/*
* 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.
Objects;
import java.util.concurrent.
RejectedExecutionException;
import java.util.concurrent.atomic.
AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.
AtomicReferenceFieldUpdater;
import org.reactivestreams.
Subscriber;
import reactor.core.
CoreSubscriber;
import reactor.core.
Disposable;
import reactor.core.
Disposables;
import reactor.core.
Fuseable;
import reactor.core.
Scannable;
import reactor.core.scheduler.
Scheduler;
import reactor.util.annotation.
Nullable;
/**
* Publisher indicating a scalar/empty source that subscribes on the specified scheduler.
*
* @param <T>
*
* @see <a href="https://github.com/reactor/reactive-streams-commons">https://github.com/reactor/reactive-streams-commons</a>
*/
final class
FluxSubscribeOnValue<T> extends
Flux<T> implements
Fuseable,
Scannable {
final T
value;
final
Scheduler scheduler;
FluxSubscribeOnValue(@
Nullable T
value,
Scheduler scheduler) {
this.
value =
value;
this.
scheduler =
Objects.
requireNonNull(
scheduler, "scheduler");
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
T
v =
value;
if (
v == null) {
ScheduledEmpty parent = new
ScheduledEmpty(
actual);
actual.
onSubscribe(
parent);
try {
parent.
setFuture(
scheduler.
schedule(
parent));
}
catch (
RejectedExecutionException ree) {
if (
parent.
future !=
OperatorDisposables.
DISPOSED) {
actual.
onError(
Operators.
onRejectedExecution(
ree,
actual.
currentContext()));
}
}
}
else {
actual.
onSubscribe(new
ScheduledScalar<>(
actual,
v,
scheduler));
}
}
@
Override
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
RUN_ON) return
scheduler;
return null;
}
static final class
ScheduledScalar<T>
implements
QueueSubscription<T>,
InnerProducer<T>,
Runnable {
final
CoreSubscriber<? super T>
actual;
final T
value;
final
Scheduler scheduler;
volatile int
once;
@
SuppressWarnings("rawtypes")
static final
AtomicIntegerFieldUpdater<
ScheduledScalar>
ONCE =
AtomicIntegerFieldUpdater.
newUpdater(
ScheduledScalar.class, "once");
volatile
Disposable future;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
ScheduledScalar,
Disposable>
FUTURE =
AtomicReferenceFieldUpdater.
newUpdater(
ScheduledScalar.class,
Disposable.class,
"future");
static final
Disposable FINISHED =
Disposables.
disposed();
int
fusionState;
static final int
NO_VALUE = 1;
static final int
HAS_VALUE = 2;
static final int
COMPLETE = 3;
ScheduledScalar(
CoreSubscriber<? super T>
actual, T
value,
Scheduler scheduler) {
this.
actual =
actual;
this.
value =
value;
this.
scheduler =
scheduler;
}
@
Override
public
CoreSubscriber<? super T>
actual() {
return
actual;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Scannable.
Attr key) {
if (
key ==
Attr.
CANCELLED) {
return
future ==
OperatorDisposables.
DISPOSED;
}
if (
key ==
Attr.
TERMINATED) {
return
future ==
FINISHED;
}
if (
key ==
Attr.
BUFFERED) {
return 1;
}
if (
key ==
Attr.
RUN_ON) return
scheduler;
return
InnerProducer.super.scanUnsafe(
key);
}
@
Override
public void
request(long
n) {
if (
Operators.
validate(
n)) {
if (
ONCE.
compareAndSet(this, 0, 1)) {
try {
Disposable f =
scheduler.
schedule(this);
if (!
FUTURE.
compareAndSet(this,
null,
f) &&
future !=
FINISHED &&
future !=
OperatorDisposables.
DISPOSED) {
f.
dispose();
}
}
catch (
RejectedExecutionException ree) {
if (
future !=
FINISHED &&
future !=
OperatorDisposables.
DISPOSED) {
actual.
onError(
Operators.
onRejectedExecution(
ree,
this,
null,
value,
actual.
currentContext()));
}
}
}
}
}
@
Override
public void
cancel() {
ONCE.
lazySet(this, 1);
Disposable f =
future;
if (
f !=
OperatorDisposables.
DISPOSED &&
future !=
FINISHED) {
f =
FUTURE.
getAndSet(this,
OperatorDisposables.
DISPOSED);
if (
f != null &&
f !=
OperatorDisposables.
DISPOSED &&
f !=
FINISHED) {
f.
dispose();
}
}
}
@
Override
public void
run() {
try {
if (
fusionState ==
NO_VALUE) {
fusionState =
HAS_VALUE;
}
actual.
onNext(
value);
actual.
onComplete();
}
finally {
FUTURE.
lazySet(this,
FINISHED);
}
}
@
Override
public int
requestFusion(int
requestedMode) {
if ((
requestedMode &
Fuseable.
ASYNC) != 0) {
fusionState =
NO_VALUE;
return
Fuseable.
ASYNC;
}
return
Fuseable.
NONE;
}
@
Override
@
Nullable
public T
poll() {
if (
fusionState ==
HAS_VALUE) {
fusionState =
COMPLETE;
return
value;
}
return null;
}
@
Override
public boolean
isEmpty() {
return
fusionState !=
HAS_VALUE;
}
@
Override
public int
size() {
return
isEmpty() ? 0 : 1;
}
@
Override
public void
clear() {
fusionState =
COMPLETE;
}
}
static final class
ScheduledEmpty implements
QueueSubscription<
Void>,
Runnable {
final
Subscriber<?>
actual;
volatile
Disposable future;
static final
AtomicReferenceFieldUpdater<
ScheduledEmpty,
Disposable>
FUTURE =
AtomicReferenceFieldUpdater.
newUpdater(
ScheduledEmpty.class,
Disposable.class,
"future");
static final
Disposable FINISHED =
Disposables.
disposed();
ScheduledEmpty(
Subscriber<?>
actual) {
this.
actual =
actual;
}
@
Override
public void
request(long
n) {
Operators.
validate(
n);
}
@
Override
public void
cancel() {
Disposable f =
future;
if (
f !=
OperatorDisposables.
DISPOSED &&
f !=
FINISHED) {
f =
FUTURE.
getAndSet(this,
OperatorDisposables.
DISPOSED);
if (
f != null &&
f !=
OperatorDisposables.
DISPOSED &&
f !=
FINISHED) {
f.
dispose();
}
}
}
@
Override
public void
run() {
try {
actual.
onComplete();
}
finally {
FUTURE.
lazySet(this,
FINISHED);
}
}
void
setFuture(
Disposable f) {
if (!
FUTURE.
compareAndSet(this, null,
f)) {
Disposable a =
future;
if (
a !=
FINISHED &&
a !=
OperatorDisposables.
DISPOSED) {
f.
dispose();
}
}
}
@
Override
public int
requestFusion(int
requestedMode) {
return
requestedMode &
Fuseable.
ASYNC;
}
@
Override
@
Nullable
public
Void poll() {
return null;
}
@
Override
public boolean
isEmpty() {
return true;
}
@
Override
public int
size() {
return 0;
}
@
Override
public void
clear() {
// nothing to do
}
}
}