1 |
dl |
1.1 |
/* |
2 |
|
|
* Written by Doug Lea with assistance from members of JCP JSR-166 |
3 |
|
|
* Expert Group and released to the public domain, as explained at |
4 |
|
|
* http://creativecommons.org/licenses/publicdomain |
5 |
|
|
*/ |
6 |
|
|
|
7 |
|
|
package jsr166y; |
8 |
jsr166 |
1.9 |
|
9 |
dl |
1.1 |
import java.util.concurrent.*; |
10 |
jsr166 |
1.20 |
|
11 |
|
|
import java.util.concurrent.atomic.AtomicReference; |
12 |
dl |
1.1 |
import java.util.concurrent.locks.LockSupport; |
13 |
|
|
|
14 |
|
|
/** |
15 |
|
|
* A reusable synchronization barrier, similar in functionality to a |
16 |
jsr166 |
1.9 |
* {@link java.util.concurrent.CyclicBarrier CyclicBarrier} and |
17 |
|
|
* {@link java.util.concurrent.CountDownLatch CountDownLatch} |
18 |
|
|
* but supporting more flexible usage. |
19 |
dl |
1.1 |
* |
20 |
|
|
* <ul> |
21 |
|
|
* |
22 |
dl |
1.4 |
* <li> The number of parties synchronizing on a phaser may vary over |
23 |
|
|
* time. A task may register to be a party at any time, and may |
24 |
|
|
* deregister upon arriving at the barrier. As is the case with most |
25 |
|
|
* basic synchronization constructs, registration and deregistration |
26 |
|
|
* affect only internal counts; they do not establish any further |
27 |
|
|
* internal bookkeeping, so tasks cannot query whether they are |
28 |
jsr166 |
1.9 |
* registered. (However, you can introduce such bookkeeping by |
29 |
dl |
1.4 |
* subclassing this class.) |
30 |
dl |
1.1 |
* |
31 |
|
|
* <li> Each generation has an associated phase value, starting at |
32 |
|
|
* zero, and advancing when all parties reach the barrier (wrapping |
33 |
jsr166 |
1.7 |
* around to zero after reaching {@code Integer.MAX_VALUE}). |
34 |
jsr166 |
1.3 |
* |
35 |
jsr166 |
1.26 |
* <li> Like a {@code CyclicBarrier}, a phaser may be repeatedly |
36 |
jsr166 |
1.24 |
* awaited. Method {@link #arriveAndAwaitAdvance} has effect |
37 |
|
|
* analogous to {@link java.util.concurrent.CyclicBarrier#await |
38 |
|
|
* CyclicBarrier.await}. However, phasers separate two aspects of |
39 |
dl |
1.27 |
* coordination, which may also be invoked independently: |
40 |
dl |
1.1 |
* |
41 |
|
|
* <ul> |
42 |
|
|
* |
43 |
jsr166 |
1.24 |
* <li> Arriving at a barrier. Methods {@link #arrive} and |
44 |
|
|
* {@link #arriveAndDeregister} do not block, but return |
45 |
dl |
1.4 |
* the phase value current upon entry to the method. |
46 |
dl |
1.1 |
* |
47 |
jsr166 |
1.24 |
* <li> Awaiting others. Method {@link #awaitAdvance} requires an |
48 |
dl |
1.1 |
* argument indicating the entry phase, and returns when the |
49 |
|
|
* barrier advances to a new phase. |
50 |
|
|
* </ul> |
51 |
|
|
* |
52 |
|
|
* |
53 |
|
|
* <li> Barrier actions, performed by the task triggering a phase |
54 |
dl |
1.27 |
* advance, are arranged by overriding method {@link #onAdvance(int, |
55 |
|
|
* int)}, which also controls termination. Overriding this method is |
56 |
|
|
* similar to, but more flexible than, providing a barrier action to a |
57 |
|
|
* {@code CyclicBarrier}. |
58 |
dl |
1.1 |
* |
59 |
|
|
* <li> Phasers may enter a <em>termination</em> state in which all |
60 |
dl |
1.10 |
* actions immediately return without updating phaser state or waiting |
61 |
|
|
* for advance, and indicating (via a negative phase value) that |
62 |
dl |
1.27 |
* execution is complete. Termination is triggered when an invocation |
63 |
|
|
* of {@code onAdvance} returns {@code true}. When a phaser is |
64 |
|
|
* controlling an action with a fixed number of iterations, it is |
65 |
|
|
* often convenient to override this method to cause termination when |
66 |
|
|
* the current phase number reaches a threshold. Method {@link |
67 |
|
|
* #forceTermination} is also available to abruptly release waiting |
68 |
|
|
* threads and allow them to terminate. |
69 |
dl |
1.4 |
* |
70 |
|
|
* <li> Phasers may be tiered to reduce contention. Phasers with large |
71 |
|
|
* numbers of parties that would otherwise experience heavy |
72 |
|
|
* synchronization contention costs may instead be arranged in trees. |
73 |
|
|
* This will typically greatly increase throughput even though it |
74 |
|
|
* incurs somewhat greater per-operation overhead. |
75 |
jsr166 |
1.3 |
* |
76 |
jsr166 |
1.7 |
* <li> By default, {@code awaitAdvance} continues to wait even if |
77 |
dl |
1.4 |
* the waiting thread is interrupted. And unlike the case in |
78 |
jsr166 |
1.24 |
* {@code CyclicBarrier}, exceptions encountered while tasks wait |
79 |
dl |
1.1 |
* interruptibly or with timeout do not change the state of the |
80 |
|
|
* barrier. If necessary, you can perform any associated recovery |
81 |
dl |
1.4 |
* within handlers of those exceptions, often after invoking |
82 |
jsr166 |
1.7 |
* {@code forceTermination}. |
83 |
dl |
1.1 |
* |
84 |
dl |
1.27 |
* <li>Phasers may be used to coordinate tasks executing in a {@link |
85 |
|
|
* ForkJoinPool}, which will ensure sufficient parallelism to execute |
86 |
|
|
* tasks when others are blocked waiting for a phase to advance. |
87 |
dl |
1.10 |
* |
88 |
dl |
1.1 |
* </ul> |
89 |
|
|
* |
90 |
dl |
1.4 |
* <p><b>Sample usages:</b> |
91 |
|
|
* |
92 |
