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/publicdomain/zero/1.0/ |
5 |
|
|
*/ |
6 |
|
|
|
7 |
|
|
package java.util.concurrent; |
8 |
|
|
|
9 |
jsr166 |
1.10 |
import java.util.ArrayList; |
10 |
|
|
import java.util.List; |
11 |
dl |
1.1 |
import java.util.concurrent.locks.LockSupport; |
12 |
|
|
import java.util.function.BiPredicate; |
13 |
|
|
import java.util.function.Function; |
14 |
|
|
|
15 |
|
|
/** |
16 |
|
|
* A {@link Flow.Publisher} that asynchronously issues submitted items |
17 |
|
|
* to current subscribers until it is closed. Each current subscriber |
18 |
|
|
* receives newly submitted items in the same order unless drops or |
19 |
|
|
* exceptions are encountered. Using a SubmissionPublisher allows |
20 |
|
|
* item generators to act as Publishers, although without integrated |
21 |
|
|
* flow control. Instead they rely on drop handling and/or blocking. |
22 |
|
|
* This class may also serve as a base for subclasses that generate |
23 |
|
|
* items, and use the methods in this class to publish them. |
24 |
|
|
* |
25 |
|
|
* <p>A SubmissionPublisher uses the Executor supplied in its |
26 |
|
|
* constructor for delivery to subscribers. The best choice of |
27 |
|
|
* Executor depends on expected usage. If the generator(s) of |
28 |
|
|
* submitted items run in separate threads, and the number of |
29 |
|
|
* subscribers can be estimated, consider using a {@link |
30 |
|
|
* Executors#newFixedThreadPool}. Otherwise consider using a |
31 |
|
|
* work-stealing pool (including {@link ForkJoinPool#commonPool}). |
32 |
|
|
* |
33 |
|
|
* <p>Buffering allows producers and consumers to transiently operate |
34 |
|
|
* at different rates. Each subscriber uses an independent buffer. |
35 |
|
|
* Buffers are created upon first use with a given initial capacity, |
36 |
|
|
* and are resized as needed up to the maximum. (Capacity arguments |
37 |
|
|
* may be rounded up to powers of two.) Invocations of {@code |
38 |
|
|
* subscription.request} do not directly result in buffer expansion, |
39 |
|
|
* but risk saturation if unfulfilled requests exceed the maximum |
40 |
|
|
* capacity. Choices of buffer parameters rely on expected rates, |
41 |
|
|
* resources, and usages, that usually benefit from empirical testing. |
42 |
|
|
* As first guesses, consider initial 8 and maximum 1024. |
43 |
|
|
* |
44 |
|
|
* <p>Publication methods support different policies about what to do |
45 |
|
|
* when buffers are saturated. Method {@link #submit} blocks until |
46 |
|
|
* resources are available. This is simplest (and often appropriate |
47 |
jsr166 |
1.11 |
* for relay stages; see {@link #newTransformProcessor newTransformProcessor}), |
48 |
|
|
* but least responsive. The {@code offer} methods may either |
49 |
|
|
* immediately, or with bounded timeout, drop items, but provide an |
50 |
|
|
* opportunity to interpose a handler and then retry. While the |
51 |
|
|
* handler is invoked, other calls to methods in this class by other |
52 |
|
|
* threads are blocked. Unless recovery is assured, options are |
53 |
|
|
* usually limited to logging the error and/or issuing an onError |
54 |
|
|
* signal to the subscriber. |
55 |
dl |
1.1 |
* |
56 |
|
|
* <p>If any Subscriber method throws an exception, its subscription |
57 |
|
|
* is cancelled. If the supplied Executor throws |
58 |
|
|
* RejectedExecutionException (or any other RuntimeException or Error) |
59 |
|
|
* when attempting to execute a task, or a drop handler throws an |
60 |
|
|
* exception when processing a dropped item, then the exception is |
61 |
|
|
* rethrown. In these cases, some but not all subscribers may have |
62 |
|
|
* received items. It is usually good practice to {@link |
63 |
jsr166 |
1.11 |
* #closeExceptionally closeExceptionally} in these cases. |
64 |
dl |
1.1 |
* |
65 |
|
|
* @param <T> the published item type |
66 |
|
|
* @author Doug Lea |
67 |
|
|
* @since 1.9 |
68 |
|
|
*/ |
69 |
|
|
public class SubmissionPublisher<T> implements Flow.Publisher<T>, |
70 |
|
|
AutoCloseable { |
71 |
|
|
/* |
72 |
|
|
* Most mechanics are handled by BufferedSubscription. This class |
73 |
|
|
* mainly ensures sequentiality by using built-in synchronization |
74 |
|
|
* locks across public methods. (Using built-in locks works well |
75 |
|
|
* in the most typical case in which only one thread submits |
76 |
|
|
* items). |
77 |
|
|
*/ |
78 |
|
|
|
79 |
|
|
// Ensuring that all arrays have power of two length |
80 |
|
|
|
81 |
|
|
static final int MAXIMUM_BUFFER_CAPACITY = 1 << 30; |
82 |
|
|
static final int roundCapacity(int cap) { // to nearest power of 2 |
83 |
|
|
int n = cap - 1; |
84 |
|
|
n |= n >>> 1; |
85 |
|
|
n |= n >>> 2; |
86 |
|
|
n |= n >>> 4; |
87 |
|
|
n |= n >>> 8; |
88 |
|
|
n |= n >>> 16; |
89 |
|
|
return (n < 0) ? 1 : |
90 |
|
|
(n >= MAXIMUM_BUFFER_CAPACITY) ? MAXIMUM_BUFFER_CAPACITY : n + 1; |
91 |
|
|
} |
92 |
|
|
|
93 |
|
|
/** |
94 |
|
|
* Clients (BufferedSubscriptions) are maintained in a linked list |
95 |
|
|
* (via their "next" fields). This works well for publish loops. |
96 |
|
|
* It requires O(n) traversal to check for duplicate subscribers, |
97 |
|
|
* but we expect that subscribing is much less common than |
98 |
|
|
* publishing. Unsubscribing occurs only during publish loops, |
99 |
|
|
* when BufferedSubscription methods return negative values |
100 |
|
|
* signifying that they have been disabled (cancelled or closed). |
101 |
|
|
*/ |
102 |
|
|
BufferedSubscription<T> clients; |
103 |
|
|
|
104 |
|
|
// Parameters for constructing BufferedSubscriptions |
105 |
