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org.neo4j.driver.internal.shaded.reactor.core.publisher.FluxSwitchMap Maven / Gradle / Ivy
/*
* 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.BiPredicate;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Stream;
import org.reactivestreams.Publisher;
import org.reactivestreams.Subscriber;
import org.reactivestreams.Subscription;
import reactor.core.CoreSubscriber;
import reactor.core.Exceptions;
import reactor.core.Scannable;
import reactor.util.annotation.Nullable;
import reactor.util.context.Context;
/**
* Switches to a new Publisher generated via a function whenever the upstream produces an
* item.
*
* @param the source value type
* @param the output value type
*
* @see Reactive-Streams-Commons
*/
final class FluxSwitchMap extends InternalFluxOperator {
final Function> mapper;
final Supplier> queueSupplier;
final int prefetch;
@SuppressWarnings("ConstantConditions")
static final SwitchMapInner CANCELLED_INNER =
new SwitchMapInner<>(null, 0, Long.MAX_VALUE);
FluxSwitchMap(Flux source,
Function> mapper,
Supplier> queueSupplier,
int prefetch) {
super(source);
if (prefetch <= 0) {
throw new IllegalArgumentException("prefetch > 0 required but it was " +
prefetch);
}
this.mapper = Objects.requireNonNull(mapper, "mapper");
this.queueSupplier = Objects.requireNonNull(queueSupplier, "queueSupplier");
this.prefetch = prefetch;
}
@Override
public int getPrefetch() {
return Integer.MAX_VALUE;
}
@Override
public CoreSubscriber subscribeOrReturn(CoreSubscriber actual) {
//for now switchMap doesn't support onErrorContinue, so the scalar version shouldn't either
if (FluxFlatMap.trySubscribeScalarMap(source, actual, mapper, false, false)) {
return null;
}
return new SwitchMapMain(actual,
mapper,
queueSupplier.get(), prefetch);
}
@Override
public Object scanUnsafe(Attr key) {
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return super.scanUnsafe(key);
}
static final class SwitchMapMain implements InnerOperator {
final Function> mapper;
final Queue queue;
final BiPredicate queueBiAtomic;
final int prefetch;
final CoreSubscriber actual;
Subscription s;
volatile boolean done;
volatile Throwable error;
@SuppressWarnings("rawtypes")
static final AtomicReferenceFieldUpdater ERROR =
AtomicReferenceFieldUpdater.newUpdater(SwitchMapMain.class,
Throwable.class,
"error");
volatile boolean cancelled;
volatile int once;
@SuppressWarnings("rawtypes")
static final AtomicIntegerFieldUpdater ONCE =
AtomicIntegerFieldUpdater.newUpdater(SwitchMapMain.class, "once");
volatile long requested;
@SuppressWarnings("rawtypes")
static final AtomicLongFieldUpdater REQUESTED =
AtomicLongFieldUpdater.newUpdater(SwitchMapMain.class, "requested");
volatile int wip;
@SuppressWarnings("rawtypes")
static final AtomicIntegerFieldUpdater WIP =
AtomicIntegerFieldUpdater.newUpdater(SwitchMapMain.class, "wip");
volatile SwitchMapInner inner;
@SuppressWarnings("rawtypes")
static final AtomicReferenceFieldUpdater INNER =
AtomicReferenceFieldUpdater.newUpdater(SwitchMapMain.class,
SwitchMapInner.class,
"inner");
volatile long index;
@SuppressWarnings("rawtypes")
static final AtomicLongFieldUpdater INDEX =
AtomicLongFieldUpdater.newUpdater(SwitchMapMain.class, "index");
volatile int active;
@SuppressWarnings("rawtypes")
static final AtomicIntegerFieldUpdater ACTIVE =
AtomicIntegerFieldUpdater.newUpdater(SwitchMapMain.class, "active");