jsr166 |
1.24 |
* <p>A {@code Phaser} may be used instead of a {@code CountDownLatch} |
93 |
|
|
* to control a one-shot action serving a variable number of |
94 |
|
|
* parties. The typical idiom is for the method setting this up to |
95 |
|
|
* first register, then start the actions, then deregister, as in: |
96 |
dl |
1.1 |
* |
97 |
jsr166 |
1.13 |
* <pre> {@code |
98 |
|
|
* void runTasks(List<Runnable> list) { |
99 |
|
|
* final Phaser phaser = new Phaser(1); // "1" to register self |
100 |
dl |
1.27 |
* // create and start threads |
101 |
jsr166 |
1.13 |
* for (Runnable r : list) { |
102 |
|
|
* phaser.register(); |
103 |
|
|
* new Thread() { |
104 |
|
|
* public void run() { |
105 |
|
|
* phaser.arriveAndAwaitAdvance(); // await all creation |
106 |
|
|
* r.run(); |
107 |
|
|
* } |
108 |
|
|
* }.start(); |
109 |
dl |
1.4 |
* } |
110 |
dl |
1.6 |
* |
111 |
dl |
1.27 |
* // allow threads to start and deregister self |
112 |
|
|
* phaser.arriveAndDeregister(); |
113 |
jsr166 |
1.13 |
* }}</pre> |
114 |
dl |
1.1 |
* |
115 |
dl |
1.4 |
* <p>One way to cause a set of threads to repeatedly perform actions |
116 |
jsr166 |
1.7 |
* for a given number of iterations is to override {@code onAdvance}: |
117 |
dl |
1.1 |
* |
118 |
jsr166 |
1.13 |
* <pre> {@code |
119 |
|
|
* void startTasks(List<Runnable> list, final int iterations) { |
120 |
|
|
* final Phaser phaser = new Phaser() { |
121 |
|
|
* public boolean onAdvance(int phase, int registeredParties) { |
122 |
|
|
* return phase >= iterations || registeredParties == 0; |
123 |
|
|
* } |
124 |
|
|
* }; |
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 |
dl |
1.4 |
* } |
135 |
jsr166 |
1.13 |
* }.start(); |
136 |
dl |
1.1 |
* } |
137 |
dl |
1.4 |
* phaser.arriveAndDeregister(); // deregister self, don't wait |
138 |
jsr166 |
1.13 |
* }}</pre> |
139 |
dl |
1.1 |
* |
140 |
jsr166 |
1.25 |
* <p>To create a set of tasks using a tree of phasers, |
141 |
dl |
1.4 |
* you could use code of the following form, assuming a |
142 |
jsr166 |
1.24 |
* Task class with a constructor accepting a phaser that |
143 |
dl |
1.4 |
* it registers for upon construction: |
144 |
jsr166 |
1.13 |
* <pre> {@code |
145 |
|
|
* void build(Task[] actions, int lo, int hi, Phaser b) { |
146 |
|
|
* int step = (hi - lo) / TASKS_PER_PHASER; |
147 |
|
|
* if (step > 1) { |
148 |
|
|
* int i = lo; |
149 |
|
|
* while (i < hi) { |
150 |
|
|
* int r = Math.min(i + step, hi); |
151 |
|
|
* build(actions, i, r, new Phaser(b)); |
152 |
|
|
* i = r; |
153 |
|
|
* } |
154 |
|
|
* } else { |
155 |
|
|
* for (int i = lo; i < hi; ++i) |
156 |
|
|
* actions[i] = new Task(b); |
157 |
|
|
* // assumes new Task(b) performs b.register() |
158 |
|
|
* } |
159 |
|
|
* } |
160 |
|
|
* // .. initially called, for n tasks via |
161 |
|
|
* build(new Task[n], 0, n, new Phaser());}</pre> |
162 |
dl |
1.4 |
* |
163 |
jsr166 |
1.7 |
* The best value of {@code TASKS_PER_PHASER} depends mainly on |
164 |
dl |
1.4 |
* expected barrier synchronization rates. A value as low as four may |
165 |
|
|
* be appropriate for extremely small per-barrier task bodies (thus |
166 |
|
|
* high rates), or up to hundreds for extremely large ones. |
167 |
|
|
* |
168 |
|
|
* </pre> |
169 |
|
|
* |
170 |
dl |
1.1 |
* <p><b>Implementation notes</b>: This implementation restricts the |
171 |
dl |
1.4 |
* maximum number of parties to 65535. Attempts to register additional |
172 |
|
|
* parties result in IllegalStateExceptions. However, you can and |
173 |
|
|
* should create tiered phasers to accommodate arbitrarily large sets |
174 |
|
|
* of participants. |
175 |
jsr166 |
1.16 |
* |
176 |
|
|
* @since 1.7 |
177 |
|
|
* @author Doug Lea |
178 |
dl |
1.1 |
*/ |
179 |
|
|
public class Phaser { |
180 |
|
|
/* |
181 |
|
|
* This class implements an extension of X10 "clocks". Thanks to |
182 |
dl |
1.4 |
* Vijay Saraswat for the idea, and to Vivek Sarkar for |
183 |
|
|
* enhancements to extend functionality. |
184 |
dl |
1.1 |
*/ |
185 |
|
|
|
186 |
|
|
/** |
187 |
|
|
* Barrier state representation. Conceptually, a barrier contains |
188 |
|
|
* four values: |
189 |
jsr166 |
1.3 |
* |
190 |
dl |
1.1 |
* * parties -- the number of parties to wait (16 bits) |
191 |
|
|
* * unarrived -- the number of parties yet to hit barrier (16 bits) |
192 |
|
|
* * phase -- the generation of the barrier (31 bits) |
193 |
|
|
* * terminated -- set if barrier is terminated (1 bit) |
194 |
|
|
* |
195 |
|
|
* However, to efficiently maintain atomicity, these values are |
196 |
dl |
1.4 |
* packed into a single (atomic) long. Termination uses the sign |
197 |
|
|
* bit of 32 bit representation of phase, so phase is set to -1 on |
198 |
jsr166 |
1.8 |
* termination. Good performance relies on keeping state decoding |
199 |
dl |
1.4 |
* and encoding simple, and keeping race windows short. |
200 |
|
|
* |
201 |
|
|
* Note: there are some cheats in arrive() that rely on unarrived |
202 |
dl |
1.10 |
* count being lowest 16 bits. |
203 |
dl |
1.1 |
*/ |
204 |
dl |
1.4 |
private volatile long state; |
205 |
dl |
1.1 |
|
206 |
|
|
private static final int ushortBits = 16; |
207 |
dl |
1.10 |
private static final int ushortMask = 0xffff; |
