phase, parties)? -1 :
551	>	trippedStateFor(onAdvance(phase, parties) ? -1 :
552		((phase + 1) & phaseMask), parties))) {
553		releaseWaiters(phase);
554		break;
555		}
556		continue;
557		}
494	–	if (phase < 0)
495	–	break;
558		if (par != null && phase != phaseOf(root.state)) {
559		reconcileState();
560		continue;
561		}
562		}
563	<	throw badBounds(parties, unarrived);
563	>	throw new IllegalStateException(badBounds(parties, unarrived));
564		}
565		return phase;
566		}
567
568		/**
569		* Arrives at the barrier and awaits others. Equivalent in effect
570	<	* to <tt>awaitAdvance(arrive())</tt>.  If you instead need to
571	<	* await with interruption of timeout, and/or deregister upon
572	<	* arrival, you can arrange them using analogous constructions.
573	<	* @return the phase on entry to this method
570	>	* to {@code awaitAdvance(arrive())}.  If you need to await with
571	>	* interruption or timeout, you can arrange this with an analogous
572	>	* construction using one of the other forms of the awaitAdvance
573	>	* method.  If instead you need to deregister upon arrival use
574	>	* {@code arriveAndDeregister}. It is an unenforced usage error
575	>	* for an unregistered party to invoke this method.
576	>	*
577	>	* @return the arrival phase number, or a negative number if terminated
578		* @throws IllegalStateException if not terminated and the number
579	<	* of unarrived parties would become negative.
579	>	* of unarrived parties would become negative
580		*/
581		public int arriveAndAwaitAdvance() {
582		return awaitAdvance(arrive());
583		}
584
585		/**
586	<	* Awaits the phase of the barrier to advance from the given
587	<	* value, or returns immediately if argument is negative or this
588	<	* barrier is terminated.
589	<	* @param phase the phase on entry to this method
590	<	* @return the phase on exit from this method
586	>	* Awaits the phase of the barrier to advance from the given phase
587	>	* value, returning immediately if the current phase of the
588	>	* barrier is not equal to the given phase value or this barrier
589	>	* is terminated.  It is an unenforced usage error for an
590	>	* unregistered party to invoke this method.
591	>	*
592	>	* @param phase an arrival phase number, or negative value if
593	>	* terminated; this argument is normally the value returned by a
594	>	* previous call to {@code arrive} or its variants
595	>	* @return the next arrival phase number, or a negative value
596	>	* if terminated or argument is negative
597		*/
598		public int awaitAdvance(int phase) {
599		if (phase < 0)
#	Line 530 | Line 602 | public class Phaser {
602		int p = phaseOf(s);
603		if (p != phase)
604		return p;
605	<	if (unarrivedOf(s) == 0)
605	>	if (unarrivedOf(s) == 0 && parent != null)
606		parent.awaitAdvance(phase);
607		// Fall here even if parent waited, to reconcile and help release
608		return untimedWait(phase);
609		}
610
611		/**
612	<	* Awaits the phase of the barrier to advance from the given
613	<	* value, or returns immediately if argumet is negative or this
614	<	* barrier is terminated, or throws InterruptedException if
615	<	* interrupted while waiting.
616	<	* @param phase the phase on entry to this method
617	<	* @return the phase on exit from this method
612	>	* Awaits the phase of the barrier to advance from the given phase
613	>	* value, throwing {@code InterruptedException} if interrupted
614	>	* while waiting, or returning immediately if the current phase of
615	>	* the barrier is not equal to the given phase value or this
616	>	* barrier is terminated. It is an unenforced usage error for an
617	>	* unregistered party to invoke this method.
