/*
* Copyright (c) 2011-2018 Pivotal Software Inc, All Rights Reserved.
*
* 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 reactor.core.publisher;
import java.util.
Objects;
import java.util.concurrent.
Callable;
import java.util.function.
Function;
import org.reactivestreams.
Publisher;
import org.reactivestreams.
Subscriber;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Fuseable.
ConditionalSubscriber;
import reactor.core.publisher.
FluxUsingWhen.
UsingWhenSubscriber;
import reactor.core.publisher.
Operators.
DeferredSubscription;
import reactor.util.annotation.
Nullable;
import reactor.util.context.
Context;
/**
* Uses a resource, generated by a {@link Publisher} for each individual {@link Subscriber},
* while streaming the values from a {@link Publisher} derived from the same resource.
* Whenever the resulting sequence terminates, the relevant {@link Function} generates
* a "cleanup" {@link Publisher} that is invoked but doesn't change the content of the
* main sequence. Instead it just defers the termination (unless it errors, in which case
* the error suppresses the original termination signal).
*
* @param <T> the value type streamed
* @param <S> the resource type
*/
final class
MonoUsingWhen<T, S> extends
Mono<T> implements
SourceProducer<T> {
final
Publisher<S>
resourceSupplier;
final
Function<? super S, ? extends
Mono<? extends T>>
resourceClosure;
final
Function<? super S, ? extends
Publisher<?>>
asyncComplete;
final
Function<? super S, ? extends
Publisher<?>>
asyncError;
@
Nullable
final
Function<? super S, ? extends
Publisher<?>>
asyncCancel;
MonoUsingWhen(
Publisher<S>
resourceSupplier,
Function<? super S, ? extends
Mono<? extends T>>
resourceClosure,
Function<? super S, ? extends
Publisher<?>>
asyncComplete,
Function<? super S, ? extends
Publisher<?>>
asyncError,
@
Nullable Function<? super S, ? extends
Publisher<?>>
asyncCancel) {
this.
resourceSupplier =
Objects.
requireNonNull(
resourceSupplier, "resourceSupplier");
this.
resourceClosure =
Objects.
requireNonNull(
resourceClosure, "resourceClosure");
this.
asyncComplete =
Objects.
requireNonNull(
asyncComplete, "asyncComplete");
this.
asyncError =
Objects.
requireNonNull(
asyncError, "asyncError");
this.
asyncCancel =
asyncCancel;
}
@
Override
@
SuppressWarnings("unchecked")
public void
subscribe(
CoreSubscriber<? super T>
actual) {
if (
resourceSupplier instanceof
Callable) {
try {
Callable<S>
resourceCallable = (
Callable<S>)
resourceSupplier;
S
resource =
resourceCallable.
call();
if (
resource == null) {
Operators.
complete(
actual);
}
else {
final
Mono<? extends T>
p =
deriveMonoFromResource(
resource,
resourceClosure);
final
UsingWhenSubscriber<? super T, S>
subscriber =
prepareSubscriberForResource(
resource,
actual,
asyncComplete,
asyncError,
asyncCancel,
null);
p.
subscribe(
subscriber);
}
}
catch (
Throwable e) {
Operators.
error(
actual,
e);
}
return;
}
resourceSupplier.
subscribe(new
ResourceSubscriber(
actual,
resourceClosure,
asyncComplete,
asyncError,
asyncCancel,
resourceSupplier instanceof
Mono));
}
@
Override
public
Object scanUnsafe(
Attr key) {
return null; //no particular key to be represented, still useful in hooks
}
private static <RESOURCE, T>
Mono<? extends T>
deriveMonoFromResource(
RESOURCE
resource,
Function<? super RESOURCE, ? extends
Mono<? extends T>>
resourceClosure) {
Mono<? extends T>
p;
try {
p =
Objects.
requireNonNull(
resourceClosure.
apply(
resource),
"The resourceClosure function returned a null value");
}
catch (
Throwable e) {
p =
Mono.
error(
e);
}
return
p;
}
private static <RESOURCE, T>
UsingWhenSubscriber<? super T, RESOURCE>
prepareSubscriberForResource(
RESOURCE
resource,
CoreSubscriber<? super T>
actual,
Function<? super RESOURCE, ? extends
Publisher<?>>
asyncComplete,
Function<? super RESOURCE, ? extends
Publisher<?>>
asyncError,
@
Nullable Function<? super RESOURCE, ? extends
Publisher<?>>
asyncCancel,
@
Nullable DeferredSubscription arbiter) {
if (
actual instanceof
ConditionalSubscriber) {
@
SuppressWarnings("unchecked")
ConditionalSubscriber<? super T>
conditionalActual = (
ConditionalSubscriber<? super T>)
actual;
return new
FluxUsingWhen.