208 |
|
|
private static final int phaseMask = 0x7fffffff; |
209 |
dl |
1.1 |
|
210 |
|
|
private static int unarrivedOf(long s) { |
211 |
jsr166 |
1.18 |
return (int) (s & ushortMask); |
212 |
dl |
1.1 |
} |
213 |
|
|
|
214 |
|
|
private static int partiesOf(long s) { |
215 |
jsr166 |
1.17 |
return ((int) s) >>> 16; |
216 |
dl |
1.1 |
} |
217 |
|
|
|
218 |
|
|
private static int phaseOf(long s) { |
219 |
jsr166 |
1.17 |
return (int) (s >>> 32); |
220 |
dl |
1.1 |
} |
221 |
|
|
|
222 |
|
|
private static int arrivedOf(long s) { |
223 |
|
|
return partiesOf(s) - unarrivedOf(s); |
224 |
|
|
} |
225 |
|
|
|
226 |
|
|
private static long stateFor(int phase, int parties, int unarrived) { |
227 |
jsr166 |
1.17 |
return ((((long) phase) << 32) | (((long) parties) << 16) | |
228 |
|
|
(long) unarrived); |
229 |
dl |
1.1 |
} |
230 |
|
|
|
231 |
dl |
1.4 |
private static long trippedStateFor(int phase, int parties) { |
232 |
jsr166 |
1.17 |
long lp = (long) parties; |
233 |
|
|
return (((long) phase) << 32) | (lp << 16) | lp; |
234 |
dl |
1.4 |
} |
235 |
|
|
|
236 |
dl |
1.10 |
/** |
237 |
jsr166 |
1.14 |
* Returns message string for bad bounds exceptions. |
238 |
dl |
1.10 |
*/ |
239 |
|
|
private static String badBounds(int parties, int unarrived) { |
240 |
|
|
return ("Attempt to set " + unarrived + |
241 |
|
|
" unarrived of " + parties + " parties"); |
242 |
dl |
1.4 |
} |
243 |
|
|
|
244 |
|
|
/** |
245 |
|
|
* The parent of this phaser, or null if none |
246 |
|
|
*/ |
247 |
|
|
private final Phaser parent; |
248 |
|
|
|
249 |
|
|
/** |
250 |
jsr166 |
1.24 |
* The root of phaser tree. Equals this if not in a tree. Used to |
251 |
dl |
1.4 |
* support faster state push-down. |
252 |
|
|
*/ |
253 |
|
|
private final Phaser root; |
254 |
|
|
|
255 |
|
|
// Wait queues |
256 |
|
|
|
257 |
|
|
/** |
258 |
dl |
1.10 |
* Heads of Treiber stacks for waiting threads. To eliminate |
259 |
dl |
1.4 |
* contention while releasing some threads while adding others, we |
260 |
|
|
* use two of them, alternating across even and odd phases. |
261 |
|
|
*/ |
262 |
|
|
private final AtomicReference<QNode> evenQ = new AtomicReference<QNode>(); |
263 |
|
|
private final AtomicReference<QNode> oddQ = new AtomicReference<QNode>(); |
264 |
|
|
|
265 |
|
|
private AtomicReference<QNode> queueFor(int phase) { |
266 |
jsr166 |
1.18 |
return ((phase & 1) == 0) ? evenQ : oddQ; |
267 |
dl |
1.4 |
} |
268 |
|
|
|
269 |
|
|
/** |
270 |
|
|
* Returns current state, first resolving lagged propagation from |
271 |
|
|
* root if necessary. |
272 |
|
|
*/ |
273 |
|
|
private long getReconciledState() { |
274 |
jsr166 |
1.18 |
return (parent == null) ? state : reconcileState(); |
275 |
dl |
1.4 |
} |
276 |
|
|
|
277 |
|
|
/** |
278 |
|
|
* Recursively resolves state. |
279 |
|
|
*/ |
280 |
|
|
private long reconcileState() { |
281 |
|
|
Phaser p = parent; |
282 |
|
|
long s = state; |
283 |
|
|
if (p != null) { |
284 |
|
|
while (unarrivedOf(s) == 0 && phaseOf(s) != phaseOf(root.state)) { |
285 |
|
|
long parentState = p.getReconciledState(); |
286 |
|
|
int parentPhase = phaseOf(parentState); |
287 |
|
|
int phase = phaseOf(s = state); |
288 |
|
|
if (phase != parentPhase) { |
289 |
|
|
long next = trippedStateFor(parentPhase, partiesOf(s)); |
290 |
|
|
if (casState(s, next)) { |
291 |
|
|
releaseWaiters(phase); |
292 |
|
|
s = next; |
293 |
|
|
} |
294 |
|
|
} |
295 |
|
|
} |
296 |
|
|
} |
297 |
|
|
return s; |
298 |
dl |
1.1 |
} |
299 |
|
|
|
300 |
|
|
/** |
301 |
jsr166 |
1.24 |
* Creates a new phaser without any initially registered parties, |
302 |
dl |
1.10 |
* initial phase number 0, and no parent. Any thread using this |
303 |
jsr166 |
1.24 |
* phaser will need to first register for it. |
304 |
dl |
1.1 |
*/ |
305 |
|
|
public Phaser() { |
306 |
dl |
1.4 |
this(null); |
307 |
dl |
1.1 |
} |
308 |
|
|
|
309 |
|
|
/** |
310 |
jsr166 |
1.24 |
* Creates a new phaser with the given numbers of registered |
311 |
dl |
1.4 |
* unarrived parties, initial phase number 0, and no parent. |
312 |
jsr166 |
1.14 |
* |
313 |
|
|
* @param parties the number of parties required to trip barrier |
314 |
dl |
1.1 |
* @throws IllegalArgumentException if parties less than zero |
315 |
jsr166 |
1.14 |
* or greater than the maximum number of parties supported |
316 |
dl |
1.1 |
*/ |
317 |
|
|
public Phaser(int parties) { |
318 |
dl |
1.4 |
this(null, parties); |
319 |
|
|
} |
320 |
|
|
|
321 |
|
|
/** |
322 |
jsr166 |
1.24 |
* Creates a new phaser with the given parent, without any |
323 |
dl |
1.4 |
* initially registered parties. If parent is non-null this phaser |
324 |
|
|
* is registered with the parent and its initial phase number is |
325 |
|
|
* the same as that of parent phaser. |
326 |
jsr166 |
1.14 |
* |
327 |
|
|
* @param parent the parent phaser |
328 |
dl |
1.4 |
*/ |
329 |
|
|
public Phaser(Phaser parent) { |
330 |
|
|
int phase = 0; |
331 |
|
|
this.parent = parent; |
332 |
|
|
if (parent != null) { |
333 |
|
|
this.root = parent.root; |
334 |
|
|
phase = parent.register(); |
335 |
|
|
} |
336 |
|
|
else |
337 |
|
|
this.root = this; |
338 |
|
|
this.state = trippedStateFor(phase, 0); |