|
|
final Executor executor; |
106 |
|
|
final int minBufferCapacity; |
107 |
|
|
final int maxBufferCapacity; |
108 |
|
|
|
109 |
|
|
/** Run status, updated only within locks */ |
110 |
|
|
volatile boolean closed; |
111 |
|
|
|
112 |
|
|
/** |
113 |
|
|
* Creates a new SubmissionPublisher using the given Executor for |
114 |
|
|
* async delivery to subscribers, and with the given initial and |
115 |
|
|
* maximum buffer sizes for each subscriber. In the absence of |
116 |
|
|
* other constraints, consider using {@code |
117 |
jsr166 |
1.5 |
* ForkJoinPool.commonPool(), 8, 1024}. |
118 |
dl |
1.1 |
* |
119 |
|
|
* @param executor the executor to use for async delivery, |
120 |
|
|
* supporting creation of at least one independent thread |
121 |
|
|
* @param initialBufferCapacity the initial capacity for each |
122 |
|
|
* subscriber's buffer (the actual capacity may be rounded up to |
123 |
|
|
* the nearest power of two) |
124 |
|
|
* @param maxBufferCapacity the maximum capacity for each |
125 |
|
|
* subscriber's buffer (the actual capacity may be rounded up to |
126 |
|
|
* the nearest power of two) |
127 |
|
|
* @throws NullPointerException if executor is null |
128 |
|
|
* @throws IllegalArgumentException if initialBufferCapacity is |
129 |
|
|
* not positive or exceeds maxBufferCapacity, or maxBufferCapacity |
130 |
|
|
* exceeds {@code 1<<30} (about 1 billion), the maximum bound for |
131 |
|
|
* a power of two array size |
132 |
|
|
*/ |
133 |
|
|
public SubmissionPublisher(Executor executor, |
134 |
|
|
int initialBufferCapacity, |
135 |
|
|
int maxBufferCapacity) { |
136 |
|
|
if (executor == null) |
137 |
|
|
throw new NullPointerException(); |
138 |
|
|
if (initialBufferCapacity <= 0 || maxBufferCapacity <= 0) |
139 |
|
|
throw new IllegalArgumentException("capacity must be positive"); |
140 |
|
|
if (maxBufferCapacity > MAXIMUM_BUFFER_CAPACITY) |
141 |
|
|
throw new IllegalArgumentException("capacity exceeds limit"); |
142 |
|
|
if (initialBufferCapacity > maxBufferCapacity) |
143 |
|
|
throw new IllegalArgumentException("initial cannot exceed max capacity"); |
144 |
|
|
int minc = roundCapacity(initialBufferCapacity); |
145 |
|
|
int maxc = roundCapacity(maxBufferCapacity); |
146 |
|
|
this.executor = executor; |
147 |
|
|
this.minBufferCapacity = minc; |
148 |
|
|
this.maxBufferCapacity = maxc; |
149 |
|
|
} |
150 |
|
|
|
151 |
|
|
/** |
152 |
|
|
* Adds the given Subscriber unless already subscribed. If |
153 |
|
|
* already subscribed, the Subscriber's onError method is invoked |
154 |
|
|
* with an IllegalStateException. Otherwise, upon success, the |
155 |
|
|
* Subscriber's onSubscribe method is invoked with a new |
156 |
|
|
* Subscription (upon exception, the exception is rethrown and the |
157 |
|
|
* Subscriber remains unsubscribed). If this SubmissionPublisher |
158 |
|
|
* is closed, the subscriber's onComplete method is then invoked. |
159 |
|
|
* Subscribers may enable receiving items by invoking the request |
160 |
|
|
* method of the returned Subscription, and may unsubscribe by |
161 |
|
|
* invoking its cancel method. |
162 |
|
|
* |
163 |
|
|
* @param subscriber the subscriber |
164 |
|
|
* @throws NullPointerException if subscriber is null |
165 |
|
|
*/ |
166 |
|
|
public void subscribe(Flow.Subscriber<? super T> subscriber) { |
167 |
|
|
if (subscriber == null) throw new NullPointerException(); |
168 |
|
|
BufferedSubscription<T> sub = new BufferedSubscription<T>( |
169 |
|
|
subscriber, executor, minBufferCapacity, maxBufferCapacity); |
170 |
|
|
boolean present = false, clsd; |
171 |
jsr166 |
1.2 |
synchronized (this) { |
172 |
dl |
1.1 |
clsd = closed; |
173 |
|
|
BufferedSubscription<T> pred = null, next; |
174 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
175 |
|
|
next = b.next; |
176 |
|
|
if (b.ctl < 0) { // disabled; remove |
177 |
|
|
if (pred == null) |
178 |
|
|
clients = next; |
179 |
|
|
else |
180 |
|
|
pred.next = next; |
181 |
jsr166 |
1.2 |
} |
182 |
dl |
1.1 |
else if (subscriber == b.subscriber) { |
183 |
|
|
present = true; |
184 |
|
|
break; |
185 |
|
|
} |
186 |
|
|
pred = b; |
187 |
|
|
} |
188 |
|
|
if (!present) { |
189 |
|
|
subscriber.onSubscribe(sub); // don't link on exception |
190 |
|
|
if (!clsd) { |
191 |
|
|
if (pred == null) |
192 |
|
|
clients = sub; |
193 |
|
|
else |
194 |
|
|
pred.next = sub; |
195 |
|
|
} |
196 |
|
|
} |
197 |
|
|
} |
198 |
|
|
if (clsd) |
199 |
|
|
subscriber.onComplete(); |
200 |
|
|
else if (present) |
201 |
|
|
subscriber.onError(new IllegalStateException("Already subscribed")); |
202 |
|
|
} |
203 |
|
|
|
204 |
|
|
/** |
205 |
|
|
* Publishes the given item, if possible, to each current |
206 |
|
|
* subscriber by asynchronously invoking its onNext method. The |
207 |
|
|
* item may be dropped by one or more subscribers if resource |
208 |
|
|
* limits are exceeded, in which case the given handler (if |
209 |
|
|
* non-null) is invoked, and if it returns true, retried once. |
210 |
|
|
* |
211 |
|
|
* <p>If the Executor for this publisher throws a |
212 |
|
|
* RejectedExecutionException (or any other RuntimeException or |
213 |
|
|
* Error) when attempting to asynchronously notify subscribers, or |
214 |
|
|
* the drop handler throws an exception when processing a dropped |
215 |
|
|
* item, then this exception is rethrown. |
216 |
|
|
* |
217 |
|
|
* @param item the (non-null) item to publish |
218 |
|
|
* @param onDrop if non-null, the handler invoked upon a drop to a |
219 |
|
|
* subscriber, with arguments of the subscriber and item; if it |
220 |
|
|
