/*
* 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.function.
BiFunction;
import java.util.function.
Supplier;
import org.reactivestreams.
Subscriber;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Fuseable;
import reactor.core.
Scannable;
import reactor.util.annotation.
Nullable;
/**
* Reduce the sequence of values in each 'rail' to a single value.
*
* @param <T> the input value type
* @param <R> the result value type
*/
final class
ParallelReduceSeed<T, R> extends
ParallelFlux<R> implements
Scannable,
Fuseable {
final
ParallelFlux<? extends T>
source;
final
Supplier<R>
initialSupplier;
final
BiFunction<R, ? super T, R>
reducer;
ParallelReduceSeed(
ParallelFlux<? extends T>
source,
Supplier<R>
initialSupplier,
BiFunction<R, ? super T, R>
reducer) {
this.
source =
source;
this.
initialSupplier =
initialSupplier;
this.
reducer =
reducer;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Scannable.
Attr key) {
if (
key ==
Attr.
PARENT) return
source;
if (
key ==
Attr.
PREFETCH) return
getPrefetch();
return null;
}
@
Override
public int
getPrefetch() {
return
Integer.
MAX_VALUE;
}
@
Override
public void
subscribe(
CoreSubscriber<? super R>[]
subscribers) {
if (!
validate(
subscribers)) {
return;
}
int
n =
subscribers.length;
@
SuppressWarnings("unchecked")
CoreSubscriber<T>[]
parents = new
CoreSubscriber[
n];
for (int
i = 0;
i <
n;
i++) {
R
initialValue;
try {
initialValue =
Objects.
requireNonNull(
initialSupplier.
get(),
"The initialSupplier returned a null value");
}
catch (
Throwable ex) {
reportError(
subscribers,
Operators.
onOperatorError(
ex,
subscribers[
i].
currentContext()));
return;
}
parents[
i] =
new
ParallelReduceSeedSubscriber<>(
subscribers[
i],
initialValue,
reducer);
}
source.
subscribe(
parents);
}
void
reportError(
Subscriber<?>[]
subscribers,
Throwable ex) {
for (
Subscriber<?>
s :
subscribers) {
Operators.
error(
s,
ex);
}
}
@
Override
public int
parallelism() {
return
source.
parallelism();
}
static final class
ParallelReduceSeedSubscriber<T, R>
extends
Operators.
MonoSubscriber<T, R> {
final
BiFunction<R, ? super T, R>
reducer;
R
accumulator;
Subscription s;
boolean
done;
ParallelReduceSeedSubscriber(
CoreSubscriber<? super R>
subscriber,
R
initialValue,
BiFunction<R, ? super T, R>
reducer) {
super(
subscriber);
this.
accumulator =
initialValue;
this.
reducer =
reducer;
}
@
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,
actual.
currentContext());
return;
}
R
v;
try {
v =
Objects.
requireNonNull(
reducer.
apply(
accumulator,
t), "The reducer returned a null value");
}
catch (
Throwable ex) {
onError(
Operators.
onOperatorError(this,
ex,
t,
actual.
currentContext()));
return;
}
accumulator =
v;
}
@
Override
public void
onError(
Throwable t) {
if (
done) {
Operators.
onErrorDropped(
t,
actual.
currentContext());
return;
}
done = true;
accumulator = null;
actual.
onError(
t);
}
@
Override
public void
onComplete() {
if (
done) {
return;
}
done = true;
R
a =
accumulator;
accumulator = null;
complete(
a);
}
@
Override
public void
cancel() {
super.cancel();
s.
cancel();
}
}
}