io.reactivex.internal.operators.flowable.FlowableThrottleLatest Maven / Gradle / Ivy
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/**
* Copyright (c) 2016-present, RxJava Contributors.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is
* distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
* the License for the specific language governing permissions and limitations under the License.
*/
package io.reactivex.internal.operators.flowable;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.*;
import org.reactivestreams.*;
import io.reactivex.*;
import io.reactivex.exceptions.MissingBackpressureException;
import io.reactivex.internal.subscriptions.SubscriptionHelper;
import io.reactivex.internal.util.BackpressureHelper;
/**
* Emits the next or latest item when the given time elapses.
*
* The operator emits the next item, then starts a timer. When the timer fires,
* it tries to emit the latest item from upstream. If there was no upstream item,
* in the meantime, the next upstream item is emitted immediately and the
* timed process repeats.
*
History: 2.1.14 - experimental
* @param the upstream and downstream value type
* @since 2.2
*/
public final class FlowableThrottleLatest extends AbstractFlowableWithUpstream {
final long timeout;
final TimeUnit unit;
final Scheduler scheduler;
final boolean emitLast;
public FlowableThrottleLatest(Flowable source,
long timeout, TimeUnit unit, Scheduler scheduler,
boolean emitLast) {
super(source);
this.timeout = timeout;
this.unit = unit;
this.scheduler = scheduler;
this.emitLast = emitLast;
}
@Override
protected void subscribeActual(Subscriber s) {
source.subscribe(new ThrottleLatestSubscriber(s, timeout, unit, scheduler.createWorker(), emitLast));
}
static final class ThrottleLatestSubscriber
extends AtomicInteger
implements FlowableSubscriber, Subscription, Runnable {
private static final long serialVersionUID = -8296689127439125014L;
final Subscriber downstream;
final long timeout;
final TimeUnit unit;
final Scheduler.Worker worker;
final boolean emitLast;
final AtomicReference latest;
final AtomicLong requested;
Subscription upstream;
volatile boolean done;
Throwable error;
volatile boolean cancelled;
volatile boolean timerFired;
long emitted;
boolean timerRunning;
ThrottleLatestSubscriber(Subscriber downstream,
long timeout, TimeUnit unit, Scheduler.Worker worker,
boolean emitLast) {
this.downstream = downstream;
this.timeout = timeout;
this.unit = unit;
this.worker = worker;
this.emitLast = emitLast;
this.latest = new AtomicReference();
this.requested = new AtomicLong();
}
@Override
public void onSubscribe(Subscription s) {
if (SubscriptionHelper.validate(upstream, s)) {
upstream = s;
downstream.onSubscribe(this);
s.request(Long.MAX_VALUE);
}
}
@Override
public void onNext(T t) {
latest.set(t);
drain();
}
@Override
public void onError(Throwable t) {
error = t;
done = true;
drain();
}
@Override
public void onComplete() {
done = true;
drain();
}
@Override
public void request(long n) {
if (SubscriptionHelper.validate(n)) {
BackpressureHelper.add(requested, n);
}
}
@Override
public void cancel() {
cancelled = true;
upstream.cancel();
worker.dispose();
if (getAndIncrement() == 0) {
latest.lazySet(null);
}
}
@Override
public void run() {
timerFired = true;
drain();
}
void drain() {
if (getAndIncrement() != 0) {
return;
}
int missed = 1;
AtomicReference latest = this.latest;
AtomicLong requested = this.requested;
Subscriber downstream = this.downstream;
for (;;) {
for (;;) {
if (cancelled) {
latest.lazySet(null);
return;
}
boolean d = done;
if (d && error != null) {
latest.lazySet(null);
downstream.onError(error);
worker.dispose();
return;
}
T v = latest.get();
boolean empty = v == null;
if (d) {
if (!empty && emitLast) {
v = latest.getAndSet(null);
long e = emitted;
if (e != requested.get()) {
emitted = e + 1;
downstream.onNext(v);
downstream.onComplete();
} else {
downstream.onError(new MissingBackpressureException(
"Could not emit final value due to lack of requests"));
}
} else {
latest.lazySet(null);
downstream.onComplete();
}
worker.dispose();
return;
}
if (empty) {
if (timerFired) {
timerRunning = false;
timerFired = false;
}
break;
}
if (!timerRunning || timerFired) {
v = latest.getAndSet(null);
long e = emitted;
if (e != requested.get()) {
downstream.onNext(v);
emitted = e + 1;
} else {
upstream.cancel();
downstream.onError(new MissingBackpressureException(
"Could not emit value due to lack of requests"));
worker.dispose();
return;
}
timerFired = false;
timerRunning = true;
worker.schedule(this, timeout, unit);
} else {
break;
}
}
missed = addAndGet(-missed);
if (missed == 0) {
break;
}
}
}
}
}