618	>	*
619	>	* @param phase an arrival phase number, or negative value if
620	>	* terminated; this argument is normally the value returned by a
621	>	* previous call to {@code arrive} or its variants
622	>	* @return the next arrival phase number, or a negative value
623	>	* if terminated or argument is negative
624		* @throws InterruptedException if thread interrupted while waiting
625		*/
626	<	public int awaitAdvanceInterruptibly(int phase) throws InterruptedException {
626	>	public int awaitAdvanceInterruptibly(int phase)
627	>	throws InterruptedException {
628		if (phase < 0)
629		return phase;
630		long s = getReconciledState();
631		int p = phaseOf(s);
632		if (p != phase)
633		return p;
634	<	if (unarrivedOf(s) != 0)
634	>	if (unarrivedOf(s) == 0 && parent != null)
635		parent.awaitAdvanceInterruptibly(phase);
636		return interruptibleWait(phase);
637		}
638
639		/**
640	<	* Awaits the phase of the barrier to advance from the given value
641	<	* or the given timeout elapses, or returns immediately if
642	<	* argument is negative or this barrier is terminated.
643	<	* @param phase the phase on entry to this method
644	<	* @return the phase on exit from this method
640	>	* Awaits the phase of the barrier to advance from the given phase
641	>	* value or the given timeout to elapse, throwing {@code
642	>	* InterruptedException} if interrupted while waiting, or
643	>	* returning immediately if the current phase of the barrier is
644	>	* not equal to the given phase value or this barrier is
645	>	* terminated.  It is an unenforced usage error for an
646	>	* unregistered party to invoke this method.
647	>	*
648	>	* @param phase an arrival phase number, or negative value if
649	>	* terminated; this argument is normally the value returned by a
650	>	* previous call to {@code arrive} or its variants
651	>	* @param timeout how long to wait before giving up, in units of
652	>	*        {@code unit}
653	>	* @param unit a {@code TimeUnit} determining how to interpret the
654	>	*        {@code timeout} parameter
655	>	* @return the next arrival phase number, or a negative value
656	>	* if terminated or argument is negative
657		* @throws InterruptedException if thread interrupted while waiting
658		* @throws TimeoutException if timed out while waiting
659		*/
660	<	public int awaitAdvanceInterruptibly(int phase, long timeout, TimeUnit unit)
660	>	public int awaitAdvanceInterruptibly(int phase,
661	>	long timeout, TimeUnit unit)
662		throws InterruptedException, TimeoutException {
663		if (phase < 0)
664		return phase;
#	Line 574 | Line 666 | public class Phaser {
666		int p = phaseOf(s);
667		if (p != phase)
668		return p;
669	<	if (unarrivedOf(s) == 0)
669	>	if (unarrivedOf(s) == 0 && parent != null)
670		parent.awaitAdvanceInterruptibly(phase, timeout, unit);
671		return timedWait(phase, unit.toNanos(timeout));
672		}
#	Line 605 | Line 697 | public class Phaser {
697
698		/**
699		* Returns the current phase number. The maximum phase number is
700	<	* <tt>Integer.MAX_VALUE</tt>, after which it restarts at
700	>	* {@code Integer.MAX_VALUE}, after which it restarts at
701		* zero. Upon termination, the phase number is negative.
702	+	*
703		* @return the phase number, or a negative value if terminated
704		*/
705		public final int getPhase() {
#	Line 614 | Line 707 | public class Phaser {
707		}
708
709		/**
617	–	* Returns true if the current phase number equals the given phase.
618	–	* @param phase the phase
619	–	* @return true if the current phase number equals the given phase.
620	–	*/
621	–	public final boolean hasPhase(int phase) {
622	–	return phaseOf(getReconciledState()) == phase;
623	–	}
624	–
625	–	/**
710		* Returns the number of parties registered at this barrier.
711	+	*
712		* @return the number of parties
713		*/
714		public int getRegisteredParties() {
#	Line 631 | Line 716 | public class Phaser {
716		}
717
718		/**
719	<	* Returns the number of parties that have arrived at the current
720	<	* phase of this barrier.
719	>	* Returns the number of registered parties that have arrived at
720	>	* the current phase of this barrier.
721	>	*
722		* @return the number of arrived parties
723		*/
724		public int getArrivedParties() {
#	Line 642 | Line 728 | public class Phaser {
728		/**
729		* Returns the number of registered parties that have not yet
730		* arrived at the current phase of this barrier.
