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Reactive Extensions for Java
/*
* Copyright (c) 2016-present, RxJava Contributors.
*
* 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 io.reactivex.rxjava3.internal.operators.flowable;
import java.util.concurrent.atomic.*;
import org.reactivestreams.*;
import io.reactivex.rxjava3.core.*;
import io.reactivex.rxjava3.disposables.Disposable;
import io.reactivex.rxjava3.exceptions.*;
import io.reactivex.rxjava3.functions.Cancellable;
import io.reactivex.rxjava3.internal.disposables.*;
import io.reactivex.rxjava3.internal.subscriptions.SubscriptionHelper;
import io.reactivex.rxjava3.internal.util.*;
import io.reactivex.rxjava3.operators.SimplePlainQueue;
import io.reactivex.rxjava3.operators.SpscLinkedArrayQueue;
import io.reactivex.rxjava3.plugins.RxJavaPlugins;
public final class FlowableCreate extends Flowable {
final FlowableOnSubscribe source;
final BackpressureStrategy backpressure;
public FlowableCreate(FlowableOnSubscribe source, BackpressureStrategy backpressure) {
this.source = source;
this.backpressure = backpressure;
}
@Override
public void subscribeActual(Subscriber t) {
BaseEmitter emitter;
switch (backpressure) {
case MISSING: {
emitter = new MissingEmitter<>(t);
break;
}
case ERROR: {
emitter = new ErrorAsyncEmitter<>(t);
break;
}
case DROP: {
emitter = new DropAsyncEmitter<>(t);
break;
}
case LATEST: {
emitter = new LatestAsyncEmitter<>(t);
break;
}
default: {
emitter = new BufferAsyncEmitter<>(t, bufferSize());
break;
}
}
t.onSubscribe(emitter);
try {
source.subscribe(emitter);
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
emitter.onError(ex);
}
}
/**
* Serializes calls to onNext, onError and onComplete.
*
* @param the value type
*/
static final class SerializedEmitter
extends AtomicInteger
implements FlowableEmitter {
private static final long serialVersionUID = 4883307006032401862L;
final BaseEmitter emitter;
final AtomicThrowable errors;
final SimplePlainQueue queue;
volatile boolean done;
SerializedEmitter(BaseEmitter emitter) {
this.emitter = emitter;
this.errors = new AtomicThrowable();
this.queue = new SpscLinkedArrayQueue<>(16);
}
@Override
public void onNext(T t) {
if (emitter.isCancelled() || done) {
return;
}
if (t == null) {
onError(ExceptionHelper.createNullPointerException("onNext called with a null value."));
return;
}
if (get() == 0 && compareAndSet(0, 1)) {
emitter.onNext(t);
if (decrementAndGet() == 0) {
return;
}
} else {
SimplePlainQueue q = queue;
synchronized (q) {
q.offer(t);
}
if (getAndIncrement() != 0) {
return;
}
}
drainLoop();
}
@Override
public void onError(Throwable t) {
if (!tryOnError(t)) {
RxJavaPlugins.onError(t);
}
}
@Override
public boolean tryOnError(Throwable t) {
if (emitter.isCancelled() || done) {
return false;
}
if (t == null) {
t = ExceptionHelper.createNullPointerException("onError called with a null Throwable.");
}
if (errors.tryAddThrowable(t)) {
done = true;
drain();
return true;
}
return false;
}
@Override
public void onComplete() {
if (emitter.isCancelled() || done) {
return;
}
done = true;
drain();
}
void drain() {
if (getAndIncrement() == 0) {
drainLoop();
}
}
void drainLoop() {
BaseEmitter e = emitter;
SimplePlainQueue q = queue;
AtomicThrowable errors = this.errors;
int missed = 1;
for (;;) {
for (;;) {
if (e.isCancelled()) {
q.clear();
return;
}
if (errors.get() != null) {
q.clear();
errors.tryTerminateConsumer(e);
return;
}
boolean d = done;
T v = q.poll();
boolean empty = v == null;
if (d && empty) {
e.onComplete();
return;
}
if (empty) {
break;
}
e.onNext(v);
}
missed = addAndGet(-missed);
if (missed == 0) {
break;
}
}
}
@Override
public void setDisposable(Disposable d) {
emitter.setDisposable(d);
}
@Override
public void setCancellable(Cancellable c) {