* returns true, an offer is re-attempted (once) |
221 |
jsr166 |
1.4 |
* @return the number of drops (failed attempts to issue the item |
222 |
|
|
* to a subscriber) |
223 |
dl |
1.1 |
* @throws IllegalStateException if closed |
224 |
|
|
* @throws NullPointerException if item is null |
225 |
|
|
* @throws RejectedExecutionException if thrown by Executor |
226 |
|
|
*/ |
227 |
|
|
public int offer(T item, |
228 |
|
|
BiPredicate<Flow.Subscriber<? super T>, ? super T> onDrop) { |
229 |
|
|
if (item == null) throw new NullPointerException(); |
230 |
|
|
int drops = 0; |
231 |
jsr166 |
1.2 |
synchronized (this) { |
232 |
dl |
1.1 |
if (closed) |
233 |
|
|
throw new IllegalStateException("Closed"); |
234 |
|
|
BufferedSubscription<T> pred = null, next; |
235 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
236 |
|
|
int stat; |
237 |
|
|
next = b.next; |
238 |
|
|
if ((stat = b.offer(item)) == 0 && |
239 |
|
|
onDrop != null && |
240 |
|
|
onDrop.test(b.subscriber, item)) |
241 |
|
|
stat = b.offer(item); |
242 |
|
|
if (stat < 0) { |
243 |
|
|
if (pred == null) |
244 |
|
|
clients = next; |
245 |
|
|
else |
246 |
|
|
pred.next = next; |
247 |
|
|
} |
248 |
|
|
else { |
249 |
|
|
pred = b; |
250 |
|
|
if (stat == 0) |
251 |
|
|
++drops; |
252 |
|
|
} |
253 |
|
|
} |
254 |
|
|
return drops; |
255 |
|
|
} |
256 |
|
|
} |
257 |
|
|
|
258 |
|
|
/** |
259 |
|
|
* Publishes the given item, if possible, to each current |
260 |
|
|
* subscriber by asynchronously invoking its onNext method, |
261 |
|
|
* blocking while resources for any subscription are unavailable, |
262 |
|
|
* up to the specified timeout or the caller thread is |
263 |
jsr166 |
1.4 |
* interrupted, at which point the given handler (if non-null) |
264 |
dl |
1.1 |
* is invoked, and if it returns true, retried once. |
265 |
|
|
* |
266 |
|
|
* <p>If the Executor for this publisher throws a |
267 |
|
|
* RejectedExecutionException (or any other RuntimeException or |
268 |
|
|
* Error) when attempting to asynchronously notify subscribers, or |
269 |
|
|
* the drop handler throws an exception when processing a dropped |
270 |
|
|
* item, then this exception is rethrown. |
271 |
|
|
* |
272 |
|
|
* @param item the (non-null) item to publish |
273 |
|
|
* @param timeout how long to wait for resources for any subscriber |
274 |
|
|
* before giving up, in units of {@code unit} |
275 |
|
|
* @param unit a {@code TimeUnit} determining how to interpret the |
276 |
|
|
* {@code timeout} parameter |
277 |
|
|
* @param onDrop if non-null, the handler invoked upon a drop to a |
278 |
|
|
* subscriber, with arguments of the subscriber and item; if it |
279 |
|
|
* returns true, an offer is re-attempted (once) |
280 |
jsr166 |
1.4 |
* @return the number of drops (failed attempts to issue the item |
281 |
|
|
* to a subscriber) |
282 |
dl |
1.1 |
* @throws IllegalStateException if closed |
283 |
|
|
* @throws NullPointerException if item is null |
284 |
|
|
* @throws RejectedExecutionException if thrown by Executor |
285 |
|
|
*/ |
286 |
|
|
public int offer(T item, long timeout, TimeUnit unit, |
287 |
|
|
BiPredicate<Flow.Subscriber<? super T>, ? super T> onDrop) { |
288 |
|
|
if (item == null) throw new NullPointerException(); |
289 |
|
|
long nanos = unit.toNanos(timeout); |
290 |
|
|
int drops = 0; |
291 |
jsr166 |
1.2 |
synchronized (this) { |
292 |
dl |
1.1 |
if (closed) |
293 |
|
|
throw new IllegalStateException("Closed"); |
294 |
|
|
BufferedSubscription<T> pred = null, next; |
295 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
296 |
|
|
int stat; |
297 |
|
|
next = b.next; |
298 |
|
|
if ((stat = b.offer(item)) == 0 && |
299 |
|
|
(stat = b.timedOffer(item, nanos)) == 0 && |
300 |
|
|
onDrop != null && |
301 |
|
|
onDrop.test(b.subscriber, item)) |
302 |
|
|
stat = b.offer(item); |
303 |
|
|
if (stat < 0) { |
304 |
|
|
if (pred == null) |
305 |
|
|
clients = next; |
306 |
|
|
else |
307 |
|
|
pred.next = next; |
308 |
|
|
} |
309 |
|
|
else { |
310 |
|
|
pred = b; |
311 |
|
|
if (stat == 0) |
312 |
|
|
++drops; |
313 |
|
|
} |
314 |
|
|
} |
315 |
|
|
} |
316 |
|
|
return drops; |
317 |
|
|
} |
318 |
|
|
|
319 |
|
|
/** |
320 |
|
|
* Publishes the given item to each current subscriber by |
321 |
|
|
* asynchronously invoking its onNext method, blocking |
322 |
|
|
* uninterruptibly while resources for any subscriber are |
323 |
|
|
* unavailable. |
324 |
|
|
* |
325 |
|
|
* <p>If the Executor for this publisher throws a |
326 |
|
|
* RejectedExecutionException (or any other RuntimeException or |
327 |
|
|
* Error) when attempting to asynchronously notify subscribers, |
328 |
|
|
* then this exception is rethrown. |
329 |
|
|
* |
330 |
|
|
* @param item the (non-null) item to publish |
331 |
|
|
* @throws IllegalStateException if closed |
332 |
|
|
* @throws NullPointerException if item is null |
333 |
|
|
* @throws RejectedExecutionException if thrown by Executor |
334 |
|
|
*/ |
335 |
|
|
public void submit(T item) { |
336 |
|
|
if (item == null) throw new NullPointerException(); |
337 |
jsr166 |
1.2 |
synchronized (this) { |
338 |
dl |
1.1 |
if (closed) |
339 |
|
|
throw new IllegalStateException("Closed"); |
340 |
|
|
BufferedSubscription<T> pred = null, next; |
341 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
342 |
|
|
int stat; |
343 |
|
|
next = b.next; |
344 |
|
|
if ((stat = b.offer(item)) == 0) |
345 |
|
|
stat = b.submit(item); |
346 |
|
|
if (stat < 0) { |
347 |
|
|
if (pred == null) |
348 |
|
|
clients = next; |
349 |
|
|
else |
350 |
|
|
pred.next = next; |
351 |
|
|
} |
352 |
|
|
else |
353 |
|