339 |
|
|
} |
340 |
|
|
|
341 |
|
|
/** |
342 |
jsr166 |
1.24 |
* Creates a new phaser with the given parent and numbers of |
343 |
jsr166 |
1.14 |
* registered unarrived parties. If parent is non-null, this phaser |
344 |
dl |
1.4 |
* is registered with the parent and its initial phase number is |
345 |
|
|
* the same as that of parent phaser. |
346 |
jsr166 |
1.14 |
* |
347 |
|
|
* @param parent the parent phaser |
348 |
|
|
* @param parties the number of parties required to trip barrier |
349 |
dl |
1.4 |
* @throws IllegalArgumentException if parties less than zero |
350 |
jsr166 |
1.14 |
* or greater than the maximum number of parties supported |
351 |
dl |
1.4 |
*/ |
352 |
|
|
public Phaser(Phaser parent, int parties) { |
353 |
dl |
1.1 |
if (parties < 0 || parties > ushortMask) |
354 |
|
|
throw new IllegalArgumentException("Illegal number of parties"); |
355 |
dl |
1.4 |
int phase = 0; |
356 |
|
|
this.parent = parent; |
357 |
|
|
if (parent != null) { |
358 |
|
|
this.root = parent.root; |
359 |
|
|
phase = parent.register(); |
360 |
|
|
} |
361 |
|
|
else |
362 |
|
|
this.root = this; |
363 |
|
|
this.state = trippedStateFor(phase, parties); |
364 |
dl |
1.1 |
} |
365 |
|
|
|
366 |
|
|
/** |
367 |
|
|
* Adds a new unarrived party to this phaser. |
368 |
jsr166 |
1.14 |
* |
369 |
dl |
1.1 |
* @return the current barrier phase number upon registration |
370 |
|
|
* @throws IllegalStateException if attempting to register more |
371 |
jsr166 |
1.14 |
* than the maximum supported number of parties |
372 |
dl |
1.1 |
*/ |
373 |
dl |
1.4 |
public int register() { |
374 |
|
|
return doRegister(1); |
375 |
|
|
} |
376 |
|
|
|
377 |
|
|
/** |
378 |
|
|
* Adds the given number of new unarrived parties to this phaser. |
379 |
jsr166 |
1.14 |
* |
380 |
|
|
* @param parties the number of parties required to trip barrier |
381 |
dl |
1.4 |
* @return the current barrier phase number upon registration |
382 |
|
|
* @throws IllegalStateException if attempting to register more |
383 |
jsr166 |
1.14 |
* than the maximum supported number of parties |
384 |
dl |
1.4 |
*/ |
385 |
|
|
public int bulkRegister(int parties) { |
386 |
|
|
if (parties < 0) |
387 |
|
|
throw new IllegalArgumentException(); |
388 |
|
|
if (parties == 0) |
389 |
|
|
return getPhase(); |
390 |
|
|
return doRegister(parties); |
391 |
|
|
} |
392 |
|
|
|
393 |
|
|
/** |
394 |
|
|
* Shared code for register, bulkRegister |
395 |
|
|
*/ |
396 |
|
|
private int doRegister(int registrations) { |
397 |
|
|
int phase; |
398 |
dl |
1.1 |
for (;;) { |
399 |
dl |
1.4 |
long s = getReconciledState(); |
400 |
|
|
phase = phaseOf(s); |
401 |
|
|
int unarrived = unarrivedOf(s) + registrations; |
402 |
|
|
int parties = partiesOf(s) + registrations; |
403 |
jsr166 |
1.12 |
if (phase < 0) |
404 |
dl |
1.4 |
break; |
405 |
dl |
1.1 |
if (parties > ushortMask || unarrived > ushortMask) |
406 |
dl |
1.10 |
throw new IllegalStateException(badBounds(parties, unarrived)); |
407 |
dl |
1.4 |
if (phase == phaseOf(root.state) && |
408 |
|
|
casState(s, stateFor(phase, parties, unarrived))) |
409 |
|
|
break; |
410 |
dl |
1.1 |
} |
411 |
dl |
1.4 |
return phase; |
412 |
dl |
1.1 |
} |
413 |
|
|
|
414 |
|
|
/** |
415 |
|
|
* Arrives at the barrier, but does not wait for others. (You can |
416 |
|
|
* in turn wait for others via {@link #awaitAdvance}). |
417 |
|
|
* |
418 |
dl |
1.4 |
* @return the barrier phase number upon entry to this method, or a |
419 |
jsr166 |
1.14 |
* negative value if terminated |
420 |
dl |
1.4 |
* @throws IllegalStateException if not terminated and the number |
421 |
jsr166 |
1.14 |
* of unarrived parties would become negative |
422 |
dl |
1.1 |
*/ |
423 |
dl |
1.4 |
public int arrive() { |
424 |
|
|
int phase; |
425 |
dl |
1.1 |
for (;;) { |
426 |
dl |
1.4 |
long s = state; |
427 |
|
|
phase = phaseOf(s); |
428 |
dl |
1.10 |
if (phase < 0) |
429 |
|
|
break; |
430 |
dl |
1.1 |
int parties = partiesOf(s); |
431 |
|
|
int unarrived = unarrivedOf(s) - 1; |
432 |
dl |
1.4 |
if (unarrived > 0) { // Not the last arrival |
433 |
|
|
if (casState(s, s - 1)) // s-1 adds one arrival |
434 |
|
|
break; |
435 |
|
|
} |
436 |
|
|
else if (unarrived == 0) { // the last arrival |
437 |
|
|
Phaser par = parent; |
438 |
|
|
if (par == null) { // directly trip |
439 |
|
|
if (casState |
440 |
|
|
(s, |
441 |
jsr166 |
1.18 |
trippedStateFor(onAdvance(phase, parties) ? -1 : |
442 |
dl |
1.4 |
((phase + 1) & phaseMask), parties))) { |
443 |
|
|
releaseWaiters(phase); |
444 |
|
|
break; |
445 |
|
|
} |
446 |
|
|
} |
447 |
|
|
else { // cascade to parent |
448 |
|
|
if (casState(s, s - 1)) { // zeroes unarrived |
449 |
|
|
par.arrive(); |
450 |
|
|
reconcileState(); |
451 |
|
|
break; |
452 |
|
|
} |
453 |
|
|
} |
454 |
|
|
} |
455 |
|
|
else if (phase != phaseOf(root.state)) // or if unreconciled |
456 |
|
|
reconcileState(); |
457 |
|
|
else |
458 |
dl |
1.10 |
throw new IllegalStateException(badBounds(parties, unarrived)); |
459 |
dl |
1.1 |
} |
460 |
dl |
1.4 |
return phase; |
461 |
dl |
1.1 |
} |
462 |
|
|
|
463 |
|
|
/** |
464 |
dl |
1.27 |
* Arrives at the barrier and deregisters from it without waiting |
465 |
|
|
