/*
* 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.
Callable;
import java.util.concurrent.atomic.
AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.
AtomicLongFieldUpdater;
import java.util.concurrent.atomic.
AtomicReferenceArray;
import java.util.concurrent.atomic.
AtomicReferenceFieldUpdater;
import java.util.function.
Function;
import java.util.stream.
Stream;
import org.reactivestreams.
Publisher;
import org.reactivestreams.
Subscriber;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Exceptions;
import reactor.core.
Scannable;
import reactor.util.annotation.
Nullable;
import reactor.util.concurrent.
Queues;
import reactor.util.context.
Context;
/**
* Maps each upstream value into a single {@code true} or {@code false} value provided by
* a generated Publisher for that input value and emits the input value if the inner
* Publisher returned {@code true}.
* <p>
* Only the first item emitted by the inner Publisher's are considered. If
* the inner Publisher is empty, no resulting item is generated for that input value.
*
* @param <T> the input value type
*
* @author David Karnok
* @author Simon Baslé
*/
//adapted from RxJava2Extensions: https://github.com/akarnokd/RxJava2Extensions/blob/master/src/main/java/hu/akarnokd/rxjava2/operators/FlowableFilterAsync.java
class
FluxFilterWhen<T> extends
FluxOperator<T, T> {
final
Function<? super T, ? extends
Publisher<
Boolean>>
asyncPredicate;
final int
bufferSize;
FluxFilterWhen(
Flux<T>
source,
Function<? super T, ? extends
Publisher<
Boolean>>
asyncPredicate,
int
bufferSize) {
super(
source);
this.
asyncPredicate =
asyncPredicate;
this.
bufferSize =
bufferSize;
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
source.
subscribe(new
FluxFilterWhenSubscriber<>(
actual,
asyncPredicate,
bufferSize));
}
static final class
FluxFilterWhenSubscriber<T> implements
InnerOperator<T, T> {
final
Function<? super T, ? extends
Publisher<
Boolean>>
asyncPredicate;
final int
bufferSize;
final
AtomicReferenceArray<T>
toFilter;
final
CoreSubscriber<? super T>
actual;
final
Context ctx;
int
consumed;
long
consumerIndex;
long
emitted;
Boolean innerResult;
long
producerIndex;
Subscription upstream;
volatile boolean
cancelled;
volatile
FilterWhenInner current;
volatile boolean
done;
volatile
Throwable error;
volatile long
requested;
volatile int
state;
volatile int
wip;
static final
AtomicReferenceFieldUpdater<
FluxFilterWhenSubscriber,
Throwable>
ERROR =
AtomicReferenceFieldUpdater.
newUpdater(
FluxFilterWhenSubscriber.class,
Throwable.class, "error");
static final
AtomicLongFieldUpdater<
FluxFilterWhenSubscriber>
REQUESTED =
AtomicLongFieldUpdater.
newUpdater(
FluxFilterWhenSubscriber.class, "requested");
static final
AtomicIntegerFieldUpdater<
FluxFilterWhenSubscriber>
WIP =
AtomicIntegerFieldUpdater.
newUpdater(
FluxFilterWhenSubscriber.class, "wip");
static final
AtomicReferenceFieldUpdater<
FluxFilterWhenSubscriber,
FilterWhenInner>
CURRENT =
AtomicReferenceFieldUpdater.
newUpdater(
FluxFilterWhenSubscriber.class,
FilterWhenInner.class, "current");
@
SuppressWarnings("ConstantConditions")
static final
FilterWhenInner INNER_CANCELLED = new
FilterWhenInner(null, false);
static final int
STATE_FRESH = 0;
static final int
STATE_RUNNING = 1;
static final int
STATE_RESULT = 2;
FluxFilterWhenSubscriber(
CoreSubscriber<? super T>
actual,
Function<? super T, ? extends
Publisher<
Boolean>>
asyncPredicate,
int
bufferSize) {
this.
actual =
actual;
this.
ctx =
actual.
currentContext();
this.
toFilter = new
AtomicReferenceArray<>(
Queues.
ceilingNextPowerOfTwo(
bufferSize));
this.
asyncPredicate =
asyncPredicate;
this.
