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/*
* Copyright 2016-2018 David Karnok
*
* 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 hu.akarnokd.rxjava2.operators;
import java.util.concurrent.Callable;
import java.util.concurrent.atomic.*;
import org.reactivestreams.*;
import io.reactivex.*;
import io.reactivex.exceptions.Exceptions;
import io.reactivex.functions.*;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.subscriptions.SubscriptionHelper;
import io.reactivex.internal.util.*;
import io.reactivex.plugins.RxJavaPlugins;
/**
* Maps each upstream value into a single value provided by a generated Publisher for that
* input value and comines the original and generated single value into a final result item
* to be emitted to downstream.
* Only the first item emitted by the inner Publisher's are considered. If
* the inner Publisher is empty, no resulting item is generated for that input value.
* @param the input value type
* @param the intermediate value type
* @param the result value type
*
* @since 0.16.2
*/
final class FlowableMapAsync extends Flowable implements FlowableTransformer {
final Flowable source;
final Function> mapper;
final BiFunction combiner;
final int bufferSize;
FlowableMapAsync(Flowable source, Function> mapper,
BiFunction combiner, int bufferSize) {
this.source = source;
this.mapper = mapper;
this.combiner = combiner;
this.bufferSize = bufferSize;
}
@Override
public Publisher apply(Flowable upstream) {
return new FlowableMapAsync(upstream, mapper, combiner, bufferSize);
}
@Override
protected void subscribeActual(Subscriber s) {
source.subscribe(new MapAsyncSubscriber(s, mapper, combiner, bufferSize));
}
interface AsyncSupport {
void innerResult(U u);
void innerError(Throwable ex);
void innerComplete();
}
static final class MapAsyncSubscriber
extends AtomicReferenceArray
implements FlowableSubscriber, Subscription, AsyncSupport {
private static final long serialVersionUID = -1557840206706079339L;
final Subscriber actual;
final Function> mapper;
final BiFunction combiner;
final int bufferSize;
final AtomicThrowable error;
final AtomicLong requested;
final AtomicInteger wip;
final AtomicReference> current;
@SuppressWarnings({ "rawtypes", "unchecked" })
static final InnerSubscriber INNER_CANCELLED = new InnerSubscriber(null);
Subscription upstream;
long producerIndex;
long consumerIndex;
int consumed;
volatile boolean done;
volatile boolean cancelled;
U innerResult;
long emitted;
volatile int state;
static final int STATE_FRESH = 0;
static final int STATE_RUNNING = 1;
static final int STATE_RESULT = 2;
MapAsyncSubscriber(Subscriber actual,
Function> mapper,
BiFunction combiner, int bufferSize) {
super(Pow2.roundToPowerOfTwo(bufferSize));
this.actual = actual;
this.mapper = mapper;
this.combiner = combiner;
this.bufferSize = bufferSize;
this.error = new AtomicThrowable();
this.requested = new AtomicLong();
this.wip = new AtomicInteger();
this.current = new AtomicReference>();
}
@Override
public void onNext(T t) {
long pi = producerIndex;
int m = length() - 1;
int offset = (int)pi & m;
lazySet(offset, t);
producerIndex = pi + 1;
drain();
}
@Override
public void onError(Throwable t) {
error.addThrowable(t);
done = true;
drain();
}
@Override
public void onComplete() {
done = true;
drain();
}
@Override
public void request(long n) {
if (SubscriptionHelper.validate(n)) {
BackpressureHelper.add(requested, n);
drain();
}
}
@Override
public void cancel() {
if (!cancelled) {
cancelled = true;
upstream.cancel();
cancelInner();
if (wip.getAndIncrement() == 0) {
clear();
}
}
}
@SuppressWarnings("unchecked")
void cancelInner() {
InnerSubscriber a = current.get();
if (a != INNER_CANCELLED) {
a = current.getAndSet(INNER_CANCELLED);
if (a != null && a != INNER_CANCELLED) {
a.cancel();