emitter.setCancellable(c);
}
@Override
public long requested() {
return emitter.requested();
}
@Override
public boolean isCancelled() {
return emitter.isCancelled();
}
@Override
public FlowableEmitter serialize() {
return this;
}
@Override
public String toString() {
return emitter.toString();
}
}
abstract static class BaseEmitter
extends AtomicLong
implements FlowableEmitter, Subscription {
private static final long serialVersionUID = 7326289992464377023L;
final Subscriber downstream;
final SequentialDisposable serial;
BaseEmitter(Subscriber downstream) {
this.downstream = downstream;
this.serial = new SequentialDisposable();
}
@Override
public void onComplete() {
completeDownstream();
}
protected void completeDownstream() {
if (isCancelled()) {
return;
}
try {
downstream.onComplete();
} finally {
serial.dispose();
}
}
@Override
public final void onError(Throwable e) {
if (e == null) {
e = ExceptionHelper.createNullPointerException("onError called with a null Throwable.");
}
if (!signalError(e)) {
RxJavaPlugins.onError(e);
}
}
@Override
public final boolean tryOnError(Throwable e) {
if (e == null) {
e = ExceptionHelper.createNullPointerException("tryOnError called with a null Throwable.");
}
return signalError(e);
}
public boolean signalError(Throwable e) {
return errorDownstream(e);
}
protected boolean errorDownstream(Throwable e) {
if (isCancelled()) {
return false;
}
try {
downstream.onError(e);
} finally {
serial.dispose();
}
return true;
}
@Override
public final void cancel() {
serial.dispose();
onUnsubscribed();
}
void onUnsubscribed() {
// default is no-op
}
@Override
public final boolean isCancelled() {
return serial.isDisposed();
}
@Override
public final void request(long n) {
if (SubscriptionHelper.validate(n)) {
BackpressureHelper.add(this, n);
onRequested();
}
}
void onRequested() {
// default is no-op
}
@Override
public final void setDisposable(Disposable d) {
serial.update(d);
}
@Override
public final void setCancellable(Cancellable c) {
setDisposable(new CancellableDisposable(c));
}
@Override
public final long requested() {
return get();
}
@Override
public final FlowableEmitter serialize() {
return new SerializedEmitter<>(this);
}
@Override
public String toString() {
return String.format("%s{%s}", getClass().getSimpleName(), super.toString());
}
}
static final class MissingEmitter extends BaseEmitter {
private static final long serialVersionUID = 3776720187248809713L;
MissingEmitter(Subscriber downstream) {
super(downstream);
}
@Override
public void onNext(T t) {
if (isCancelled()) {
return;
}
if (t != null) {
downstream.onNext(t);
} else {
onError(ExceptionHelper.createNullPointerException("onNext called with a null value."));
return;
}
for (;;) {
long r = get();
if (r == 0L || compareAndSet(r, r - 1)) {
return;
}
}
}
}
abstract static class NoOverflowBaseAsyncEmitter extends BaseEmitter {
private static final long serialVersionUID = 4127754106204442833L;
NoOverflowBaseAsyncEmitter(Subscriber downstream) {
super(downstream);
}
@Override
public final void onNext(T t) {
if (isCancelled()) {
return;
}
if (t == null) {
onError(ExceptionHelper.createNullPointerException("onNext called with a null value."));
return;
}
if (get() != 0) {
downstream.onNext(t);
BackpressureHelper.produced(this, 1);
} else {
onOverflow();
}
}
abstract void onOverflow();
}
static final class DropAsyncEmitter extends NoOverflowBaseAsyncEmitter {
private static final long serialVersionUID = 8360058422307496563L;
DropAsyncEmitter(Subscriber downstream) {
super(downstream);
}
@Override
void onOverflow() {
// nothing to do
}
}
static final class ErrorAsyncEmitter extends NoOverflowBaseAsyncEmitter {
private static final long serialVersionUID = 338953216916120960L;
