io.reactivex.internal.operators.flowable.FlowableOnBackpressureBufferStrategy Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of rxjava Show documentation
Show all versions of rxjava Show documentation
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.internal.operators.flowable;
import java.util.*;
import java.util.concurrent.atomic.*;
import org.reactivestreams.*;
import io.reactivex.*;
import io.reactivex.exceptions.*;
import io.reactivex.functions.Action;
import io.reactivex.internal.subscriptions.SubscriptionHelper;
import io.reactivex.internal.util.BackpressureHelper;
import io.reactivex.plugins.RxJavaPlugins;
/**
* Handle backpressure with a bounded buffer and custom strategy.
*
* @param the input and output value type
*/
public final class FlowableOnBackpressureBufferStrategy extends AbstractFlowableWithUpstream {
final long bufferSize;
final Action onOverflow;
final BackpressureOverflowStrategy strategy;
public FlowableOnBackpressureBufferStrategy(Flowable source,
long bufferSize, Action onOverflow, BackpressureOverflowStrategy strategy) {
super(source);
this.bufferSize = bufferSize;
this.onOverflow = onOverflow;
this.strategy = strategy;
}
@Override
protected void subscribeActual(Subscriber s) {
source.subscribe(new OnBackpressureBufferStrategySubscriber(s, onOverflow, strategy, bufferSize));
}
static final class OnBackpressureBufferStrategySubscriber
extends AtomicInteger
implements FlowableSubscriber, Subscription {
private static final long serialVersionUID = 3240706908776709697L;
final Subscriber downstream;
final Action onOverflow;
final BackpressureOverflowStrategy strategy;
final long bufferSize;
final AtomicLong requested;
final Deque deque;
Subscription upstream;
volatile boolean cancelled;
volatile boolean done;
Throwable error;
OnBackpressureBufferStrategySubscriber(Subscriber actual, Action onOverflow,
BackpressureOverflowStrategy strategy, long bufferSize) {
this.downstream = actual;
this.onOverflow = onOverflow;
this.strategy = strategy;
this.bufferSize = bufferSize;
this.requested = new AtomicLong();
this.deque = new ArrayDeque();
}
@Override
public void onSubscribe(Subscription s) {
if (SubscriptionHelper.validate(this.upstream, s)) {
this.upstream = s;
downstream.onSubscribe(this);
s.request(Long.MAX_VALUE);
}
}
@Override
public void onNext(T t) {
if (done) {
return;
}
boolean callOnOverflow = false;
boolean callError = false;
Deque dq = deque;
synchronized (dq) {
if (dq.size() == bufferSize) {
switch (strategy) {
case DROP_LATEST:
dq.pollLast();
dq.offer(t);
callOnOverflow = true;
break;
case DROP_OLDEST:
dq.poll();
dq.offer(t);
callOnOverflow = true;
break;
default:
// signal error
callError = true;
break;
}
} else {
dq.offer(t);
}
}
if (callOnOverflow) {
if (onOverflow != null) {
try {
onOverflow.run();
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
upstream.cancel();
onError(ex);
}
}
} else if (callError) {
upstream.cancel();
onError(new MissingBackpressureException());
} else {
drain();
}
}
@Override
public void onError(Throwable t) {
if (done) {
RxJavaPlugins.onError(t);
return;
}
error = 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() {
cancelled = true;
upstream.cancel();
if (getAndIncrement() == 0) {
clear(deque);
}
}
void clear(Deque dq) {
synchronized (dq) {
dq.clear();
}
}
void drain() {
if (getAndIncrement() != 0) {
return;
}
int missed = 1;
Deque dq = deque;
Subscriber a = downstream;
for (;;) {
long r = requested.get();
long e = 0L;
while (e != r) {
if (cancelled) {
clear(dq);
return;
}
boolean d = done;
T v;
synchronized (dq) {
v = dq.poll();
}
boolean empty = v == null;
if (d) {
Throwable ex = error;
if (ex != null) {
clear(dq);
a.onError(ex);
return;
}
if (empty) {
a.onComplete();
return;
}
}
if (empty) {
break;
}
a.onNext(v);
e++;
}
if (e == r) {
if (cancelled) {
clear(dq);
return;
}
boolean d = done;
boolean empty;
synchronized (dq) {
empty = dq.isEmpty();
}
if (d) {
Throwable ex = error;
if (ex != null) {
clear(dq);
a.onError(ex);
return;
}
if (empty) {
a.onComplete();
return;
}
}
}
if (e != 0L) {
BackpressureHelper.produced(requested, e);
}
missed = addAndGet(-missed);
if (missed == 0) {
break;
}
}
}
}
}