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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.internal.operators.flowable;
import java.util.concurrent.atomic.*;
import org.reactivestreams.*;
import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.exceptions.*;
import io.reactivex.functions.Function;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.fuseable.*;
import io.reactivex.internal.subscriptions.*;
import io.reactivex.internal.util.*;
import io.reactivex.plugins.RxJavaPlugins;
/**
* Multicasts a Flowable over a selector function.
*
* @param the input value type
* @param the output value type
*/
public final class FlowablePublishMulticast extends AbstractFlowableWithUpstream {
final Function, ? extends Publisher> selector;
final int prefetch;
final boolean delayError;
public FlowablePublishMulticast(Flowable source,
Function, ? extends Publisher> selector, int prefetch,
boolean delayError) {
super(source);
this.selector = selector;
this.prefetch = prefetch;
this.delayError = delayError;
}
@Override
protected void subscribeActual(Subscriber s) {
MulticastProcessor mp = new MulticastProcessor(prefetch, delayError);
Publisher other;
try {
other = ObjectHelper.requireNonNull(selector.apply(mp), "selector returned a null Publisher");
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
EmptySubscription.error(ex, s);
return;
}
OutputCanceller out = new OutputCanceller(s, mp);
other.subscribe(out);
source.subscribe(mp);
}
static final class OutputCanceller implements FlowableSubscriber, Subscription {
final Subscriber downstream;
final MulticastProcessor processor;
Subscription upstream;
OutputCanceller(Subscriber actual, MulticastProcessor processor) {
this.downstream = actual;
this.processor = processor;
}
@Override
public void onSubscribe(Subscription s) {
if (SubscriptionHelper.validate(this.upstream, s)) {
this.upstream = s;
downstream.onSubscribe(this);
}
}
@Override
public void onNext(R t) {
downstream.onNext(t);
}
@Override
public void onError(Throwable t) {
downstream.onError(t);
processor.dispose();
}
@Override
public void onComplete() {
downstream.onComplete();
processor.dispose();
}
@Override
public void request(long n) {
upstream.request(n);
}
@Override
public void cancel() {
upstream.cancel();
processor.dispose();
}
}
static final class MulticastProcessor extends Flowable implements FlowableSubscriber, Disposable {
@SuppressWarnings("rawtypes")
static final MulticastSubscription[] EMPTY = new MulticastSubscription[0];
@SuppressWarnings("rawtypes")
static final MulticastSubscription[] TERMINATED = new MulticastSubscription[0];
final AtomicInteger wip;
final AtomicReference[]> subscribers;
final int prefetch;
final int limit;
final boolean delayError;
final AtomicReference upstream;
volatile SimpleQueue queue;
int sourceMode;
volatile boolean done;
Throwable error;
int consumed;
@SuppressWarnings("unchecked")
MulticastProcessor(int prefetch, boolean delayError) {
this.prefetch = prefetch;
this.limit = prefetch - (prefetch >> 2); // request after 75% consumption
this.delayError = delayError;
this.wip = new AtomicInteger();
this.upstream = new AtomicReference();
this.subscribers = new AtomicReference[]>(EMPTY);
}
@Override
public void onSubscribe(Subscription s) {
if (SubscriptionHelper.setOnce(this.upstream, s)) {
if (s instanceof QueueSubscription) {
@SuppressWarnings("unchecked")
QueueSubscription qs = (QueueSubscription) s;
int m = qs.requestFusion(QueueSubscription.ANY);
if (m == QueueSubscription.SYNC) {
sourceMode = m;
queue = qs;
done = true;
drain();
return;
}
if (m == QueueSubscription.ASYNC) {
sourceMode = m;
queue = qs;
QueueDrainHelper.request(s, prefetch);
return;
}
}
queue = QueueDrainHelper.createQueue(prefetch);
QueueDrainHelper.request(s, prefetch);
}
}
@Override
public void dispose() {
SubscriptionHelper.cancel(upstream);
if (wip.getAndIncrement() == 0) {
SimpleQueue q = queue;
if (q != null) {
q.clear();
}
}
}
@Override
public boolean isDisposed() {
return upstream.get() == SubscriptionHelper.CANCELLED;
}
@Override
public void onNext(T t) {
if (done) {
return;
}
if (sourceMode == QueueSubscription.NONE && !queue.offer(t)) {
upstream.get().cancel();
onError(new MissingBackpressureException());
return;
}
drain();
}
@Override
public void onError(Throwable t) {
if (done) {
RxJavaPlugins.onError(t);
return;
}
error = t;
done = true;
drain();
}
@Override
