/*
* 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.
Queue;
import java.util.concurrent.atomic.
AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.
AtomicLongFieldUpdater;
import java.util.function.
Consumer;
import org.reactivestreams.
Subscriber;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Exceptions;
import reactor.core.
Fuseable;
import reactor.util.annotation.
Nullable;
import reactor.util.concurrent.
Queues;
import reactor.util.context.
Context;
/**
* @author Stephane Maldini
*/
final class
FluxOnBackpressureBuffer<O> extends
FluxOperator<O, O> implements
Fuseable {
final
Consumer<? super O>
onOverflow;
final int
bufferSize;
final boolean
unbounded;
final boolean
delayError;
FluxOnBackpressureBuffer(
Flux<? extends O>
source,
int
bufferSize,
boolean
unbounded,
@
Nullable Consumer<? super O>
onOverflow) {
super(
source);
if (
bufferSize < 1) {
throw new
IllegalArgumentException("Buffer Size must be strictly positive");
}
this.
bufferSize =
bufferSize;
this.
unbounded =
unbounded;
this.
onOverflow =
onOverflow;
this.
delayError =
unbounded ||
onOverflow != null;
}
@
Override
public void
subscribe(
CoreSubscriber<? super O>
actual) {
source.
subscribe(new
BackpressureBufferSubscriber<>(
actual,
bufferSize,
unbounded,
delayError,
onOverflow));
}
@
Override
public int
getPrefetch() {
return
Integer.
MAX_VALUE;
}
static final class
BackpressureBufferSubscriber<T>
implements
QueueSubscription<T>,
InnerOperator<T, T> {
final
CoreSubscriber<? super T>
actual;
final
Context ctx;
final
Queue<T>
queue;
final
Consumer<? super T>
onOverflow;
final boolean
delayError;
Subscription s;
volatile boolean
cancelled;
volatile boolean
enabledFusion;
volatile boolean
done;
Throwable error;
volatile int
wip;
static final
AtomicIntegerFieldUpdater<
BackpressureBufferSubscriber>
WIP =
AtomicIntegerFieldUpdater.
newUpdater(
BackpressureBufferSubscriber.class,
"wip");
volatile long
requested;
static final
AtomicLongFieldUpdater<
BackpressureBufferSubscriber>
REQUESTED =
AtomicLongFieldUpdater.
newUpdater(
BackpressureBufferSubscriber.class,
"requested");
BackpressureBufferSubscriber(
CoreSubscriber<? super T>
actual,
int
bufferSize,
boolean
unbounded,
boolean
delayError,
@
Nullable Consumer<? super T>
onOverflow) {
this.
actual =
actual;
this.
ctx =
actual.
currentContext();
this.
delayError =
delayError;
this.
onOverflow =
onOverflow;
Queue<T>
q;
if (
unbounded) {
q =
Queues.<T>
unbounded(
bufferSize).
get();
}
else {
q =
Queues.<T>
get(
bufferSize).
get();
}
this.
queue =
q;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
s;
if (
key ==
Attr.
REQUESTED_FROM_DOWNSTREAM) return
requested;
if (
key ==
Attr.
TERMINATED) return
done &&
queue.
isEmpty();
if (
key ==
Attr.
CANCELLED) return
cancelled;
if (
key ==
Attr.
BUFFERED) return
queue.
size();
if (
key ==
Attr.
ERROR) return
error;
if (
key ==
Attr.
PREFETCH) return
Integer.
MAX_VALUE;
if (
key ==
Attr.