* for others. Deregistration reduces the number of parties |
466 |
dl |
1.4 |
* required to trip the barrier in future phases. If this phaser |
467 |
|
|
* has a parent, and deregistration causes this phaser to have |
468 |
dl |
1.27 |
* zero parties, this phaser also arrives at and is deregistered |
469 |
|
|
* from its parent. |
470 |
dl |
1.1 |
* |
471 |
|
|
* @return the current barrier phase number upon entry to |
472 |
jsr166 |
1.14 |
* this method, or a negative value if terminated |
473 |
dl |
1.4 |
* @throws IllegalStateException if not terminated and the number |
474 |
jsr166 |
1.14 |
* of registered or unarrived parties would become negative |
475 |
dl |
1.1 |
*/ |
476 |
dl |
1.4 |
public int arriveAndDeregister() { |
477 |
|
|
// similar code to arrive, but too different to merge |
478 |
|
|
Phaser par = parent; |
479 |
|
|
int phase; |
480 |
dl |
1.1 |
for (;;) { |
481 |
dl |
1.4 |
long s = state; |
482 |
|
|
phase = phaseOf(s); |
483 |
dl |
1.10 |
if (phase < 0) |
484 |
|
|
break; |
485 |
dl |
1.1 |
int parties = partiesOf(s) - 1; |
486 |
|
|
int unarrived = unarrivedOf(s) - 1; |
487 |
dl |
1.4 |
if (parties >= 0) { |
488 |
|
|
if (unarrived > 0 || (unarrived == 0 && par != null)) { |
489 |
|
|
if (casState |
490 |
|
|
(s, |
491 |
|
|
stateFor(phase, parties, unarrived))) { |
492 |
|
|
if (unarrived == 0) { |
493 |
|
|
par.arriveAndDeregister(); |
494 |
|
|
reconcileState(); |
495 |
|
|
} |
496 |
|
|
break; |
497 |
|
|
} |
498 |
|
|
continue; |
499 |
|
|
} |
500 |
|
|
if (unarrived == 0) { |
501 |
|
|
if (casState |
502 |
|
|
(s, |
503 |
jsr166 |
1.18 |
trippedStateFor(onAdvance(phase, parties) ? -1 : |
504 |
dl |
1.4 |
((phase + 1) & phaseMask), parties))) { |
505 |
|
|
releaseWaiters(phase); |
506 |
|
|
break; |
507 |
|
|
} |
508 |
|
|
continue; |
509 |
|
|
} |
510 |
|
|
if (par != null && phase != phaseOf(root.state)) { |
511 |
|
|
reconcileState(); |
512 |
|
|
continue; |
513 |
|
|
} |
514 |
dl |
1.1 |
} |
515 |
dl |
1.10 |
throw new IllegalStateException(badBounds(parties, unarrived)); |
516 |
dl |
1.1 |
} |
517 |
dl |
1.4 |
return phase; |
518 |
dl |
1.1 |
} |
519 |
|
|
|
520 |
|
|
/** |
521 |
dl |
1.4 |
* Arrives at the barrier and awaits others. Equivalent in effect |
522 |
dl |
1.27 |
* to {@code awaitAdvance(arrive())}. If you need to await with |
523 |
|
|
* interruption or timeout, you can arrange this with an analogous |
524 |
|
|
* construction using one of the other forms of the awaitAdvance |
525 |
|
|
* method. If instead you need to deregister upon arrival use |
526 |
|
|
* {@code arriveAndDeregister}. |
527 |
jsr166 |
1.14 |
* |
528 |
dl |
1.4 |
* @return the phase on entry to this method |
529 |
|
|
* @throws IllegalStateException if not terminated and the number |
530 |
jsr166 |
1.14 |
* of unarrived parties would become negative |
531 |
dl |
1.1 |
*/ |
532 |
|
|
public int arriveAndAwaitAdvance() { |
533 |
dl |
1.4 |
return awaitAdvance(arrive()); |
534 |
dl |
1.1 |
} |
535 |
|
|
|
536 |
|
|
/** |
537 |
dl |
1.27 |
* Awaits the phase of the barrier to advance from the given phase |
538 |
|
|
* value, or returns immediately if current phase of the barrier |
539 |
|
|
* is not equal to the given phase value or this barrier is |
540 |
|
|
* terminated. |
541 |
jsr166 |
1.14 |
* |
542 |
dl |
1.1 |
* @param phase the phase on entry to this method |
543 |
|
|
* @return the phase on exit from this method |
544 |
|
|
*/ |
545 |
|
|
public int awaitAdvance(int phase) { |
546 |
|
|
if (phase < 0) |
547 |
|
|
return phase; |
548 |
dl |
1.4 |
long s = getReconciledState(); |
549 |
|
|
int p = phaseOf(s); |
550 |
|
|
if (p != phase) |
551 |
|
|
return p; |
552 |
dl |
1.10 |
if (unarrivedOf(s) == 0 && parent != null) |
553 |
dl |
1.4 |
parent.awaitAdvance(phase); |
554 |
|
|
// Fall here even if parent waited, to reconcile and help release |
555 |
|
|
return untimedWait(phase); |
556 |
dl |
1.1 |
} |
557 |
|
|
|
558 |
|
|
/** |
559 |
|
|
* Awaits the phase of the barrier to advance from the given |
560 |
jsr166 |
1.8 |
* value, or returns immediately if argument is negative or this |
561 |
dl |
1.4 |
* barrier is terminated, or throws InterruptedException if |
562 |
|
|
* interrupted while waiting. |
563 |
jsr166 |
1.14 |
* |
564 |
dl |
1.1 |
* @param phase the phase on entry to this method |
565 |
|
|
* @return the phase on exit from this method |
566 |
|
|
* @throws InterruptedException if thread interrupted while waiting |
567 |
|
|
*/ |
568 |
jsr166 |
1.12 |
public int awaitAdvanceInterruptibly(int phase) |
569 |
dl |
1.10 |
throws InterruptedException { |
570 |
dl |
1.1 |
if (phase < 0) |
571 |
|
|
return phase; |
572 |
dl |
1.4 |
long s = getReconciledState(); |
573 |
|
|
int p = phaseOf(s); |
574 |
|
|
if (p != phase) |
575 |
|
|
return p; |
576 |
dl |
1.10 |
if (unarrivedOf(s) == 0 && parent != null) |
577 |
dl |
1.4 |
parent.awaitAdvanceInterruptibly(phase); |
578 |
|
|
return interruptibleWait(phase); |
579 |
dl |
1.1 |
} |
580 |
|
|
|
581 |
|
|
/** |
582 |
|
|
* Awaits the phase of the barrier to advance from the given value |
583 |
dl |
1.4 |
* or the given timeout elapses, or returns immediately if |
584 |
|
|