public void onComplete() {
if (!done) {
done = true;
drain();
}
}
boolean add(MulticastSubscription s) {
for (;;) {
MulticastSubscription[] current = subscribers.get();
if (current == TERMINATED) {
return false;
}
int n = current.length;
@SuppressWarnings("unchecked")
MulticastSubscription[] next = new MulticastSubscription[n + 1];
System.arraycopy(current, 0, next, 0, n);
next[n] = s;
if (subscribers.compareAndSet(current, next)) {
return true;
}
}
}
@SuppressWarnings("unchecked")
void remove(MulticastSubscription s) {
for (;;) {
MulticastSubscription[] current = subscribers.get();
int n = current.length;
if (n == 0) {
return;
}
int j = -1;
for (int i = 0; i < n; i++) {
if (current[i] == s) {
j = i;
break;
}
}
if (j < 0) {
return;
}
MulticastSubscription[] next;
if (n == 1) {
next = EMPTY;
} else {
next = new MulticastSubscription[n - 1];
System.arraycopy(current, 0, next, 0, j);
System.arraycopy(current, j + 1, next, j, n - j - 1);
}
if (subscribers.compareAndSet(current, next)) {
return;
}
}
}
@Override
protected void subscribeActual(Subscriber s) {
MulticastSubscription ms = new MulticastSubscription(s, this);
s.onSubscribe(ms);
if (add(ms)) {
if (ms.isCancelled()) {
remove(ms);
return;
}
drain();
} else {
Throwable ex = error;
if (ex != null) {
s.onError(ex);
} else {
s.onComplete();
}
}
}
void drain() {
if (wip.getAndIncrement() != 0) {
return;
}
int missed = 1;
SimpleQueue q = queue;
int upstreamConsumed = consumed;
int localLimit = limit;
boolean canRequest = sourceMode != QueueSubscription.SYNC;
AtomicReference[]> subs = subscribers;
MulticastSubscription[] array = subs.get();
outer:
for (;;) {
int n = array.length;
if (q != null && n != 0) {
long r = Long.MAX_VALUE;
for (MulticastSubscription ms : array) {
long u = ms.get() - ms.emitted;
if (u != Long.MIN_VALUE) {
if (r > u) {
r = u;
}
} else {
n--;
}
}
if (n == 0) {
r = 0;
}
while (r != 0) {
if (isDisposed()) {
q.clear();
return;
}
boolean d = done;
if (d && !delayError) {
Throwable ex = error;
if (ex != null) {
errorAll(ex);
return;
}
}
T v;
try {
v = q.poll();
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
SubscriptionHelper.cancel(upstream);
errorAll(ex);
return;
}
boolean empty = v == null;
if (d && empty) {
Throwable ex = error;
if (ex != null) {
errorAll(ex);
} else {
completeAll();
}
return;
}
if (empty) {
break;
}
boolean subscribersChange = false;
for (MulticastSubscription ms : array) {
long msr = ms.get();
if (msr != Long.MIN_VALUE) {
if (msr != Long.MAX_VALUE) {
ms.emitted++;
}
ms.downstream.onNext(v);
} else {
subscribersChange = true;
}
}
r--;
if (canRequest && ++upstreamConsumed == localLimit) {
upstreamConsumed = 0;
upstream.get().request(localLimit);
}
MulticastSubscription[] freshArray = subs.get();
if (subscribersChange || freshArray != array) {
array = freshArray;
continue outer;
}
}
if (r == 0) {
if (isDisposed()) {
q.clear();
return;
}
boolean d = done;
if (d && !delayError) {
Throwable ex = error;
if (ex != null) {
errorAll(ex);
return;
}
}
if (d && q.isEmpty()) {
Throwable ex = error;
if (ex != null) {
errorAll(ex);
} else {
completeAll();
}
return;
}
}
}
consumed = upstreamConsumed;
missed = wip.addAndGet(-missed);
if (missed == 0) {
break;
}
if (q == null) {
q = queue;
}
array = subs.get();
}
}
@SuppressWarnings("unchecked")
void errorAll(Throwable ex) {
for (MulticastSubscription ms : subscribers.getAndSet(TERMINATED)) {
if (ms.get() != Long.MIN_VALUE) {
ms.downstream.onError(ex);
}
}
}
@SuppressWarnings("unchecked")
void completeAll() {
for (MulticastSubscription ms : subscribers.getAndSet(TERMINATED)) {
if (ms.get() != Long.MIN_VALUE) {
ms.downstream.onComplete();
}
}
}
}
static final class MulticastSubscription
extends AtomicLong
implements Subscription {
private static final long serialVersionUID = 8664815189257569791L;
final Subscriber downstream;
final MulticastProcessor parent;
long emitted;
MulticastSubscription(Subscriber actual, MulticastProcessor parent) {
this.downstream = actual;
this.parent = parent;
}
@Override
public void request(long n) {
if (SubscriptionHelper.validate(n)) {
BackpressureHelper.addCancel(this, n);
parent.drain();
}
}
@Override
public void cancel() {
if (getAndSet(Long.MIN_VALUE) != Long.MIN_VALUE) {
parent.remove(this);
parent.drain(); // unblock the others
}
}
public boolean isCancelled() {
return get() == Long.MIN_VALUE;
}
}
}
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