DELAY_ERROR) return
delayError;
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) {
if (
done) {
Operators.
onNextDropped(
t,
ctx);
return;
}
if (!
queue.
offer(
t)) {
Throwable ex =
Operators.
onOperatorError(
s,
Exceptions.
failWithOverflow(),
t,
ctx);
if (
onOverflow != null) {
try {
onOverflow.
accept(
t);
}
catch (
Throwable e) {
Exceptions.
throwIfFatal(
e);
ex.
initCause(
e);
}
}
Operators.
onDiscard(
t,
ctx);
onError(
ex);
return;
}
drain();
}
@
Override
public void
onError(
Throwable t) {
if (
done) {
Operators.
onErrorDropped(
t,
ctx);
return;
}
error =
t;
done = true;
drain();
}
@
Override
public void
onComplete() {
if (
done) {
return;
}
done = true;
drain();
}
void
drain() {
if (
WIP.
getAndIncrement(this) != 0) {
return;
}
int
missed = 1;
for (; ; ) {
Subscriber<? super T>
a =
actual;
if (
a != null) {
if (
enabledFusion) {
drainFused(
a);
}
else {
drainRegular(
a);
}
return;
}
missed =
WIP.
addAndGet(this, -
missed);
if (
missed == 0) {
break;
}
}
}
void
drainRegular(
Subscriber<? super T>
a) {
int
missed = 1;
final
Queue<T>
q =
queue;
for (; ; ) {
long
r =
requested;
long
e = 0L;
while (
r !=
e) {
boolean
d =
done;
T
t =
q.
poll();
boolean
empty =
t == null;
if (
checkTerminated(
d,
empty,
a)) {
return;
}
if (
empty) {
break;
}
a.
onNext(
t);
e++;
}
if (
r ==
e) {
if (
checkTerminated(
done,
q.
isEmpty(),
a)) {
return;
}
}
if (
e != 0 &&
r !=
Long.
MAX_VALUE) {
REQUESTED.
addAndGet(this, -
e);
}
missed =
WIP.
addAndGet(this, -
missed);
if (
missed == 0) {
break;
}
}
}
void
drainFused(
Subscriber<? super T>
a) {
int
missed = 1;
final
Queue<T>
q =
queue;
for (; ; ) {
if (
cancelled) {
s.
cancel();
Operators.
onDiscardQueueWithClear(
q,
ctx, null);
return;
}
boolean
d =
done;
a.
onNext(null);
if (
d) {
Throwable ex =
error;
if (
ex != null) {
a.
onError(
ex);
}
else {
a.
onComplete();
}
return;
}
missed =
WIP.
addAndGet(this, -
missed);
if (
missed == 0) {
break;
}
}
}
@
Override
public void
request(long
n) {
if (
Operators.
validate(
n)) {
Operators.
addCap(
REQUESTED, this,
n);
drain();
}
}
@
Override
public void
cancel() {
if (!
cancelled) {
cancelled = true;
s.
cancel();
if (!
enabledFusion) {
if (
WIP.
getAndIncrement(this) == 0) {
Operators.
onDiscardQueueWithClear(
queue,
ctx, null);
}
}
}
}
@
Override
@
Nullable
public T
poll() {
return
queue.
poll();
}
@
Override
public int
size() {
return
queue.
size();
}
@
Override
public boolean
isEmpty() {
return
queue.
isEmpty();
}
@
Override
public void
clear() {
Operators.
onDiscardQueueWithClear(
queue,
ctx, null);
}
@
Override
public int
requestFusion(int
requestedMode) {
if ((
requestedMode &
Fuseable.
ASYNC) != 0) {
enabledFusion = true;
return
Fuseable.
ASYNC;
}
return
Fuseable.
NONE;
}
@
Override
public
CoreSubscriber<? super T>
actual() {
return
actual;
}
boolean
checkTerminated(boolean
d, boolean
empty,
Subscriber<? super T>
a) {
if (
cancelled) {
s.
cancel();
Operators.
onDiscardQueueWithClear(
queue,
ctx, null);
return true;
}
if (
d) {
if (
delayError) {
if (
empty) {
Throwable e =
error;
if (
e != null) {
a.
onError(
e);
}
else {
a.
onComplete();
}
return true;
}
}
else {
Throwable e =
error;
if (
e != null) {
Operators.
onDiscardQueueWithClear(
queue,
ctx, null);
a.
onError(
e);
return true;
}
else if (
empty) {
a.
onComplete();
return true;
}
}
}
return false;
}
}
}