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/*
* Copyright (c) 2016-2021 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.concurrent.atomic.AtomicIntegerFieldUpdater;
import org.reactivestreams.Subscription;
import reactor.core.CoreSubscriber;
import reactor.core.Fuseable;
import reactor.core.Fuseable.ConditionalSubscriber;
import reactor.core.Fuseable.QueueSubscription;
import reactor.util.annotation.Nullable;
/**
* Takes only the first N values from the source Publisher.
*
* If N is zero, the subscriber gets completed if the source completes, signals an error or
* signals its first value (which is not not relayed though).
*
* @param the value type
* @see Reactive-Streams-Commons
*/
final class FluxTake extends InternalFluxOperator {
final long n;
FluxTake(Flux extends T> source, long n) {
super(source);
if (n < 0) {
throw new IllegalArgumentException("n >= 0 required but it was " + n);
}
this.n = n;
}
@Override
@SuppressWarnings("unchecked")
public CoreSubscriber super T> subscribeOrReturn(CoreSubscriber super T> actual) {
if (actual instanceof ConditionalSubscriber) {
return new TakeConditionalSubscriber<>((ConditionalSubscriber super T>) actual, n);
}
else {
return new TakeSubscriber<>(actual, n);
}
}
@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 TakeSubscriber
implements InnerOperator {
final CoreSubscriber super T> actual;
final long n;
long remaining;
Subscription s;
boolean done;
volatile int wip;
@SuppressWarnings("rawtypes")
static final AtomicIntegerFieldUpdater WIP =
AtomicIntegerFieldUpdater.newUpdater(TakeSubscriber.class, "wip");
public TakeSubscriber(CoreSubscriber super T> actual, long n) {
this.actual = actual;
this.n = n;
this.remaining = n;
}
@Override
public void onSubscribe(Subscription s) {
if (Operators.validate(this.s, s)) {
if (n == 0) {
s.cancel();
done = true;
Operators.complete(actual);
}
else {
this.s = s;
actual.onSubscribe(this);
}
}
}
@Override
public void onNext(T t) {
if (done) {
Operators.onNextDropped(t, actual.currentContext());
return;
}
long r = remaining;
if (r == 0) {
s.cancel();
onComplete();
return;
}
remaining = --r;
boolean stop = r == 0L;
actual.onNext(t);
if (stop) {
s.cancel();
onComplete();
}
}
@Override
public void onError(Throwable t) {
if (done) {
Operators.onErrorDropped(t, actual.currentContext());
return;
}
done = true;
actual.onError(t);
}
@Override
public void onComplete() {
if (done) {
return;
}
done = true;
actual.onComplete();
}
@Override
public void request(long n) {
if (wip == 0 && WIP.compareAndSet(this, 0, 1)) {
if (n >= this.n) {
s.request(Long.MAX_VALUE);
} else {
s.request(n);
}
return;
}
s.request(n);
}
@Override
public void cancel() {
s.cancel();
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.TERMINATED) return done;
if (key == Attr.PARENT) return s;
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return InnerOperator.super.scanUnsafe(key);
}
@Override
public CoreSubscriber super T> actual() {
return actual;
}
}
static final class TakeConditionalSubscriber
implements ConditionalSubscriber, InnerOperator {
final ConditionalSubscriber super T> actual;
final long n;
long remaining;
Subscription s;
boolean done;
volatile int wip;
@SuppressWarnings("rawtypes")
static final AtomicIntegerFieldUpdater WIP =
AtomicIntegerFieldUpdater.newUpdater(TakeConditionalSubscriber.class,
"wip");
TakeConditionalSubscriber(ConditionalSubscriber super T> actual,
long n) {
this.actual = actual;
this.n = n;
this.remaining = n;
}
@Override
public void onSubscribe(Subscription s) {
if (Operators.validate(this.s, s)) {
if (n == 0) {
s.cancel();
done = true;
Operators.complete(actual);
}
else {
this.s = s;
actual.onSubscribe(this);
}
}
}
@Override
public void onNext(T t) {
if (done) {
Operators.onNextDropped(t, actual.currentContext());
return;
}
long r = remaining;