ErrorAsyncEmitter(Subscriber downstream) {
super(downstream);
}
@Override
void onOverflow() {
onError(new MissingBackpressureException("create: could not emit value due to lack of requests"));
}
}
static final class BufferAsyncEmitter extends BaseEmitter {
private static final long serialVersionUID = 2427151001689639875L;
final SpscLinkedArrayQueue queue;
Throwable error;
volatile boolean done;
final AtomicInteger wip;
BufferAsyncEmitter(Subscriber actual, int capacityHint) {
super(actual);
this.queue = new SpscLinkedArrayQueue<>(capacityHint);
this.wip = new AtomicInteger();
}
@Override
public void onNext(T t) {
if (done || isCancelled()) {
return;
}
if (t == null) {
onError(ExceptionHelper.createNullPointerException("onNext called with a null value."));
return;
}
queue.offer(t);
drain();
}
@Override
public boolean signalError(Throwable e) {
if (done || isCancelled()) {
return false;
}
error = e;
done = true;
drain();
return true;
}
@Override
public void onComplete() {
done = true;
drain();
}
@Override
void onRequested() {
drain();
}
@Override
void onUnsubscribed() {
if (wip.getAndIncrement() == 0) {
queue.clear();
}
}
void drain() {
if (wip.getAndIncrement() != 0) {
return;
}
int missed = 1;
final Subscriber a = downstream;
final SpscLinkedArrayQueue q = queue;
for (;;) {
long r = get();
long e = 0L;
while (e != r) {
if (isCancelled()) {
q.clear();
return;
}
boolean d = done;
T o = q.poll();
boolean empty = o == null;
if (d && empty) {
Throwable ex = error;
if (ex != null) {
errorDownstream(ex);
} else {
completeDownstream();
}
return;
}
if (empty) {
break;
}
a.onNext(o);
e++;
}
if (e == r) {
if (isCancelled()) {
q.clear();
return;
}
boolean d = done;
boolean empty = q.isEmpty();
if (d && empty) {
Throwable ex = error;
if (ex != null) {
errorDownstream(ex);
} else {
completeDownstream();
}
return;
}
}
if (e != 0) {
BackpressureHelper.produced(this, e);
}
missed = wip.addAndGet(-missed);
if (missed == 0) {
break;
}
}
}
}
static final class LatestAsyncEmitter extends BaseEmitter {
private static final long serialVersionUID = 4023437720691792495L;
final AtomicReference queue;
Throwable error;
volatile boolean done;
final AtomicInteger wip;
LatestAsyncEmitter(Subscriber downstream) {
super(downstream);
this.queue = new AtomicReference<>();
this.wip = new AtomicInteger();
}
@Override
public void onNext(T t) {
if (done || isCancelled()) {
return;
}
if (t == null) {
onError(ExceptionHelper.createNullPointerException("onNext called with a null value."));
return;
}
queue.set(t);
drain();
}
@Override
public boolean signalError(Throwable e) {
if (done || isCancelled()) {
return false;
}
error = e;
done = true;
drain();
return true;
}
@Override
public void onComplete() {
done = true;
drain();
}
@Override
void onRequested() {
drain();
}
@Override
void onUnsubscribed() {
if (wip.getAndIncrement() == 0) {
queue.lazySet(null);
}
}
void drain() {
if (wip.getAndIncrement() != 0) {
return;
}
int missed = 1;
final Subscriber a = downstream;
final AtomicReference q = queue;
for (;;) {
long r = get();
long e = 0L;
while (e != r) {
if (isCancelled()) {
q.lazySet(null);
return;
}
boolean d = done;
T o = q.getAndSet(null);
boolean empty = o == null;
if (d && empty) {
Throwable ex = error;
if (ex != null) {
errorDownstream(ex);
} else {
completeDownstream();
}
return;
}
if (empty) {
break;
}
a.onNext(o);
e++;
}
if (e == r) {
if (isCancelled()) {
q.lazySet(null);
return;
}
boolean d = done;
boolean empty = q.get() == null;
if (d && empty) {
Throwable ex = error;
if (ex != null) {
errorDownstream(ex);
} else {
completeDownstream();
}
return;
}
}
if (e != 0) {
BackpressureHelper.produced(this, e);
}
missed = wip.addAndGet(-missed);
if (missed == 0) {
break;
}
}
}
}
}
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