/*
* 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.
Queue;
import java.util.concurrent.
CancellationException;
import java.util.concurrent.atomic.
AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.
AtomicLongFieldUpdater;
import java.util.concurrent.atomic.
AtomicReferenceFieldUpdater;
import java.util.function.
Consumer;
import java.util.function.
Supplier;
import java.util.stream.
Stream;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Disposable;
import reactor.core.
Exceptions;
import reactor.core.
Fuseable;
import reactor.core.
Scannable;
import reactor.util.annotation.
Nullable;
/**
* A connectable publisher which shares an underlying source and dispatches source values
* to subscribers in a backpressure-aware manner.
*
* @param <T> the value type
*
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class
FluxPublish<T> extends
ConnectableFlux<T> implements
Scannable {
/**
* The source observable.
*/
final
Flux<? extends T>
source;
/**
* The size of the prefetch buffer.
*/
final int
prefetch;
final
Supplier<? extends
Queue<T>>
queueSupplier;
volatile
PublishSubscriber<T>
connection;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
FluxPublish,
PublishSubscriber>
CONNECTION =
AtomicReferenceFieldUpdater.
newUpdater(
FluxPublish.class,
PublishSubscriber.class,
"connection");
FluxPublish(
Flux<? extends T>
source,
int
prefetch,
Supplier<? extends
Queue<T>>
queueSupplier) {
if (
prefetch <= 0) {
throw new
IllegalArgumentException("bufferSize > 0 required but it was " +
prefetch);
}
this.
source =
Objects.
requireNonNull(
source, "source");
this.
prefetch =
prefetch;
this.
queueSupplier =
Objects.
requireNonNull(
queueSupplier, "queueSupplier");
}
@
Override
public void
connect(
Consumer<? super
Disposable>
cancelSupport) {
boolean
doConnect;
PublishSubscriber<T>
s;
for (; ; ) {
s =
connection;
if (
s == null ||
s.
isTerminated()) {
PublishSubscriber<T>
u = new
PublishSubscriber<>(
prefetch, this);
if (!
CONNECTION.
compareAndSet(this,
s,
u)) {
continue;
}
s =
u;
}
doConnect =
s.
tryConnect();
break;
}
cancelSupport.
accept(
s);
if (
doConnect) {
source.
subscribe(
s);
}
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
PublishInner<T>
inner = new
PublishInner<>(
actual);
actual.
onSubscribe(
inner);
for (; ; ) {
if (
inner.
isCancelled()) {
break;
}
PublishSubscriber<T>
c =
connection;
if (
c == null ||
c.
isTerminated()) {
PublishSubscriber<T>
u = new
PublishSubscriber<>(
prefetch, this);
if (!
CONNECTION.
compareAndSet(this,
c,
u)) {
continue;
}
c =
u;
}
if (
c.
add(
inner)) {
if (
inner.
isCancelled()) {
c.
remove(
inner);
}
else {
inner.
parent =
c;
}
c.
drain();
break;
}
}
}
@
Override
public int
getPrefetch() {
return
prefetch;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PREFETCH) return
getPrefetch();
if (
key ==
Attr.
PARENT) return
source;
return null;
}
static final class
PublishSubscriber<T>
implements
InnerConsumer<T>,
Disposable {
final int
prefetch;
final
FluxPublish<T>
parent;
volatile
Subscription s;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
PublishSubscriber,
Subscription>
S =
AtomicReferenceFieldUpdater.
newUpdater(
PublishSubscriber.class,
Subscription.class,
"s");
volatile
PubSubInner<T>[]
subscribers;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
PublishSubscriber,
PubSubInner[]>
SUBSCRIBERS =
AtomicReferenceFieldUpdater.
newUpdater(
PublishSubscriber.class,
PubSubInner[].class,
"subscribers");
volatile int
wip;
@
SuppressWarnings("rawtypes")
static final
AtomicIntegerFieldUpdater<
PublishSubscriber>
WIP =
AtomicIntegerFieldUpdater.
newUpdater(
PublishSubscriber.class, "wip");
volatile int
connected;
@
SuppressWarnings("rawtypes")
static final
AtomicIntegerFieldUpdater<
PublishSubscriber>
CONNECTED =
AtomicIntegerFieldUpdater.
newUpdater(
PublishSubscriber.class,
"connected");
@
SuppressWarnings("rawtypes")
static final
PubSubInner[]
EMPTY = new
PublishInner[0];
@
SuppressWarnings("rawtypes")
static final
PubSubInner[]
TERMINATED = new
PublishInner[0];
volatile
Queue<T>
queue;
int
sourceMode;
volatile boolean
done;
volatile
Throwable error;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
PublishSubscriber,
Throwable>
ERROR =
AtomicReferenceFieldUpdater.
newUpdater(
PublishSubscriber.class,
Throwable.class,
"error");
@
SuppressWarnings("unchecked")
PublishSubscriber(int
prefetch,
FluxPublish<T>
parent) {
this.
prefetch =
prefetch;
this.
parent =
parent;
SUBSCRIBERS.
lazySet(this,
EMPTY);
}
boolean
isTerminated(){
return
subscribers ==
TERMINATED;
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
setOnce(
S, this,
s)) {
if (
s instanceof
Fuseable.
