/*
* 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.
ArrayDeque;
import java.util.concurrent.atomic.
AtomicLongFieldUpdater;
import java.util.function.
BooleanSupplier;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.util.annotation.
Nullable;
/**
* Emits the last N values the source emitted before its completion.
*
* @param <T> the value type
*
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class
FluxTakeLast<T> extends
FluxOperator<T, T> {
final int
n;
FluxTakeLast(
Flux<? extends T>
source, int
n) {
super(
source);
if (
n < 0) {
throw new
IllegalArgumentException("n >= required but it was " +
n);
}
this.
n =
n;
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
if (
n == 0) {
source.
subscribe(new
TakeLastZeroSubscriber<>(
actual));
}
else {
source.
subscribe(new
TakeLastManySubscriber<>(
actual,
n));
}
}
@
Override
public int
getPrefetch() {
return
Integer.
MAX_VALUE;
}
static final class
TakeLastZeroSubscriber<T> implements
InnerOperator<T, T> {
final
CoreSubscriber<? super T>
actual;
Subscription s;
TakeLastZeroSubscriber(
CoreSubscriber<? super T>
actual) {
this.
actual =
actual;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
s;
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) {
// ignoring all values
}
@
Override
public void
onError(
Throwable t) {
actual.
onError(
t);
}
@
Override
public void
onComplete() {
actual.
onComplete();
}
@
Override
public
CoreSubscriber<? super T>
actual() {
return
actual;
}
@
Override
public void
request(long
n) {
s.
request(
n);
}
@
Override
public void
cancel() {
s.
cancel();
}
}
static final class
TakeLastManySubscriber<T> extends
ArrayDeque<T>
implements
BooleanSupplier,
InnerOperator<T, T> {
final
CoreSubscriber<? super T>
actual;
final int
n;
volatile boolean
cancelled;
Subscription s;
volatile long
requested;
@
SuppressWarnings("rawtypes")
static final
AtomicLongFieldUpdater<
TakeLastManySubscriber>
REQUESTED =
AtomicLongFieldUpdater.
newUpdater(
TakeLastManySubscriber.class,
"requested");
TakeLastManySubscriber(
CoreSubscriber<? super T>
actual, int
n) {
this.
actual =
actual;
this.
n =
n;
}
@
Override
public boolean
getAsBoolean() {
return
cancelled;
}
@
Override
public void
request(long
n) {
if (
Operators.
validate(
n)) {
DrainUtils.
postCompleteRequest(
n,
actual, this,
REQUESTED, this, this);
}
}
@
Override
public void
cancel() {
cancelled = true;
s.
cancel();
}
@
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 (
size() ==
n) {
poll();
}
offer(
t);
}
@
Override
public void
onError(
Throwable t) {
actual.
onError(
t);
}
@
Override
public void
onComplete() {
DrainUtils.
postComplete(
actual, this,
REQUESTED, this, this);
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
CANCELLED) return
cancelled;
if (
key ==
Attr.
REQUESTED_FROM_DOWNSTREAM) return
requested;
if (
key ==
Attr.
PARENT) return
s;
if (
key ==
Attr.
BUFFERED) return
size();
return
InnerOperator.super.scanUnsafe(
key);
}
@
Override
public
CoreSubscriber<? super T>
actual() {
return
actual;
}
}
}