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 * You may obtain a copy of the License at
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 *       https://www.apache.org/licenses/LICENSE-2.0
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package reactor.core.publisher;

import java.util.Objects;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.TimeUnit;

import org.reactivestreams.Subscription;
import reactor.core.CoreSubscriber;
import reactor.core.Disposable;
import reactor.core.scheduler.Scheduler;
import reactor.util.annotation.Nullable;

Emits the first value emitted by a given source publisher, delayed by some time amount with the help of a ScheduledExecutorService instance or a generic function callback that wraps other form of async-delayed execution of tasks.
Author:Simon Baslé TODO : Review impl
See Also:
/** * Emits the first value emitted by a given source publisher, delayed by some time amount * with the help of a ScheduledExecutorService instance or a generic function callback that * wraps other form of async-delayed execution of tasks. * * @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a> * @author Simon Baslé * TODO : Review impl */
final class MonoDelayElement<T> extends InternalMonoOperator<T, T> { final Scheduler timedScheduler; final long delay; final TimeUnit unit; MonoDelayElement(Mono<? extends T> source, long delay, TimeUnit unit, Scheduler timedScheduler) { super(source); this.delay = delay; this.unit = Objects.requireNonNull(unit, "unit"); this.timedScheduler = Objects.requireNonNull(timedScheduler, "timedScheduler"); } @Override public CoreSubscriber<? super T> subscribeOrReturn(CoreSubscriber<? super T> actual) { return new DelayElementSubscriber<>(actual, timedScheduler, delay, unit); } @Override public Object scanUnsafe(Attr key) { if (key == Attr.RUN_ON) return timedScheduler; if (key == Attr.RUN_STYLE) return Attr.RunStyle.ASYNC; return super.scanUnsafe(key); } static final class DelayElementSubscriber<T> extends Operators.MonoSubscriber<T,T> { final long delay; final Scheduler scheduler; final TimeUnit unit; Subscription s; volatile Disposable task; boolean done; DelayElementSubscriber(CoreSubscriber<? super T> actual, Scheduler scheduler, long delay, TimeUnit unit) { super(actual); this.scheduler = scheduler; this.delay = delay; this.unit = unit; } @Override @Nullable public Object scanUnsafe(Attr key) { if (key == Attr.TERMINATED) return done; if (key == Attr.PARENT) return s; if (key == Attr.RUN_ON) return scheduler; if (key == Attr.RUN_STYLE) return Attr.RunStyle.ASYNC; return super.scanUnsafe(key); } @Override public void cancel() { super.cancel(); if (task != null) { task.dispose(); } if (s != Operators.cancelledSubscription()) { s.cancel(); } } @Override public void onSubscribe(Subscription s) { if (Operators.validate(this.s, s)) { this.s = s; actual.onSubscribe(this); s.request(Long.MAX_VALUE); } } @Override public void onNext(T t) { if (done) { Operators.onNextDropped(t, actual.currentContext()); return; } this.done = true; try { this.task = scheduler.schedule(() -> complete(t), delay, unit); } catch (RejectedExecutionException ree) { actual.onError(Operators.onRejectedExecution(ree, this, null, t, actual.currentContext())); return; } } @Override public void onComplete() { if (done) { return; } this.done = true; actual.onComplete(); } @Override public void onError(Throwable t) { if (done) { Operators.onErrorDropped(t, actual.currentContext()); return; } this.done = true; actual.onError(t); } } }