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rxjava2-backport developed by David Karnok
/**
* Copyright 2015 David Karnok and Netflix, Inc.
*
* 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.internal.operators;
import java.util.Queue;
import java.util.concurrent.atomic.*;
import org.reactivestreams.*;
import hu.akarnokd.rxjava2.Observable.Operator;
import hu.akarnokd.rxjava2.functions.Function;
import hu.akarnokd.rxjava2.internal.queue.*;
import hu.akarnokd.rxjava2.internal.subscriptions.SubscriptionHelper;
import hu.akarnokd.rxjava2.internal.util.*;
import hu.akarnokd.rxjava2.plugins.RxJavaPlugins;
public final class OperatorSwitchMap implements Operator {
final Function> mapper;
final int bufferSize;
public OperatorSwitchMap(Function> mapper, int bufferSize) {
this.mapper = mapper;
this.bufferSize = bufferSize;
}
@Override
public Subscriber apply(Subscriber t) {
return new SwitchMapSubscriber(t, mapper, bufferSize);
}
static final class SwitchMapSubscriber extends AtomicInteger implements Subscriber, Subscription {
/** */
private static final long serialVersionUID = -3491074160481096299L;
final Subscriber actual;
final Function> mapper;
final int bufferSize;
volatile boolean done;
Throwable error;
volatile boolean cancelled;
Subscription s;
volatile SwitchMapInnerSubscriber active;
@SuppressWarnings("rawtypes")
static final AtomicReferenceFieldUpdater ACTIVE =
AtomicReferenceFieldUpdater.newUpdater(SwitchMapSubscriber.class, SwitchMapInnerSubscriber.class, "active");
volatile long requested;
@SuppressWarnings("rawtypes")
static final AtomicLongFieldUpdater REQUESTED =
AtomicLongFieldUpdater.newUpdater(SwitchMapSubscriber.class, "requested");
static final SwitchMapInnerSubscriber CANCELLED;
static {
CANCELLED = new SwitchMapInnerSubscriber(null, -1L, 1);
CANCELLED.cancel();
}
volatile long unique;
public SwitchMapSubscriber(Subscriber actual, Function> mapper, int bufferSize) {
this.actual = actual;
this.mapper = mapper;
this.bufferSize = bufferSize;
}
@Override
public void onSubscribe(Subscription s) {
if (SubscriptionHelper.validateSubscription(this.s, s)) {
return;
}
this.s = s;
actual.onSubscribe(this);
}
@Override
public void onNext(T t) {
long c = unique + 1;
unique = c;
SwitchMapInnerSubscriber inner = active;
if (inner != null) {
inner.cancel();
}
Publisher p;
try {
p = mapper.apply(t);
} catch (Throwable e) {
s.cancel();
onError(e);
return;
}
if (p == null) {
s.cancel();
onError(new NullPointerException("The publisher returned is null"));
return;
}
SwitchMapInnerSubscriber nextInner = new SwitchMapInnerSubscriber(this, c, bufferSize);
for (;;) {
inner = active;
if (inner == CANCELLED) {
break;
}
if (ACTIVE.compareAndSet(this, inner, nextInner)) {
p.subscribe(nextInner);
break;
}
}
}
@Override
public void onError(Throwable t) {
if (done) {
RxJavaPlugins.onError(t);
return;
}
error = t;
done = true;
drain();
}
@Override
public void onComplete() {
if (done) {
return;
}
done = true;
drain();
}
@Override
public void request(long n) {
if (SubscriptionHelper.validateRequest(n)) {
return;
}
BackpressureHelper.add(REQUESTED, this, n);
if (unique == 0L) {
s.request(Long.MAX_VALUE);
} else {
drain();
}
}
@Override
public void cancel() {
if (!cancelled) {
cancelled = true;
disposeInner();
}
}
@SuppressWarnings("unchecked")
void disposeInner() {
