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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.rxjava3.internal.operators.observable;
import java.util.concurrent.atomic.*;
import io.reactivex.rxjava3.core.*;
import io.reactivex.rxjava3.disposables.Disposable;
import io.reactivex.rxjava3.exceptions.Exceptions;
import io.reactivex.rxjava3.functions.Consumer;
import io.reactivex.rxjava3.internal.disposables.DisposableHelper;
import io.reactivex.rxjava3.internal.fuseable.HasUpstreamObservableSource;
import io.reactivex.rxjava3.internal.util.ExceptionHelper;
import io.reactivex.rxjava3.observables.ConnectableObservable;
import io.reactivex.rxjava3.plugins.RxJavaPlugins;
/**
* Shares a single underlying connection to the upstream ObservableSource
* and multicasts events to all subscribed observers until the upstream
* completes or the connection is disposed.
*
* The difference to ObservablePublish is that when the upstream terminates,
* late observers will receive that terminal event until the connection is
* disposed and the ConnectableObservable is reset to its fresh state.
*
* @param the element type
* @since 2.2.10
*/
public final class ObservablePublish extends ConnectableObservable
implements HasUpstreamObservableSource {
final ObservableSource source;
final AtomicReference> current;
public ObservablePublish(ObservableSource source) {
this.source = source;
this.current = new AtomicReference<>();
}
@Override
public void connect(Consumer connection) {
boolean doConnect = false;
PublishConnection conn;
for (;;) {
conn = current.get();
if (conn == null || conn.isDisposed()) {
PublishConnection fresh = new PublishConnection<>(current);
if (!current.compareAndSet(conn, fresh)) {
continue;
}
conn = fresh;
}
doConnect = !conn.connect.get() && conn.connect.compareAndSet(false, true);
break;
}
try {
connection.accept(conn);
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
throw ExceptionHelper.wrapOrThrow(ex);
}
if (doConnect) {
source.subscribe(conn);
}
}
@Override
protected void subscribeActual(Observer observer) {
PublishConnection conn;
for (;;) {
conn = current.get();
// we don't create a fresh connection if the current is terminated
if (conn == null) {
PublishConnection fresh = new PublishConnection<>(current);
if (!current.compareAndSet(conn, fresh)) {
continue;
}
conn = fresh;
}
break;
}
InnerDisposable inner = new InnerDisposable<>(observer, conn);
observer.onSubscribe(inner);
if (conn.add(inner)) {
if (inner.isDisposed()) {
conn.remove(inner);
}
return;
}
// Late observers will be simply terminated
Throwable error = conn.error;
if (error != null) {
observer.onError(error);
} else {
observer.onComplete();
}
}
@Override
public void reset() {
PublishConnection conn = current.get();
if (conn != null && conn.isDisposed()) {
current.compareAndSet(conn, null);
}
}
@Override
public ObservableSource source() {
return source;
}
static final class PublishConnection
extends AtomicReference[]>
implements Observer, Disposable {
private static final long serialVersionUID = -3251430252873581268L;
final AtomicBoolean connect;
final AtomicReference> current;
final AtomicReference upstream;
@SuppressWarnings("rawtypes")
static final InnerDisposable[] EMPTY = new InnerDisposable[0];
@SuppressWarnings("rawtypes")
static final InnerDisposable[] TERMINATED = new InnerDisposable[0];
Throwable error;
@SuppressWarnings("unchecked")
PublishConnection(AtomicReference> current) {
this.connect = new AtomicBoolean();
this.current = current;
this.upstream = new AtomicReference<>();
lazySet(EMPTY);
}
@SuppressWarnings("unchecked")
@Override
public void dispose() {
getAndSet(TERMINATED);
current.compareAndSet(this, null);
DisposableHelper.dispose(upstream);
}
@Override
public boolean isDisposed() {
return get() == TERMINATED;
}
@Override
public void onSubscribe(Disposable d) {
DisposableHelper.setOnce(upstream, d);
}
@Override
public void onNext(T t) {
for (InnerDisposable inner : get()) {
inner.downstream.onNext(t);
}
}
@Override
@SuppressWarnings("unchecked")
public void onError(Throwable e) {
if (upstream.get() != DisposableHelper.DISPOSED) {
error = e;
upstream.lazySet(DisposableHelper.DISPOSED);
for (InnerDisposable inner : getAndSet(TERMINATED)) {
inner.downstream.onError(e);
}
} else {
RxJavaPlugins.onError(e);
}
}
@Override
@SuppressWarnings("unchecked")
public void onComplete() {
upstream.lazySet(DisposableHelper.DISPOSED);
for (InnerDisposable inner : getAndSet(TERMINATED)) {
inner.downstream.onComplete();
}
}
public boolean add(InnerDisposable inner) {
for (;;) {
InnerDisposable[] a = get();
if (a == TERMINATED) {
return false;
}
int n = a.length;
@SuppressWarnings("unchecked")
InnerDisposable[] b = new InnerDisposable[n + 1];
System.arraycopy(a, 0, b, 0, n);
b[n] = inner;
if (compareAndSet(a, b)) {
return true;
}
}
}
@SuppressWarnings("unchecked")
public void remove(InnerDisposable inner) {
for (;;) {
InnerDisposable[] a = get();
int n = a.length;
if (n == 0) {
return;
}
int j = -1;
for (int i = 0; i < n; i++) {
if (a[i] == inner) {
j = i;
break;
}
}
if (j < 0) {
return;
}
InnerDisposable[] b = EMPTY;
if (n != 1) {
b = new InnerDisposable[n - 1];
System.arraycopy(a, 0, b, 0, j);
System.arraycopy(a, j + 1, b, j, n - j - 1);
}
if (compareAndSet(a, b)) {
return;
}
}
}
}
/**
* Intercepts the dispose signal from the downstream and
* removes itself from the connection's observers array
* at most once.
* @param the element type
*/
static final class InnerDisposable
extends AtomicReference>
implements Disposable {
private static final long serialVersionUID = 7463222674719692880L;
final Observer downstream;
InnerDisposable(Observer downstream, PublishConnection parent) {
this.downstream = downstream;
lazySet(parent);
}
@Override
public void dispose() {
PublishConnection p = getAndSet(null);
if (p != null) {
p.remove(this);
}
}
@Override
public boolean isDisposed() {
return get() == null;
}
}
}