/*
* Copyright (c) 2011-2018 Pivotal Software Inc, 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
*
* 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 reactor.core.publisher;
import java.time.
Duration;
import java.util.
Objects;
import java.util.concurrent.
ThreadLocalRandom;
import java.util.concurrent.atomic.
AtomicIntegerFieldUpdater;
import java.util.function.
Function;
import java.util.stream.
Stream;
import org.reactivestreams.
Publisher;
import org.reactivestreams.
Subscriber;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Scannable;
import reactor.util.annotation.
Nullable;
import reactor.util.context.
Context;
/**
* retries a source when a companion sequence signals
* an item in response to the main's error signal
* <p>
* <p>If the companion sequence signals when the main source is active, the repeat
* attempt is suppressed and any terminal signal will terminate the main source with the same signal immediately.
*
* @param <T> the source value type
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class
FluxRetryWhen<T> extends
FluxOperator<T, T> {
static final
Duration MAX_BACKOFF =
Duration.
ofMillis(
Long.
MAX_VALUE);
final
Function<? super
Flux<
Throwable>, ? extends
Publisher<?>>
whenSourceFactory;
FluxRetryWhen(
Flux<? extends T>
source,
Function<? super
Flux<
Throwable>, ? extends
Publisher<?>>
whenSourceFactory) {
super(
source);
this.
whenSourceFactory =
Objects.
requireNonNull(
whenSourceFactory, "whenSourceFactory");
}
static <T> void
subscribe(
CoreSubscriber<? super T>
s,
Function<? super
Flux<
Throwable>, ?
extends
Publisher<?>>
whenSourceFactory,
Publisher<? extends T>
source) {
RetryWhenOtherSubscriber other = new
RetryWhenOtherSubscriber();
Subscriber<
Throwable>
signaller =
Operators.
serialize(
other.
completionSignal);
signaller.
onSubscribe(
Operators.
emptySubscription());
CoreSubscriber<T>
serial =
Operators.
serialize(
s);
RetryWhenMainSubscriber<T>
main =
new
RetryWhenMainSubscriber<>(
serial,
signaller,
source);
other.
main =
main;
serial.
onSubscribe(
main);
Publisher<?>
p;
try {
p =
Objects.
requireNonNull(
whenSourceFactory.
apply(
other),
"The whenSourceFactory returned a null Publisher");
}
catch (
Throwable e) {
s.
onError(
Operators.
onOperatorError(
e,
s.
currentContext()));
return;
}
p.
subscribe(
other);
if (!
main.
cancelled) {
source.
subscribe(
main);
}
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
subscribe(
actual,
whenSourceFactory,
source);
}
static final class
RetryWhenMainSubscriber<T> extends
Operators.
MultiSubscriptionSubscriber<T, T> {
final
Operators.
DeferredSubscription otherArbiter;
final
Subscriber<
Throwable>
signaller;
final
Publisher<? extends T>
source;
Context context;
volatile int
wip;
static final
AtomicIntegerFieldUpdater<
RetryWhenMainSubscriber>
WIP =
AtomicIntegerFieldUpdater.
newUpdater(
RetryWhenMainSubscriber.class, "wip");
long
produced;
RetryWhenMainSubscriber(
CoreSubscriber<? super T>
actual,
Subscriber<
Throwable>
signaller,
Publisher<? extends T>
source) {
super(
actual);
this.
signaller =
signaller;
this.
source =
source;
this.
otherArbiter = new
Operators.
DeferredSubscription();
this.
context =
actual.
currentContext();
}
@
Override
public
Context currentContext() {
return this.
context;
}
@
Override
public
Stream<? extends
Scannable>
inners() {
return
Stream.
of(
Scannable.
from(
signaller),
otherArbiter);
}
@
Override
public void
cancel() {
if (!
cancelled) {
otherArbiter.
cancel();
super.cancel();
}
}
public void
setWhen(
Subscription w) {
otherArbiter.
set(
w);
}
@
Override
public void
onNext(T
t) {
actual.
onNext(
t);
produced++;
}
@
Override
public void
onError(
Throwable t) {
long
p =
produced;
if (
p != 0L) {
produced = 0;
produced(
p);
}
otherArbiter.
