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Access to the Neo4j graph database through Java
/*
* 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.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.function.Consumer;
import java.util.function.LongConsumer;
import reactor.core.CoreSubscriber;
import reactor.core.Disposable;
import reactor.core.publisher.FluxCreate.SinkDisposable;
import reactor.util.annotation.Nullable;
import reactor.util.context.Context;
/**
* Wraps a the downstream Subscriber into a single emission object and calls the given
* callback to produce a signal (a)synchronously.
*
* @param the value type
*/
final class MonoCreate extends Mono implements SourceProducer {
final Consumer> callback;
MonoCreate(Consumer> callback) {
this.callback = callback;
}
@Override
public void subscribe(CoreSubscriber actual) {
DefaultMonoSink emitter = new DefaultMonoSink<>(actual);
actual.onSubscribe(emitter);
try {
callback.accept(emitter);
}
catch (Throwable ex) {
emitter.error(Operators.onOperatorError(ex, actual.currentContext()));
}
}
@Override
public Object scanUnsafe(Attr key) {
return null; //no particular key to be represented, still useful in hooks
}
static final class DefaultMonoSink extends AtomicBoolean
implements MonoSink, InnerProducer {
final CoreSubscriber actual;
final Context ctx;
volatile Disposable disposable;
@SuppressWarnings("rawtypes")
static final AtomicReferenceFieldUpdater DISPOSABLE =
AtomicReferenceFieldUpdater.newUpdater(DefaultMonoSink.class,
Disposable.class,
"disposable");
volatile int state;
@SuppressWarnings("rawtypes")
static final AtomicIntegerFieldUpdater STATE =
AtomicIntegerFieldUpdater.newUpdater(DefaultMonoSink.class, "state");
volatile LongConsumer requestConsumer;
@SuppressWarnings("rawtypes")
static final AtomicReferenceFieldUpdater
REQUEST_CONSUMER =
AtomicReferenceFieldUpdater.newUpdater(DefaultMonoSink.class,
LongConsumer.class,
"requestConsumer");
T value;
static final int NO_REQUEST_HAS_VALUE = 1;
static final int HAS_REQUEST_NO_VALUE = 2;
static final int HAS_REQUEST_HAS_VALUE = 3;
DefaultMonoSink(CoreSubscriber actual) {
this.actual = actual;
this.ctx = actual.currentContext();
}
@Override
public Context currentContext() {
return this.actual.currentContext();
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.TERMINATED) {
return state == HAS_REQUEST_HAS_VALUE || state == NO_REQUEST_HAS_VALUE;
}
if (key == Attr.CANCELLED) {
return OperatorDisposables.isDisposed(disposable);
}
return InnerProducer.super.scanUnsafe(key);
}
@Override
public void success() {
if (STATE.getAndSet(this, HAS_REQUEST_HAS_VALUE) != HAS_REQUEST_HAS_VALUE) {
try {
actual.onComplete();
}
finally {
disposeResource(false);
}
}
}
@Override
public void success(@Nullable T value) {
if (value == null) {
success();
return;
}
for (; ; ) {
int s = state;
if (s == HAS_REQUEST_HAS_VALUE || s == NO_REQUEST_HAS_VALUE) {
Operators.onNextDropped(value, actual.currentContext());
return;
}
if (s == HAS_REQUEST_NO_VALUE) {
if (STATE.compareAndSet(this, s, HAS_REQUEST_HAS_VALUE)) {
try {
actual.onNext(value);
actual.onComplete();
}
finally {
disposeResource(false);
}
}
return;
}
this.value = value;
if (STATE.compareAndSet(this, s, NO_REQUEST_HAS_VALUE)) {
return;
}
}
}
@Override
public void error(Throwable e) {
if (STATE.getAndSet(this, HAS_REQUEST_HAS_VALUE) != HAS_REQUEST_HAS_VALUE) {
try {
actual.onError(e);
}
finally {
disposeResource(false);
}
}
else {
Operators.onOperatorError(e, actual.currentContext());
}
}
@Override
public MonoSink onRequest(LongConsumer consumer) {
Objects.requireNonNull(consumer, "onRequest");
if (!REQUEST_CONSUMER.compareAndSet(this, null, consumer)) {
throw new IllegalStateException(
"A consumer has already been assigned to consume requests");
}
return this;
}
@Override
public CoreSubscriber actual() {
return actual;
}
@Override
public MonoSink onCancel(Disposable d) {
Objects.requireNonNull(d, "onCancel");
SinkDisposable sd = new SinkDisposable(null, d);
if (!DISPOSABLE.compareAndSet(this, null, sd)) {
Disposable c = disposable;
if (c instanceof SinkDisposable) {
SinkDisposable current = (SinkDisposable) c;
if (current.onCancel == null) {
current.onCancel = d;
}
else {
d.dispose();
}
}
}
return this;
}
@Override
public MonoSink onDispose(Disposable d) {
Objects.requireNonNull(d, "onDispose");
SinkDisposable sd = new SinkDisposable(d, null);
if (!DISPOSABLE.compareAndSet(this, null, sd)) {
Disposable c = disposable;
if (c instanceof SinkDisposable) {
SinkDisposable current = (SinkDisposable) c;
if (current.disposable == null) {
current.disposable = d;
}
else {
d.dispose();
}
}
}
return this;
}
@Override
public void request(long n) {
if (Operators.validate(n)) {
LongConsumer consumer = requestConsumer;
if (consumer != null) {
consumer.accept(n);
}
for (; ; ) {
int s = state;
if (s == HAS_REQUEST_NO_VALUE || s == HAS_REQUEST_HAS_VALUE) {
return;
}
if (s == NO_REQUEST_HAS_VALUE) {
if (STATE.compareAndSet(this, s, HAS_REQUEST_HAS_VALUE)) {
try {
actual.onNext(value);
actual.onComplete();
}
finally {
disposeResource(false);
}
}
return;
}
if (STATE.compareAndSet(this, s, HAS_REQUEST_NO_VALUE)) {
return;
}
}
}
}
@Override
public void cancel() {
if (STATE.getAndSet(this, HAS_REQUEST_HAS_VALUE) != HAS_REQUEST_HAS_VALUE) {
T old = value;
value = null;
Operators.onDiscard(old, actual.currentContext());
disposeResource(true);
}
}
void disposeResource(boolean isCancel) {
Disposable d = disposable;
if (d != OperatorDisposables.DISPOSED) {
d = DISPOSABLE.getAndSet(this, OperatorDisposables.DISPOSED);
if (d != null && d != OperatorDisposables.DISPOSED) {
if (isCancel && d instanceof SinkDisposable) {
((SinkDisposable) d).cancel();
}
d.dispose();
}
}
}
@Override
public String toString() {
return "MonoSink";
}
}
}