731	+	*
732		* @return the number of unarrived parties
733		*/
734		public int getUnarrivedParties() {
#	Line 649 | Line 736 | public class Phaser {
736		}
737
738		/**
739	<	* Returns the parent of this phaser, or null if none.
740	<	* @return the parent of this phaser, or null if none.
739	>	* Returns the parent of this phaser, or {@code null} if none.
740	>	*
741	>	* @return the parent of this phaser, or {@code null} if none
742		*/
743		public Phaser getParent() {
744		return parent;
#	Line 659 | Line 747 | public class Phaser {
747		/**
748		* Returns the root ancestor of this phaser, which is the same as
749		* this phaser if it has no parent.
750	<	* @return the root ancestor of this phaser.
750	>	*
751	>	* @return the root ancestor of this phaser
752		*/
753		public Phaser getRoot() {
754		return root;
755		}
756
757		/**
758	<	* Returns true if this barrier has been terminated.
759	<	* @return true if this barrier has been terminated
758	>	* Returns {@code true} if this barrier has been terminated.
759	>	*
760	>	* @return {@code true} if this barrier has been terminated
761		*/
762		public boolean isTerminated() {
763		return getPhase() < 0;
#	Line 677 | Line 767 | public class Phaser {
767		* Overridable method to perform an action upon phase advance, and
768		* to control termination. This method is invoked whenever the
769		* barrier is tripped (and thus all other waiting parties are
770	<	* dormant). If it returns true, then, rather than advance the
771	<	* phase number, this barrier will be set to a final termination
772	<	* state, and subsequent calls to <tt>isTerminated</tt> will
773	<	* return true.
770	>	* dormant). If it returns {@code true}, then, rather than advance
771	>	* the phase number, this barrier will be set to a final
772	>	* termination state, and subsequent calls to {@link #isTerminated}
773	>	* will return true.
774		*
775	<	* <p> The default version returns true when the number of
775	>	* <p>The default version returns {@code true} when the number of
776		* registered parties is zero. Normally, overrides that arrange
777		* termination for other reasons should also preserve this
778		* property.
779		*
780	<	* <p> You may override this method to perform an action with side
780	>	* <p>You may override this method to perform an action with side
781		* effects visible to participating tasks, but it is in general
782		* only sensible to do so in designs where all parties register
783	<	* before any arrive, and all <tt>awaitAdvance</tt> at each phase.
784	<	* Otherwise, you cannot ensure lack of interference. In
785	<	* particular, this method may be invoked more than once per
696	<	* transition if other parties successfully register while the
697	<	* invocation of this method is in progress, thus postponing the
698	<	* transition until those parties also arrive, re-triggering this
699	<	* method.
783	>	* before any arrive, and all {@link #awaitAdvance} at each phase.
784	>	* Otherwise, you cannot ensure lack of interference from other
785	>	* parties during the invocation of this method.
786		*
787		* @param phase the phase number on entering the barrier
788	<	* @param registeredParties the current number of registered
789	<	* parties.
704	<	* @return true if this barrier should terminate
788	>	* @param registeredParties the current number of registered parties
789	>	* @return {@code true} if this barrier should terminate
790		*/
791		protected boolean onAdvance(int phase, int registeredParties) {
792		return registeredParties <= 0;
#	Line 710 | Line 795 | public class Phaser {
795		/**
796		* Returns a string identifying this phaser, as well as its
797		* state.  The state, in brackets, includes the String {@code
798	<	* "phase ="} followed by the phase number, {@code "parties ="}
798	>	* "phase = "} followed by the phase number, {@code "parties = "}
799		* followed by the number of registered parties, and {@code
800	<	* "arrived ="} followed by the number of arrived parties
800	>	* "arrived = "} followed by the number of arrived parties.
