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Reactive Extensions for Java
/*
* 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.rxjava3.internal.operators.parallel;
import java.util.concurrent.atomic.*;
import org.reactivestreams.*;
import io.reactivex.rxjava3.core.*;
import io.reactivex.rxjava3.core.Scheduler.Worker;
import io.reactivex.rxjava3.exceptions.*;
import io.reactivex.rxjava3.internal.schedulers.SchedulerMultiWorkerSupport;
import io.reactivex.rxjava3.internal.schedulers.SchedulerMultiWorkerSupport.WorkerCallback;
import io.reactivex.rxjava3.internal.subscriptions.SubscriptionHelper;
import io.reactivex.rxjava3.internal.util.BackpressureHelper;
import io.reactivex.rxjava3.operators.ConditionalSubscriber;
import io.reactivex.rxjava3.operators.SpscArrayQueue;
import io.reactivex.rxjava3.parallel.ParallelFlowable;
import io.reactivex.rxjava3.plugins.RxJavaPlugins;
/**
* Ensures each 'rail' from upstream runs on a Worker from a Scheduler.
*
* @param the value type
*/
public final class ParallelRunOn extends ParallelFlowable {
final ParallelFlowable source;
final Scheduler scheduler;
final int prefetch;
public ParallelRunOn(ParallelFlowable parent,
Scheduler scheduler, int prefetch) {
this.source = parent;
this.scheduler = scheduler;
this.prefetch = prefetch;
}
@Override
public void subscribe(Subscriber[] subscribers) {
subscribers = RxJavaPlugins.onSubscribe(this, subscribers);
if (!validate(subscribers)) {
return;
}
int n = subscribers.length;
@SuppressWarnings("unchecked")
final Subscriber[] parents = new Subscriber[n];
if (scheduler instanceof SchedulerMultiWorkerSupport) {
SchedulerMultiWorkerSupport multiworker = (SchedulerMultiWorkerSupport) scheduler;
multiworker.createWorkers(n, new MultiWorkerCallback(subscribers, parents));
} else {
for (int i = 0; i < n; i++) {
createSubscriber(i, subscribers, parents, scheduler.createWorker());
}
}
source.subscribe(parents);
}
void createSubscriber(int i, Subscriber[] subscribers,
Subscriber[] parents, Scheduler.Worker worker) {
Subscriber a = subscribers[i];
SpscArrayQueue q = new SpscArrayQueue<>(prefetch);
if (a instanceof ConditionalSubscriber) {
parents[i] = new RunOnConditionalSubscriber<>((ConditionalSubscriber)a, prefetch, q, worker);
} else {
parents[i] = new RunOnSubscriber<>(a, prefetch, q, worker);
}
}
final class MultiWorkerCallback implements WorkerCallback {
final Subscriber[] subscribers;
final Subscriber[] parents;
MultiWorkerCallback(Subscriber[] subscribers,
Subscriber[] parents) {
this.subscribers = subscribers;
this.parents = parents;
}
@Override
public void onWorker(int i, Worker w) {
createSubscriber(i, subscribers, parents, w);
}
}
@Override
public int parallelism() {
return source.parallelism();
}
abstract static class BaseRunOnSubscriber extends AtomicInteger
implements FlowableSubscriber, Subscription, Runnable {
private static final long serialVersionUID = 9222303586456402150L;
final int prefetch;
final int limit;
final SpscArrayQueue queue;
final Worker worker;
Subscription upstream;
volatile boolean done;
Throwable error;
final AtomicLong requested = new AtomicLong();
volatile boolean cancelled;
int consumed;
BaseRunOnSubscriber(int prefetch, SpscArrayQueue queue, Worker worker) {
this.prefetch = prefetch;
this.queue = queue;
this.limit = prefetch - (prefetch >> 2);
this.worker = worker;
}
@Override
public final void onNext(T t) {
if (done) {
return;
}
if (!queue.offer(t)) {
upstream.cancel();
onError(new QueueOverflowException());
return;
}
schedule();
}
@Override
public final void onError(Throwable t) {
if (done) {