QueueSubscription) {
@
SuppressWarnings("unchecked")
Fuseable.
QueueSubscription<T>
f =
(
Fuseable.
QueueSubscription<T>)
s;
int
m =
f.
requestFusion(
Fuseable.
ANY |
Fuseable.
THREAD_BARRIER);
if (
m ==
Fuseable.
SYNC) {
sourceMode =
m;
queue =
f;
drain();
return;
}
if (
m ==
Fuseable.
ASYNC) {
sourceMode =
m;
queue =
f;
s.
request(
Operators.
unboundedOrPrefetch(
prefetch));
return;
}
}
queue =
parent.
queueSupplier.
get();
s.
request(
Operators.
unboundedOrPrefetch(
prefetch));
}
}
@
Override
public void
onNext(T
t) {
if (
done) {
if (
t != null) {
Operators.
onNextDropped(
t,
currentContext());
}
return;
}
if (
sourceMode ==
Fuseable.
ASYNC) {
drain();
return;
}
if (!
queue.
offer(
t)) {
Throwable ex =
Operators.
onOperatorError(
s,
Exceptions.
failWithOverflow(
Exceptions.
BACKPRESSURE_ERROR_QUEUE_FULL),
t,
currentContext());
if (!
Exceptions.
addThrowable(
ERROR, this,
ex)) {
Operators.
onErrorDroppedMulticast(
ex);
return;
}
done = true;
}
drain();
}
@
Override
public void
onError(
Throwable t) {
if (
done) {
Operators.
onErrorDroppedMulticast(
t);
return;
}
if (
Exceptions.
addThrowable(
ERROR, this,
t)) {
done = true;
drain();
}
else {
Operators.
onErrorDroppedMulticast(
t);
}
}
@
Override
public void
onComplete() {
if (
done) {
return;
}
done = true;
drain();
}
@
Override
public void
dispose() {
if (
SUBSCRIBERS.
get(this) ==
TERMINATED) {
return;
}
if (
CONNECTION.
compareAndSet(
parent, this, null)) {
Operators.
terminate(
S, this);
if (
WIP.
getAndIncrement(this) != 0) {
return;
}
disconnectAction(
terminate());
}
}
void
disconnectAction(
PubSubInner<T>[]
inners) {
if (
inners.length > 0) {
queue.
clear();
CancellationException ex = new
CancellationException("Disconnected");
for (
PubSubInner<T>
inner :
inners) {
inner.
actual.
onError(
ex);
}
}
}
boolean
add(
PublishInner<T>
inner) {
for (; ; ) {
FluxPublish.
PubSubInner<T>[]
a =
subscribers;
if (
a ==
TERMINATED) {
return false;
}
int
n =
a.length;
PubSubInner<?>[]
b = new
PubSubInner[
n + 1];
System.
arraycopy(
a, 0,
b, 0,
n);
b[
n] =
inner;
if (
SUBSCRIBERS.
compareAndSet(this,
a,
b)) {
return true;
}
}
}
@
SuppressWarnings("unchecked")
public void
remove(
PubSubInner<T>
inner) {
for (; ; ) {
PubSubInner<T>[]
a =
subscribers;
if (
a ==
TERMINATED ||
a ==
EMPTY) {
return;
}
int
n =
a.length;
int
j = 0;
for (int
i = 0;
i <
n;
i++) {
if (
a[
i] ==
inner) {
j =
i;
break;
}
}
if (
j < 0) { //TODO investigate condition always false
return;
}
PubSubInner<?>[]
b;
if (
n == 1) {
b =
EMPTY;
}
else {
b = new
PubSubInner<?>[
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;
}
}
}
@
SuppressWarnings("unchecked")
PubSubInner<T>[]
terminate() {
return
SUBSCRIBERS.
getAndSet(this,
TERMINATED);
}
boolean
tryConnect() {
return
connected == 0 &&
CONNECTED.
compareAndSet(this, 0, 1);
}
final void
drain() {
if (
WIP.
getAndIncrement(this) != 0) {
return;
}
int
missed = 1;
for (; ; ) {
boolean
d =
done;
Queue<T>
q =
queue;
boolean
empty =
q == null ||
q.
isEmpty();
if (
checkTerminated(
d,
empty)) {
return;
}
if (!
empty) {
PubSubInner<T>[]
a =
subscribers;
long
maxRequested =
Long.
MAX_VALUE;
int
len =
a.length;
int
cancel = 0;
for (
PubSubInner<T>
inner :
a) {
long
r =
inner.
requested;
if (
r >= 0L) {
maxRequested =
Math.
min(
maxRequested,
r);
}
else { //Long.MIN
cancel++;
}
}
if (
len ==
cancel) {
T
v;
try {
v =
q.
poll();
}
catch (
Throwable ex) {
Exceptions.
addThrowable(
ERROR,
this,
Operators.
onOperatorError(
s,
ex,
currentContext()));
d = true;
v = null;
}
if (
checkTerminated(
d,
v == null)) {
return;
}
if (
sourceMode !=
Fuseable.
