/*
* 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.atomic.
AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.
AtomicReferenceFieldUpdater;
import java.util.function.
Function;
import java.util.stream.
Stream;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Fuseable;
import reactor.core.
Scannable;
import reactor.util.annotation.
Nullable;
import reactor.util.context.
Context;
/**
* Shares a {@link Mono} for the duration of a function that may transform it and
* consume it as many times as necessary without causing multiple subscriptions
* to the upstream.
*
* @param <T> the source value type
* @param <R> the output value type
*
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class
MonoPublishMulticast<T, R> extends
MonoOperator<T, R> implements
Fuseable {
final
Function<? super
Mono<T>, ? extends
Mono<? extends R>>
transform;
MonoPublishMulticast(
Mono<? extends T>
source,
Function<? super
Mono<T>, ? extends
Mono<? extends R>>
transform) {
super(
source);
this.
transform =
Objects.
requireNonNull(
transform, "transform");
}
@
Override
public void
subscribe(
CoreSubscriber<? super R>
actual) {
MonoPublishMulticaster<T>
multicast = new
MonoPublishMulticaster<>(
actual.
currentContext());
Mono<? extends R>
out;
try {
out =
Objects.
requireNonNull(
transform.
apply(
fromDirect(
multicast)),
"The transform returned a null Mono");
}
catch (
Throwable ex) {
Operators.
error(
actual,
Operators.
onOperatorError(
ex,
actual.
currentContext()));
return;
}
if (
out instanceof
Fuseable) {
out.
subscribe(new
FluxPublishMulticast.
CancelFuseableMulticaster<>(
actual,
multicast));
}
else {
out.
subscribe(new
FluxPublishMulticast.
CancelMulticaster<>(
actual,
multicast));
}
source.
subscribe(
multicast);
}
static final class
MonoPublishMulticaster<T> extends
Mono<T>
implements
InnerConsumer<T>,
FluxPublishMulticast.
PublishMulticasterParent {
volatile
Subscription s;
static final
AtomicReferenceFieldUpdater<
MonoPublishMulticaster,
Subscription>
S =
AtomicReferenceFieldUpdater.
newUpdater(
MonoPublishMulticaster.class,
Subscription.class,
"s");
volatile int
wip;
static final
AtomicIntegerFieldUpdater<
MonoPublishMulticaster>
WIP =
AtomicIntegerFieldUpdater.
newUpdater(
MonoPublishMulticaster.class, "wip");
volatile
PublishMulticastInner<T>[]
subscribers;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
MonoPublishMulticaster,
PublishMulticastInner[]>
SUBSCRIBERS =
AtomicReferenceFieldUpdater.
newUpdater(
MonoPublishMulticaster.class,
PublishMulticastInner[].class, "subscribers");
@
SuppressWarnings("rawtypes")
static final
PublishMulticastInner[]
EMPTY = new
PublishMulticastInner[0];
@
SuppressWarnings("rawtypes")
static final
PublishMulticastInner[]
TERMINATED = new
PublishMulticastInner[0];
volatile boolean
done;
@
Nullable
T
value;
Throwable error;
volatile boolean
connected;
final
Context context;
@
SuppressWarnings("unchecked")
MonoPublishMulticaster(
Context ctx) {
SUBSCRIBERS.
lazySet(this,
EMPTY);
this.
context =
ctx;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) {
return
s;
}
if (
key ==
Attr.
ERROR) {
return
error;
}
if (
key ==
Attr.
CANCELLED) {
return
s ==
Operators.
cancelledSubscription();
}
if (
key ==
Attr.
TERMINATED) {
return
done;
}
if (
key ==
Attr.
PREFETCH) {
return 1;
}
if (
key ==
Attr.
BUFFERED) {
return
value != null ? 1 : 0;
}
return null;
}
@
Override
public
Stream<? extends
Scannable>
inners() {
return
Stream.
of(
subscribers);
}
@
Override
public
Context currentContext() {
return
context;
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
PublishMulticastInner<T>
pcs = new
PublishMulticastInner<>(this,
actual);
actual.
onSubscribe(
pcs);
if (
add(
pcs)) {
if (
pcs.
cancelled == 1) {
remove(
pcs);
return;
}
drain();
}
else {
Throwable ex =
error;
if (
ex != null) {
actual.
onError(
ex);
}
else {
actual.
onComplete();
}
}
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
setOnce(
S, this,
s)) {
connected = true;
s.
request(
Long.