RxJavaPlugins.onError(t);
return;
}
error = t;
done = true;
schedule();
}
@Override
public final void onComplete() {
if (done) {
return;
}
done = true;
schedule();
}
@Override
public final void request(long n) {
if (SubscriptionHelper.validate(n)) {
BackpressureHelper.add(requested, n);
schedule();
}
}
@Override
public final void cancel() {
if (!cancelled) {
cancelled = true;
upstream.cancel();
worker.dispose();
if (getAndIncrement() == 0) {
queue.clear();
}
}
}
final void schedule() {
if (getAndIncrement() == 0) {
worker.schedule(this);
}
}
}
static final class RunOnSubscriber extends BaseRunOnSubscriber {
private static final long serialVersionUID = 1075119423897941642L;
final Subscriber downstream;
RunOnSubscriber(Subscriber actual, int prefetch, SpscArrayQueue queue, Worker worker) {
super(prefetch, queue, worker);
this.downstream = actual;
}
@Override
public void onSubscribe(Subscription s) {
if (SubscriptionHelper.validate(this.upstream, s)) {
this.upstream = s;
downstream.onSubscribe(this);
s.request(prefetch);
}
}
@Override
public void run() {
int missed = 1;
int c = consumed;
SpscArrayQueue q = queue;
Subscriber a = downstream;
int lim = limit;
for (;;) {
long r = requested.get();
long e = 0L;
while (e != r) {
if (cancelled) {
q.clear();
return;
}
boolean d = done;
if (d) {
Throwable ex = error;
if (ex != null) {
q.clear();
a.onError(ex);
worker.dispose();
return;
}
}
T v = q.poll();
boolean empty = v == null;
if (d && empty) {
a.onComplete();
worker.dispose();
return;
}
if (empty) {
break;
}
a.onNext(v);
e++;
int p = ++c;
if (p == lim) {
c = 0;
upstream.request(p);
}
}
if (e == r) {
if (cancelled) {
q.clear();
return;
}
if (done) {
Throwable ex = error;
if (ex != null) {
q.clear();
a.onError(ex);
worker.dispose();
return;
}
if (q.isEmpty()) {
a.onComplete();
worker.dispose();
return;
}
}
}
if (e != 0L && r != Long.MAX_VALUE) {
requested.addAndGet(-e);
}
int w = get();
if (w == missed) {
consumed = c;
missed = addAndGet(-missed);
if (missed == 0) {
break;
}
} else {
missed = w;
}
}
}
}
static final class RunOnConditionalSubscriber extends BaseRunOnSubscriber {
private static final long serialVersionUID = 1075119423897941642L;
final ConditionalSubscriber downstream;
RunOnConditionalSubscriber(ConditionalSubscriber actual, int prefetch, SpscArrayQueue queue, Worker worker) {
super(prefetch, queue, worker);
this.downstream = actual;
}
@Override
public void onSubscribe(Subscription s) {
if (SubscriptionHelper.validate(this.upstream, s)) {
this.upstream = s;
downstream.onSubscribe(this);
s.request(prefetch);
}
}
@Override
public void run() {
int missed = 1;
int c = consumed;
SpscArrayQueue q = queue;
ConditionalSubscriber a = downstream;
int lim = limit;
for (;;) {
long r = requested.get();
long e = 0L;
while (e != r) {
if (cancelled) {
q.clear();
return;
}
boolean d = done;
if (d) {
Throwable ex = error;
if (ex != null) {
q.clear();
a.onError(ex);
worker.dispose();
return;
}
}
T v = q.poll();
boolean empty = v == null;
if (d && empty) {
a.onComplete();
worker.dispose();
return;
}
if (empty) {
break;
}
if (a.tryOnNext(v)) {
e++;
}
int p = ++c;
if (p == lim) {
c = 0;
upstream.request(p);
}
}
if (e == r) {
if (cancelled) {
q.clear();
return;
}
if (done) {
Throwable ex = error;
if (ex != null) {
q.clear();
a.onError(ex);
worker.dispose();
return;
}
if (q.isEmpty()) {
a.onComplete();
worker.dispose();
return;
}
}
}
if (e != 0L) {
BackpressureHelper.produced(requested, e);
}
consumed = c;
missed = addAndGet(-missed);
if (missed == 0) {
break;
}
}
}
}
}
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