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/*
* Copyright (c) 2016-2021 VMware Inc. or its affiliates, 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
*
* https://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.Queue;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.AtomicLongFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Stream;
import org.reactivestreams.Publisher;
import org.reactivestreams.Subscription;
import reactor.core.CoreSubscriber;
import reactor.core.Exceptions;
import reactor.core.Fuseable;
import reactor.core.Scannable;
import reactor.util.annotation.Nullable;
import reactor.util.context.Context;
import static reactor.core.Scannable.Attr.RUN_STYLE;
import static reactor.core.Scannable.Attr.RunStyle.SYNC;
/**
* Shares a sequence 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 the source value type
* @param the output value type
*
* @see Reactive-Streams-Commons
*/
final class FluxPublishMulticast extends InternalFluxOperator implements Fuseable {
final Function, ? extends Publisher> transform;
final Supplier> queueSupplier;
final int prefetch;
FluxPublishMulticast(Flux source,
Function, ? extends Publisher> transform,
int prefetch,
Supplier> queueSupplier) {
super(source);
if (prefetch < 1) {
throw new IllegalArgumentException("prefetch > 0 required but it was " + prefetch);
}
this.prefetch = prefetch;
this.transform = Objects.requireNonNull(transform, "transform");
this.queueSupplier = Objects.requireNonNull(queueSupplier, "queueSupplier");
}
@Override
public int getPrefetch() {
return prefetch;
}
@Override
public CoreSubscriber subscribeOrReturn(CoreSubscriber actual) {
FluxPublishMulticaster multicast = new FluxPublishMulticaster<>(prefetch,
queueSupplier,
actual.currentContext());
Publisher out = Objects.requireNonNull(transform.apply(multicast),
"The transform returned a null Publisher");
if (out instanceof Fuseable) {
out.subscribe(new CancelFuseableMulticaster<>(actual, multicast));
}
else {
out.subscribe(new CancelMulticaster<>(actual, multicast));
}
return multicast;
}
@Override
public Object scanUnsafe(Attr key) {
if (key == RUN_STYLE) return Attr.RunStyle.SYNC;
return super.scanUnsafe(key);
}
static final class FluxPublishMulticaster extends Flux
implements InnerConsumer, PublishMulticasterParent {
final int limit;
final int prefetch;
final Supplier> queueSupplier;
Queue queue;
volatile Subscription s;
@SuppressWarnings("rawtypes")
static final AtomicReferenceFieldUpdater S =
AtomicReferenceFieldUpdater.newUpdater(FluxPublishMulticaster.class,
Subscription.class,
"s");
volatile int wip;
@SuppressWarnings("rawtypes")
static final AtomicIntegerFieldUpdater WIP =
AtomicIntegerFieldUpdater.newUpdater(FluxPublishMulticaster.class, "wip");
volatile PublishMulticastInner[] subscribers;
@SuppressWarnings("rawtypes")
static final AtomicReferenceFieldUpdater
SUBSCRIBERS = AtomicReferenceFieldUpdater.newUpdater(
FluxPublishMulticaster.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;
volatile boolean connected;
Throwable error;
final Context context;
int produced;
int sourceMode;
@SuppressWarnings("unchecked")
FluxPublishMulticaster(int prefetch,
Supplier> queueSupplier,
Context ctx) {
this.prefetch = prefetch;
this.limit = Operators.unboundedOrLimit(prefetch);
this.queueSupplier = queueSupplier;
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 prefetch;
}
if (key == Attr.BUFFERED) {
return queue != null ? queue.size() : 0;
}
if (key == RUN_STYLE) {
return Attr.RunStyle.SYNC;
}
return null;
}
@Override
public Stream inners() {
return Stream.of(subscribers);
}
@Override
public Context currentContext() {
return context;
}
@Override
public void subscribe(CoreSubscriber actual) {
PublishMulticastInner pcs = new PublishMulticastInner<>(this, actual);
actual.onSubscribe(pcs);
if (add(pcs)) {
if (pcs.requested == Long.MIN_VALUE) {
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)) {
if (s instanceof QueueSubscription) {
@SuppressWarnings("unchecked") QueueSubscription qs =
(QueueSubscription) s;
int m = qs.requestFusion(Fuseable.ANY);
if (m == Fuseable.SYNC) {
sourceMode = m;
queue = qs;
done = true;
connected = true;
drain();
return;
}
if (m == Fuseable.ASYNC) {
sourceMode = m;
queue = qs;
