/*
* 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.concurrent.atomic.
AtomicLongFieldUpdater;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
/**
* @author Simon Baslé
* @author David Karnok
*/
final class
FluxLimitRequest<T> extends
FluxOperator<T, T> {
final long
cap;
FluxLimitRequest(
Flux<T>
flux, long
cap) {
super(
flux);
this.
cap =
cap;
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
source.
subscribe(new
FluxLimitRequestSubscriber<>(
actual, this.
cap));
}
@
Override
public int
getPrefetch() {
return 0;
}
@
Override
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
REQUESTED_FROM_DOWNSTREAM) return
cap;
//FluxOperator defines PREFETCH and PARENT
return super.scanUnsafe(
key);
}
static class
FluxLimitRequestSubscriber<T> implements
InnerOperator<T, T> {
final
CoreSubscriber<? super T>
actual;
Subscription parent;
long
toProduce;
volatile long
requestRemaining;
static final
AtomicLongFieldUpdater<
FluxLimitRequestSubscriber>
REQUEST_REMAINING =
AtomicLongFieldUpdater.
newUpdater(
FluxLimitRequestSubscriber.class, "requestRemaining");
FluxLimitRequestSubscriber(
CoreSubscriber<? super T>
actual, long
cap) {
this.
actual =
actual;
this.
toProduce =
cap;
this.
requestRemaining =
cap;
}
@
Override
public
CoreSubscriber<? super T>
actual() {
return this.
actual;
}
@
Override
public void
onNext(T
t) {
long
r =
toProduce;
if (
r > 0L) {
toProduce = --
r;
actual.
onNext(
t);
if (
r == 0) {
parent.
cancel();
actual.
onComplete();
}
}
}
@
Override
public void
onError(
Throwable throwable) {
if (
toProduce != 0L) {
toProduce = 0L;
actual.
onError(
throwable);
}
}
@
Override
public void
onComplete() {
if (
toProduce != 0L) {
toProduce = 0L;
actual.
onComplete();
}
}
@
Override
public void
onSubscribe(
Subscription s) {
parent =
s;
actual.
onSubscribe(this);
}
@
Override
public void
request(long
l) {
for (;;) {
long
r =
requestRemaining;
long
newRequest;
if (
r <=
l) {
newRequest =
r;
} else {
newRequest =
l;
}
long
u =
r -
newRequest;
if (
REQUEST_REMAINING.
compareAndSet(this,
r,
u)) {
if (
newRequest != 0) {
parent.
request(
newRequest);
}
break;
}
}
}
@
Override
public void
cancel() {
parent.
cancel();
}
@
Override
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
parent;
if (
key ==
Attr.
TERMINATED) return
toProduce == 0L;
//InnerOperator defines ACTUAL
return
InnerOperator.super.scanUnsafe(
key);
}
}
}