@SuppressWarnings("unchecked")
SwitchMapMain(CoreSubscriber actual,
Function> mapper,
Queue queue,
int prefetch) {
this.actual = actual;
this.mapper = mapper;
this.queue = queue;
this.prefetch = prefetch;
this.active = 1;
if(queue instanceof BiPredicate){
this.queueBiAtomic = (BiPredicate) queue;
}
else {
this.queueBiAtomic = null;
}
}
@Override
public final CoreSubscriber actual() {
return actual;
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.CANCELLED) return cancelled;
if (key == Attr.PARENT) return s;
if (key == Attr.TERMINATED) return done;
if (key == Attr.ERROR) return error;
if (key == Attr.PREFETCH) return prefetch;
if (key == Attr.BUFFERED) return queue.size();
if (key == Attr.REQUESTED_FROM_DOWNSTREAM) return requested;
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return InnerOperator.super.scanUnsafe(key);
}
@Override
public Stream inners() {
return Stream.of(inner);
}
@Override
public void onSubscribe(Subscription s) {
if (Operators.validate(this.s, s)) {
this.s = s;
actual.onSubscribe(this);
s.request(Long.MAX_VALUE);
}
}
@Override
public void onNext(T t) {
if (done) {
Operators.onNextDropped(t, actual.currentContext());
return;
}
long idx = INDEX.incrementAndGet(this);
SwitchMapInner si = inner;
if (si != null) {
si.deactivate();
si.cancel();
}
Publisher p;
try {
p = Objects.requireNonNull(mapper.apply(t),
"The mapper returned a null publisher");
}
catch (Throwable e) {
onError(Operators.onOperatorError(s, e, t, actual.currentContext()));
return;
}
SwitchMapInner innerSubscriber =
new SwitchMapInner<>(this, prefetch, idx);
if (INNER.compareAndSet(this, si, innerSubscriber)) {
ACTIVE.getAndIncrement(this);
p.subscribe(innerSubscriber);
}
}
@Override
public void onError(Throwable t) {
if (done) {
Operators.onErrorDropped(t, actual.currentContext());
return;
}
if (Exceptions.addThrowable(ERROR, this, t)) {
if (ONCE.compareAndSet(this, 0, 1)) {
deactivate();
}
cancelInner();
done = true;
drain();
}
else {
Operators.onErrorDropped(t, actual.currentContext());
}
}
@Override
public void onComplete() {
if (done) {
return;
}
if (ONCE.compareAndSet(this, 0, 1)) {
deactivate();
}
done = true;
drain();
}
@Override
public void request(long n) {
if (Operators.validate(n)) {
Operators.addCap(REQUESTED, this, n);
drain();
}
}
@Override
public void cancel() {
if (!cancelled) {
cancelled = true;
if (WIP.getAndIncrement(this) == 0) {
cancelAndCleanup(queue);
}
}
}
void deactivate() {
ACTIVE.decrementAndGet(this);
}
void cancelInner() {
SwitchMapInner si = INNER.getAndSet(this, CANCELLED_INNER);
if (si != null && si != CANCELLED_INNER) {
si.cancel();
si.deactivate();
}
}
void cancelAndCleanup(Queue q) {
s.cancel();
cancelInner();
q.clear();
}
void drain() {
if (WIP.getAndIncrement(this) != 0) {
return;
}
Subscriber a = actual;
Queue q = queue;
int missed = 1;
for (; ; ) {
long r = requested;
long e = 0L;
while (r != e) {
boolean d = active == 0;
@SuppressWarnings("unchecked") SwitchMapInner si =
(SwitchMapInner) q.poll();
boolean empty = si == null;
if (checkTerminated(d, empty, a, q)) {
return;
}
if (empty) {
break;
}
Object second;
while ((second = q.poll()) == null) {
}
if (index == si.index) {
@SuppressWarnings("unchecked") R v = (R) second;
a.onNext(v);
si.requestOne();
e++;
}
}
if (r == e) {
if (checkTerminated(active == 0, q.isEmpty(), a, q)) {
return;
}
}
if (e != 0 && r != Long.MAX_VALUE) {