* argument is negative or this barrier is terminated. |
585 |
jsr166 |
1.14 |
* |
586 |
dl |
1.1 |
* @param phase the phase on entry to this method |
587 |
|
|
* @return the phase on exit from this method |
588 |
|
|
* @throws InterruptedException if thread interrupted while waiting |
589 |
|
|
* @throws TimeoutException if timed out while waiting |
590 |
|
|
*/ |
591 |
jsr166 |
1.18 |
public int awaitAdvanceInterruptibly(int phase, |
592 |
|
|
long timeout, TimeUnit unit) |
593 |
dl |
1.1 |
throws InterruptedException, TimeoutException { |
594 |
|
|
if (phase < 0) |
595 |
|
|
return phase; |
596 |
dl |
1.4 |
long s = getReconciledState(); |
597 |
|
|
int p = phaseOf(s); |
598 |
|
|
if (p != phase) |
599 |
|
|
return p; |
600 |
dl |
1.10 |
if (unarrivedOf(s) == 0 && parent != null) |
601 |
dl |
1.4 |
parent.awaitAdvanceInterruptibly(phase, timeout, unit); |
602 |
|
|
return timedWait(phase, unit.toNanos(timeout)); |
603 |
dl |
1.1 |
} |
604 |
|
|
|
605 |
|
|
/** |
606 |
|
|
* Forces this barrier to enter termination state. Counts of |
607 |
dl |
1.4 |
* arrived and registered parties are unaffected. If this phaser |
608 |
|
|
* has a parent, it too is terminated. This method may be useful |
609 |
|
|
* for coordinating recovery after one or more tasks encounter |
610 |
|
|
* unexpected exceptions. |
611 |
dl |
1.1 |
*/ |
612 |
|
|
public void forceTermination() { |
613 |
|
|
for (;;) { |
614 |
dl |
1.4 |
long s = getReconciledState(); |
615 |
dl |
1.1 |
int phase = phaseOf(s); |
616 |
|
|
int parties = partiesOf(s); |
617 |
|
|
int unarrived = unarrivedOf(s); |
618 |
|
|
if (phase < 0 || |
619 |
dl |
1.4 |
casState(s, stateFor(-1, parties, unarrived))) { |
620 |
|
|
releaseWaiters(0); |
621 |
|
|
releaseWaiters(1); |
622 |
|
|
if (parent != null) |
623 |
|
|
parent.forceTermination(); |
624 |
dl |
1.1 |
return; |
625 |
|
|
} |
626 |
|
|
} |
627 |
|
|
} |
628 |
|
|
|
629 |
|
|
/** |
630 |
dl |
1.4 |
* Returns the current phase number. The maximum phase number is |
631 |
jsr166 |
1.7 |
* {@code Integer.MAX_VALUE}, after which it restarts at |
632 |
dl |
1.4 |
* zero. Upon termination, the phase number is negative. |
633 |
jsr166 |
1.14 |
* |
634 |
dl |
1.4 |
* @return the phase number, or a negative value if terminated |
635 |
dl |
1.1 |
*/ |
636 |
dl |
1.4 |
public final int getPhase() { |
637 |
|
|
return phaseOf(getReconciledState()); |
638 |
dl |
1.1 |
} |
639 |
|
|
|
640 |
|
|
/** |
641 |
|
|
* Returns the number of parties registered at this barrier. |
642 |
jsr166 |
1.14 |
* |
643 |
dl |
1.1 |
* @return the number of parties |
644 |
|
|
*/ |
645 |
|
|
public int getRegisteredParties() { |
646 |
dl |
1.4 |
return partiesOf(state); |
647 |
dl |
1.1 |
} |
648 |
|
|
|
649 |
|
|
/** |
650 |
|
|
* Returns the number of parties that have arrived at the current |
651 |
|
|
* phase of this barrier. |
652 |
jsr166 |
1.14 |
* |
653 |
dl |
1.1 |
* @return the number of arrived parties |
654 |
|
|
*/ |
655 |
|
|
public int getArrivedParties() { |
656 |
dl |
1.4 |
return arrivedOf(state); |
657 |
dl |
1.1 |
} |
658 |
|
|
|
659 |
|
|
/** |
660 |
|
|
* Returns the number of registered parties that have not yet |
661 |
|
|
* arrived at the current phase of this barrier. |
662 |
jsr166 |
1.14 |
* |
663 |
dl |
1.1 |
* @return the number of unarrived parties |
664 |
|
|
*/ |
665 |
|
|
public int getUnarrivedParties() { |
666 |
dl |
1.4 |
return unarrivedOf(state); |
667 |
|
|
} |
668 |
|
|
|
669 |
|
|
/** |
670 |
jsr166 |
1.23 |
* Returns the parent of this phaser, or {@code null} if none. |
671 |
jsr166 |
1.14 |
* |
672 |
jsr166 |
1.23 |
* @return the parent of this phaser, or {@code null} if none |
673 |
dl |
1.4 |
*/ |
674 |
|
|
public Phaser getParent() { |
675 |
|
|
return parent; |
676 |
|
|
} |
677 |
|
|
|
678 |
|
|
/** |
679 |
|
|
* Returns the root ancestor of this phaser, which is the same as |
680 |
|
|
* this phaser if it has no parent. |
681 |
jsr166 |
1.14 |
* |
682 |
jsr166 |
1.9 |
* @return the root ancestor of this phaser |
683 |
dl |
1.4 |
*/ |
684 |
|
|
public Phaser getRoot() { |
685 |
|
|
return root; |
686 |
dl |
1.1 |
} |
687 |
|
|
|
688 |
|
|
/** |
689 |
jsr166 |
1.9 |
* Returns {@code true} if this barrier has been terminated. |
690 |
jsr166 |
1.14 |
* |
691 |
jsr166 |
1.9 |
* @return {@code true} if this barrier has been terminated |
692 |
dl |
1.1 |
*/ |
693 |
|
|
public boolean isTerminated() { |
694 |
dl |
1.4 |
return getPhase() < 0; |
695 |
dl |
1.1 |
} |
696 |
|
|
|
697 |
|
|
/** |
698 |
|
|
* Overridable method to perform an action upon phase advance, and |
699 |
|
|
* to control termination. This method is invoked whenever the |
700 |
|
|
* barrier is tripped (and thus all other waiting parties are |
701 |
jsr166 |
1.23 |
* dormant). If it returns {@code true}, then, rather than advance |
702 |
|
|
* the phase number, this barrier will be set to a final |
703 |
|
|
* termination state, and subsequent calls to {@link #isTerminated} |
704 |
|
|
* will return true. |
705 |
jsr166 |
1.3 |
* |
706 |
jsr166 |
1.25 |
* <p>The default version returns {@code true} when the number of |
707 |
dl |
1.1 |
* registered parties is zero. Normally, overrides that arrange |
708 |