if (r == 0) {
s.cancel();
onComplete();
return;
}
remaining = --r;
boolean stop = r == 0L;
actual.onNext(t);
if (stop) {
s.cancel();
onComplete();
}
}
@Override
public boolean tryOnNext(T t) {
if (done) {
Operators.onNextDropped(t, actual.currentContext());
return true;
}
long r = remaining;
if (r == 0) {
s.cancel();
onComplete();
return true;
}
remaining = --r;
boolean stop = r == 0L;
boolean b = actual.tryOnNext(t);
if (stop) {
s.cancel();
onComplete();
}
return b;
}
@Override
public void onError(Throwable t) {
if (done) {
Operators.onErrorDropped(t, actual.currentContext());
return;
}
done = true;
actual.onError(t);
}
@Override
public void onComplete() {
if (done) {
return;
}
done = true;
actual.onComplete();
}
@Override
public void request(long n) {
if (wip == 0 && WIP.compareAndSet(this, 0, 1)) {
if (n >= this.n) {
s.request(Long.MAX_VALUE);
}
else {
s.request(n);
}
return;
}
s.request(n);
}
@Override
public void cancel() {
s.cancel();
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.TERMINATED) return done;
if (key == Attr.PARENT) return s;
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return InnerOperator.super.scanUnsafe(key);
}
@Override
public CoreSubscriber super T> actual() {
return actual;
}
}
static final class TakeFuseableSubscriber
implements QueueSubscription, InnerOperator {
final CoreSubscriber super T> actual;
final long n;
long remaining;
QueueSubscription qs;
boolean done;
volatile int wip;
@SuppressWarnings("rawtypes")
static final AtomicIntegerFieldUpdater WIP =
AtomicIntegerFieldUpdater.newUpdater(TakeFuseableSubscriber.class, "wip");
int inputMode;
TakeFuseableSubscriber(CoreSubscriber super T> actual, long n) {
this.actual = actual;
this.n = n;
this.remaining = n;
}
@SuppressWarnings("unchecked")
@Override
public void onSubscribe(Subscription s) {
if (Operators.validate(this.qs, s)) {
if (n == 0) {
s.cancel();
done = true;
Operators.complete(actual);
}
else {
this.qs = (QueueSubscription) s;
actual.onSubscribe(this);
}
}
}
@Override
public void onNext(T t) {
if (inputMode == Fuseable.ASYNC) {
actual.onNext(null);
return;
}
if (done) {
Operators.onNextDropped(t, actual.currentContext());
return;
}
long r = remaining;
if (r == 0) {
qs.cancel();
onComplete();
return;
}
remaining = --r;
boolean stop = r == 0L;
actual.onNext(t);
if (stop) {
qs.cancel();
onComplete();
}
}
@Override
public void onError(Throwable t) {
if (done) {
Operators.onErrorDropped(t, actual.currentContext());
return;
}
done = true;
actual.onError(t);
}
@Override
public void onComplete() {
if (done) {
return;
}
done = true;
actual.onComplete();
}
@Override
public void request(long n) {
if (wip == 0 && WIP.compareAndSet(this, 0, 1)) {
if (n >= this.n) {
qs.request(Long.MAX_VALUE);
}
else {
qs.request(n);
}
return;
}
qs.request(n);
}
@Override
public void cancel() {
qs.cancel();
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.TERMINATED) return done;
if (key == Attr.PARENT) return qs;
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return InnerOperator.super.scanUnsafe(key);
}
@Override
public CoreSubscriber super T> actual() {
return actual;
}
@Override
public int requestFusion(int requestedMode) {
int m = qs.requestFusion(requestedMode);
this.inputMode = m;
return m;
}
@Override
@Nullable
public T poll() {
if (done) {
return null;
}
long r = remaining;
T v = qs.poll();
if (r == 0L) {
done = true;
if (inputMode == Fuseable.ASYNC) {
qs.cancel();
actual.onComplete();
}
return null;
}
if (v != null) {
remaining = --r;
if (r == 0L) {
if (!done) {
done = true;
if (inputMode == Fuseable.ASYNC) {
qs.cancel();
actual.onComplete();
}
}
}
}
return v;
}
@Override
public boolean isEmpty() {
return remaining == 0 || qs.isEmpty();
}
@Override
public void clear() {
qs.clear();
}
@Override
public int size() {
return qs.size();
}
}
}