801		*
802		* @return a string identifying this barrier, as well as its state
803		*/
804		public String toString() {
805		long s = getReconciledState();
806	<	return super.toString() + "[phase = " + phaseOf(s) + " parties = " + partiesOf(s) + " arrived = " + arrivedOf(s) + "]";
806	>	return super.toString() +
807	>	"[phase = " + phaseOf(s) +
808	>	" parties = " + partiesOf(s) +
809	>	" arrived = " + arrivedOf(s) + "]";
810		}
811
812		// methods for waiting
813
726	–	/** The number of CPUs, for spin control */
727	–	static final int NCPUS = Runtime.getRuntime().availableProcessors();
728	–
729	–	/**
730	–	* The number of times to spin before blocking in timed waits.
731	–	* The value is empirically derived.
732	–	*/
733	–	static final int maxTimedSpins = (NCPUS < 2)? 0 : 32;
734	–
735	–	/**
736	–	* The number of times to spin before blocking in untimed waits.
737	–	* This is greater than timed value because untimed waits spin
738	–	* faster since they don't need to check times on each spin.
739	–	*/
740	–	static final int maxUntimedSpins = maxTimedSpins * 32;
741	–
742	–	/**
743	–	* The number of nanoseconds for which it is faster to spin
744	–	* rather than to use timed park. A rough estimate suffices.
745	–	*/
746	–	static final long spinForTimeoutThreshold = 1000L;
747	–
814		/**
815	<	* Wait nodes for Treiber stack representing wait queue for non-FJ
750	<	* tasks.
815	>	* Wait nodes for Treiber stack representing wait queue
816		*/
817	<	static final class QNode {
818	<	QNode next;
817	>	static final class QNode implements ForkJoinPool.ManagedBlocker {
818	>	final Phaser phaser;
819	>	final int phase;
820	>	final long startTime;
821	>	final long nanos;
822	>	final boolean timed;
823	>	final boolean interruptible;
824	>	volatile boolean wasInterrupted = false;
825		volatile Thread thread; // nulled to cancel wait
826	<	QNode() {
826	>	QNode next;
827	>	QNode(Phaser phaser, int phase, boolean interruptible,
828	>	boolean timed, long startTime, long nanos) {
829	>	this.phaser = phaser;
830	>	this.phase = phase;
831	>	this.timed = timed;
832	>	this.interruptible = interruptible;
833	>	this.startTime = startTime;
834	>	this.nanos = nanos;
835		thread = Thread.currentThread();
836		}
837	+	public boolean isReleasable() {
838	+	return (thread == null ||
839	+	phaser.getPhase() != phase ||
840	+	(interruptible && wasInterrupted) ||
841	+	(timed && (nanos - (System.nanoTime() - startTime)) <= 0));
842	+	}
843	+	public boolean block() {
844	+	if (Thread.interrupted()) {
845	+	wasInterrupted = true;
846	+	if (interruptible)
847	+	return true;
848	+	}
849	+	if (!timed)
850	+	LockSupport.park(this);
851	+	else {
852	+	long waitTime = nanos - (System.nanoTime() - startTime);
853	+	if (waitTime <= 0)
854	+	return true;
855	+	LockSupport.parkNanos(this, waitTime);
856	+	}
857	+	return isReleasable();
858	+	}
859		void signal() {
860		Thread t = thread;
861		if (t != null) {
#	Line 762 | Line 863 | public class Phaser {
863		LockSupport.unpark(t);
864		}
865		}
866	+	boolean doWait() {
867	+	if (thread != null) {
868	+	try {
869	+	ForkJoinPool.managedBlock(this, false);
870	+	} catch (InterruptedException ie) {
871	+	}
872	+	}
873	+	return wasInterrupted;
874	+	}
875	+
876		}
877
878		/**
879	<	* Removes and signals waiting threads from wait queue
879	>	* Removes and signals waiting threads from wait queue.
880		*/
881		private void releaseWaiters(int phase) {
882		AtomicReference<QNode> head = queueFor(phase);
#	Line 777 | Line 888 | public class Phaser {
888		}
889
890		/**
891	+	* Tries to enqueue given node in the appropriate wait queue.