bufferSize =
bufferSize;
}
@
Override
public final
CoreSubscriber<? super T>
actual() {
return
actual;
}
@
Override
public void
onNext(T
t) {
long
pi =
producerIndex;
int
m =
toFilter.
length() - 1;
int
offset = (int)
pi &
m;
toFilter.
lazySet(
offset,
t);
producerIndex =
pi + 1;
drain();
}
@
Override
public void
onError(
Throwable t) {
ERROR.
set(this,
t);
done = true;
drain();
}
@
Override
public void
onComplete() {
done = true;
drain();
}
@
Override
public void
request(long
n) {
if (
Operators.
validate(
n)) {
Operators.
addCap(
REQUESTED, this,
n);
drain();
}
}
@
Override
public void
cancel() {
if (!
cancelled) {
cancelled = true;
upstream.
cancel();
cancelInner();
if (
WIP.
getAndIncrement(this) == 0) {
clear();
}
}
}
void
cancelInner() {
FilterWhenInner a =
CURRENT.
get(this);
if (
a !=
INNER_CANCELLED) {
a =
CURRENT.
getAndSet(this,
INNER_CANCELLED);
if (
a != null &&
a !=
INNER_CANCELLED) {
a.
cancel();
}
}
}
void
clear() {
int
n =
toFilter.
length();
for (int
i = 0;
i <
n;
i++) {
T
old =
toFilter.
getAndSet(
i, null);
Operators.
onDiscard(
old,
ctx);
}
innerResult = null;
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
validate(
upstream,
s)) {
upstream =
s;
actual.
onSubscribe(this);
s.
request(
bufferSize);
}
}
@
SuppressWarnings("unchecked")
void
drain() {
if (
WIP.
getAndIncrement(this) != 0) {
return;
}
int
missed = 1;
int
limit =
Operators.
unboundedOrLimit(
bufferSize);
long
e =
emitted;
long
ci =
consumerIndex;
int
f =
consumed;
int
m =
toFilter.
length() - 1;
Subscriber<? super T>
a =
actual;
for (;;) {
long
r =
requested;
while (
e !=
r) {
if (
cancelled) {
clear();
return;
}
boolean
d =
done;
int
offset = (int)
ci &
m;
T
t =
toFilter.
get(
offset);
boolean
empty =
t == null;
if (
d &&
empty) {
Throwable ex =
Exceptions.
terminate(
ERROR, this);
if (
ex == null) {
a.
onComplete();
} else {
a.
onError(
ex);
}
return;
}
if (
empty) {
break;
}
int
s =
state;
if (
s ==
STATE_FRESH) {
Publisher<
Boolean>
p;
try {
p =
Objects.
requireNonNull(
asyncPredicate.
apply(
t), "The asyncPredicate returned a null value");
} catch (
Throwable ex) {
Exceptions.
throwIfFatal(
ex);
Exceptions.
addThrowable(
ERROR, this,
ex);
p = null; //discarded as "old" below
}
if (
p != null) {
if (
p instanceof
Callable) {
Boolean u;
try {
u = ((
Callable<
Boolean>)
p).
call();
} catch (
Throwable ex) {
Exceptions.
throwIfFatal(
ex);
Exceptions.
addThrowable(
ERROR, this,
ex);
u = null; //triggers discard below
}
if (
u != null &&
u) {
a.
onNext(
t);
e++;
}
else {
Operators.
onDiscard(
t,
ctx);
}
} else {
FilterWhenInner inner = new
FilterWhenInner(this, !(
p instanceof
Mono));
if (
CURRENT.
compareAndSet(this,null,
inner)) {
state =
STATE_RUNNING;
p.
subscribe(
inner);
break;
}
}
}
T
old =
toFilter.
getAndSet(
offset, null);
Operators.
onDiscard(
old,
ctx);
ci++;
if (++
f ==
limit) {
f = 0;
upstream.
request(
limit);
}
} else
if (
s ==
STATE_RESULT) {
Boolean u =
innerResult;
innerResult = null;
if (
u != null &&
u) {
a.
onNext(
t);
e++;
}
else {
Operators.
onDiscard(
t,
ctx);
}
toFilter.
lazySet(
offset, null);
ci++;
if (++
f ==
limit) {
f = 0;
upstream.
