/*
* 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.
Iterator;
import java.util.
Objects;
import java.util.concurrent.atomic.
AtomicIntegerFieldUpdater;
import java.util.stream.
Stream;
import org.reactivestreams.
Publisher;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Scannable;
import reactor.util.annotation.
Nullable;
/**
* Given a set of source Publishers the values of that Publisher is forwarded to the
* subscriber which responds first with any signal.
*
* @param <T> the value type
*
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class
FluxFirstEmitting<T> extends
Flux<T> implements
SourceProducer<T> {
final
Publisher<? extends T>[]
array;
final
Iterable<? extends
Publisher<? extends T>>
iterable;
@
SafeVarargs
FluxFirstEmitting(
Publisher<? extends T>...
array) {
this.
array =
Objects.
requireNonNull(
array, "array");
this.
iterable = null;
}
FluxFirstEmitting(
Iterable<? extends
Publisher<? extends T>>
iterable) {
this.
array = null;
this.
iterable =
Objects.
requireNonNull(
iterable);
}
@
SuppressWarnings("unchecked")
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
Publisher<? extends T>[]
a =
array;
int
n;
if (
a == null) {
n = 0;
a = new
Publisher[8];
Iterator<? extends
Publisher<? extends T>>
it;
try {
it =
Objects.
requireNonNull(
iterable.
iterator(),
"The iterator returned is null");
}
catch (
Throwable e) {
Operators.
error(
actual,
Operators.
onOperatorError(
e,
actual.
currentContext()));
return;
}
for (; ; ) {
boolean
b;
try {
b =
it.
hasNext();
}
catch (
Throwable e) {
Operators.
error(
actual,
Operators.
onOperatorError(
e,
actual.
currentContext()));
return;
}
if (!
b) {
break;
}
Publisher<? extends T>
p;
try {
p =
Objects.
requireNonNull(
it.
next(),
"The Publisher returned by the iterator is null");
}
catch (
Throwable e) {
Operators.
error(
actual,
Operators.
onOperatorError(
e,
actual.
currentContext()));
return;
}
if (
n ==
a.length) {
Publisher<? extends T>[]
c = new
Publisher[
n + (
n >> 2)];
System.
arraycopy(
a, 0,
c, 0,
n);
a =
c;
}
a[
n++] =
p;
}
}
else {
n =
a.length;
}
if (
n == 0) {
Operators.
complete(
actual);
return;
}
if (
n == 1) {
Publisher<? extends T>
p =
a[0];
if (
p == null) {
Operators.
error(
actual,
new
NullPointerException("The single source Publisher is null"));
}
else {
p.
subscribe(
actual);
}
return;
}
RaceCoordinator<T>
coordinator = new
RaceCoordinator<>(
n);
coordinator.
subscribe(
a,
n,
actual);
}
/**
* Returns a new instance which has the additional source to be amb'd together with
* the current array of sources.
* <p>
* This operation doesn't change the current FluxFirstEmitting instance.
*
* @param source the new source to merge with the others
*
* @return the new FluxFirstEmitting instance or null if the Amb runs with an Iterable
*/
@
Nullable
FluxFirstEmitting<T>
ambAdditionalSource(
Publisher<? extends T>
source) {
if (
array != null) {
int
n =
array.length;
@
SuppressWarnings("unchecked")
Publisher<? extends T>[]
newArray =
new
Publisher[
n + 1];
System.
arraycopy(
array, 0,
newArray, 0,
n);
newArray[
n] =
source;
return new
FluxFirstEmitting<>(
newArray);
}
return null;
}
@
Override
public
Object scanUnsafe(
Attr key) {
return null; //no particular key to be represented, still useful in hooks
}
static final class
RaceCoordinator<T>
implements
Subscription,
Scannable {
final
FirstEmittingSubscriber<T>[]
subscribers;
volatile boolean
cancelled;
volatile int
wip;
@
SuppressWarnings("rawtypes")
static final
AtomicIntegerFieldUpdater<
RaceCoordinator>
WIP =
AtomicIntegerFieldUpdater.
newUpdater(
RaceCoordinator.class, "wip");
@
SuppressWarnings("unchecked")
RaceCoordinator(int
n) {
subscribers = new
FirstEmittingSubscriber[
n];
wip =
Integer.
MIN_VALUE;
}
@
Override
public
Stream<? extends
Scannable>
inners() {
return
Stream.
of(
subscribers);
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
CANCELLED) return
cancelled;
return null;
}
void
subscribe(
Publisher<? extends T>[]
sources,
int
n,
CoreSubscriber<? super T>
actual) {
FirstEmittingSubscriber<T>[]
a =
subscribers;
for (int
i = 0;
i <
n;
i++) {
a[
i] = new
FirstEmittingSubscriber<>(
actual, this,
i);
}
actual.
onSubscribe(this);
for (int
i = 0;
i <
n;
i++) {
if (
cancelled ||
wip !=
Integer.
MIN_VALUE) {
return;
}
Publisher<? extends T>
p =
sources[
i];
if (
p == null) {
if (
WIP.
compareAndSet(this,
Integer.
MIN_VALUE, -1)) {
actual.
onError(new
NullPointerException("The " +
i + " th Publisher source is null"));
}
return;
}
p.
subscribe(
a[
i]);
}
}
@
Override
public void
request(long
n) {
if (
Operators.
validate(
n)) {
int
w =
wip;
if (
w >= 0) {
subscribers[
w].
request(
n);
}
else {
for (
FirstEmittingSubscriber<T>
s :
subscribers) {
s.
request(
n);
}
}
}
}
@
Override
public void
cancel() {
if (
cancelled) {
return;
}
cancelled = true;
int
w =
wip;
if (
w >= 0) {
subscribers[
w].
cancel();
}
else {
for (
FirstEmittingSubscriber<T>
s :
subscribers) {
s.
cancel();
}
}
}
boolean
tryWin(int
index) {
if (
wip ==
Integer.
MIN_VALUE) {
if (
WIP.
compareAndSet(this,
Integer.
MIN_VALUE,
index)) {
FirstEmittingSubscriber<T>[]
a =
subscribers;
int
n =
a.length;
for (int
i = 0;
i <
n;
i++) {
if (
i !=
index) {
a[
i].
cancel();
}
}
return true;
}
}
return false;
}
}
static final class
FirstEmittingSubscriber<T> extends
Operators.
DeferredSubscription
implements
InnerOperator<T, T> {
final
RaceCoordinator<T>
parent;
final
CoreSubscriber<? super T>
actual;
final int
index;
boolean
won;
FirstEmittingSubscriber(
CoreSubscriber<? super T>
actual,
RaceCoordinator<T>
parent,
int
index) {
this.
actual =
actual;
this.
parent =
parent;
this.
index =
index;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
s;
if (
key ==
Attr.
CANCELLED) return
parent.
cancelled;
return
InnerOperator.super.scanUnsafe(
key);
}
@
Override
public void
onSubscribe(
Subscription s) {
set(
s);
}
@
Override
public
CoreSubscriber<? super T>
actual() {
return
actual;
}
@
Override
public void
onNext(T
t) {
if (
won) {
actual.
onNext(
t);
}
else if (
parent.
tryWin(
index)) {
won = true;
actual.
onNext(
t);
}
}
@
Override
public void
onError(
Throwable t) {
if (
won) {
actual.
onError(
t);
}
else if (
parent.
tryWin(
index)) {
won = true;
actual.
onError(
t);
}
}
@
Override
public void
onComplete() {
if (
won) {
actual.
onComplete();
}
else if (
parent.
tryWin(
index)) {
won = true;
actual.
onComplete();
}
}
}
}