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Easy Redis Java client and Real-Time Data Platform. Valkey compatible. Sync/Async/RxJava3/Reactive API. Client side caching. Over 50 Redis based Java objects and services: JCache API, Apache Tomcat, Hibernate, Spring, Set, Multimap, SortedSet, Map, List, Queue, Deque, Semaphore, Lock, AtomicLong, Map Reduce, Bloom filter, Scheduler, RPC
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/*
* 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.rxjava3.internal.operators.flowable;
import java.util.*;
import java.util.concurrent.atomic.*;
import org.reactivestreams.*;
import io.reactivex.rxjava3.core.*;
import io.reactivex.rxjava3.exceptions.*;
import io.reactivex.rxjava3.functions.*;
import io.reactivex.rxjava3.internal.subscriptions.SubscriptionHelper;
import io.reactivex.rxjava3.internal.util.BackpressureHelper;
import io.reactivex.rxjava3.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;
final Consumer super T> onDropped;
public FlowableOnBackpressureBufferStrategy(Flowable source,
long bufferSize, Action onOverflow, BackpressureOverflowStrategy strategy,
Consumer super T> onDropped) {
super(source);
this.bufferSize = bufferSize;
this.onOverflow = onOverflow;
this.strategy = strategy;
this.onDropped = onDropped;
}
@Override
protected void subscribeActual(Subscriber super T> s) {
source.subscribe(new OnBackpressureBufferStrategySubscriber<>(s, onOverflow, strategy, bufferSize, onDropped));
}
static final class OnBackpressureBufferStrategySubscriber
extends AtomicInteger
implements FlowableSubscriber, Subscription {
private static final long serialVersionUID = 3240706908776709697L;
final Subscriber super T> downstream;
final Action onOverflow;
final Consumer super T> onDropped;
final BackpressureOverflowStrategy strategy;
final long bufferSize;
final AtomicLong requested;
final Deque deque;
Subscription upstream;
volatile boolean cancelled;
volatile boolean done;
Throwable error;
OnBackpressureBufferStrategySubscriber(Subscriber super T> actual, Action onOverflow,
BackpressureOverflowStrategy strategy, long bufferSize,
Consumer super T> onDropped) {
this.downstream = actual;
this.onOverflow = onOverflow;
this.strategy = strategy;
this.bufferSize = bufferSize;
this.requested = new AtomicLong();
this.deque = new ArrayDeque<>();
this.onDropped = onDropped;
}
@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;
boolean callDrain = false;
Deque dq = deque;
T toDrop = null;
synchronized (dq) {
if (dq.size() == bufferSize) {
switch (strategy) {
case DROP_LATEST:
toDrop = dq.pollLast();
dq.offer(t);
callOnOverflow = true;
break;
case DROP_OLDEST:
toDrop = dq.poll();
dq.offer(t);
callOnOverflow = true;
break;
default:
// signal error
toDrop = t;
callError = true;
break;
}
} else {
dq.offer(t);
callDrain = true;
}
}
if (callOnOverflow && onOverflow != null) {
try {
onOverflow.run();
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
upstream.cancel();
onError(ex);
}
}
if (onDropped != null && toDrop != null) {
try {
onDropped.accept(toDrop);
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
upstream.cancel();
onError(ex);
}
}
if (callError) {
upstream.cancel();
onError(MissingBackpressureException.createDefault());
}
if (callDrain) {
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 super T> 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;
}
}
}
}
}
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