SYNC) {
s.
request(1);
}
continue;
}
int
e = 0;
while (
e <
maxRequested &&
cancel !=
Integer.
MIN_VALUE) {
d =
done;
T
v;
try {
v =
q.
poll();
}
catch (
Throwable ex) {
Exceptions.
addThrowable(
ERROR,
this,
Operators.
onOperatorError(
s,
ex,
currentContext()));
d = true;
v = null;
}
empty =
v == null;
if (
checkTerminated(
d,
empty)) {
return;
}
if (
empty) {
//async mode only needs to break but SYNC mode needs to perform terminal cleanup here...
if (
sourceMode ==
Fuseable.
SYNC) {
q.
poll();
done = true;
checkTerminated(true, true);
}
break;
}
for (
PubSubInner<T>
inner :
a) {
inner.
actual.
onNext(
v);
if(
Operators.
producedCancellable(
PubSubInner.
REQUESTED,
inner,1) ==
Long.
MIN_VALUE){
cancel =
Integer.
MIN_VALUE;
}
}
e++;
}
if (
e != 0 &&
sourceMode !=
Fuseable.
SYNC) {
s.
request(
e);
}
if (
maxRequested != 0L && !
empty) {
continue;
}
}
else if (
sourceMode ==
Fuseable.
SYNC) {
q.
poll();
done = true;
checkTerminated(true, true);
return;
}
missed =
WIP.
addAndGet(this, -
missed);
if (
missed == 0) {
break;
}
}
}
boolean
checkTerminated(boolean
d, boolean
empty) {
if (
s ==
Operators.
cancelledSubscription()) {
disconnectAction(
terminate());
return true;
}
if (
d) {
Throwable e =
error;
if (
e != null &&
e !=
Exceptions.
TERMINATED) {
CONNECTION.
compareAndSet(
parent, this, null);
e =
Exceptions.
terminate(
ERROR, this);
queue.
clear();
for (
PubSubInner<T>
inner :
terminate()) {
inner.
actual.
onError(
e);
}
return true;
}
else if (
empty) {
CONNECTION.
compareAndSet(
parent, this, null);
for (
PubSubInner<T>
inner :
terminate()) {
inner.
actual.
onComplete();
}
return true;
}
}
return false;
}
@
Override
public
Stream<? extends
Scannable>
inners() {
return
Stream.
of(
subscribers);
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
s;
if (
key ==
Attr.
PREFETCH) return
prefetch;
if (
key ==
Attr.
ERROR) return
error;
if (
key ==
Attr.
BUFFERED) return
queue != null ?
queue.
size() : 0;
if (
key ==
Attr.
TERMINATED) return
isTerminated();
if (
key ==
Attr.
CANCELLED) return
s ==
Operators.
cancelledSubscription();
return null;
}
@
Override
public boolean
isDisposed() {
return
s ==
Operators.
cancelledSubscription() ||
done;
}
}
static abstract class
PubSubInner<T> implements
InnerProducer<T> {
final
CoreSubscriber<? super T>
actual;
volatile long
requested;
@
SuppressWarnings("rawtypes")
static final
AtomicLongFieldUpdater<
PubSubInner>
REQUESTED =
AtomicLongFieldUpdater.
newUpdater(
PubSubInner.class, "requested");
PubSubInner(
CoreSubscriber<? super T>
actual) {
this.
actual =
actual;
}
@
Override
public final void
request(long
n) {
if (
Operators.
validate(
n)) {
Operators.
addCapCancellable(
REQUESTED, this,
n);
drainParent();
}
}
@
Override
public final void
cancel() {
long
r =
requested;
if (
r !=
Long.
MIN_VALUE) {
r =
REQUESTED.
getAndSet(this,
Long.
MIN_VALUE);
if (
r !=
Long.
MIN_VALUE) {
removeAndDrainParent();
}
}
}
final boolean
isCancelled() {
return
requested ==
Long.
MIN_VALUE;
}
@
Override
public final
CoreSubscriber<? super T>
actual() {
return
actual;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
CANCELLED) return
isCancelled();
if (
key ==
Attr.
REQUESTED_FROM_DOWNSTREAM) return
isCancelled() ? 0L :
requested;
return
InnerProducer.super.scanUnsafe(
key);
}
abstract void
drainParent();
abstract void
removeAndDrainParent();
}
static final class
PublishInner<T> extends
PubSubInner<T> {
PublishSubscriber<T>
parent;
PublishInner(
CoreSubscriber<? super T>
actual) {
super(
actual);
}
@
Override
void
drainParent() {
PublishSubscriber<T>
p =
parent;
if (
p != null) {
p.
drain();
}
}
@
Override
void
removeAndDrainParent() {
PublishSubscriber<T>
p =
parent;
if (
p != null) {
p.
remove(this);
p.
drain();
}
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
parent;
if (
key ==
Attr.
TERMINATED) return
parent != null &&
parent.
isTerminated();
return super.scanUnsafe(
key);
}
}
}