/*
* 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.
Iterator;
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;
/**
* Combines the latest values from multiple sources through a function.
*
* @param <T> the value type of the sources
* @param <R> the result type
*
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class
FluxCombineLatest<T, R> extends
Flux<R> implements
Fuseable,
SourceProducer<R> {
final
Publisher<? extends T>[]
array;
final
Iterable<? extends
Publisher<? extends T>>
iterable;
final
Function<
Object[], R>
combiner;
final
Supplier<? extends
Queue<
SourceAndArray>>
queueSupplier;
final int
prefetch;
FluxCombineLatest(
Publisher<? extends T>[]
array,
Function<
Object[], R>
combiner,
Supplier<? extends
Queue<
SourceAndArray>>
queueSupplier, int
prefetch) {
if (
prefetch <= 0) {
throw new
IllegalArgumentException("prefetch > 0 required but it was " +
prefetch);
}
this.
array =
Objects.
requireNonNull(
array, "array");
this.
iterable = null;
this.
combiner =
Objects.
requireNonNull(
combiner, "combiner");
this.
queueSupplier =
Objects.
requireNonNull(
queueSupplier, "queueSupplier");
this.
prefetch =
prefetch;
}
FluxCombineLatest(
Iterable<? extends
Publisher<? extends T>>
iterable,
Function<
Object[], R>
combiner,
Supplier<? extends
Queue<
SourceAndArray>>
queueSupplier, int
prefetch) {
if (
prefetch < 0) {
throw new
IllegalArgumentException("prefetch > 0 required but it was " +
prefetch);
}
this.
array = null;
this.
iterable =
Objects.
requireNonNull(
iterable, "iterable");
this.
combiner =
Objects.
requireNonNull(
combiner, "combiner");
this.
queueSupplier =
Objects.
requireNonNull(
queueSupplier, "queueSupplier");
this.
prefetch =
prefetch;
}
@
Override
public int
getPrefetch() {
return
prefetch;
}
@
SuppressWarnings("unchecked")
@
Override
public void
subscribe(
CoreSubscriber<? super R>
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) {
Function<T, R>
f =
t ->
combiner.
apply(new
Object[]{
t});
if (
a[0] instanceof
Fuseable) {
new
FluxMapFuseable<>(
from(
a[0]),
f).
subscribe(
actual);
}
else {
new
FluxMap<>(
from(
a[0]),
f).
subscribe(
actual);
}
return;
}
Queue<
SourceAndArray>
queue =
queueSupplier.
get();
CombineLatestCoordinator<T, R>
coordinator =
new
CombineLatestCoordinator<>(
actual,
combiner,
n,
queue,
prefetch);
actual.
onSubscribe(
coordinator);
coordinator.
subscribe(
a,
n);
}
@
Override
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PREFETCH) return
prefetch;
return null;
}
static final class
CombineLatestCoordinator<T, R>
implements
QueueSubscription<R>,
InnerProducer<R> {
final
Function<
Object[], R>
combiner;
final
CombineLatestInner<T>[]
subscribers;
final
Queue<
SourceAndArray>
queue;
final
Object[]
latest;
final
CoreSubscriber<? super R>
actual;
final
Context ctx;
boolean
outputFused;
int
nonEmptySources;
int
completedSources;
volatile boolean
cancelled;
volatile long
requested;
@
SuppressWarnings("rawtypes")
static final
AtomicLongFieldUpdater<
CombineLatestCoordinator>
REQUESTED =
AtomicLongFieldUpdater.
newUpdater(
CombineLatestCoordinator.class,
"requested");
volatile int
wip;
@
SuppressWarnings("rawtypes")
static final
AtomicIntegerFieldUpdater<
CombineLatestCoordinator>
WIP =
AtomicIntegerFieldUpdater.
newUpdater(
CombineLatestCoordinator.class,
"wip");
volatile boolean
done;
volatile
Throwable error;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
CombineLatestCoordinator,
Throwable>
ERROR =
AtomicReferenceFieldUpdater.
newUpdater(
CombineLatestCoordinator.class,
Throwable.class,
"error");
CombineLatestCoordinator(
CoreSubscriber<? super R>
actual,
Function<
Object[], R>
combiner,
int
n,
Queue<
SourceAndArray>
queue, int
prefetch) {
this.
actual =
actual;
this.
ctx =
actual.
currentContext();
this.
