/*
* Copyright (c) 2011-2017 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.util.
Objects;
import java.util.concurrent.atomic.
AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.
AtomicLongFieldUpdater;
import java.util.concurrent.atomic.
AtomicReferenceFieldUpdater;
import java.util.function.
Function;
import java.util.stream.
Stream;
import org.reactivestreams.
Publisher;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Exceptions;
import reactor.core.
Scannable;
import reactor.util.annotation.
Nullable;
import reactor.util.context.
Context;
/**
* Takes a value from upstream then uses the duration provided by a
* generated Publisher to skip other values until that other Publisher signals.
*
* @param <T> the source and output value type
* @param <U> the value type of the publisher signalling the end of the throttling
* duration
*
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class
FluxSampleFirst<T, U> extends
FluxOperator<T, T> {
final
Function<? super T, ? extends
Publisher<U>>
throttler;
FluxSampleFirst(
Flux<? extends T>
source,
Function<? super T, ? extends
Publisher<U>>
throttler) {
super(
source);
this.
throttler =
Objects.
requireNonNull(
throttler, "throttler");
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
SampleFirstMain<T, U>
main = new
SampleFirstMain<>(
actual,
throttler);
actual.
onSubscribe(
main);
source.
subscribe(
main);
}
@
Override
public int
getPrefetch() {
return
Integer.
MAX_VALUE;
}
static final class
SampleFirstMain<T, U> implements
InnerOperator<T, T> {
final
Function<? super T, ? extends
Publisher<U>>
throttler;
final
CoreSubscriber<? super T>
actual;
final
Context ctx;
volatile boolean
gate;
volatile
Subscription s;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
SampleFirstMain,
Subscription>
S =
AtomicReferenceFieldUpdater.
newUpdater(
SampleFirstMain.class,
Subscription.class,
"s");
volatile
Subscription other;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
SampleFirstMain,
Subscription>
OTHER =
AtomicReferenceFieldUpdater.
newUpdater(
SampleFirstMain.class,
Subscription.class,
"other");
volatile long
requested;
@
SuppressWarnings("rawtypes")
static final
AtomicLongFieldUpdater<
SampleFirstMain>
REQUESTED =
AtomicLongFieldUpdater.
newUpdater(
SampleFirstMain.class, "requested");
volatile int
wip;
@
SuppressWarnings("rawtypes")
static final
AtomicIntegerFieldUpdater<
SampleFirstMain>
WIP =
AtomicIntegerFieldUpdater.
newUpdater(
SampleFirstMain.class, "wip");
volatile
Throwable error;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
SampleFirstMain,
Throwable>
ERROR =
AtomicReferenceFieldUpdater.
newUpdater(
SampleFirstMain.class,
Throwable.class,
"error");
SampleFirstMain(
CoreSubscriber<? super T>
actual,
Function<? super T, ? extends
Publisher<U>>
throttler) {
this.
actual =
actual;
this.
ctx =
actual.
currentContext();
this.
throttler =
throttler;
}
@
Override
public final
CoreSubscriber<? super T>
actual() {
return
actual;
}
@
Override
public
Stream<? extends
Scannable>
inners() {
return
Stream.
of(
Scannable.
from(
other));
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
CANCELLED) return
s ==
Operators.
cancelledSubscription();
if (
key ==
Attr.
PARENT) return
s;
if (
key ==
Attr.
ERROR) return
error;
if (
key ==
Attr.
REQUESTED_FROM_DOWNSTREAM) return
requested;
return
InnerOperator.super.scanUnsafe(
key);
}
@
Override
public void
request(long
n) {
if (
Operators.
validate(
n)) {
Operators.
addCap(
REQUESTED, this,
n);
}
}
@
Override
public void
cancel() {
Operators.
terminate(
S, this);
Operators.
terminate(
OTHER, this);
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
setOnce(
S, this,
s)) {
s.
request(
Long.
MAX_VALUE);
}
}
@
Override
public void
onNext(T
t) {
if (!
gate) {
gate = true;
if (
wip == 0 &&
WIP.
compareAndSet(this, 0, 1)) {
actual.
onNext(
t);
if (
WIP.
decrementAndGet(this) != 0) {
handleTermination();
return;
}
}
else {
return;
}
Publisher<U>
p;
try {
p =
Objects.
requireNonNull(
throttler.
apply(
t),
"The throttler returned a null publisher");
}
catch (
Throwable e) {
Operators.
terminate(
S, this);
error(
Operators.
onOperatorError(null,
e,
t,
ctx));
return;
}
SampleFirstOther<U>
other = new
SampleFirstOther<>(this);
if (
Operators.
replace(
OTHER, this,
other)) {
p.
subscribe(
other);
}
}
else {
Operators.
onDiscard(
t,
ctx);
}
}
void
handleTermination() {
Throwable e =
Exceptions.
terminate(
ERROR, this);
if (
e != null &&
e !=
Exceptions.
TERMINATED) {
actual.
onError(
e);
}
else {
actual.
onComplete();
}
}
void
error(
Throwable e) {
if (
Exceptions.
addThrowable(
ERROR, this,
e)) {
if (
WIP.
getAndIncrement(this) == 0) {
handleTermination();
}
}
else {
Operators.
onErrorDropped(
e,
ctx);
}
}
@
Override
public void
onError(
Throwable t) {
Operators.
terminate(
OTHER, this);
error(
t);
}
@
Override
public void
onComplete() {
Operators.
terminate(
OTHER, this);
if (
WIP.
getAndIncrement(this) == 0) {
handleTermination();
}
}
void
otherNext() {
gate = false;
}
void
otherError(
Throwable e) {
Operators.
terminate(
S, this);
error(
e);
}
}
static final class
SampleFirstOther<U> extends
Operators.
DeferredSubscription
implements
InnerConsumer<U> {
final
SampleFirstMain<?, U>
main;
SampleFirstOther(
SampleFirstMain<?, U>
main) {
this.
main =
main;
}
@
Override
public
Context currentContext() {
return
main.
currentContext();
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
ACTUAL) return
main;
return super.scanUnsafe(
key);
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
set(
s)) {
s.
request(
Long.
MAX_VALUE);
}
}
@
Override
public void
onNext(U
t) {
cancel();
main.
otherNext();
}
@
Override
public void
onError(
Throwable t) {
main.
otherError(
t);
}
@
Override
public void
onComplete() {
main.
otherNext();
}
}
}