|
|
* termination for other reasons should also preserve this |
709 |
|
|
* property. |
710 |
|
|
* |
711 |
jsr166 |
1.25 |
* <p>You may override this method to perform an action with side |
712 |
dl |
1.4 |
* effects visible to participating tasks, but it is in general |
713 |
|
|
* only sensible to do so in designs where all parties register |
714 |
jsr166 |
1.24 |
* before any arrive, and all {@link #awaitAdvance} at each phase. |
715 |
dl |
1.27 |
* Otherwise, you cannot ensure lack of interference from other |
716 |
|
|
* parties during the the invocation of this method. |
717 |
dl |
1.4 |
* |
718 |
dl |
1.1 |
* @param phase the phase number on entering the barrier |
719 |
jsr166 |
1.9 |
* @param registeredParties the current number of registered parties |
720 |
|
|
* @return {@code true} if this barrier should terminate |
721 |
dl |
1.1 |
*/ |
722 |
|
|
protected boolean onAdvance(int phase, int registeredParties) { |
723 |
|
|
return registeredParties <= 0; |
724 |
|
|
} |
725 |
|
|
|
726 |
|
|
/** |
727 |
dl |
1.4 |
* Returns a string identifying this phaser, as well as its |
728 |
dl |
1.1 |
* state. The state, in brackets, includes the String {@code |
729 |
jsr166 |
1.9 |
* "phase = "} followed by the phase number, {@code "parties = "} |
730 |
dl |
1.1 |
* followed by the number of registered parties, and {@code |
731 |
jsr166 |
1.9 |
* "arrived = "} followed by the number of arrived parties. |
732 |
dl |
1.1 |
* |
733 |
|
|
* @return a string identifying this barrier, as well as its state |
734 |
|
|
*/ |
735 |
|
|
public String toString() { |
736 |
dl |
1.4 |
long s = getReconciledState(); |
737 |
jsr166 |
1.9 |
return super.toString() + |
738 |
|
|
"[phase = " + phaseOf(s) + |
739 |
|
|
" parties = " + partiesOf(s) + |
740 |
|
|
" arrived = " + arrivedOf(s) + "]"; |
741 |
dl |
1.1 |
} |
742 |
|
|
|
743 |
dl |
1.4 |
// methods for waiting |
744 |
dl |
1.1 |
|
745 |
|
|
/** |
746 |
dl |
1.10 |
* Wait nodes for Treiber stack representing wait queue |
747 |
dl |
1.1 |
*/ |
748 |
dl |
1.10 |
static final class QNode implements ForkJoinPool.ManagedBlocker { |
749 |
|
|
final Phaser phaser; |
750 |
|
|
final int phase; |
751 |
|
|
final long startTime; |
752 |
|
|
final long nanos; |
753 |
|
|
final boolean timed; |
754 |
|
|
final boolean interruptible; |
755 |
|
|
volatile boolean wasInterrupted = false; |
756 |
|
|
volatile Thread thread; // nulled to cancel wait |
757 |
dl |
1.4 |
QNode next; |
758 |
dl |
1.10 |
QNode(Phaser phaser, int phase, boolean interruptible, |
759 |
|
|
boolean timed, long startTime, long nanos) { |
760 |
|
|
this.phaser = phaser; |
761 |
|
|
this.phase = phase; |
762 |
|
|
this.timed = timed; |
763 |
|
|
this.interruptible = interruptible; |
764 |
|
|
this.startTime = startTime; |
765 |
|
|
this.nanos = nanos; |
766 |
dl |
1.4 |
thread = Thread.currentThread(); |
767 |
|
|
} |
768 |
dl |
1.10 |
public boolean isReleasable() { |
769 |
|
|
return (thread == null || |
770 |
|
|
phaser.getPhase() != phase || |
771 |
|
|
(interruptible && wasInterrupted) || |
772 |
|
|
(timed && (nanos - (System.nanoTime() - startTime)) <= 0)); |
773 |
|
|
} |
774 |
|
|
public boolean block() { |
775 |
|
|
if (Thread.interrupted()) { |
776 |
|
|
wasInterrupted = true; |
777 |
|
|
if (interruptible) |
778 |
|
|
return true; |
779 |
|
|
} |
780 |
|
|
if (!timed) |
781 |
|
|
LockSupport.park(this); |
782 |
|
|
else { |
783 |
|
|
long waitTime = nanos - (System.nanoTime() - startTime); |
784 |
|
|
if (waitTime <= 0) |
785 |
|
|
return true; |
786 |
|
|
LockSupport.parkNanos(this, waitTime); |
787 |
|
|
} |
788 |
|
|
return isReleasable(); |
789 |
|
|
} |
790 |
dl |
1.4 |
void signal() { |
791 |
|
|
Thread t = thread; |
792 |
|
|
if (t != null) { |
793 |
|
|
thread = null; |
794 |
|
|
LockSupport.unpark(t); |
795 |
|
|
} |
796 |
|
|
} |
797 |
dl |
1.10 |
boolean doWait() { |
798 |
|
|
if (thread != null) { |
799 |
|
|
try { |
800 |
|
|
ForkJoinPool.managedBlock(this, false); |
801 |
|
|
} catch (InterruptedException ie) { |
802 |
jsr166 |
1.12 |
} |
803 |
dl |
1.10 |
} |
804 |
|
|
return wasInterrupted; |
805 |
|
|
} |
806 |
|
|
|
807 |
dl |
1.4 |
} |
808 |
|
|
|
809 |
|
|
/** |
810 |
jsr166 |
1.14 |
* Removes and signals waiting threads from wait queue. |
811 |
dl |
1.4 |
*/ |
812 |
|
|
private void releaseWaiters(int phase) { |
813 |
|
|
AtomicReference<QNode> head = queueFor(phase); |
814 |
|
|
QNode q; |
815 |
|
|
while ((q = head.get()) != null) { |
816 |
|
|
if (head.compareAndSet(q, q.next)) |
817 |
|
|
q.signal(); |
818 |
|
|
} |
819 |
|
|
} |
820 |
|
|
|
821 |
|
|
/** |
822 |
jsr166 |
1.14 |
* Tries to enqueue given node in the appropriate wait queue. |
823 |
|
|
* |
824 |
dl |
1.10 |
* @return true if successful |
825 |
|
|
*/ |
826 |
|
|
private boolean tryEnqueue(QNode node) { |
827 |
|
|
AtomicReference<QNode> head = queueFor(node.phase); |
828 |
|
|
return head.compareAndSet(node.next = head.get(), node); |
829 |
|
|
} |
830 |
|
|
|
831 |
|
|
/** |
832 |
dl |
1.1 |
* Enqueues node and waits unless aborted or signalled. |
833 |
jsr166 |
1.14 |
* |
834 |
dl |
1.10 |
* @return current phase |
835 |
dl |
1.1 |
*/ |
836 |
dl |
1.4 |