combiner =
combiner;
@
SuppressWarnings("unchecked")
CombineLatestInner<T>[]
a =
new
CombineLatestInner[
n];
for (int
i = 0;
i <
n;
i++) {
a[
i] = new
CombineLatestInner<>(this,
i,
prefetch);
}
this.
subscribers =
a;
this.
latest = new
Object[
n];
this.
queue =
queue;
}
@
Override
public final
CoreSubscriber<? super R>
actual() {
return
actual;
}
@
Override
public void
request(long
n) {
if (
Operators.
validate(
n)) {
Operators.
addCap(
REQUESTED, this,
n);
drain();
}
}
@
Override
public void
cancel() {
if (
cancelled) {
return;
}
cancelled = true;
cancelAll();
if (
WIP.
getAndIncrement(this) == 0) {
clear();
}
}
@
Override
public
Stream<? extends
Scannable>
inners() {
return
Stream.
of(
subscribers);
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
TERMINATED) return
done;
if (
key ==
Attr.
CANCELLED) return
cancelled;
if (
key ==
Attr.
ERROR) return
error;
if (
key ==
Attr.
REQUESTED_FROM_DOWNSTREAM) return
requested;
return
InnerProducer.super.scanUnsafe(
key);
}
void
subscribe(
Publisher<? extends T>[]
sources, int
n) {
CombineLatestInner<T>[]
a =
subscribers;
for (int
i = 0;
i <
n;
i++) {
if (
done ||
cancelled) {
return;
}
sources[
i].
subscribe(
a[
i]);
}
}
void
innerValue(int
index, T
value) {
boolean
replenishInsteadOfDrain;
synchronized (this) {
Object[]
os =
latest;
int
localNonEmptySources =
nonEmptySources;
if (
os[
index] == null) {
localNonEmptySources++;
nonEmptySources =
localNonEmptySources;
}
os[
index] =
value;
if (
os.length ==
localNonEmptySources) {
SourceAndArray sa =
new
SourceAndArray(
subscribers[
index],
os.
clone());
if (!
queue.
offer(
sa)) {
innerError(
Operators.
onOperatorError(this,
Exceptions.
failWithOverflow(
Exceptions.
BACKPRESSURE_ERROR_QUEUE_FULL),
this.
ctx));
return;
}
replenishInsteadOfDrain = false;
}
else {
replenishInsteadOfDrain = true;
}
}
if (
replenishInsteadOfDrain) {
subscribers[
index].
requestOne();
}
else {
drain();
}
}
void
innerComplete(int
index) {
synchronized (this) {
Object[]
os =
latest;
if (
os[
index] != null) {
int
localCompletedSources =
completedSources + 1;
if (
localCompletedSources ==
os.length) {
done = true;
}
else {
completedSources =
localCompletedSources;
return;
}
}
else {
done = true;
}
}
drain();
}
void
innerError(
Throwable e) {
if (
Exceptions.
addThrowable(
ERROR, this,
e)) {
done = true;
drain();
}
else {
discardQueue(
queue);
Operators.
onErrorDropped(
e, this.
ctx);
}
}
void
drainOutput() {
final
CoreSubscriber<? super R>
a =
actual;
final
Queue<
SourceAndArray>
q =
queue;
int
missed = 1;
for (; ; ) {
if (
cancelled) {
discardQueue(
q);
return;
}
Throwable ex =
error;
if (
ex != null) {
discardQueue(
q);
a.
onError(
ex);
return;
}
boolean
d =
done;
boolean
empty =
q.
isEmpty();
if (!
empty) {
a.
onNext(null);
}
if (
d &&
empty) {
a.
onComplete();
return;
}
missed =
WIP.
addAndGet(this, -
missed);
if (
missed == 0) {
break;
}
}
}
void
drainAsync() {
final
Queue<
SourceAndArray>
q =
queue;
int
missed = 1;
for (; ; ) {
long
r =
requested;
long
e = 0L;
while (
e !=
r) {
boolean
d =
done;
SourceAndArray v =
q.
poll();
boolean
empty =
v == null;
if (
checkTerminated(
d,
empty,
q)) {
return;
}
if (
empty) {
break;
}
R
w;
try {
w =
Objects.
requireNonNull(
combiner.
apply(
v.
array), "Combiner returned null");
}
catch (
Throwable ex) {
Operators.
onDiscardMultiple(
Stream.
of(
v.
array), this.
ctx);
ex =
Operators.
onOperatorError(this,
ex,
v.
array,
this.
ctx);
Exceptions.
addThrowable(
ERROR, this,
ex);
//noinspection ConstantConditions
ex =
Exceptions.
terminate(
ERROR, this);
actual.
onError(
ex);
return;
}
actual.
onNext(
w);
v.
source.
requestOne();
e++;
}
if (
e ==
r) {
if (
checkTerminated(
done,
q.
isEmpty(),
q)) {
return;
}
}
if (
e != 0L &&
r !=
Long.
