/**
* Copyright 2014 Netflix, Inc.
*
* 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 rx.internal.operators;
import rx.*;
import rx.
Observable.
Operator;
import rx.exceptions.
Exceptions;
import rx.functions.
Func1;
import rx.internal.producers.
ProducerArbiter;
import rx.plugins.
RxJavaHooks;
import rx.subscriptions.
SerialSubscription;
/**
* Instruct an Observable to pass control to another Observable (the return value of a function)
* rather than invoking {@code onError} if it encounters an error.
* <p>
* <img width="640" src="https://github.com/ReactiveX/RxJava/wiki/images/rx-operators/onErrorResumeNext.png" alt="">
* <p>
* By default, when an Observable encounters an error that prevents it from emitting the expected item to its
* Observer, the Observable invokes its Observer's {@code onError} method, and then quits without invoking any
* more of its Observer's methods. The {@code onErrorResumeNext} operation changes this behavior. If you pass a
* function that returns an Observable ({@code resumeFunction}) to {@code onErrorResumeNext}, if the source
* Observable encounters an error, instead of invoking its Observer's {@code onError} method, it will instead
* relinquish control to this new Observable, which will invoke the Observer's {@code onNext} method if it is
* able to do so. In such a case, because no Observable necessarily invokes {@code onError}, the Observer may
* never know that an error happened.
* <p>
* You can use this to prevent errors from propagating or to supply fallback data should errors be
* encountered.
* @param <T> the value type
*/
public final class
OperatorOnErrorResumeNextViaFunction<T> implements
Operator<T, T> {
final
Func1<? super
Throwable, ? extends
Observable<? extends T>>
resumeFunction;
public static <T>
OperatorOnErrorResumeNextViaFunction<T>
withSingle(final
Func1<? super
Throwable, ? extends T>
resumeFunction) {
return new
OperatorOnErrorResumeNextViaFunction<T>(new
Func1<
Throwable,
Observable<? extends T>>() {
@
Override
public
Observable<? extends T>
call(
Throwable t) {
return
Observable.
just(
resumeFunction.
call(
t));
}
});
}
public static <T>
OperatorOnErrorResumeNextViaFunction<T>
withOther(final
Observable<? extends T>
other) {
return new
OperatorOnErrorResumeNextViaFunction<T>(new
Func1<
Throwable,
Observable<? extends T>>() {
@
Override
public
Observable<? extends T>
call(
Throwable t) {
return
other;
}
});
}
public static <T>
OperatorOnErrorResumeNextViaFunction<T>
withException(final
Observable<? extends T>
other) {
return new
OperatorOnErrorResumeNextViaFunction<T>(new
Func1<
Throwable,
Observable<? extends T>>() {
@
Override
public
Observable<? extends T>
call(
Throwable t) {
if (
t instanceof
Exception) {
return
other;
}
return
Observable.
error(
t);
}
});
}
public
OperatorOnErrorResumeNextViaFunction(
Func1<? super
Throwable, ? extends
Observable<? extends T>>
f) {
this.
resumeFunction =
f;
}
@
Override
public
Subscriber<? super T>
call(final
Subscriber<? super T>
child) {
final
ProducerArbiter pa = new
ProducerArbiter();
final
SerialSubscription serial = new
SerialSubscription();
Subscriber<T>
parent = new
Subscriber<T>() {
private boolean
done;
long
produced;
@
Override
public void
onCompleted() {
if (
done) {
return;
}
done = true;
child.
onCompleted();
}
@
Override
public void
onError(
Throwable e) {
if (
done) {
Exceptions.
throwIfFatal(
e);
RxJavaHooks.
onError(
e);
return;
}
done = true;
try {
unsubscribe();
Subscriber<T>
next = new
Subscriber<T>() {
@
Override
public void
onNext(T
t) {
child.
onNext(
t);
}
@
Override
public void
onError(
Throwable e) {
child.
onError(
e);
}
@
Override
public void
onCompleted() {
child.
onCompleted();
}
@
Override
public void
setProducer(
Producer producer) {
pa.
setProducer(
producer);
}
};
serial.
set(
next);
long
p =
produced;
if (
p != 0L) {
pa.
produced(
p);
}
Observable<? extends T>
resume =
resumeFunction.
call(
e);
resume.
unsafeSubscribe(
next);
} catch (
Throwable e2) {
Exceptions.
throwOrReport(
e2,
child);
}
}
@
Override
public void
onNext(T
t) {
if (
done) {
return;
}
produced++;
child.
onNext(
t);
}
@
Override
public void
setProducer(final
Producer producer) {
pa.
setProducer(
producer);
}
};
serial.
set(
parent);
child.
add(
serial);
child.
setProducer(
pa);
return
parent;
}
}