request(1);
signaller.
onNext(
t);
}
@
Override
public void
onComplete() {
otherArbiter.
cancel();
actual.
onComplete();
}
void
resubscribe(
Object trigger) {
if (
WIP.
getAndIncrement(this) == 0) {
do {
if (
cancelled) {
return;
}
//flow that emit a Context as a trigger for the re-subscription are
//used to REPLACE the currentContext()
if (
trigger instanceof
Context) {
this.
context = (
Context)
trigger;
}
source.
subscribe(this);
} while (
WIP.
decrementAndGet(this) != 0);
}
}
void
whenError(
Throwable e) {
super.cancel();
actual.
onError(
e);
}
void
whenComplete() {
super.cancel();
actual.
onComplete();
}
}
static final class
RetryWhenOtherSubscriber extends
Flux<
Throwable>
implements
InnerConsumer<
Object> {
RetryWhenMainSubscriber<?>
main;
final
DirectProcessor<
Throwable>
completionSignal = new
DirectProcessor<>();
@
Override
public
Context currentContext() {
return
main.
currentContext();
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
main.
otherArbiter;
if (
key ==
Attr.
ACTUAL) return
main;
return null;
}
@
Override
public void
onSubscribe(
Subscription s) {
main.
setWhen(
s);
}
@
Override
public void
onNext(
Object t) {
main.
resubscribe(
t);
}
@
Override
public void
onError(
Throwable t) {
main.
whenError(
t);
}
@
Override
public void
onComplete() {
main.
whenComplete();
}
@
Override
public void
subscribe(
CoreSubscriber<? super
Throwable>
actual) {
completionSignal.
subscribe(
actual);
}
}
static
Function<
Flux<
Throwable>,
Publisher<
Long>>
randomExponentialBackoffFunction(
long
numRetries,
Duration firstBackoff,
Duration maxBackoff,
double
jitterFactor) {
if (
jitterFactor < 0 ||
jitterFactor > 1) throw new
IllegalArgumentException("jitterFactor must be between 0 and 1 (default 0.5)");
Objects.
requireNonNull(
firstBackoff, "firstBackoff is required");
Objects.
requireNonNull(
maxBackoff, "maxBackoff is required");
return
t ->
t.
index()
.
flatMap(
t2 -> {
long
iteration =
t2.
getT1();
if (
iteration >=
numRetries) {
return
Mono.<
Long>
error(new
IllegalStateException("Retries exhausted: " +
iteration + "/" +
numRetries,
t2.
getT2()));
}
Duration nextBackoff;
try {
nextBackoff =
firstBackoff.
multipliedBy((long)
Math.
pow(2,
iteration));
if (
nextBackoff.
compareTo(
maxBackoff) > 0) {
nextBackoff =
maxBackoff;
}
}
catch (
ArithmeticException overflow) {
nextBackoff =
maxBackoff;
}
//short-circuit delay == 0 case
if (
nextBackoff.
isZero()) {
return
Mono.
just(
iteration);
}
ThreadLocalRandom random =
ThreadLocalRandom.
current();
long
jitterOffset;
try {
jitterOffset =
nextBackoff.
multipliedBy((long) (100 *
jitterFactor))
.
dividedBy(100)
.
toMillis();
}
catch (
ArithmeticException ae) {
jitterOffset =
Math.
round(
Long.
MAX_VALUE *
jitterFactor);
}
long
lowBound =
Math.
max(
firstBackoff.
minus(
nextBackoff)
.
toMillis(), -
jitterOffset);
long
highBound =
Math.
min(
maxBackoff.
minus(
nextBackoff)
.
toMillis(),
jitterOffset);
long
jitter;
if (
highBound ==
lowBound) {
if (
highBound == 0)
jitter = 0;
else
jitter =
random.
nextLong(
highBound);
}
else {
jitter =
random.
nextLong(
lowBound,
highBound);
}
Duration effectiveBackoff =
nextBackoff.
plusMillis(
jitter);
return
Mono.
delay(
effectiveBackoff);
});
}
}