|
pred = b; |
354 |
|
|
} |
355 |
|
|
} |
356 |
|
|
} |
357 |
|
|
|
358 |
|
|
/** |
359 |
|
|
* Unless already closed, issues onComplete signals to current |
360 |
|
|
* subscribers, and disallows subsequent attempts to publish. |
361 |
|
|
*/ |
362 |
|
|
public void close() { |
363 |
|
|
if (!closed) { |
364 |
|
|
BufferedSubscription<T> b, next; |
365 |
jsr166 |
1.2 |
synchronized (this) { |
366 |
dl |
1.1 |
b = clients; |
367 |
|
|
clients = null; |
368 |
|
|
closed = true; |
369 |
|
|
} |
370 |
|
|
while (b != null) { |
371 |
|
|
next = b.next; |
372 |
|
|
b.close(); |
373 |
|
|
b = next; |
374 |
|
|
} |
375 |
|
|
} |
376 |
|
|
} |
377 |
|
|
|
378 |
|
|
/** |
379 |
|
|
* Unless already closed, issues onError signals to current |
380 |
|
|
* subscribers with the given error, and disallows subsequent |
381 |
|
|
* attempts to publish. |
382 |
|
|
* |
383 |
jsr166 |
1.5 |
* @param error the onError argument sent to subscribers |
384 |
dl |
1.1 |
* @throws NullPointerException if error is null |
385 |
|
|
*/ |
386 |
|
|
public void closeExceptionally(Throwable error) { |
387 |
|
|
if (error == null) |
388 |
|
|
throw new NullPointerException(); |
389 |
|
|
if (!closed) { |
390 |
|
|
BufferedSubscription<T> b, next; |
391 |
jsr166 |
1.2 |
synchronized (this) { |
392 |
dl |
1.1 |
b = clients; |
393 |
|
|
clients = null; |
394 |
|
|
closed = true; |
395 |
|
|
} |
396 |
|
|
while (b != null) { |
397 |
|
|
next = b.next; |
398 |
|
|
b.closeExceptionally(error); |
399 |
|
|
b = next; |
400 |
|
|
} |
401 |
|
|
} |
402 |
|
|
} |
403 |
|
|
|
404 |
|
|
/** |
405 |
|
|
* Returns true if this publisher is not accepting submissions. |
406 |
|
|
* |
407 |
|
|
* @return true if closed |
408 |
|
|
*/ |
409 |
|
|
public boolean isClosed() { |
410 |
|
|
return closed; |
411 |
|
|
} |
412 |
|
|
|
413 |
|
|
/** |
414 |
jsr166 |
1.6 |
* Returns true if this publisher has any subscribers. |
415 |
dl |
1.1 |
* |
416 |
|
|
* @return true if this publisher has any subscribers |
417 |
|
|
*/ |
418 |
|
|
public boolean hasSubscribers() { |
419 |
|
|
boolean nonEmpty = false; |
420 |
|
|
if (!closed) { |
421 |
jsr166 |
1.2 |
synchronized (this) { |
422 |
dl |
1.1 |
BufferedSubscription<T> pred = null, next; |
423 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
424 |
|
|
next = b.next; |
425 |
|
|
if (b.ctl < 0) { |
426 |
|
|
if (pred == null) |
427 |
|
|
clients = next; |
428 |
|
|
else |
429 |
|
|
pred.next = next; |
430 |
jsr166 |
1.2 |
} |
431 |
dl |
1.1 |
else { |
432 |
|
|
nonEmpty = true; |
433 |
|
|
break; |
434 |
|
|
} |
435 |
|
|
} |
436 |
|
|
} |
437 |
|
|
} |
438 |
|
|
return nonEmpty; |
439 |
|
|
} |
440 |
|
|
|
441 |
|
|
/** |
442 |
|
|
* Returns the Executor used for asynchronous delivery. |
443 |
|
|
* |
444 |
|
|
* @return the Executor used for asynchronous delivery |
445 |
|
|
*/ |
446 |
|
|
public Executor getExecutor() { |
447 |
|
|
return executor; |
448 |
|
|
} |
449 |
|
|
|
450 |
jsr166 |
1.7 |
/** |
451 |
jsr166 |
1.5 |
* Returns the initial per-subscriber buffer capacity. |
452 |
dl |
1.1 |
* |
453 |
jsr166 |
1.5 |
* @return the initial per-subscriber buffer capacity |
454 |
dl |
1.1 |
*/ |
455 |
|
|
public int getInitialBufferCapacity() { |
456 |
|
|
return minBufferCapacity; |
457 |
|
|
} |
458 |
|
|
|
459 |
jsr166 |
1.7 |
/** |
460 |
jsr166 |
1.5 |
* Returns the maximum per-subscriber buffer capacity. |
461 |
dl |
1.1 |
* |
462 |
jsr166 |
1.5 |
* @return the maximum per-subscriber buffer capacity |
463 |
dl |
1.1 |
*/ |
464 |
|
|
public int getMaxBufferCapacity() { |
465 |
|
|
return maxBufferCapacity; |
466 |
|
|
} |
467 |
|
|
|
468 |
|
|
/** |
469 |
|
|
* Returns a list of current subscribers. |
470 |
|
|
* |
471 |
|
|
* @return list of current subscribers |
472 |
|
|
*/ |
473 |
|
|
public List<Flow.Subscriber<? super T>> getSubscribers() { |
474 |
|
|
ArrayList<Flow.Subscriber<? super T>> subs = new ArrayList<>(); |
475 |
jsr166 |
1.2 |
synchronized (this) { |
476 |
dl |
1.1 |
BufferedSubscription<T> pred = null, next; |
477 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
478 |
|
|
next = b.next; |
479 |
|
|
if (b.ctl < 0) { |
480 |
|
|
if (pred == null) |
481 |
|
|
clients = next; |
482 |
|
|
else |
483 |
|
|
pred.next = next; |
484 |
jsr166 |
1.2 |
} |
485 |
dl |
1.1 |
else |
486 |
|
|
subs.add(b.subscriber); |
487 |
|
|
} |
488 |
|
|
} |
489 |
|
|
return subs; |
490 |
|
|
} |
491 |
jsr166 |
1.2 |
|
492 |
dl |
1.1 |
/** |
493 |
|
|
* Returns true if the given Subscriber is currently subscribed. |
494 |
|
|
* |
495 |
|
|
* @param subscriber the subscriber |
496 |
|
|
* @return true if currently subscribed |
497 |
|
|
*/ |
498 |
|
|
public boolean isSubscribed(Flow.Subscriber<? super T> subscriber) { |
499 |
jsr166 |
1.2 |
if (!closed) { |
500 |
|
|
synchronized (this) { |
501 |
dl |
1.1 |
BufferedSubscription<T> pred = null, next; |
502 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
503 |
|
|
next = b.next; |
504 |
|
|
if (b.ctl < 0) { |
505 |
|
|
if (pred == null) |
506 |
|
|
clients = next; |
507 |
|
|
else |
508 |
|
|
pred.next = next; |
509 |
jsr166 |
1.2 |
} |
510 |
dl |
1.1 |
else if (subscriber == b.subscriber) |
511 |
|
|
return true; |
512 |
|
|
} |
513 |
|
|
} |
514 |
|
|
} |
515 |
|
|
return false; |
516 |
|
|
} |
517 |
|
|
|
518 |
|
|
/** |
519 |
|
|
* If the given subscription is managed by a SubmissionPublisher, |
520 |
|
|
* returns an estimate of the number of items produced but not yet |
521 |
|
|
* consumed; otherwise returns zero. This method is designed only |
522 |
|
|
* for monitoring purposes, not for control. |
523 |
|
|
* |
