/*
* Copyright (c) 2011-2017 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.concurrent.
RejectedExecutionException;
import java.util.concurrent.atomic.
AtomicLongFieldUpdater;
import java.util.concurrent.atomic.
AtomicReferenceFieldUpdater;
import org.reactivestreams.
Publisher;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.scheduler.
Scheduler;
import reactor.core.scheduler.
Scheduler.
Worker;
import reactor.util.annotation.
Nullable;
/**
* Subscribes to the upstream Mono on the specified Scheduler and makes sure
* any request from downstream is issued on the same worker where the subscription
* happened.
*
* @param <T> the value type
*/
final class
MonoSubscribeOn<T> extends
MonoOperator<T, T> {
final
Scheduler scheduler;
MonoSubscribeOn(
Mono<? extends T>
source,
Scheduler scheduler) {
super(
source);
this.
scheduler =
scheduler;
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
Scheduler.
Worker worker =
scheduler.
createWorker();
SubscribeOnSubscriber<T>
parent = new
SubscribeOnSubscriber<>(
source,
actual,
worker);
actual.
onSubscribe(
parent);
try {
worker.
schedule(
parent);
}
catch (
RejectedExecutionException ree) {
if (
parent.
s !=
Operators.
cancelledSubscription()) {
actual.
onError(
Operators.
onRejectedExecution(
ree,
parent, null, null,
actual.
currentContext()));
}
}
}
@
Override
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
RUN_ON) return
scheduler;
return super.scanUnsafe(
key);
}
static final class
SubscribeOnSubscriber<T>
implements
InnerOperator<T, T>,
Runnable {
final
CoreSubscriber<? super T>
actual;
final
Publisher<? extends T>
parent;
final
Scheduler.
Worker worker;
volatile
Subscription s;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
SubscribeOnSubscriber,
Subscription>
S =
AtomicReferenceFieldUpdater.
newUpdater(
SubscribeOnSubscriber.class,
Subscription.class,
"s");
volatile long
requested;
@
SuppressWarnings("rawtypes")
static final
AtomicLongFieldUpdater<
SubscribeOnSubscriber>
REQUESTED =
AtomicLongFieldUpdater.
newUpdater(
SubscribeOnSubscriber.class,
"requested");
volatile
Thread thread;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
SubscribeOnSubscriber,
Thread>
THREAD =
AtomicReferenceFieldUpdater.
newUpdater(
SubscribeOnSubscriber.class,
Thread.class,
"thread");
SubscribeOnSubscriber(
Publisher<? extends T>
parent,
CoreSubscriber<? super T>
actual,
Worker worker) {
this.
actual =
actual;
this.
parent =
parent;
this.
worker =
worker;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
CANCELLED) return
s ==
Operators.
cancelledSubscription();
if (
key ==
Attr.
PARENT) return
s;
if (
key ==
Attr.
REQUESTED_FROM_DOWNSTREAM) return
requested;
if (
key ==
Attr.
RUN_ON) return
worker;
return
InnerOperator.super.scanUnsafe(
key);
}
@
Override
public void
run() {
THREAD.
lazySet(this,
Thread.
currentThread());
parent.
subscribe(this);
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
setOnce(
S, this,
s)) {
long
r =
REQUESTED.
getAndSet(this, 0L);
if (
r != 0L) {
trySchedule(
r,
s);
}
}
}
@
Override
public
CoreSubscriber<? super T>
actual() {
return
actual;
}
@
Override
public void
onNext(T
t) {
actual.
onNext(
t);
}
@
Override
public void
onError(
Throwable t) {
try{
actual.
onError(
t);
}
finally {
worker.
dispose();
THREAD.
lazySet(this,null);
}
}
@
Override
public void
onComplete() {
actual.
onComplete();
worker.
dispose();
THREAD.
lazySet(this,null);
}
@
Override
public void
request(long
n) {
if (
Operators.
validate(
n)) {
Subscription a =
s;
if (
a != null) {
trySchedule(
n,
a);
}
else {
Operators.
addCap(
REQUESTED, this,
n);
a =
s;
if (
a != null) {
long
r =
REQUESTED.
getAndSet(this, 0L);
if (
r != 0L) {
trySchedule(
n,
a);
}
}
}
}
}
void
trySchedule(long
n,
Subscription s) {
if (
Thread.
currentThread() ==
THREAD.
get(this)) {
s.
request(
n);
}
else {
try {
worker.
schedule(() ->
s.
request(
n));
}
catch (
RejectedExecutionException ree) {
if (!
worker.
isDisposed()) {
actual.
onError(
Operators.
onRejectedExecution(
ree,
this,
null,
null,
actual.
currentContext()));
}
}
}
}
@
Override
public void
cancel() {
if (
Operators.
terminate(
S, this)) {
worker.
dispose();
}
}
}
}