REQUESTED.addAndGet(this, -e);
}
missed = WIP.addAndGet(this, -missed);
if (missed == 0) {
break;
}
}
}
boolean checkTerminated(boolean d, boolean empty, Subscriber a, Queue q) {
if (cancelled) {
cancelAndCleanup(q);
return true;
}
if (d) {
Throwable e = Exceptions.terminate(ERROR, this);
if (e != null && e != Exceptions.TERMINATED) {
cancelAndCleanup(q);
a.onError(e);
return true;
}
else if (empty) {
a.onComplete();
return true;
}
}
return false;
}
void innerNext(SwitchMapInner inner, R value) {
if (queueBiAtomic != null) {
//the queue is a "BiQueue" from Reactor, test(A, B) actually does double insertion
queueBiAtomic.test(inner, value);
}
else {
//the queue is a regular queue, a bit more overhead to do double insertion
queue.offer(inner);
queue.offer(value);
}
drain();
}
void innerError(SwitchMapInner inner, Throwable e) {
if (Exceptions.addThrowable(ERROR, this, e)) {
s.cancel();
if (ONCE.compareAndSet(this, 0, 1)) {
deactivate();
}
inner.deactivate();
drain();
}
else {
Operators.onErrorDropped(e, actual.currentContext());
}
}
void innerComplete(SwitchMapInner inner) {
inner.deactivate();
drain();
}
}
static final class SwitchMapInner implements InnerConsumer, Subscription {
final SwitchMapMain parent;
final int prefetch;
final int limit;
final long index;
volatile int once;
@SuppressWarnings("rawtypes")
static final AtomicIntegerFieldUpdater ONCE =
AtomicIntegerFieldUpdater.newUpdater(SwitchMapInner.class, "once");
volatile Subscription s;
@SuppressWarnings("rawtypes")
static final AtomicReferenceFieldUpdater S =
AtomicReferenceFieldUpdater.newUpdater(SwitchMapInner.class,
Subscription.class,
"s");
int produced;
SwitchMapInner(SwitchMapMain parent, int prefetch, long index) {
this.parent = parent;
this.prefetch = prefetch;
this.limit = Operators.unboundedOrLimit(prefetch);
this.index = index;
}
@Override
public Context currentContext() {
return parent.currentContext();
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.CANCELLED) return s == Operators.cancelledSubscription();
if (key == Attr.PARENT) return s;
if (key == Attr.ACTUAL) return parent;
if (key == Attr.PREFETCH) return prefetch;
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return null;
}
@Override
public void onSubscribe(Subscription s) {
Subscription a = this.s;
if (a == Operators.cancelledSubscription()) {
s.cancel();
}
if (a != null) {
s.cancel();
Operators.reportSubscriptionSet();
return;
}
if (S.compareAndSet(this, null, s)) {
s.request(Operators.unboundedOrPrefetch(prefetch));
return;
}
a = this.s;
if (a != Operators.cancelledSubscription()) {
s.cancel();
Operators.reportSubscriptionSet();
}
}
@Override
public void onNext(R t) {
parent.innerNext(this, t);
}
@Override
public void onError(Throwable t) {
parent.innerError(this, t);
}
@Override
public void onComplete() {
parent.innerComplete(this);
}
void deactivate() {
if (ONCE.compareAndSet(this, 0, 1)) {
parent.deactivate();
}
}
void requestOne() {
int p = produced + 1;
if (p == limit) {
produced = 0;
s.request(p);
}
else {
produced = p;
}
}
@Override
public void request(long n) {
long p = produced + n;
if (p >= limit) {
produced = 0;
s.request(p);
}
else {
produced = (int) p;
}
}
@Override
public void cancel() {
Subscription a = s;
if (a != Operators.cancelledSubscription()) {
a = S.getAndSet(this, Operators.cancelledSubscription());
if (a != null && a != Operators.cancelledSubscription()) {
a.cancel();
}
}
}
}
}