892	+	*
893	+	* @return true if successful
894	+	*/
895	+	private boolean tryEnqueue(QNode node) {
896	+	AtomicReference<QNode> head = queueFor(node.phase);
897	+	return head.compareAndSet(node.next = head.get(), node);
898	+	}
899	+
900	+	/**
901		* Enqueues node and waits unless aborted or signalled.
902	+	*
903	+	* @return current phase
904		*/
905		private int untimedWait(int phase) {
783	–	int spins = maxUntimedSpins;
906		QNode node = null;
785	–	boolean interrupted = false;
907		boolean queued = false;
908	+	boolean interrupted = false;
909		int p;
910		while ((p = getPhase()) == phase) {
911	<	interrupted = Thread.interrupted();
912	<	if (node != null) {
913	<	if (!queued) {
914	<	AtomicReference<QNode> head = queueFor(phase);
915	<	queued = head.compareAndSet(node.next = head.get(), node);
916	<	}
795	<	else if (node.thread != null)
796	<	LockSupport.park(this);
797	<	}
798	<	else if (spins <= 0)
799	<	node = new QNode();
911	>	if (Thread.interrupted())
912	>	interrupted = true;
913	>	else if (node == null)
914	>	node = new QNode(this, phase, false, false, 0, 0);
915	>	else if (!queued)
916	>	queued = tryEnqueue(node);
917		else
918	<	--spins;
918	>	interrupted = node.doWait();
919		}
920		if (node != null)
921		node.thread = null;
922	+	releaseWaiters(phase);
923		if (interrupted)
924		Thread.currentThread().interrupt();
807	–	releaseWaiters(phase);
925		return p;
926		}
927
928		/**
929	<	* Messier interruptible version
929	>	* Interruptible version
930	>	* @return current phase
931		*/
932		private int interruptibleWait(int phase) throws InterruptedException {
815	–	int spins = maxUntimedSpins;
933		QNode node = null;
934		boolean queued = false;
935		boolean interrupted = false;
936		int p;
937	<	while ((p = getPhase()) == phase) {
938	<	if (interrupted = Thread.interrupted())
939	<	break;
940	<	if (node != null) {
941	<	if (!queued) {
942	<	AtomicReference<QNode> head = queueFor(phase);
943	<	queued = head.compareAndSet(node.next = head.get(), node);
827	<	}
828	<	else if (node.thread != null)
829	<	LockSupport.park(this);
830	<	}
831	<	else if (spins <= 0)
832	<	node = new QNode();
937	>	while ((p = getPhase()) == phase && !interrupted) {
938	>	if (Thread.interrupted())
939	>	interrupted = true;
940	>	else if (node == null)
941	>	node = new QNode(this, phase, true, false, 0, 0);
942	>	else if (!queued)
943	>	queued = tryEnqueue(node);
944		else
945	<	--spins;
945	>	interrupted = node.doWait();
946		}
947		if (node != null)
948		node.thread = null;
949	+	if (p != phase || (p = getPhase()) != phase)
950	+	releaseWaiters(phase);
951		if (interrupted)
952		throw new InterruptedException();
840	–	releaseWaiters(phase);
953		return p;
954		}
955
956		/**
957	<	* Even messier timeout version.
957	>	* Timeout version.
