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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
/*
* Copyright (c) 2015-2021 VMware Inc. or its affiliates, All Rights Reserved.
*
* 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
*
* https://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 reactor.core.publisher;
import java.util.ArrayDeque;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.AtomicLongFieldUpdater;
import java.util.function.Consumer;
import org.reactivestreams.Subscriber;
import org.reactivestreams.Subscription;
import reactor.core.CoreSubscriber;
import reactor.core.Exceptions;
import reactor.util.annotation.Nullable;
import reactor.util.context.Context;
/**
* Buffers values if the subscriber doesn't request fast enough, bounding the
* buffer to a chosen size. If the buffer overflows, apply a pre-determined
* overflow strategy.
* @author Stephane Maldini
* @author Simon Baslé
*/
final class FluxOnBackpressureBufferStrategy extends InternalFluxOperator {
final Consumer onBufferOverflow;
final int bufferSize;
final boolean delayError;
final BufferOverflowStrategy bufferOverflowStrategy;
FluxOnBackpressureBufferStrategy(Flux source,
int bufferSize,
@Nullable Consumer onBufferOverflow,
BufferOverflowStrategy bufferOverflowStrategy) {
super(source);
if (bufferSize < 1) {
throw new IllegalArgumentException("Buffer Size must be strictly positive");
}
this.bufferSize = bufferSize;
this.onBufferOverflow = onBufferOverflow;
this.bufferOverflowStrategy = bufferOverflowStrategy;
this.delayError = onBufferOverflow != null || bufferOverflowStrategy == BufferOverflowStrategy.ERROR;
}
@Override
public CoreSubscriber subscribeOrReturn(CoreSubscriber actual) {
return new BackpressureBufferDropOldestSubscriber<>(actual,
bufferSize,
delayError, onBufferOverflow, bufferOverflowStrategy);
}
@Override
public int getPrefetch() {
return Integer.MAX_VALUE;
}
@Override
public Object scanUnsafe(Attr key) {
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return super.scanUnsafe(key);
}
static final class BackpressureBufferDropOldestSubscriber
extends ArrayDeque
implements InnerOperator {
final CoreSubscriber actual;
final Context ctx;
final int bufferSize;
final Consumer onOverflow;
final boolean delayError;
final BufferOverflowStrategy overflowStrategy;
Subscription s;
volatile boolean cancelled;
volatile boolean done;
Throwable error;
volatile int wip;
static final AtomicIntegerFieldUpdater WIP =
AtomicIntegerFieldUpdater.newUpdater(BackpressureBufferDropOldestSubscriber.class,
"wip");
volatile long requested;
static final AtomicLongFieldUpdater REQUESTED =
AtomicLongFieldUpdater.newUpdater(BackpressureBufferDropOldestSubscriber.class,
"requested");
BackpressureBufferDropOldestSubscriber(
CoreSubscriber actual,
int bufferSize,
boolean delayError,
@Nullable Consumer onOverflow,
BufferOverflowStrategy overflowStrategy) {
this.actual = actual;
this.ctx = actual.currentContext();
this.delayError = delayError;
this.onOverflow = onOverflow;
this.overflowStrategy = overflowStrategy;
this.bufferSize = bufferSize;
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.PARENT) return s;
if (key == Attr.REQUESTED_FROM_DOWNSTREAM) return requested;
if (key == Attr.TERMINATED) return done && isEmpty();
if (key == Attr.CANCELLED) return cancelled;
if (key == Attr.BUFFERED) return size();
if (key == Attr.ERROR) return error;
if (key == Attr.PREFETCH) return Integer.MAX_VALUE;
if (key == Attr.DELAY_ERROR) return delayError;
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return InnerOperator.super.scanUnsafe(key);
}
@Override
public void onSubscribe(Subscription s) {
if (Operators.validate(this.s, s)) {
this.s = s;
actual.onSubscribe(this);
s.request(Long.MAX_VALUE);
}
}
@Override
public void onNext(T t) {
if (done) {
Operators.onNextDropped(t, ctx);
return;
}
boolean callOnOverflow = false;
boolean callOnError = false;
T overflowElement = t;
synchronized(this) {
if (size() == bufferSize) {
callOnOverflow = true;
switch (overflowStrategy) {
case DROP_OLDEST:
overflowElement = pollFirst();
offer(t);
break;
case DROP_LATEST:
//do nothing
break;
case ERROR:
default:
callOnError = true;
break;
}
}
else {
offer(t);
}
}
if (callOnOverflow) {
if (onOverflow != null) {
try {
onOverflow.accept(overflowElement);
}
catch (Throwable e) {
Throwable ex = Operators.onOperatorError(s, e, overflowElement, ctx);
onError(ex);
return;
}
finally {
Operators.onDiscard(overflowElement, ctx);
}
}
else {
Operators.onDiscard(overflowElement, ctx);
}
}
if (callOnError) {
Throwable ex = Operators.onOperatorError(s, Exceptions.failWithOverflow(), overflowElement, ctx);
onError(ex);
}
if (!callOnError && !callOnOverflow) {
drain();
}
}
@Override
public void onError(Throwable t) {
if (done) {
Operators.onErrorDropped(t, ctx);
return;
}
error = t;
done = true;
drain();
}
@Override
public void onComplete() {
if (done) {
return;
}
done = true;
drain();
}
void drain() {
if (WIP.getAndIncrement(this) != 0) {
return;
}
int missed = 1;
for (; ; ) {
Subscriber a = actual;
//noinspection ConstantConditions
if (a != null) {
innerDrain(a);
return;
}
missed = WIP.addAndGet(this, -missed);
if (missed == 0) {
break;
}
}
}
void innerDrain(Subscriber a) {
int missed = 1;
for (; ; ) {
long r = requested;
long e = 0L;
while (r != e) {
boolean d = done;
T t;
synchronized (this) {
t = poll();
}
boolean empty = t == null;
if (checkTerminated(d, empty, a)) {
return;
}
if (empty) {
break;
}
a.onNext(t);
e++;
}
if (r == e) {
boolean empty;
synchronized (this) {
empty = isEmpty();
}
if (checkTerminated(done, empty, a)) {
return;
}
}
if (e != 0L && r != Long.MAX_VALUE) {
Operators.produced(REQUESTED, this, e);
}
missed = WIP.addAndGet(this, -missed);
if (missed == 0) {
break;
}
}
}
@Override
public void request(long n) {
if (Operators.validate(n)) {
Operators.addCap(REQUESTED, this, n);
drain();
}
}
@Override
public void cancel() {
if (!cancelled) {
cancelled = true;
s.cancel();
if (WIP.getAndIncrement(this) == 0) {
synchronized (this) {
clear();
}
}
}
}
@Override
public CoreSubscriber actual() {
return actual;
}
boolean checkTerminated(boolean d, boolean empty, Subscriber a) {
if (cancelled) {
s.cancel();
synchronized (this) {
clear();
}
return true;
}
if (d) {
if (delayError) {
if (empty) {
Throwable e = error;
if (e != null) {
a.onError(e);
}
else {
a.onComplete();
}
return true;
}
}
else {
Throwable e = error;
if (e != null) {
synchronized (this) {
clear();
}
a.onError(e);
return true;
}
else if (empty) {
a.onComplete();
return true;
}
}
}
return false;
}
@Override
public void clear() {
Operators.onDiscardMultiple(this, ctx);
super.clear();
}
}
}
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