connected = true;
s.request(Operators.unboundedOrPrefetch(prefetch));
return;
}
}
queue = queueSupplier.get();
connected = true;
s.request(Operators.unboundedOrPrefetch(prefetch));
}
}
@Override
public void onNext(T t) {
if (done) {
Operators.onNextDropped(t, context);
return;
}
if (sourceMode != Fuseable.ASYNC) {
if (!queue.offer(t)) {
onError(Operators.onOperatorError(s,
Exceptions.failWithOverflow(Exceptions.BACKPRESSURE_ERROR_QUEUE_FULL),
t,
context));
return;
}
}
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;
}
if (sourceMode == Fuseable.SYNC) {
drainSync();
}
else {
drainAsync();
}
}
@SuppressWarnings("unchecked")
void drainSync() {
int missed = 1;
for (; ; ) {
if (connected) {
if (s == Operators.cancelledSubscription()) {
queue.clear();
return;
}
final Queue queue = this.queue;
PublishMulticastInner[] a = subscribers;
int n = a.length;
if (n != 0) {
long r = Long.MAX_VALUE;
long u;
for (int i = 0; i < n; i++) {
u = a[i].requested;
if (u != Long.MIN_VALUE) {
r = Math.min(r, u);
}
}
long e = 0L;
while (e != r) {
if (s == Operators.cancelledSubscription()) {
queue.clear();
return;
}
T v;
try {
v = queue.poll();
}
catch (Throwable ex) {
error = Operators.onOperatorError(s, ex, context);
queue.clear();
a = SUBSCRIBERS.getAndSet(this, TERMINATED);
n = a.length;
for (int i = 0; i < n; i++) {
a[i].actual.onError(ex);
}
return;
}
if (v == null) {
a = SUBSCRIBERS.getAndSet(this, TERMINATED);
n = a.length;
for (int i = 0; i < n; i++) {
a[i].actual.onComplete();
}
return;
}
for (int i = 0; i < n; i++) {
a[i].actual.onNext(v);
}
e++;
}
if (s == Operators.cancelledSubscription()) {
queue.clear();
return;
}
if (queue.isEmpty()) {
a = SUBSCRIBERS.getAndSet(this, TERMINATED);
n = a.length;
for (int i = 0; i < n; i++) {
a[i].actual.onComplete();
}
return;
}
if (e != 0L) {
for (int i = 0; i < n; i++) {
a[i].produced(e);
}
}
}
}
missed = WIP.addAndGet(this, -missed);
if (missed == 0) {
break;
}
}
}
@SuppressWarnings("unchecked")
void drainAsync() {
int missed = 1;
int p = produced;
for (; ; ) {
if (connected) {
if (s == Operators.cancelledSubscription()) {
queue.clear();
return;
}
final Queue queue = this.queue;
PublishMulticastInner[] a = subscribers;
int n = a.length;
if (n != 0) {
long r = Long.MAX_VALUE;
long u;
for (int i = 0; i < n; i++) {
u = a[i].requested;
if (u != Long.MIN_VALUE) {
r = Math.min(r, u);
}
}
long e = 0L;
while (e != r) {
if (s == Operators.cancelledSubscription()) {
queue.clear();
return;
}
boolean d = done;
T v;
try {
v = queue.poll();
}
catch (Throwable ex) {
queue.clear();
error = Operators.onOperatorError(s, ex, context);
a = SUBSCRIBERS.getAndSet(this, TERMINATED);
n = a.length;
for (int i = 0; i < n; i++) {
a[i].actual.onError(ex);
}
return;
}
boolean empty = v == null;
if (d) {
Throwable ex = error;
if (ex != null) {
queue.clear();
a = SUBSCRIBERS.getAndSet(this, TERMINATED);
n = a.length;
for (int i = 0; i < n; i++) {
a[i].actual.onError(ex);
}
return;
}
if (empty) {
a = SUBSCRIBERS.getAndSet(this, TERMINATED);
n = a.length;
for (int i = 0; i < n; i++) {
a[i].actual.onComplete();
}
return;
}
}
if (empty) {
break;
}
for (int i = 0; i < n; i++) {
a[i].actual.onNext(v);
}
e++;
if (++p == limit) {
s.request(p);
p = 0;
}
}
if (e == r) {
if (s == Operators.cancelledSubscription()) {
queue.clear();
return;
}
boolean d = done;
if (d) {
Throwable ex = error;
if (ex != null) {
queue.clear();
a = SUBSCRIBERS.getAndSet(this, TERMINATED);
n = a.length;
for (int i = 0; i < n; i++) {
a[i].actual.onError(ex);
}
return;
}
if (queue.isEmpty()) {
a = SUBSCRIBERS.getAndSet(this, TERMINATED);
n = a.length;
for (int i = 0; i < n; i++) {
a[i].actual.onComplete();
}
return;
}
}
}
if (e != 0L) {
for (int i = 0; i < n; i++) {
a[i].produced(e);
}
}
}
}
produced = p;
missed = WIP.addAndGet(this, -missed);
if (missed == 0) {
break;
}
}
}
boolean add(PublishMulticastInner s) {
for (; ; ) {
PublishMulticastInner[] a = subscribers;
if (a == TERMINATED) {
return false;
}
int n = a.length;
@SuppressWarnings("unchecked") PublishMulticastInner[] 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 s) {
for (; ; ) {
PublishMulticastInner[] 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[] 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
@SuppressWarnings("unchecked")