SwitchMapInnerSubscriber a = active;
if (a != CANCELLED) {
a = ACTIVE.getAndSet(this, CANCELLED);
if (a != CANCELLED && a != null) {
s.cancel();
}
}
}
void drain() {
if (getAndIncrement() != 0) {
return;
}
final Subscriber a = actual;
int missing = 1;
for (;;) {
if (cancelled) {
return;
}
if (done) {
Throwable err = error;
if (err != null) {
disposeInner();
s.cancel();
a.onError(err);
return;
} else
if (active == null) {
a.onComplete();
return;
}
}
SwitchMapInnerSubscriber inner = active;
if (inner != null) {
Queue q = inner.queue;
if (inner.done) {
Throwable err = inner.error;
if (err != null) {
s.cancel();
disposeInner();
a.onError(err);
return;
} else
if (q.isEmpty()) {
ACTIVE.compareAndSet(this, inner, null);
continue;
}
}
long r = requested;
boolean unbounded = r == Long.MAX_VALUE;
long e = 0L;
boolean retry = false;
while (r != 0L) {
boolean d = inner.done;
R v = q.poll();
boolean empty = v == null;
if (cancelled) {
return;
}
if (inner != active) {
retry = true;
break;
}
if (d) {
Throwable err = inner.error;
if (err != null) {
s.cancel();
a.onError(err);
return;
} else
if (empty) {
ACTIVE.compareAndSet(this, inner, null);
retry = true;
break;
}
}
if (empty) {
break;
}
a.onNext(v);
r--;
e--;
}
if (e != 0L) {
if (!cancelled) {
if (!unbounded) {
REQUESTED.addAndGet(this, e);
}
inner.get().request(-e);
}
}
if (retry) {
continue;
}
}
missing = addAndGet(-missing);
if (missing == 0) {
break;
}
}
}
boolean checkTerminated(boolean d, boolean empty, Subscriber a) {
if (cancelled) {
s.cancel();
return true;
}
if (d) {
Throwable e = error;
if (e != null) {
cancelled = true;
s.cancel();
a.onError(e);
return true;
} else
if (empty) {
a.onComplete();
return true;
}
}
return false;
}
}
static final class SwitchMapInnerSubscriber extends AtomicReference implements Subscriber {
/** */
private static final long serialVersionUID = 3837284832786408377L;
final SwitchMapSubscriber parent;
final long index;
final int bufferSize;
final Queue queue;
volatile boolean done;
Throwable error;
static final Subscription CANCELLED = new Subscription() {
@Override
public void request(long n) {
}
@Override
public void cancel() {
}
};
public SwitchMapInnerSubscriber(SwitchMapSubscriber parent, long index, int bufferSize) {
this.parent = parent;
this.index = index;
this.bufferSize = bufferSize;
Queue q;
if (Pow2.isPowerOfTwo(bufferSize)) {
q = new SpscArrayQueue(bufferSize);
} else {
q = new SpscExactArrayQueue(bufferSize);
}
this.queue = q;
}
@Override
public void onSubscribe(Subscription s) {
if (index == parent.unique) {
if (!compareAndSet(null, s)) {
s.cancel();
if (get() != CANCELLED) {
SubscriptionHelper.reportSubscriptionSet();
}
return;
}
s.request(bufferSize);
} else {
s.cancel();
}
}
@Override
public void onNext(R t) {
if (index == parent.unique) {
if (!queue.offer(t)) {
onError(new IllegalStateException("Queue full?!"));
return;
}
parent.drain();
}
}
@Override
public void onError(Throwable t) {
if (index == parent.unique) {
error = t;
done = true;
parent.drain();
} else {
RxJavaPlugins.onError(t);
}
}
@Override
public void onComplete() {
if (index == parent.unique) {
done = true;
parent.drain();
}
}
public void cancel() {
Subscription s = get();
if (s != CANCELLED) {
s = getAndSet(CANCELLED);
if (s != CANCELLED && s != null) {
s.cancel();
}
}
}
}
}
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