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rxjava2-extensions developed by David Karnok
/*
* Copyright 2016 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.parallel;
import java.util.concurrent.atomic.*;
import org.reactivestreams.*;
import io.reactivex.Flowable;
import io.reactivex.exceptions.Exceptions;
import io.reactivex.internal.fuseable.SimpleQueue;
import io.reactivex.internal.queue.SpscArrayQueue;
import io.reactivex.internal.subscriptions.SubscriptionHelper;
import io.reactivex.internal.util.*;
import io.reactivex.plugins.RxJavaPlugins;
/**
* Merges the individual 'rails' of the source ParallelFlowable, unordered,
* into a single regular Publisher sequence (exposed as Px).
*
* @param the value type
*/
final class ParallelJoin extends Flowable {
final ParallelFlowable source;
final int prefetch;
ParallelJoin(ParallelFlowable source, int prefetch) {
this.source = source;
this.prefetch = prefetch;
}
@Override
protected void subscribeActual(Subscriber s) {
JoinSubscription parent = new JoinSubscription(s, source.parallelism(), prefetch);
s.onSubscribe(parent);
source.subscribe(parent.subscribers);
}
static final class JoinSubscription
extends AtomicInteger
implements Subscription {
private static final long serialVersionUID = 3100232009247827843L;
final Subscriber actual;
final JoinInnerSubscriber[] subscribers;
final AtomicThrowable error = new AtomicThrowable();
final AtomicLong requested = new AtomicLong();
volatile boolean cancelled;
final AtomicInteger done = new AtomicInteger();
JoinSubscription(Subscriber actual, int n, int prefetch) {
this.actual = actual;
@SuppressWarnings("unchecked")
JoinInnerSubscriber[] a = new JoinInnerSubscriber[n];
for (int i = 0; i < n; i++) {
a[i] = new JoinInnerSubscriber(this, prefetch);
}
this.subscribers = a;
done.lazySet(n);
}
@Override
public void request(long n) {
if (SubscriptionHelper.validate(n)) {
BackpressureHelper.add(requested, n);
drain();
}
}
@Override
public void cancel() {
if (!cancelled) {
cancelled = true;
cancelAll();
if (getAndIncrement() == 0) {
cleanup();
}
}
}
void cancelAll() {
for (JoinInnerSubscriber s : subscribers) {
s.cancel();
}
}
void cleanup() {
for (JoinInnerSubscriber s : subscribers) {
s.queue = null;
}
}
void onNext(JoinInnerSubscriber inner, T value) {
if (get() == 0 && compareAndSet(0, 1)) {
if (requested.get() != 0) {
actual.onNext(value);
if (requested.get() != Long.MAX_VALUE) {
requested.decrementAndGet();
}
inner.request(1);
} else {
SimpleQueue q = inner.getQueue();
// FIXME overflow handling
q.offer(value);
}
if (decrementAndGet() == 0) {
return;
}
} else {
SimpleQueue q = inner.getQueue();
// FIXME overflow handling
q.offer(value);
if (getAndIncrement() != 0) {
return;
}
}
drainLoop();
}
void onError(Throwable e) {
if (error.addThrowable(e)) {
cancelAll();
drain();
} else {
RxJavaPlugins.onError(e);
}
}
void onComplete() {
done.decrementAndGet();
drain();
}
void drain() {
if (getAndIncrement() != 0) {
return;
}
drainLoop();
}
void drainLoop() {
int missed = 1;
JoinInnerSubscriber[] s = this.subscribers;
int n = s.length;
Subscriber a = this.actual;
for (;;) {
long r = requested.get();
long e = 0;
middle:
while (e != r) {
if (cancelled) {
cleanup();
return;
}
Throwable ex = error.get();
if (ex != null) {
cleanup();
a.onError(error.terminate());
return;
}
boolean d = done.get() == 0;
boolean empty = true;
for (int i = 0; i < n; i++) {
JoinInnerSubscriber inner = s[i];
SimpleQueue q = inner.queue;
if (q != null) {
T v;
try {
v = q.poll();
} catch (Throwable exc) {
Exceptions.throwIfFatal(exc);
error.addThrowable(exc);
cancelAll();
actual.onError(error.terminate());
return;
}
if (v != null) {
empty = false;
a.onNext(v);
inner.requestOne();
if (++e == r) {
break middle;
}
}
}
}
if (d && empty) {
a.onComplete();
return;
}
if (empty) {
break;
}
}
if (e == r) {
if (cancelled) {
cleanup();
return;
}
Throwable ex = error.get();
if (ex != null) {
cleanup();
a.onError(error.terminate());
return;
}
boolean d = done.get() == 0;
boolean empty = true;
for (int i = 0; i < n; i++) {
JoinInnerSubscriber inner = s[i];
SimpleQueue q = inner.queue;
if (q != null && !q.isEmpty()) {
empty = false;
break;
}
}
if (d && empty) {
a.onComplete();
return;
}
}
if (e != 0 && r != Long.MAX_VALUE) {
requested.addAndGet(-e);
}
int w = get();
if (w == missed) {
missed = addAndGet(-missed);
if (missed == 0) {
break;
}
} else {
missed = w;
}
}
}
}
static final class JoinInnerSubscriber
extends AtomicReference
implements Subscriber {
private static final long serialVersionUID = 8410034718427740355L;
final JoinSubscription parent;
final int prefetch;
final int limit;
long produced;
volatile SimpleQueue queue;
volatile boolean done;
JoinInnerSubscriber(JoinSubscription parent, int prefetch) {
this.parent = parent;
this.prefetch = prefetch ;
this.limit = prefetch - (prefetch >> 2);
}
@Override
public void onSubscribe(Subscription s) {
if (SubscriptionHelper.setOnce(this, s)) {
s.request(prefetch);
}
}
@Override
public void onNext(T t) {
parent.onNext(this, t);
}
@Override
public void onError(Throwable t) {
parent.onError(t);
}
@Override
public void onComplete() {
parent.onComplete();
}
public void requestOne() {
long p = produced + 1;
if (p == limit) {
produced = 0;
get().request(p);
} else {
produced = p;
}
}
public void request(long n) {
long p = produced + n;
if (p >= limit) {
produced = 0;
get().request(p);
} else {
produced = p;
}
}
public void cancel() {
SubscriptionHelper.cancel(this);
}
SimpleQueue getQueue() {
SimpleQueue q = queue;
if (q == null) {
q = new SpscArrayQueue(prefetch);
this.queue = q;
}
return q;
}
}
}
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