958	>	* @return current phase
959		*/
960		private int timedWait(int phase, long nanos)
961		throws InterruptedException, TimeoutException {
962	+	long startTime = System.nanoTime();
963	+	QNode node = null;
964	+	boolean queued = false;
965	+	boolean interrupted = false;
966		int p;
967	<	if ((p = getPhase()) == phase) {
968	<	long lastTime = System.nanoTime();
969	<	int spins = maxTimedSpins;
970	<	QNode node = null;
971	<	boolean queued = false;
972	<	boolean interrupted = false;
973	<	while ((p = getPhase()) == phase) {
974	<	if (interrupted = Thread.interrupted())
975	<	break;
976	<	long now = System.nanoTime();
977	<	if ((nanos -= now - lastTime) <= 0)
861	<	break;
862	<	lastTime = now;
863	<	if (node != null) {
864	<	if (!queued) {
865	<	AtomicReference<QNode> head = queueFor(phase);
866	<	queued = head.compareAndSet(node.next = head.get(), node);
867	<	}
868	<	else if (node.thread != null &&
869	<	nanos > spinForTimeoutThreshold) {
870	<	LockSupport.parkNanos(this, nanos);
871	<	}
872	<	}
873	<	else if (spins <= 0)
874	<	node = new QNode();
875	<	else
876	<	--spins;
877	<	}
878	<	if (node != null)
879	<	node.thread = null;
880	<	if (interrupted)
881	<	throw new InterruptedException();
882	<	if (p == phase && (p = getPhase()) == phase)
883	<	throw new TimeoutException();
967	>	while ((p = getPhase()) == phase && !interrupted) {
968	>	if (Thread.interrupted())
969	>	interrupted = true;
970	>	else if (nanos - (System.nanoTime() - startTime) <= 0)
971	>	break;
972	>	else if (node == null)
973	>	node = new QNode(this, phase, true, true, startTime, nanos);
974	>	else if (!queued)
975	>	queued = tryEnqueue(node);
976	>	else
977	>	interrupted = node.doWait();
978		}
979	<	releaseWaiters(phase);
979	>	if (node != null)
980	>	node.thread = null;
981	>	if (p != phase || (p = getPhase()) != phase)
982	>	releaseWaiters(phase);
983	>	if (interrupted)
984	>	throw new InterruptedException();
985	>	if (p == phase)
986	>	throw new TimeoutException();
987		return p;
988		}
989
990	<	// Temporary Unsafe mechanics for preliminary release
990	>	// Unsafe mechanics
991
992	<	static final Unsafe _unsafe;
993	<	static final long stateOffset;
992	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
993	>	private static final long stateOffset =
994	>	objectFieldOffset("state", Phaser.class);
995
996	<	static {
996	>	private final boolean casState(long cmp, long val) {
997	>	return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val);
998	>	}
999	>
1000	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1001		try {
1002	<	if (Phaser.class.getClassLoader() != null) {
1003	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1004	<	f.setAccessible(true);
1005	<	_unsafe = (Unsafe)f.get(null);
1006	<	}
1007	<	else
902	<	_unsafe = Unsafe.getUnsafe();
903	<	stateOffset = _unsafe.objectFieldOffset
904	<	(Phaser.class.getDeclaredField("state"));
905	<	} catch (Exception e) {
906	<	throw new RuntimeException("Could not initialize intrinsics", e);
1002	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1003	>	} catch (NoSuchFieldException e) {
1004	>	// Convert Exception to corresponding Error
1005	>	NoSuchFieldError error = new NoSuchFieldError(field);
1006	>	error.initCause(e);
1007	>	throw error;
1008		}
1009		}
1010
1011	<	final boolean casState(long cmp, long val) {
1012	<	return _unsafe.compareAndSwapLong(this, stateOffset, cmp, val);
1011	>	/**
1012	>	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1013	>	* Replace with a simple call to Unsafe.getUnsafe when integrating
1014	>	* into a jdk.
1015	>	*
1016	>	* @return a sun.misc.Unsafe
1017	>	*/
1018	>	private static sun.misc.Unsafe getUnsafe() {
1019	>	try {
1020	>	return sun.misc.Unsafe.getUnsafe();
1021	>	} catch (SecurityException se) {
1022	>	try {
1023	>	return java.security.AccessController.doPrivileged
1024	>	(new java.security
1025	>	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1026	>	public sun.misc.Unsafe run() throws Exception {
1027	>	java.lang.reflect.Field f = sun.misc
1028	>	.Unsafe.class.getDeclaredField("theUnsafe");
1029	>	f.setAccessible(true);
1030	>	return (sun.misc.Unsafe) f.get(null);
1031	>	}});
1032	>	} catch (java.security.PrivilegedActionException e) {
1033	>	throw new RuntimeException("Could not initialize intrinsics",
1034	>	e.getCause());
1035	>	}
1036	>	}
1037		}
1038		}

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