MAX_VALUE);
}
}
@
Override
public void
onNext(T
t) {
if (
done) {
Operators.
onNextDropped(
t,
context);
return;
}
value =
t;
done = true;
drain();
}
@
Override
public void
onError(
Throwable t) {
if (
done) {
Operators.
onErrorDropped(
t,
context);
return;
}
error =
t;
done = true;
drain();
}
@
Override
public void
onComplete() {
done = true;
drain();
}
void
drain() {
if (
WIP.
getAndIncrement(this) != 0) {
return;
}
int
missed = 1;
for (; ; ) {
if (
connected) {
if (
s ==
Operators.
cancelledSubscription()) {
value = null;
return;
}
final T
v =
value;
PublishMulticastInner<T>[]
a =
subscribers;
int
n =
a.length;
if (
n != 0) {
if (
s ==
Operators.
cancelledSubscription()) {
value = null;
return;
}
if (
v == null) {
//noinspection unchecked
a =
SUBSCRIBERS.
getAndSet(this,
TERMINATED);
n =
a.length;
for (int
i = 0;
i <
n;
i++) {
a[
i].
actual.
onComplete();
}
return;
}
else {
//noinspection unchecked
a =
SUBSCRIBERS.
getAndSet(this,
TERMINATED);
n =
a.length;
for (int
i = 0;
i <
n;
i++) {
a[
i].
actual.
onNext(
v);
a[
i].
actual.
onComplete();
}
value = null;
return;
}
}
}
missed =
WIP.
addAndGet(this, -
missed);
if (
missed == 0) {
break;
}
}
}
boolean
add(
PublishMulticastInner<T>
s) {
for (; ; ) {
PublishMulticastInner<T>[]
a =
subscribers;
if (
a ==
TERMINATED) {
return false;
}
int
n =
a.length;
@
SuppressWarnings("unchecked")
PublishMulticastInner<T>[]
b = new
PublishMulticastInner[
n + 1];
System.
arraycopy(
a, 0,
b, 0,
n);
b[
n] =
s;
if (
SUBSCRIBERS.
compareAndSet(this,
a,
b)) {
return true;
}
}
}
@
SuppressWarnings("unchecked")
void
remove(
PublishMulticastInner<T>
s) {
for (; ; ) {
PublishMulticastInner<T>[]
a =
subscribers;
if (
a ==
TERMINATED ||
a ==
EMPTY) {
return;
}
int
n =
a.length;
int
j = -1;
for (int
i = 0;
i <
n;
i++) {
if (
a[
i] ==
s) {
j =
i;
break;
}
}
if (
j < 0) {
return;
}
PublishMulticastInner<T>[]
b;
if (
n == 1) {
b =
EMPTY;
}
else {
b = new
PublishMulticastInner[
n - 1];
System.
arraycopy(
a, 0,
b, 0,
j);
System.
arraycopy(
a,
j + 1,
b,
j,
n -
j - 1);
}
if (
SUBSCRIBERS.
compareAndSet(this,
a,
b)) {
return;
}
}
}
@
Override
public void
terminate() {
Operators.
terminate(
S, this);
if (
WIP.
getAndIncrement(this) == 0) {
if (
connected) {
value = null;
}
}
}
}
static final class
PublishMulticastInner<T> implements
InnerProducer<T> {
final
MonoPublishMulticaster<T>
parent;
final
CoreSubscriber<? super T>
actual;
volatile int
cancelled;
static final
AtomicIntegerFieldUpdater<
PublishMulticastInner>
CANCELLED =
AtomicIntegerFieldUpdater.
newUpdater(
PublishMulticastInner.class, "cancelled");
PublishMulticastInner(
MonoPublishMulticaster<T>
parent,
CoreSubscriber<? super T>
actual) {
this.
parent =
parent;
this.
actual =
actual;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) {
return
parent;
}
if (
key ==
Attr.
CANCELLED) {
return
cancelled == 1;
}
return
InnerProducer.super.scanUnsafe(
key);
}
@
Override
public
CoreSubscriber<? super T>
actual() {
return
actual;
}
@
Override
public void
request(long
n) {
if (
Operators.
validate(
n)) {
parent.
drain();
}
}
@
Override
public void
cancel() {
if (
CANCELLED.
compareAndSet(this, 0, 1)) {
parent.
remove(this);
parent.
drain();
}
}
}
}