}
}
}
void clear() {
int n = length();
for (int i = 0; i < n; i++) {
lazySet(i, null);
}
innerResult = null;
}
@Override
public void onSubscribe(Subscription s) {
if (SubscriptionHelper.validate(upstream, s)) {
upstream = s;
actual.onSubscribe(this);
s.request(bufferSize);
}
}
void drain() {
if (wip.getAndIncrement() != 0) {
return;
}
int missed = 1;
int limit = bufferSize - (bufferSize >> 2);
long e = emitted;
long ci = consumerIndex;
int f = consumed;
int m = length() - 1;
Subscriber a = actual;
for (;;) {
long r = requested.get();
while (e != r) {
if (cancelled) {
clear();
return;
}
boolean d = done;
int offset = (int)ci & m;
T t = get(offset);
boolean empty = t == null;
if (d && empty) {
Throwable ex = error.terminate();
if (ex == null) {
a.onComplete();
} else {
a.onError(ex);
}
return;
}
if (empty) {
break;
}
int s = state;
if (s == STATE_FRESH) {
Publisher p;
try {
p = ObjectHelper.requireNonNull(mapper.apply(t), "The mapper returned a null value");
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
error.addThrowable(ex);
p = null;
}
if (p != null) {
if (p instanceof Callable) {
R v;
try {
@SuppressWarnings("unchecked")
U u = ((Callable)p).call();
if (u != null) {
v = ObjectHelper.requireNonNull(combiner.apply(t, u), "The combiner returned a null value");
} else {
v = null;
}
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
error.addThrowable(ex);
v = null;
}
if (v != null) {
a.onNext(v);
e++;
}
} else {
InnerSubscriber inner = new InnerSubscriber(this);
if (current.compareAndSet(null, inner)) {
state = STATE_RUNNING;
p.subscribe(inner);
break;
}
}
}
lazySet(offset, null);
ci++;
if (++f == limit) {
f = 0;
upstream.request(limit);
}
} else
if (s == STATE_RESULT) {
U u = innerResult;
innerResult = null;
if (u != null) {
R v;
try {
v = ObjectHelper.requireNonNull(combiner.apply(t, u), "The combiner returned a null value");
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
error.addThrowable(ex);
v = null;
}
if (v != null) {
a.onNext(v);
e++;
}
}
lazySet(offset, null);
ci++;
if (++f == limit) {
f = 0;
upstream.request(limit);
}
state = STATE_FRESH;
} else {
break;
}
}
if (e == r) {
if (cancelled) {
clear();
return;
}
boolean d = done;
int offset = (int)ci & m;
T t = get(offset);
boolean empty = t == null;
if (d && empty) {
Throwable ex = error.terminate();
if (ex == null) {
a.onComplete();
} else {
a.onError(ex);
}
return;
}
}
int w = wip.get();
if (missed == w) {
consumed = f;
consumerIndex = ci;
emitted = e;
missed = wip.addAndGet(-missed);
if (missed == 0) {
break;
}
} else {
missed = w;
}
}
}
void clearCurrent() {
InnerSubscriber c = current.get();
if (c != INNER_CANCELLED) {
current.compareAndSet(c, null);
}
}
@Override
public void innerResult(U item) {
innerResult = item;
state = STATE_RESULT;
clearCurrent();
drain();
}
@Override
public void innerError(Throwable ex) {
error.addThrowable(ex);
state = STATE_RESULT;
clearCurrent();
drain();
}
@Override
public void innerComplete() {
state = STATE_RESULT;
clearCurrent();
drain();
}
static final class InnerSubscriber extends AtomicReference implements Subscriber {
private static final long serialVersionUID = 6335578148970008248L;
final AsyncSupport parent;
boolean done;
InnerSubscriber(AsyncSupport parent) {
this.parent = parent;
}
@Override
public void onSubscribe(Subscription s) {
if (SubscriptionHelper.setOnce(this, s)) {
s.request(Long.MAX_VALUE);
}
}
@Override
public void onNext(U t) {
if (!done) {
get().cancel();
done = true;
parent.innerResult(t);
}
}
@Override
public void onError(Throwable t) {
if (!done) {
done = true;
parent.innerError(t);
} else {
RxJavaPlugins.onError(t);
}
}
@Override
public void onComplete() {
if (!done) {
done = true;
parent.innerComplete();
}
}
void cancel() {
SubscriptionHelper.cancel(this);
}
}
}
}