524 |
|
|
* @param subscription the subscription |
525 |
|
|
* @return the estimate, or zero if the subscription is of an |
526 |
jsr166 |
1.8 |
* unknown type |
527 |
dl |
1.1 |
*/ |
528 |
|
|
public static int estimateAvailable(Flow.Subscription subscription) { |
529 |
|
|
if (subscription instanceof BufferedSubscription) |
530 |
|
|
return ((BufferedSubscription)subscription).estimateAvailable(); |
531 |
|
|
else |
532 |
|
|
return 0; |
533 |
|
|
} |
534 |
|
|
|
535 |
|
|
/** |
536 |
|
|
* Returns a new {@link Flow.Processor} that uses this |
537 |
|
|
* SubmissionPublisher to relay transformed items from its source |
538 |
|
|
* using method {@link submit}, and using the given request size |
539 |
|
|
* for requests to its source subscription. (Typically, |
540 |
|
|
* requestSizes should range from the initial and maximum buffer |
541 |
|
|
* capacity of this SubmissionPublisher.) |
542 |
|
|
* |
543 |
jsr166 |
1.3 |
* @param <S> the subscribed item type |
544 |
dl |
1.1 |
* @param requestSize the request size for subscriptions |
545 |
|
|
* with the source |
546 |
|
|
* @param transform the transform function |
547 |
|
|
* @return the new Processor |
548 |
|
|
* @throws NullPointerException if transform is null |
549 |
|
|
* @throws IllegalArgumentException if requestSize not positive |
550 |
|
|
*/ |
551 |
|
|
public <S> Flow.Processor<S,T> newTransformProcessor( |
552 |
|
|
long requestSize, |
553 |
|
|
Function<? super S, ? extends T> transform) { |
554 |
|
|
if (requestSize <= 0L) |
555 |
|
|
throw new IllegalArgumentException("requestSize must be positive"); |
556 |
|
|
if (transform == null) |
557 |
|
|
throw new NullPointerException(); |
558 |
|
|
return new TransformProcessor<S,T>(requestSize, transform, this); |
559 |
|
|
} |
560 |
|
|
|
561 |
|
|
/** |
562 |
|
|
* A task for consuming buffer items and signals, created and |
563 |
|
|
* executed whenever they become available. A task consumes as |
564 |
|
|
* many items/signals as possible before terminating, at which |
565 |
|
|
* point another task is created when needed. The dual Runnable |
566 |
|
|
* and ForkJoinTask declaration saves overhead when executed by |
567 |
|
|
* ForkJoinPools, without impacting other kinds of Executors. |
568 |
|
|
*/ |
569 |
|
|
@SuppressWarnings("serial") |
570 |
|
|
static final class ConsumerTask<T> extends ForkJoinTask<Void> |
571 |
|
|
implements Runnable { |
572 |
|
|
final BufferedSubscription<T> s; |
573 |
|
|
ConsumerTask(BufferedSubscription<T> s) { this.s = s; } |
574 |
|
|
public final Void getRawResult() { return null; } |
575 |
|
|
public final void setRawResult(Void v) {} |
576 |
|
|
public final boolean exec() { s.consume(); return true; } |
577 |
|
|
public final void run() { s.consume(); } |
578 |
|
|
} |
579 |
|
|
|
580 |
|
|
/** |
581 |
|
|
* A bounded (ring) buffer with integrated control to start |
582 |
|
|
* consumer tasks whenever items are available. The buffer |
583 |
|
|
* algorithm is similar to one used inside ForkJoinPool, |
584 |
|
|
* specialized for the case of at most one concurrent producer and |
585 |
|
|
* consumer, and power of two buffer sizes. This allows methods to |
586 |
|
|
* operate without locks even while supporting resizing, blocking, |
587 |
|
|
* task-triggering, and garbage-free buffers (nulling out elements |
588 |
|
|
* when consumed), although supporting these does impose a bit of |
589 |
|
|
* overhead compared to plain fixed-size ring buffers. |
590 |
|
|
* |
591 |
|
|
* The publisher guarantees a single producer via its lock. We |
592 |
|
|
* ensure in this class that there is at most one consumer. The |
593 |
|
|
* request and cancel methods must be fully thread-safe but are |
594 |
|
|
* coded to exploit the most common case in which they are only |
595 |
|
|
* called by consumers (usually within onNext). |
596 |
|
|
* |
597 |
|
|
* Control over creating ConsumerTasks is managed using the ACTIVE |
598 |
|
|
* ctl bit. We ensure that a task is active when consumable items |
599 |
|
|
* (and usually, ERROR or COMPLETE signals) are present and there |
600 |
|
|
* is demand (unfulfilled requests). This is complicated on the |
601 |
|
|
* creation side by the possibility of exceptions when trying to |
602 |
|
|
* execute tasks. These eventually force DISABLED state, but |
603 |
|
|
* sometimes not directly. On the task side, termination (clearing |
604 |
|
|
* ACTIVE) may race with producers or request() calls, so in some |
605 |
|
|
* cases requires a re-check, re-activating if possible. |
606 |
|
|
* |
607 |
|
|
* The ctl field also manages run state. When DISABLED, no further |
608 |
|
|
* updates are possible (to simplify checks, DISABLED is defined |
609 |
|
|
* as a negative value). Disabling may be preceded by setting |
610 |
|
|
* ERROR or COMPLETE (or both -- ERROR has precedence), in which |
611 |
|
|
* case the associated Subscriber methods are invoked, possibly |
612 |
|
|
* synchronously if there is no active consumer task (including |
613 |
|
|
* cases where execute() failed). |
614 |
|
|
* |
615 |
|
|
* Support for blocking also exploits the fact that there is only |
616 |
|
|
* one possible waiter. ManagedBlocker-compatible control fields |
617 |
|
|
* are placed in this class itself rather than in wait-nodes. |
618 |
|
|
* Blocking control relies on the "waiter" field. Producers set |
619 |
|
|
* the field before trying to block, but must then recheck (via |
620 |
|
|
* offer) before parking. Signalling then just unparks and clears |
621 |
|
|
* waiter field. |
622 |
|
|
* |
623 |
|
|