public void terminate() {
Operators.terminate(S, this);
if (WIP.getAndIncrement(this) == 0) {
if (connected) {
queue.clear();
}
}
}
}
static final class PublishMulticastInner implements InnerProducer {
final FluxPublishMulticaster parent;
final CoreSubscriber actual;
volatile long requested;
@SuppressWarnings("rawtypes")
static final AtomicLongFieldUpdater REQUESTED =
AtomicLongFieldUpdater.newUpdater(PublishMulticastInner.class,
"requested");
PublishMulticastInner(FluxPublishMulticaster parent,
CoreSubscriber actual) {
this.parent = parent;
this.actual = actual;
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.REQUESTED_FROM_DOWNSTREAM) {
return Math.max(0L, requested);
}
if (key == Attr.PARENT) {
return parent;
}
if (key == Attr.CANCELLED) {
return Long.MIN_VALUE == requested;
}
if (key == RUN_STYLE) return Attr.RunStyle.SYNC;
return InnerProducer.super.scanUnsafe(key);
}
@Override
public CoreSubscriber actual() {
return actual;
}
@Override
public void request(long n) {
if (Operators.validate(n)) {
Operators.addCapCancellable(REQUESTED, this, n);
parent.drain();
}
}
@Override
public void cancel() {
if (REQUESTED.getAndSet(this, Long.MIN_VALUE) != Long.MIN_VALUE) {
parent.remove(this);
parent.drain();
}
}
void produced(long n) {
Operators.producedCancellable(REQUESTED, this, n);
}
}
interface PublishMulticasterParent {
void terminate();
}
static final class CancelMulticaster
implements InnerOperator, QueueSubscription {
final CoreSubscriber actual;
final PublishMulticasterParent parent;
Subscription s;
CancelMulticaster(CoreSubscriber actual,
PublishMulticasterParent parent) {
this.actual = actual;
this.parent = parent;
}
@Override
public CoreSubscriber actual() {
return actual;
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.PARENT) {
return s;
}
if (key == RUN_STYLE) {
return Attr.RunStyle.SYNC;
}
return InnerOperator.super.scanUnsafe(key);
}
@Override
public void request(long n) {
s.request(n);
}
@Override
public void cancel() {
s.cancel();
parent.terminate();
}
@Override
public void onSubscribe(Subscription s) {
if (Operators.validate(this.s, s)) {
this.s = s;
actual.onSubscribe(this);
}
}
@Override
public void onNext(T t) {
actual.onNext(t);
}
@Override
public void onError(Throwable t) {
actual.onError(t);
parent.terminate();
}
@Override
public void onComplete() {
actual.onComplete();
parent.terminate();
}
@Override
public int requestFusion(int requestedMode) {
return NONE;
}
@Override
public void clear() {
// should not be called because fusion is always rejected
}
@Override
public boolean isEmpty() {
// should not be called because fusion is always rejected
return false;
}
@Override
public int size() {
// should not be called because fusion is always rejected
return 0;
}
@Override
@Nullable
public T poll() {
// should not be called because fusion is always rejected
return null;
}
}
static final class CancelFuseableMulticaster
implements InnerOperator, QueueSubscription {
final CoreSubscriber actual;
final PublishMulticasterParent parent;
QueueSubscription s;
CancelFuseableMulticaster(CoreSubscriber actual,
PublishMulticasterParent parent) {
this.actual = actual;
this.parent = parent;
}
@Override
public CoreSubscriber actual() {
return actual;
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.PARENT) {
return s;
}
if (key == RUN_STYLE) {
return Attr.RunStyle.SYNC;
}
return InnerOperator.super.scanUnsafe(key);
}
@Override
public void request(long n) {
s.request(n);
}
@Override
public void cancel() {
s.cancel();
parent.terminate();
}
@SuppressWarnings("unchecked")
@Override
public void onSubscribe(Subscription s) {
if (Operators.validate(this.s, s)) {
this.s = Operators.as(s);
actual.onSubscribe(this);
}
}
@Override
public void onNext(T t) {
actual.onNext(t);
}
@Override
public void onError(Throwable t) {
actual.onError(t);
parent.terminate();
}
@Override
public void onComplete() {
actual.onComplete();
parent.terminate();
}
@Override
public int requestFusion(int requestedMode) {
return s.requestFusion(requestedMode);
}
@Override
@Nullable
public T poll() {
return s.poll();
}
@Override
public boolean isEmpty() {
return s.isEmpty();
}
@Override
public int size() {
return s.size();
}
@Override
public void clear() {
s.clear();
}
}
}