UsingWhenConditionalSubscriber<>(
conditionalActual,
resource,
asyncComplete,
asyncError,
asyncCancel,
arbiter);
}
else {
return new
UsingWhenSubscriber<>(
actual,
resource,
asyncComplete,
asyncError,
asyncCancel,
arbiter);
}
}
//needed to correctly call prepareSubscriberForResource with Mono.from conversions
static class
ResourceSubscriber<S, T> extends
DeferredSubscription implements
InnerConsumer<S> {
final
CoreSubscriber<? super T>
actual;
final
Function<? super S, ? extends
Mono<? extends T>>
resourceClosure;
final
Function<? super S, ? extends
Publisher<?>>
asyncComplete;
final
Function<? super S, ? extends
Publisher<?>>
asyncError;
@
Nullable
final
Function<? super S, ? extends
Publisher<?>>
asyncCancel;
final boolean
isMonoSource;
Subscription resourceSubscription;
boolean
resourceProvided;
UsingWhenSubscriber<? super T, S>
closureSubscriber;
ResourceSubscriber(
CoreSubscriber<? super T>
actual,
Function<? super S, ? extends
Mono<? extends T>>
resourceClosure,
Function<? super S, ? extends
Publisher<?>>
asyncComplete,
Function<? super S, ? extends
Publisher<?>>
asyncError,
@
Nullable Function<? super S, ? extends
Publisher<?>>
asyncCancel,
boolean
isMonoSource) {
this.
actual =
Objects.
requireNonNull(
actual, "actual");
this.
resourceClosure =
Objects.
requireNonNull(
resourceClosure, "resourceClosure");
this.
asyncComplete =
Objects.
requireNonNull(
asyncComplete, "asyncComplete");
this.
asyncError =
Objects.
requireNonNull(
asyncError, "asyncError");
this.
asyncCancel =
asyncCancel;
this.
isMonoSource =
isMonoSource;
}
@
Override
public
Context currentContext() {
return
actual.
currentContext();
}
@
Override
public void
onNext(S
resource) {
if (
resourceProvided) {
Operators.
onNextDropped(
resource,
actual.
currentContext());
return;
}
resourceProvided = true;
final
Mono<? extends T>
p =
deriveMonoFromResource(
resource,
resourceClosure);
this.
closureSubscriber =
prepareSubscriberForResource(
resource,
this.
actual,
this.
asyncComplete,
this.
asyncError,
this.
asyncCancel,
this);
p.
subscribe(
closureSubscriber);
if (!
isMonoSource) {
resourceSubscription.
cancel();
}
}
@
Override
public void
onError(
Throwable throwable) {
if (
resourceProvided) {
Operators.
onErrorDropped(
throwable,
actual.
currentContext());
return;
}
//even if no resource provided, actual.onSubscribe has been called
//let's immediately fail actual
actual.
onError(
throwable);
}
@
Override
public void
onComplete() {
if (
resourceProvided) {
return;
}
//even if no resource provided, actual.onSubscribe has been called
//let's immediately complete actual
actual.
onComplete();
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
validate(this.
resourceSubscription,
s)) {
this.
resourceSubscription =
s;
actual.
onSubscribe(this);
s.
request(
Long.
MAX_VALUE);
}
}
@
Override
public void
cancel() {
if (!
resourceProvided) {
resourceSubscription.
cancel();
super.cancel();
}
else {
Operators.
terminate(
S, this);
if (
closureSubscriber != null) {
closureSubscriber.
cancel();
}
}
}
@
Override
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
resourceSubscription;
if (
key ==
Attr.
ACTUAL) return
actual;
if (
key ==
Attr.
PREFETCH) return
Integer.
MAX_VALUE;
if (
key ==
Attr.
TERMINATED) return
resourceProvided;
return null;
}
}
}