* This class uses @Contended and heuristic field declaration |
624 |
|
|
* ordering to reduce memory contention on BufferedSubscription |
625 |
|
|
* itself, but it does not currently attempt to avoid memory |
626 |
|
|
* contention (especially including card-marks) among buffer |
627 |
|
|
* elements, that can significantly slow down some usages. |
628 |
|
|
* Addressing this may require allocating substantially more space |
629 |
|
|
* than users expect. |
630 |
|
|
*/ |
631 |
|
|
@sun.misc.Contended |
632 |
|
|
static final class BufferedSubscription<T> implements Flow.Subscription, |
633 |
|
|
ForkJoinPool.ManagedBlocker { |
634 |
|
|
// Order-sensitive field declarations |
635 |
|
|
long timeout; // > 0 if timed wait |
636 |
|
|
volatile long demand; // # unfilled requests |
637 |
|
|
final int minCapacity; // initial buffer size |
638 |
|
|
int maxCapacity; // reduced on OOME |
639 |
|
|
int putStat; // offer result for ManagedBlocker |
640 |
|
|
volatile int ctl; // atomic run state flags |
641 |
|
|
volatile int head; // next position to take |
642 |
|
|
volatile int tail; // next position to put |
643 |
|
|
boolean wasInterrupted; // true if interrupted while waiting |
644 |
|
|
volatile Object[] array; // buffer: null if disabled |
645 |
|
|
Flow.Subscriber<? super T> subscriber; // null if disabled |
646 |
|
|
Executor executor; // null if disabled |
647 |
|
|
volatile Throwable pendingError; // holds until onError issued |
648 |
|
|
volatile Thread waiter; // blocked producer thread |
649 |
|
|
T putItem; // for offer within ManagedBlocker |
650 |
|
|
BufferedSubscription<T> next; // used only by publisher |
651 |
|
|
|
652 |
|
|
// ctl values |
653 |
|
|
static final int ACTIVE = 0x01; // consumer task active |
654 |
|
|
static final int ERROR = 0x02; // signal pending error |
655 |
|
|
static final int COMPLETE = 0x04; // signal completion when done |
656 |
|
|
static final int DISABLED = 0x80000000; // must be negative |
657 |
|
|
|
658 |
|
|
BufferedSubscription(Flow.Subscriber<? super T> subscriber, |
659 |
|
|
Executor executor, int minBufferCapacity, |
660 |
|
|
int maxBufferCapacity) { |
661 |
|
|
this.subscriber = subscriber; |
662 |
|
|
this.executor = executor; |
663 |
|
|
this.minCapacity = minBufferCapacity; |
664 |
|
|
this.maxCapacity = maxBufferCapacity; |
665 |
|
|
} |
666 |
|
|
|
667 |
|
|
/** |
668 |
|
|
* @return -1 if disabled, 0 if dropped, else 1 |
669 |
|
|
*/ |
670 |
|
|
final int offer(T item) { |
671 |
|
|
Object[] a = array; |
672 |
|
|
int t = tail, h = head, mask; |
673 |
|
|
if (a == null || (mask = a.length - 1) < 0 || t - h >= mask) |
674 |
|
|
return growAndOffer(item); |
675 |
|
|
else { |
676 |
|
|
a[t & mask] = item; |
677 |
|
|
U.putOrderedInt(this, TAIL, t + 1); |
678 |
|
|
return (ctl & ACTIVE) != 0 ? 1 : startOnOffer(); |
679 |
|
|
} |
680 |
|
|
} |
681 |
|
|
|
682 |
|
|
/** |
683 |
jsr166 |
1.9 |
* Creates or expands buffer if possible, then offers. |
684 |
dl |
1.1 |
*/ |
685 |
|
|
final int growAndOffer(T item) { |
686 |
|
|
int oldLen, len; |
687 |
|
|
Object[] oldA = array, a = null; |
688 |
|
|
if (oldA != null) |
689 |
|
|
len = (oldLen = oldA.length) << 1; |
690 |
|
|
else if (ctl < 0) |
691 |
|
|
return -1; // disabled |
692 |
|
|
else { |
693 |
|
|
oldLen = 0; |
694 |
|
|
len = minCapacity; |
695 |
|
|
} |
696 |
|
|
if (oldLen >= maxCapacity || len <= 0) |
697 |
|
|
return 0; |
698 |
|
|
try { |
699 |
|
|
a = new Object[len]; |
700 |
|
|
} catch (Throwable ex) { // try to cope with OOME |
701 |
|
|
if (oldLen != 0) // avoid continuous failure |
702 |
|
|
maxCapacity = oldLen; |
703 |
|
|
return 0; |
704 |
|
|
} |
705 |
|
|
array = a; |
706 |
|
|
int oldMask = oldLen - 1, mask = len - 1, oldTail = tail, j = head; |
707 |
|
|
if (oldA != null && oldMask >= 0 && mask > oldMask) { |
708 |
|
|
for (Object x; j != oldTail; ++j) { // races with consumer |
709 |
|
|
int i = j & oldMask; |
710 |
|
|
if ((x = oldA[i]) != null && |
711 |
|
|
U.compareAndSwapObject(oldA, |
712 |
|
|
(((long)i) << ASHIFT) + ABASE, |
713 |
|
|
x, null)) |
714 |
|
|
a[j & mask] = x; |
715 |
|
|
} |
716 |
|
|
} |
717 |
|
|
a[j & mask] = item; |
718 |
|
|
U.putOrderedInt(this, TAIL, j + 1); |
719 |
|
|
return startOnOffer(); |
720 |
|
|
} |
721 |
|
|
|
722 |
|
|
/** |
723 |
jsr166 |
1.5 |
* Tries to start consumer task if items are available. |
724 |
|
|
* Backs out and relays exception if executor fails. |
725 |
dl |
1.1 |
*/ |
726 |
|
|
final int startOnOffer() { |
727 |
|
|
for (;;) { |
728 |
|
|
int c; Executor e; |
729 |
|
|
if (((c = ctl) & ACTIVE) != 0 || demand == 0L || tail == head) |
730 |
|
|
break; |
731 |
|
|
if (c < 0 || (e = executor) == null) |
732 |
|
|
return -1; |
733 |
|
|
if (U.compareAndSwapInt(this, CTL, c, c | ACTIVE)) { |
734 |
|
|
try { |
735 |
|
|
e.execute(new ConsumerTask<T>(this)); |
736 |
|
|
break; |
737 |
|
|
} catch (RuntimeException | Error ex) { // back out |
738 |
|
|
for (;;) { |
739 |
|
|
if ((c = ctl) < 0 || (c & ACTIVE) == 0 || |
740 |
|
|
U.compareAndSwapInt(this, CTL, c, c & ~ACTIVE)) |
741 |
|
|
throw ex; |
742 |
|
|
} |
743 |
|
|
} |
744 |
|
|
} |
745 |
|
|
} |
746 |
|
|
return 1; |
747 |
|
|
} |
748 |
|
|
|
749 |
|
|
/** |
750 |
|
|
* Tries to start consumer task upon a signal or request; |
751 |
|
|
* disables on failure |
752 |
|
|
*/ |
753 |
|
|
final void startOrDisable() { |
754 |
|
|
Executor e; // skip if already disabled |
755 |
|
|
if ((e = executor) != null) { |
756 |
|
|
try { |
757 |
|
|
e.execute(new ConsumerTask<T>(this)); |
758 |
jsr166 |
1.2 |
} catch (Throwable ex) { // back out and force signal |
