| 33 |
|
* Subscriber}. It publishes items to the subscriber asynchronously, |
| 34 |
|
* normally using an {@link Executor}. For example, here is a very |
| 35 |
|
* simple publisher that only issues (when requested) a single {@code |
| 36 |
< |
* TRUE} item to any subscriber. Because each subscriber receives |
| 37 |
< |
* only the same single item, this class does not use buffering and |
| 38 |
< |
* ordering control required in most implementations (for example |
| 39 |
< |
* {@link SubmissionPublisher}). |
| 36 |
> |
* TRUE} item to a single subscriber. Because the subscriber receives |
| 37 |
> |
* only a single item, this class does not use buffering and ordering |
| 38 |
> |
* control required in most implementations (for example {@link |
| 39 |
> |
* SubmissionPublisher}). |
| 40 |
|
* |
| 41 |
|
* <pre> {@code |
| 42 |
|
* class OneShotPublisher implements Publisher<Boolean> { |
| 43 |
|
* final Executor executor = ForkJoinPool.commonPool(); // daemon-based |
| 44 |
< |
* public void subscribe(Subscriber<? super Boolean> subscriber) { |
| 44 |
> |
* boolean subscribed = false; // true after first subscribe |
| 45 |
> |
* public synchronized void subscribe(Subscriber<? super Boolean> subscriber) { |
| 46 |
> |
* if (subscribed) |
| 47 |
> |
* subscriber.onError(new IllegalStateException()); // only one allowed |
| 48 |
> |
* else { |
| 49 |
> |
* subscribed = true; |
| 50 |
|
* subscriber.onSubscribe(new OneShotSubscription(subscriber, executor)); |
| 51 |
+ |
* } |
| 52 |
|
* } |
| 53 |
|
* static class OneShotSubscription implements Subscription { |
| 54 |
|
* final Subscriber<? super Boolean> subscriber; |
| 55 |
|
* final Executor executor; |
| 56 |
< |
* boolean completed; |
| 56 |
> |
* boolean completed = false; |
| 57 |
|
* OneShotSubscription(Subscriber<? super Boolean> subscriber, |
| 58 |
|
* Executor executor) { |
| 59 |
|
* this.subscriber = subscriber; |
| 60 |
|
* this.executor = executor; |
| 61 |
|
* } |
| 62 |
|
* public synchronized void request(long n) { |
| 63 |
< |
* if (n > 0 && !completed) { |
| 63 |
> |
* if (n != 0 && !completed) { |
| 64 |
|
* completed = true; |
| 65 |
|
* executor.execute(() -> { |
| 66 |
< |
* subscriber.onNext(Boolean.TRUE); |
| 67 |
< |
* subscriber.onComplete(); |
| 68 |
< |
* }); |
| 66 |
> |
* if (n < 0) |
| 67 |
> |
* subscriber.onError(new IllegalArgumentException()); |
| 68 |
> |
* else { |
| 69 |
> |
* subscriber.onNext(Boolean.TRUE); |
| 70 |
> |
* subscriber.onComplete(); |
| 71 |
> |
* }}); |
| 72 |
|
* } |
| 64 |
– |
* else if (n < 0) { |
| 65 |
– |
* completed = true; |
| 66 |
– |
* subscriber.onError(new IllegalArgumentException()); |
| 67 |
– |
} |
| 73 |
|
* } |
| 74 |
|
* public synchronized void cancel() { |
| 75 |
|
* completed = true; // ineffective if task already started |
