/**
* 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.mixed;
import java.util.concurrent.atomic.*;
import io.reactivex.*;
import io.reactivex.disposables.
Disposable;
import io.reactivex.exceptions.
Exceptions;
import io.reactivex.functions.
Function;
import io.reactivex.internal.disposables.
DisposableHelper;
import io.reactivex.internal.functions.
ObjectHelper;
import io.reactivex.internal.util.
AtomicThrowable;
import io.reactivex.plugins.
RxJavaPlugins;
/**
* Maps the upstream items into {@link SingleSource}s and switches (subscribes) to the newer ones
* while disposing the older ones and emits the latest success value if available, optionally delaying
* errors from the main source or the inner sources.
* <p>History: 2.1.11 - experimental
* @param <T> the upstream value type
* @param <R> the downstream value type
* @since 2.2
*/
public final class
ObservableSwitchMapSingle<T, R> extends
Observable<R> {
final
Observable<T>
source;
final
Function<? super T, ? extends
SingleSource<? extends R>>
mapper;
final boolean
delayErrors;
public
ObservableSwitchMapSingle(
Observable<T>
source,
Function<? super T, ? extends
SingleSource<? extends R>>
mapper,
boolean
delayErrors) {
this.
source =
source;
this.
mapper =
mapper;
this.
delayErrors =
delayErrors;
}
@
Override
protected void
subscribeActual(
Observer<? super R>
observer) {
if (!
ScalarXMapZHelper.
tryAsSingle(
source,
mapper,
observer)) {
source.
subscribe(new
SwitchMapSingleMainObserver<T, R>(
observer,
mapper,
delayErrors));
}
}
static final class
SwitchMapSingleMainObserver<T, R> extends
AtomicInteger
implements
Observer<T>,
Disposable {
private static final long
serialVersionUID = -5402190102429853762L;
final
Observer<? super R>
downstream;
final
Function<? super T, ? extends
SingleSource<? extends R>>
mapper;
final boolean
delayErrors;
final
AtomicThrowable errors;
final
AtomicReference<
SwitchMapSingleObserver<R>>
inner;
static final
SwitchMapSingleObserver<
Object>
INNER_DISPOSED =
new
SwitchMapSingleObserver<
Object>(null);
Disposable upstream;
volatile boolean
done;
volatile boolean
cancelled;
SwitchMapSingleMainObserver(
Observer<? super R>
downstream,
Function<? super T, ? extends
SingleSource<? extends R>>
mapper,
boolean
delayErrors) {
this.
downstream =
downstream;
this.
mapper =
mapper;
this.
delayErrors =
delayErrors;
this.
errors = new
AtomicThrowable();
this.
inner = new
AtomicReference<
SwitchMapSingleObserver<R>>();
}
@
Override
public void
onSubscribe(
Disposable d) {
if (
DisposableHelper.
validate(
upstream,
d)) {
upstream =
d;
downstream.
onSubscribe(this);
}
}
@
Override
@
SuppressWarnings({ "unchecked", "rawtypes" })
public void
onNext(T
t) {
SwitchMapSingleObserver<R>
current =
inner.
get();
if (
current != null) {
current.
dispose();
}
SingleSource<? extends R>
ss;
try {
ss =
ObjectHelper.
requireNonNull(
mapper.
apply(
t), "The mapper returned a null SingleSource");
} catch (
Throwable ex) {
Exceptions.
throwIfFatal(
ex);
upstream.
dispose();
inner.
getAndSet((
SwitchMapSingleObserver)
INNER_DISPOSED);
onError(
ex);
return;
}
SwitchMapSingleObserver<R>
observer = new
SwitchMapSingleObserver<R>(this);
for (;;) {
current =
inner.
get();
if (
current ==
INNER_DISPOSED) {
break;
}
if (
inner.
compareAndSet(
current,
observer)) {
ss.
subscribe(
observer);
break;
}
}
}
@
Override
public void
onError(
Throwable t) {
if (
errors.
addThrowable(
t)) {
if (!
delayErrors) {
disposeInner();
}
done = true;
drain();
} else {
RxJavaPlugins.
onError(
t);
}
}
@
Override
public void
onComplete() {
done = true;
drain();
}
@
SuppressWarnings({ "unchecked", "rawtypes" })
void
disposeInner() {
SwitchMapSingleObserver<R>
current =
inner.
getAndSet((
SwitchMapSingleObserver)
INNER_DISPOSED);
if (
current != null &&
current !=
INNER_DISPOSED) {
current.
dispose();
}
}
@
Override
public void
dispose() {
cancelled = true;
upstream.
dispose();
disposeInner();
}
@
Override
public boolean
isDisposed() {
return
cancelled;
}
void
innerError(
SwitchMapSingleObserver<R>
sender,
Throwable ex) {
if (
inner.
compareAndSet(
sender, null)) {
if (
errors.
addThrowable(
ex)) {
if (!
delayErrors) {
upstream.
dispose();
disposeInner();
}
drain();
return;
}
}
RxJavaPlugins.
onError(
ex);
}
void
drain() {
if (
getAndIncrement() != 0) {
return;
}
int
missed = 1;
Observer<? super R>
downstream = this.
downstream;
AtomicThrowable errors = this.
errors;
AtomicReference<
SwitchMapSingleObserver<R>>
inner = this.
inner;
for (;;) {
for (;;) {
if (
cancelled) {
return;
}
if (
errors.
get() != null) {
if (!
delayErrors) {
Throwable ex =
errors.
terminate();
downstream.
onError(
ex);
return;
}
}
boolean
d =
done;
SwitchMapSingleObserver<R>
current =
inner.
get();
boolean
empty =
current == null;
if (
d &&
empty) {
Throwable ex =
errors.
terminate();
if (
ex != null) {
downstream.
onError(
ex);
} else {
downstream.
onComplete();
}
return;
}
if (
empty ||
current.
item == null) {
break;
}
inner.
compareAndSet(
current, null);
downstream.
onNext(
current.
item);
}
missed =
addAndGet(-
missed);
if (
missed == 0) {
break;
}
}
}
static final class
SwitchMapSingleObserver<R>
extends
AtomicReference<
Disposable> implements
SingleObserver<R> {
private static final long
serialVersionUID = 8042919737683345351L;
final
SwitchMapSingleMainObserver<?, R>
parent;
volatile R
item;
SwitchMapSingleObserver(
SwitchMapSingleMainObserver<?, R>
parent) {
this.
parent =
parent;
}
@
Override
public void
onSubscribe(
Disposable d) {
DisposableHelper.
setOnce(this,
d);
}
@
Override
public void
onSuccess(R
t) {
item =
t;
parent.
drain();
}
@
Override
public void
onError(
Throwable e) {
parent.
innerError(this,
e);
}
void
dispose() {
DisposableHelper.
dispose(this);
}
}
}
}