759 |
dl |
1.1 |
for (int c;;) { |
760 |
|
|
if ((c = ctl) < 0 || (c & ACTIVE) == 0) |
761 |
|
|
break; |
762 |
|
|
if (U.compareAndSwapInt(this, CTL, c, c & ~ACTIVE)) { |
763 |
|
|
closeExceptionally(ex); |
764 |
|
|
break; |
765 |
|
|
} |
766 |
|
|
} |
767 |
|
|
} |
768 |
|
|
} |
769 |
|
|
} |
770 |
|
|
|
771 |
|
|
/** |
772 |
|
|
* Nulls out most fields, mainly to avoid garbage retention |
773 |
|
|
* until publisher unsubscribes. |
774 |
|
|
*/ |
775 |
|
|
final void detach() { |
776 |
|
|
pendingError = null; |
777 |
|
|
subscriber = null; |
778 |
|
|
executor = null; |
779 |
|
|
array = null; |
780 |
|
|
Thread w = waiter; |
781 |
|
|
if (w != null) { |
782 |
|
|
waiter = null; |
783 |
|
|
LockSupport.unpark(w); // force wakeup |
784 |
|
|
} |
785 |
|
|
} |
786 |
|
|
|
787 |
|
|
public void request(long n) { |
788 |
|
|
if (n > 0L) { |
789 |
|
|
for (;;) { |
790 |
|
|
long prev = demand, d; |
791 |
|
|
if ((d = prev + n) < prev) // saturate |
792 |
|
|
d = Long.MAX_VALUE; |
793 |
|
|
if (U.compareAndSwapLong(this, DEMAND, prev, d)) { |
794 |
|
|
for (int c, h;;) { |
795 |
|
|
if (((c = ctl) & (ACTIVE | DISABLED)) != 0 || |
796 |
|
|
demand == 0L) |
797 |
|
|
break; |
798 |
|
|
if ((h = head) != tail) { |
799 |
|
|
if (U.compareAndSwapInt(this, CTL, c, |
800 |
|
|
c | ACTIVE)) { |
801 |
|
|
startOrDisable(); |
802 |
|
|
break; |
803 |
|
|
} |
804 |
|
|
} |
805 |
|
|
else if (head == h && tail == h) |
806 |
|
|
break; |
807 |
|
|
} |
808 |
|
|
break; |
809 |
|
|
} |
810 |
|
|
} |
811 |
|
|
} |
812 |
|
|
else if (n < 0L) |
813 |
|
|
closeExceptionally(new IllegalArgumentException( |
814 |
|
|
"negative subscription request")); |
815 |
|
|
} |
816 |
|
|
|
817 |
|
|
public void cancel() { |
818 |
|
|
for (int c;;) { |
819 |
|
|
if ((c = ctl) < 0) |
820 |
|
|
break; |
821 |
|
|
else if ((c & ACTIVE) != 0) { |
822 |
|
|
if (U.compareAndSwapInt(this, CTL, c, c | ERROR)) |
823 |
|
|
break; // cause consumer task to exit |
824 |
|
|
} |
825 |
|
|
else if (U.compareAndSwapInt(this, CTL, c, DISABLED)) { |
826 |
|
|
detach(); |
827 |
|
|
break; |
828 |
|
|
} |
829 |
|
|
} |
830 |
|
|
} |
831 |
|
|
|
832 |
|
|
final void closeExceptionally(Throwable ex) { |
833 |
|
|
pendingError = ex; |
834 |
|
|
for (int c;;) { |
835 |
|
|
if ((c = ctl) < 0) |
836 |
|
|
break; |
837 |
|
|
else if ((c & ACTIVE) != 0) { |
838 |
|
|
if (U.compareAndSwapInt(this, CTL, c, c | ERROR)) |
839 |
|
|
break; // cause consumer task to exit |
840 |
|
|
} |
841 |
|
|
else if (U.compareAndSwapInt(this, CTL, c, DISABLED)) { |
842 |
|
|
Flow.Subscriber<? super T> s = subscriber; |
843 |
|
|
if (s != null) { |
844 |
|
|
try { |
845 |
|
|
s.onError(ex); |
846 |
jsr166 |
1.2 |
} catch (Throwable ignore) { |
847 |
dl |
1.1 |
} |
848 |
|
|
} |
849 |
|
|
detach(); |
850 |
|
|
break; |
851 |
|
|
} |
852 |
|
|
} |
853 |
|
|
} |
854 |
|
|
|
855 |
|
|
final void close() { |
856 |
|
|
for (int c;;) { |
857 |
|
|
if ((c = ctl) < 0) |
858 |
|
|
break; |
859 |
|
|
if (U.compareAndSwapInt(this, CTL, c, c | (ACTIVE | COMPLETE))) { |
860 |
|
|
if ((c & ACTIVE) == 0) |
861 |
|
|
startOrDisable(); |
862 |
|
|
break; |
863 |
|
|
} |
864 |
|
|
} |
865 |
|
|
} |
866 |
|
|
|
867 |
|
|
final int estimateAvailable() { |
868 |
|
|
int n; |
869 |
|
|
return (ctl >= 0 && (n = tail - head) > 0) ? n : 0; |
870 |
|
|
} |
871 |
|
|
|
872 |
|
|
// ManagedBlocker support |
873 |
|
|
|
874 |
|
|
public final boolean isReleasable() { |
875 |
|
|
T item = putItem; |
876 |
|
|
if (item != null) { |
877 |
|
|
if ((putStat = offer(item)) == 0) |
878 |
|
|
return false; |
879 |
|
|
putItem = null; |
880 |
|
|
} |
881 |
|
|
return true; |
882 |
|
|
} |
883 |
|
|
|
884 |
|
|
public final boolean block() { |
885 |
|
|
T item = putItem; |
886 |
|
|
if (item != null) { |
887 |
|
|
putItem = null; |
888 |
|
|
long nanos = timeout; |
889 |
|
|
long deadline = (nanos > 0L) ? System.nanoTime() + nanos : 0L; |
890 |
|
|
while ((putStat = offer(item)) == 0) { |
891 |
|
|
if (Thread.interrupted()) { |
892 |
|
|
wasInterrupted = true; |
893 |
|
|
if (nanos > 0L) |
894 |
|
|
break; |
895 |
|
|
} |
896 |
|
|
else if (nanos > 0L && |
897 |
|
|
(nanos = deadline - System.nanoTime()) <= 0L) |
898 |
|
|
break; |
899 |
|
|
else if (waiter == null) |
900 |
|
|
waiter = Thread.currentThread(); |
901 |
|
|
else { |
902 |
|
|
if (nanos > 0L) |
903 |
|
|
LockSupport.parkNanos(this, nanos); |
904 |
|
|
else |
905 |
|
|
LockSupport.park(this); |
906 |
|
|
waiter = null; |
907 |
|
|
} |
908 |
|
|
} |
909 |
|
|
} |
910 |
|
|
waiter = null; |
911 |
|
|
return true; |
912 |
|
|
} |
913 |
|
|
|
914 |
|
|
final int submit(T item) { |
915 |
|
|
putItem = item; |
916 |
|
|
timeout = 0L; |
917 |
|
|
wasInterrupted = false; |
918 |
|
|
try { |
919 |
|
|
ForkJoinPool.managedBlock(this); |
920 |
|
|
} catch (InterruptedException cantHappen) { |
921 |
|
|
} |
922 |
|
|
if (wasInterrupted) |
923 |
|
|
Thread.currentThread().interrupt(); |
924 |
|
|
return putStat; |
925 |
|
|
} |
926 |
|
|
|
927 |
|
|
final int timedOffer(T item, long nanos) { |
928 |
|
|
if (nanos <= 0L) |
929 |
|
|
return 0; |
930 |
|
|
putItem = item; |
931 |
|
|
timeout = nanos; |
932 |
|
|
wasInterrupted = false; |
933 |
|
|
try { |
934 |
|
|
ForkJoinPool.managedBlock(this); |
935 |
|
|
} catch (InterruptedException cantHappen) { |
936 |
|
|
} |
937 |
|
|
if (wasInterrupted) |
938 |
|
|
Thread.currentThread().interrupt(); |
939 |
|
|
return putStat; |
940 |
|
|
} |
941 |
|
|
|
942 |
|
|
/** Consume loop called only from ConsumerTask */ |
943 |
|
|
final void consume() { |
944 |
|
|
Flow.Subscriber<? super T> s; |
945 |