MAX_VALUE) {
REQUESTED.
addAndGet(this, -
e);
}
missed =
WIP.
addAndGet(this, -
missed);
if (
missed == 0) {
break;
}
}
}
void
drain() {
if (
WIP.
getAndIncrement(this) != 0) {
return;
}
if (
outputFused) {
drainOutput();
}
else {
drainAsync();
}
}
boolean
checkTerminated(boolean
d, boolean
empty,
Queue<
SourceAndArray>
q) {
if (
cancelled) {
cancelAll();
discardQueue(
q);
return true;
}
if (
d) {
Throwable e =
Exceptions.
terminate(
ERROR, this);
if (
e != null &&
e !=
Exceptions.
TERMINATED) {
cancelAll();
discardQueue(
q);
actual.
onError(
e);
return true;
}
else if (
empty) {
cancelAll();
actual.
onComplete();
return true;
}
}
return false;
}
void
cancelAll() {
for (
CombineLatestInner<T>
inner :
subscribers) {
inner.
cancel();
}
}
@
Override
public int
requestFusion(int
requestedMode) {
if ((
requestedMode &
THREAD_BARRIER) != 0) {
return
NONE;
}
int
m =
requestedMode &
ASYNC;
outputFused =
m != 0;
return
m;
}
@
Override
@
Nullable
public R
poll() {
SourceAndArray e =
queue.
poll();
if (
e == null) {
return null;
}
R
r =
combiner.
apply(
e.
array);
e.
source.
requestOne();
return
r;
}
private void
discardQueue(
Queue<
SourceAndArray>
q) {
Operators.
onDiscardQueueWithClear(
q, this.
ctx,
SourceAndArray::toStream);
}
@
Override
public void
clear() {
discardQueue(
queue);
}
@
Override
public boolean
isEmpty() {
return
queue.
isEmpty();
}
@
Override
public int
size() {
return
queue.
size();
}
}
static final class
CombineLatestInner<T>
implements
InnerConsumer<T> {
final
CombineLatestCoordinator<T, ?>
parent;
final int
index;
final int
prefetch;
final int
limit;
volatile
Subscription s;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
CombineLatestInner,
Subscription>
S =
AtomicReferenceFieldUpdater.
newUpdater(
CombineLatestInner.class,
Subscription.class,
"s");
int
produced;
CombineLatestInner(
CombineLatestCoordinator<T, ?>
parent,
int
index,
int
prefetch) {
this.
parent =
parent;
this.
index =
index;
this.
prefetch =
prefetch;
this.
limit =
Operators.
unboundedOrLimit(
prefetch);
}
@
Override
public
Context currentContext() {
return
parent.
actual.
currentContext();
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
setOnce(
S, this,
s)) {
s.
request(
Operators.
unboundedOrPrefetch(
prefetch));
}
}
@
Override
public void
onNext(T
t) {
parent.
innerValue(
index,
t);
}
@
Override
public void
onError(
Throwable t) {
parent.
innerError(
t);
}
@
Override
public void
onComplete() {
parent.
innerComplete(
index);
}
public void
cancel() {
Operators.
terminate(
S, this);
}
void
requestOne() {
int
p =
produced + 1;
if (
p ==
limit) {
produced = 0;
s.
request(
p);
}
else {
produced =
p;
}
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
s;
if (
key ==
Attr.
ACTUAL) return
parent;
if (
key ==
Attr.
CANCELLED) return
s ==
Operators.
cancelledSubscription();
if (
key ==
Attr.
PREFETCH) return
prefetch;
return null;
}
}
/**
* The queue element type for internal use with FluxCombineLatest.
*/
static final class
SourceAndArray {
final
CombineLatestInner<?>
source;
final
Object[]
array;
SourceAndArray(
CombineLatestInner<?>
source,
Object[]
array) {
this.
source =
source;
this.
array =
array;
}
final
Stream<?>
toStream() {
return
Stream.
of(this.
array);
}
}
}