private int untimedWait(int phase) { |
837 |
dl |
1.1 |
QNode node = null; |
838 |
dl |
1.10 |
boolean queued = false; |
839 |
dl |
1.4 |
boolean interrupted = false; |
840 |
|
|
int p; |
841 |
|
|
while ((p = getPhase()) == phase) { |
842 |
dl |
1.10 |
if (Thread.interrupted()) |
843 |
|
|
interrupted = true; |
844 |
|
|
else if (node == null) |
845 |
|
|
node = new QNode(this, phase, false, false, 0, 0); |
846 |
|
|
else if (!queued) |
847 |
|
|
queued = tryEnqueue(node); |
848 |
dl |
1.4 |
else |
849 |
dl |
1.10 |
interrupted = node.doWait(); |
850 |
dl |
1.4 |
} |
851 |
|
|
if (node != null) |
852 |
|
|
node.thread = null; |
853 |
dl |
1.10 |
releaseWaiters(phase); |
854 |
dl |
1.4 |
if (interrupted) |
855 |
|
|
Thread.currentThread().interrupt(); |
856 |
|
|
return p; |
857 |
|
|
} |
858 |
|
|
|
859 |
|
|
/** |
860 |
dl |
1.10 |
* Interruptible version |
861 |
|
|
* @return current phase |
862 |
dl |
1.4 |
*/ |
863 |
|
|
private int interruptibleWait(int phase) throws InterruptedException { |
864 |
|
|
QNode node = null; |
865 |
|
|
boolean queued = false; |
866 |
|
|
boolean interrupted = false; |
867 |
|
|
int p; |
868 |
dl |
1.10 |
while ((p = getPhase()) == phase && !interrupted) { |
869 |
|
|
if (Thread.interrupted()) |
870 |
|
|
interrupted = true; |
871 |
|
|
else if (node == null) |
872 |
|
|
node = new QNode(this, phase, true, false, 0, 0); |
873 |
|
|
else if (!queued) |
874 |
|
|
queued = tryEnqueue(node); |
875 |
dl |
1.1 |
else |
876 |
dl |
1.10 |
interrupted = node.doWait(); |
877 |
dl |
1.1 |
} |
878 |
|
|
if (node != null) |
879 |
|
|
node.thread = null; |
880 |
dl |
1.10 |
if (p != phase || (p = getPhase()) != phase) |
881 |
|
|
releaseWaiters(phase); |
882 |
dl |
1.4 |
if (interrupted) |
883 |
|
|
throw new InterruptedException(); |
884 |
|
|
return p; |
885 |
dl |
1.1 |
} |
886 |
|
|
|
887 |
|
|
/** |
888 |
dl |
1.10 |
* Timeout version. |
889 |
|
|
* @return current phase |
890 |
dl |
1.1 |
*/ |
891 |
dl |
1.4 |
private int timedWait(int phase, long nanos) |
892 |
dl |
1.1 |
throws InterruptedException, TimeoutException { |
893 |
dl |
1.10 |
long startTime = System.nanoTime(); |
894 |
|
|
QNode node = null; |
895 |
|
|
boolean queued = false; |
896 |
|
|
boolean interrupted = false; |
897 |
dl |
1.4 |
int p; |
898 |
dl |
1.10 |
while ((p = getPhase()) == phase && !interrupted) { |
899 |
|
|
if (Thread.interrupted()) |
900 |
|
|
interrupted = true; |
901 |
|
|
else if (nanos - (System.nanoTime() - startTime) <= 0) |
902 |
|
|
break; |
903 |
|
|
else if (node == null) |
904 |
|
|
node = new QNode(this, phase, true, true, startTime, nanos); |
905 |
|
|
else if (!queued) |
906 |
|
|
queued = tryEnqueue(node); |
907 |
|
|
else |
908 |
|
|
interrupted = node.doWait(); |
909 |
dl |
1.4 |
} |
910 |
dl |
1.10 |
if (node != null) |
911 |
|
|
node.thread = null; |
912 |
|
|
if (p != phase || (p = getPhase()) != phase) |
913 |
|
|
releaseWaiters(phase); |
914 |
|
|
if (interrupted) |
915 |
|
|
throw new InterruptedException(); |
916 |
|
|
if (p == phase) |
917 |
|
|
throw new TimeoutException(); |
918 |
dl |
1.4 |
return p; |
919 |
|
|
} |
920 |
|
|
|
921 |
jsr166 |
1.22 |
// Unsafe mechanics |
922 |
|
|
|
923 |
|
|
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
924 |
|
|
private static final long stateOffset = |
925 |
|
|
objectFieldOffset("state", Phaser.class); |
926 |
|
|
|
927 |
|
|
private final boolean casState(long cmp, long val) { |
928 |
|
|
return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val); |
929 |
|
|
} |
930 |
|
|
|
931 |
|
|
private static long objectFieldOffset(String field, Class<?> klazz) { |
932 |
|
|
try { |
933 |
|
|
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |
934 |
|
|
} catch (NoSuchFieldException e) { |
935 |
|
|
// Convert Exception to corresponding Error |
936 |
|
|
NoSuchFieldError error = new NoSuchFieldError(field); |
937 |
|
|
error.initCause(e); |
938 |
|
|
throw error; |
939 |
|
|
} |
940 |
|
|
} |
941 |
|
|
|
942 |
|
|
/** |
943 |
|
|
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
944 |
|
|
* Replace with a simple call to Unsafe.getUnsafe when integrating |
945 |
|
|
* into a jdk. |
946 |
|
|
* |
947 |
|
|
* @return a sun.misc.Unsafe |
948 |
|
|
*/ |
949 |
jsr166 |
1.19 |
private static sun.misc.Unsafe getUnsafe() { |
950 |
jsr166 |
1.11 |
try { |
951 |
jsr166 |
1.19 |
return sun.misc.Unsafe.getUnsafe(); |
952 |
jsr166 |
1.11 |
} catch (SecurityException se) { |
953 |
|
|
try { |
954 |
|
|
return java.security.AccessController.doPrivileged |
955 |
jsr166 |
1.22 |
(new java.security |
956 |
|
|
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
957 |
jsr166 |
1.19 |
public sun.misc.Unsafe run() throws Exception { |
958 |
jsr166 |
1.22 |
java.lang.reflect.Field f = sun.misc |
959 |
|
|
.Unsafe.class.getDeclaredField("theUnsafe"); |
960 |
|
|
f.setAccessible(true); |
961 |
|
|
return (sun.misc.Unsafe) f.get(null); |
962 |
jsr166 |
1.11 |
}}); |
963 |
|
|
} catch (java.security.PrivilegedActionException e) { |
964 |
jsr166 |
1.19 |
throw new RuntimeException("Could not initialize intrinsics", |
965 |
|
|
e.getCause()); |
966 |
jsr166 |
1.11 |
} |
967 |
|
|
} |
968 |
|
|
} |
969 |
dl |
1.1 |
} |