|
|
if ((s = subscriber) != null) { // else disabled |
946 |
|
|
for (;;) { |
947 |
|
|
long d = demand; // read volatile fields in acceptable order |
948 |
|
|
int c = ctl; |
949 |
|
|
int h = head; |
950 |
|
|
int t = tail; |
951 |
|
|
Object[] a = array; |
952 |
|
|
int i, n; Object x; Thread w; |
953 |
|
|
if (c < 0) { |
954 |
|
|
detach(); |
955 |
|
|
break; |
956 |
|
|
} |
957 |
|
|
else if ((c & ERROR) != 0) { |
958 |
|
|
Throwable ex = pendingError; |
959 |
|
|
ctl = DISABLED; // no need for CAS |
960 |
|
|
if (ex != null) { |
961 |
|
|
try { |
962 |
|
|
s.onError(ex); |
963 |
jsr166 |
1.2 |
} catch (Throwable ignore) { |
964 |
dl |
1.1 |
} |
965 |
|
|
} |
966 |
|
|
} |
967 |
|
|
else if (h == t) { // empty |
968 |
|
|
if (h == tail && |
969 |
|
|
U.compareAndSwapInt(this, CTL, c, c &= ~ACTIVE)) { |
970 |
|
|
if (h != tail || c != (c = ctl)) { // recheck |
971 |
|
|
if ((c & (ACTIVE | DISABLED)) != 0 || |
972 |
|
|
!U.compareAndSwapInt(this, CTL, c, |
973 |
|
|
c | ACTIVE)) |
974 |
|
|
break; |
975 |
|
|
} |
976 |
|
|
else if ((c & COMPLETE) != 0) { |
977 |
|
|
ctl = DISABLED; |
978 |
|
|
try { |
979 |
|
|
s.onComplete(); |
980 |
jsr166 |
1.2 |
} catch (Throwable ignore) { |
981 |
dl |
1.1 |
} |
982 |
|
|
} |
983 |
|
|
else |
984 |
|
|
break; |
985 |
|
|
} |
986 |
|
|
} |
987 |
|
|
else if (d == 0L) { // can't take |
988 |
|
|
if (demand == 0L && |
989 |
|
|
U.compareAndSwapInt(this, CTL, c, c &= ~ACTIVE) && |
990 |
|
|
((demand == 0L && c == (c = ctl)) || // recheck |
991 |
|
|
(c & (ACTIVE | DISABLED)) != 0 || |
992 |
|
|
!U.compareAndSwapInt(this, CTL, c, c | ACTIVE))) |
993 |
|
|
break; |
994 |
|
|
} |
995 |
|
|
else if (a != null && |
996 |
|
|
(n = a.length) > 0 && |
997 |
|
|
(x = a[i = h & (n - 1)]) != null && |
998 |
|
|
U.compareAndSwapObject( |
999 |
|
|
a, (((long)i) << ASHIFT) + ABASE, x, null)) { |
1000 |
|
|
U.putOrderedInt(this, HEAD, h + 1); |
1001 |
|
|
while (!U.compareAndSwapLong(this, DEMAND, d, d - 1L)) |
1002 |
|
|
d = demand; // almost never fails |
1003 |
|
|
if ((w = waiter) != null) { |
1004 |
|
|
waiter = null; |
1005 |
|
|
LockSupport.unpark(w); // release producer |
1006 |
|
|
} |
1007 |
|
|
try { |
1008 |
|
|
@SuppressWarnings("unchecked") T y = (T) x; |
1009 |
|
|
s.onNext(y); |
1010 |
jsr166 |
1.2 |
} catch (Throwable ex) { |
1011 |
dl |
1.1 |
ctl = DISABLED; |
1012 |
|
|
} |
1013 |
|
|
} |
1014 |
|
|
} |
1015 |
|
|
} |
1016 |
|
|
} |
1017 |
|
|
|
1018 |
jsr166 |
1.9 |
// Unsafe mechanics |
1019 |
|
|
private static final sun.misc.Unsafe U = sun.misc.Unsafe.getUnsafe(); |
1020 |
dl |
1.1 |
private static final long CTL; |
1021 |
|
|
private static final long TAIL; |
1022 |
|
|
private static final long HEAD; |
1023 |
|
|
private static final long DEMAND; |
1024 |
|
|
private static final int ABASE; |
1025 |
|
|
private static final int ASHIFT; |
1026 |
|
|
|
1027 |
|
|
static { |
1028 |
|
|
try { |
1029 |
|
|
CTL = U.objectFieldOffset |
1030 |
jsr166 |
1.9 |
(BufferedSubscription.class.getDeclaredField("ctl")); |
1031 |
dl |
1.1 |
TAIL = U.objectFieldOffset |
1032 |
jsr166 |
1.9 |
(BufferedSubscription.class.getDeclaredField("tail")); |
1033 |
dl |
1.1 |
HEAD = U.objectFieldOffset |
1034 |
jsr166 |
1.9 |
(BufferedSubscription.class.getDeclaredField("head")); |
1035 |
dl |
1.1 |
DEMAND = U.objectFieldOffset |
1036 |
jsr166 |
1.9 |
(BufferedSubscription.class.getDeclaredField("demand")); |
1037 |
|
|
|
1038 |
|
|
ABASE = U.arrayBaseOffset(Object[].class); |
1039 |
|
|
int scale = U.arrayIndexScale(Object[].class); |
1040 |
dl |
1.1 |
if ((scale & (scale - 1)) != 0) |
1041 |
|
|
throw new Error("data type scale not a power of two"); |
1042 |
|
|
ASHIFT = 31 - Integer.numberOfLeadingZeros(scale); |
1043 |
jsr166 |
1.9 |
} catch (ReflectiveOperationException e) { |
1044 |
dl |
1.1 |
throw new Error(e); |
1045 |
|
|
} |
1046 |
|
|
} |
1047 |
|
|
} |
1048 |
|
|
|
1049 |
|
|
static final class TransformProcessor<U,R> implements Flow.Processor<U,R> { |
1050 |
|
|
final Function<? super U, ? extends R> fn; |
1051 |
|
|
final SubmissionPublisher<R> sink; |
1052 |
|
|
Flow.Subscription subscription; |
1053 |
|
|
final long requestSize; |
1054 |
|
|
long count; |
1055 |
|
|
TransformProcessor(long requestSize, |
1056 |
|
|
Function<? super U, ? extends R> fn, |
1057 |
|
|
SubmissionPublisher<R> sink) { |
1058 |
|
|
this.fn = fn; |
1059 |
|
|
this.sink = sink; |
1060 |
|
|
this.requestSize = requestSize; |
1061 |
|
|
this.count = requestSize >>> 1; |
1062 |
|
|
} |
1063 |
|
|
public void subscribe(Flow.Subscriber<? super R> subscriber) { |
1064 |
|
|
sink.subscribe(subscriber); |
1065 |
|
|
} |
1066 |
|
|
public void onSubscribe(Flow.Subscription subscription) { |
1067 |
|
|
(this.subscription = subscription).request(requestSize); |
1068 |
|
|
} |
1069 |
|
|
public void onNext(U item) { |
1070 |
|
|
Flow.Subscription s = subscription; |
1071 |
|
|
if (s == null) |
1072 |
|
|
sink.closeExceptionally( |
1073 |
|
|
new IllegalStateException("onNext without subscription")); |
1074 |
|
|
else { |
1075 |
|
|
try { |
1076 |
|
|
if (--count <= 0) |
1077 |
|
|
s.request(count = requestSize); |
1078 |
|
|
sink.submit(fn.apply(item)); |
1079 |
|
|
} catch (Throwable ex) { |
1080 |
|
|
try { |
1081 |
|
|
s.cancel(); |
1082 |
|
|
} finally { |
1083 |
|
|
sink.closeExceptionally(ex); |
1084 |
|
|
} |
1085 |
|
|
} |
1086 |
|
|
} |
1087 |
|
|
} |
1088 |
|
|
public void onError(Throwable ex) { |
1089 |
|
|
sink.closeExceptionally(ex); |
1090 |
|
|
} |
1091 |
|
|
public void onComplete() { |
1092 |
|
|
sink.close(); |
1093 |
|
|
} |
1094 |
|
|
} |
1095 |
|
|
} |