request(
limit);
}
state =
STATE_FRESH;
} else {
break;
}
}
if (
e ==
r) {
if (
cancelled) {
clear();
return;
}
boolean
d =
done;
int
offset = (int)
ci &
m;
T
t =
toFilter.
get(
offset);
boolean
empty =
t == null;
if (
d &&
empty) {
Throwable ex =
Exceptions.
terminate(
ERROR, this);
if (
ex == null) {
a.
onComplete();
} else {
a.
onError(
ex);
}
return;
}
}
int
w =
wip;
if (
missed ==
w) {
consumed =
f;
consumerIndex =
ci;
emitted =
e;
missed =
WIP.
addAndGet(this, -
missed);
if (
missed == 0) {
break;
}
} else {
missed =
w;
}
}
}
void
clearCurrent() {
FilterWhenInner c =
current;
if (
c !=
INNER_CANCELLED) {
CURRENT.
compareAndSet(this,
c, null);
}
}
void
innerResult(
Boolean item) {
innerResult =
item;
state =
STATE_RESULT;
clearCurrent();
drain();
}
void
innerError(
Throwable ex) {
Exceptions.
addThrowable(
ERROR, this,
ex);
state =
STATE_RESULT;
clearCurrent();
drain();
}
void
innerComplete() {
state =
STATE_RESULT;
clearCurrent();
drain();
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
upstream;
if (
key ==
Attr.
TERMINATED) return
done;
if (
key ==
Attr.
CANCELLED) return
cancelled;
if (
key ==
Attr.
ERROR) //FIXME ERROR is often reset by Exceptions.terminate :(
return
error;
if (
key ==
Attr.
REQUESTED_FROM_DOWNSTREAM) return
requested;
if (
key ==
Attr.
CAPACITY) return
toFilter.
length();
if (
key ==
Attr.
LARGE_BUFFERED) return
producerIndex -
consumerIndex;
if (
key ==
Attr.
BUFFERED) {
long
realBuffered =
producerIndex -
consumerIndex;
if (
realBuffered <=
Integer.
MAX_VALUE) return (int)
realBuffered;
return
Integer.
MIN_VALUE;
}
if (
key ==
Attr.
PREFETCH) return
bufferSize;
return
InnerOperator.super.scanUnsafe(
key);
}
@
Override
public
Stream<? extends
Scannable>
inners() {
FilterWhenInner c =
current;
return
c == null ?
Stream.
empty() :
Stream.
of(
c);
}
}
static final class
FilterWhenInner implements
InnerConsumer<
Boolean> {
final
FluxFilterWhenSubscriber<?>
parent;
final boolean
cancelOnNext;
boolean
done;
volatile
Subscription sub;
static final
AtomicReferenceFieldUpdater<
FilterWhenInner,
Subscription>
SUB =
AtomicReferenceFieldUpdater.
newUpdater(
FilterWhenInner.class,
Subscription.class, "sub");
FilterWhenInner(
FluxFilterWhenSubscriber<?>
parent, boolean
cancelOnNext) {
this.
parent =
parent;
this.
cancelOnNext =
cancelOnNext;
}
@
Override
public
Context currentContext() {
return
parent.
currentContext();
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
setOnce(
SUB, this,
s)) {
s.
request(
Long.
MAX_VALUE);
}
}
@
Override
public void
onNext(
Boolean t) {
if (!
done) {
if (
cancelOnNext) {
sub.
cancel();
}
done = true;
parent.
innerResult(
t);
}
}
@
Override
public void
onError(
Throwable t) {
if (!
done) {
done = true;
parent.
innerError(
t);
} else {
Operators.
onErrorDropped(
t,
parent.
currentContext());
}
}
@
Override
public void
onComplete() {
if (!
done) {
done = true;
parent.
innerComplete();
}
}
void
cancel() {
Operators.
terminate(
SUB, this);
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
parent;
if (
key ==
Attr.
ACTUAL) return
sub;
if (
key ==
Attr.
CANCELLED) return
sub ==
Operators.
cancelledSubscription();
if (
key ==
Attr.
TERMINATED) return
done;
if (
key ==
Attr.
PREFETCH) return
Integer.
MAX_VALUE;
if (
key ==
Attr.
REQUESTED_FROM_DOWNSTREAM) return
done ? 0L : 1L;
return null;
}
}
}