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rxjava2-extensions developed by David Karnok
/*
* Copyright 2016-2017 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.*;
import java.util.concurrent.atomic.*;
import org.reactivestreams.*;
import io.reactivex.*;
import io.reactivex.exceptions.Exceptions;
import io.reactivex.functions.Function;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.fuseable.SimplePlainQueue;
import io.reactivex.internal.queue.SpscArrayQueue;
import io.reactivex.internal.subscriptions.SubscriptionHelper;
import io.reactivex.internal.util.*;
import io.reactivex.plugins.RxJavaPlugins;
final class FlowableSwitchFlatMap extends Flowable
implements FlowableTransformer {
final Publisher source;
final Function> mapper;
final int maxActive;
final int bufferSize;
FlowableSwitchFlatMap(Publisher source, Function> mapper,
int maxActive, int bufferSize) {
super();
this.source = source;
this.mapper = mapper;
this.maxActive = maxActive;
this.bufferSize = bufferSize;
}
@Override
public Publisher apply(Flowable upstream) {
return new FlowableSwitchFlatMap(upstream, mapper, maxActive, bufferSize);
}
@Override
protected void subscribeActual(Subscriber s) {
source.subscribe(new SwitchFlatMapSubscriber(s, mapper, maxActive, bufferSize));
}
static final class SwitchFlatMapSubscriber
extends AtomicInteger
implements Subscriber, Subscription {
private static final long serialVersionUID = 6801374887555723721L;
final Subscriber actual;
final Function> mapper;
final int maxActive;
final int bufferSize;
final ArrayDeque> active;
final AtomicLong requested;
final AtomicThrowable error;
Subscription s;
volatile boolean done;
volatile boolean cancelled;
volatile long version;
final SfmInnerSubscriber[] activeCache;
long versionCache;
@SuppressWarnings("unchecked")
SwitchFlatMapSubscriber(Subscriber actual,
Function> mapper, int maxActive,
int bufferSize) {
this.actual = actual;
this.mapper = mapper;
this.maxActive = maxActive;
this.bufferSize = bufferSize;
this.active = new ArrayDeque>();
this.requested = new AtomicLong();
this.error = new AtomicThrowable();
this.activeCache = new SfmInnerSubscriber[maxActive];
}
@Override
public void onSubscribe(Subscription s) {
if (SubscriptionHelper.validate(this.s, s)) {
this.s = s;
actual.onSubscribe(this);
s.request(Long.MAX_VALUE);
}
}
@Override
public void onNext(T t) {
Publisher p;
try {
p = ObjectHelper.requireNonNull(mapper.apply(t), "The mapper returned a null Publisher");
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
s.cancel();
onError(ex);
return;
}
SfmInnerSubscriber inner = new SfmInnerSubscriber(this, bufferSize);
if (add(inner)) {
p.subscribe(inner);
}
}
boolean add(SfmInnerSubscriber inner) {
SfmInnerSubscriber evicted = null;
synchronized (this) {
if (cancelled) {
return false;
}
if (active.size() == maxActive) {
evicted = active.poll();
}
active.offer(inner);
version++;
}
if (evicted != null) {
evicted.cancel();
}
return true;
}
void remove(SfmInnerSubscriber inner) {
synchronized (this) {
active.remove(inner);
version++;
}
}
@Override
public void onError(Throwable t) {
if (error.compareAndSet(null, t)) {
cancelInners();
done = true;
drain();
} else {
RxJavaPlugins.onError(t);
}
}
@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;
s.cancel();
cancelInners();
if (getAndIncrement() == 0) {
clearCache();
}
}
}
void clearCache() {
Arrays.fill(activeCache, null);
}
void cancelInners() {
List> subscribers = new ArrayList>();
synchronized (this) {
subscribers.addAll(active);
active.clear();
}
for (SfmInnerSubscriber inner : subscribers) {
inner.cancel();
}
}
void innerError(Throwable t) {
if (error.compareAndSet(null, t)) {
s.cancel();
cancelInners();
done = true;
drain();
} else {
RxJavaPlugins.onError(t);
}
}
void updateInners() {
SfmInnerSubscriber[] a = activeCache;
if (versionCache != version) {
synchronized (this) {
int i = 0;
Iterator> it = active.iterator();
while (it.hasNext()) {
a[i++] = it.next();
}
for (int j = i; j < a.length; j++) {
a[j] = null;
}
versionCache = version;
}
}
}
void drain() {
if (getAndIncrement() == 0) {
int missed = 1;
Subscriber a = actual;
SfmInnerSubscriber[] inners = activeCache;
AtomicThrowable err = error;
outer:
for (;;) {
long r = requested.get();
long e = 0;
for (;;) {
if (cancelled) {
clearCache();
return;
}
boolean d = done;
updateInners();
long ver = versionCache;
if (d) {
Throwable ex = err.get();
if (ex != null) {
clearCache();
a.onError(err.terminate());
return;
} else
if (inners[0] == null) {
a.onComplete();
return;
}
}
int becameEmpty = 0;
int activeCount = 0;
draining:
for (SfmInnerSubscriber inner : inners) {
if (cancelled) {
clearCache();
return;
}
if (inner == null) {
break;
}
if (ver != version) {
if (e != 0) {
BackpressureHelper.produced(requested, e);
}
continue outer;
}
activeCount++;
long f = 0;
SimplePlainQueue q = inner.queue;
while (e != r) {
if (cancelled) {
clearCache();
return;
}
Throwable ex = err.get();
if (ex != null) {
clearCache();
a.onError(err.terminate());
return;
}
if (ver != version) {
if (e != 0) {
BackpressureHelper.produced(requested, e);
}
if (f != 0L) {
inner.produced(f);
}
continue outer;
}
boolean d2 = inner.done;
R v = q.poll();
boolean empty = v == null;
if (d2 && empty) {
remove(inner);
continue draining;
}
if (empty) {
if (f != 0L) {
inner.produced(f);
f = 0L;
}
becameEmpty++;
break;
}
a.onNext(v);
e++;
f++;
}
if (inner.done && q.isEmpty()) {
remove(inner);
} else
if (f != 0L) {
inner.produced(f);
}
}
if (becameEmpty == activeCount || e == r) {
break;
}
}
if (e != 0) {
BackpressureHelper.produced(requested, e);
}
missed = addAndGet(-missed);
if (missed == 0) {
break;
}
}
}
}
static final class SfmInnerSubscriber extends AtomicReference
implements Subscriber {
private static final long serialVersionUID = 4011255448052082638L;
final SwitchFlatMapSubscriber parent;
final int bufferSize;
final int limit;
final SimplePlainQueue queue;
long produced;
volatile boolean done;
SfmInnerSubscriber(SwitchFlatMapSubscriber parent, int bufferSize) {
this.parent = parent;
this.bufferSize = bufferSize;
this.limit = bufferSize - (bufferSize >> 2);
this.queue = new SpscArrayQueue(bufferSize);
}
void cancel() {
SubscriptionHelper.cancel(this);
}
@Override
public void onSubscribe(Subscription s) {
if (SubscriptionHelper.setOnce(this, s)) {
s.request(bufferSize);
}
}
@Override
public void onNext(R t) {
queue.offer(t);
parent.drain();
}
@Override
public void onError(Throwable t) {
parent.innerError(t);
}
@Override
public void onComplete() {
done = true;
parent.drain();
}
void produced(long f) {
long p = produced + f;
if (p >= limit) {
produced = 0;
get().request(p);
} else {
produced = p;
}
}
}
}
}