/*
* 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.atomic.
AtomicIntegerFieldUpdater;
import java.util.function.
BiFunction;
import java.util.function.
Supplier;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.util.annotation.
Nullable;
/**
* Aggregates the source values with the help of an accumulator function
* and emits the intermediate results.
* <p>
* The accumulation works as follows:
* <pre><code>
* result[0] = initialValue;
* result[1] = accumulator(result[0], source[0])
* result[2] = accumulator(result[1], source[1])
* result[3] = accumulator(result[2], source[2])
* ...
* </code></pre>
*
* @param <T> the source value type
* @param <R> the aggregate type
*
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class
FluxScanSeed<T, R> extends
FluxOperator<T, R> {
final
BiFunction<R, ? super T, R>
accumulator;
final
Supplier<R>
initialSupplier;
FluxScanSeed(
Flux<? extends T>
source,
Supplier<R>
initialSupplier,
BiFunction<R, ? super T, R>
accumulator) {
super(
source);
this.
accumulator =
Objects.
requireNonNull(
accumulator, "accumulator");
this.
initialSupplier =
Objects.
requireNonNull(
initialSupplier, "initialSupplier");
}
@
Override
public void
subscribe(
CoreSubscriber<? super R>
actual) {
ScanSeedCoordinator<T, R>
coordinator =
new
ScanSeedCoordinator<>(
actual,
source,
accumulator,
initialSupplier);
actual.
onSubscribe(
coordinator);
if (!
coordinator.
isCancelled()) {
coordinator.
onComplete();
}
}
static final class
ScanSeedCoordinator<T, R>
extends
Operators.
MultiSubscriptionSubscriber<R, R> {
final
Supplier<R>
initialSupplier;
final
Flux<? extends T>
source;
final
BiFunction<R, ? super T, R>
accumulator;
volatile int
wip;
long
produced;
private
ScanSeedSubscriber<T, R>
seedSubscriber;
ScanSeedCoordinator(
CoreSubscriber<? super R>
actual,
Flux<? extends T>
source,
BiFunction<R, ? super T, R>
accumulator,
Supplier<R>
initialSupplier) {
super(
actual);
this.
source =
source;
this.
accumulator =
accumulator;
this.
initialSupplier =
initialSupplier;
}
@
Override
public void
onComplete() {
if (
WIP.
getAndIncrement(this) == 0) {
do {
if (
isCancelled()) {
return;
}
if (null !=
seedSubscriber &&
subscription ==
seedSubscriber) {
actual.
onComplete();
return;
}
long
c =
produced;
if (
c != 0L) {
produced = 0L;
produced(
c);
}
if (null ==
seedSubscriber) {
R
initialValue;
try {
initialValue =
Objects.
requireNonNull(
initialSupplier.
get(),
"The initial value supplied is null");
}
catch (
Throwable e) {
onError(
Operators.
onOperatorError(
e,
actual.
currentContext()));
return;
}
onSubscribe(
Operators.
scalarSubscription(this,
initialValue));
seedSubscriber =
new
ScanSeedSubscriber<>(this,
accumulator,
initialValue);
}
else {
source.
subscribe(
seedSubscriber);
}
if (
isCancelled()) {
return;
}
}
while (
WIP.
decrementAndGet(this) != 0);
}
}
@
Override
public void
onNext(R
r) {
produced++;
actual.
onNext(
r);
}
@
SuppressWarnings("rawtypes")
static final
AtomicIntegerFieldUpdater<
ScanSeedCoordinator>
WIP =
AtomicIntegerFieldUpdater.
newUpdater(
ScanSeedCoordinator.class, "wip");
}
static final class
ScanSeedSubscriber<T, R> implements
InnerOperator<T, R> {
final
CoreSubscriber<? super R>
actual;
final
BiFunction<R, ? super T, R>
accumulator;
Subscription s;
R
value;
boolean
done;
ScanSeedSubscriber(
CoreSubscriber<? super R>
actual,
BiFunction<R, ? super T, R>
accumulator,
R
initialValue) {
this.
actual =
actual;
this.
accumulator =
accumulator;
this.
value =
initialValue;
}
@
Override
public
CoreSubscriber<? super R>
actual() {
return
actual;
}
@
Override
public void
cancel() {
s.
cancel();
}
@
Override
public void
onComplete() {
if (
done) {
return;
}
done = true;
actual.
onComplete();
}
@
Override
public void
onError(
Throwable t) {
if (
done) {
Operators.
onErrorDropped(
t,
actual.
currentContext());
return;
}
done = true;
actual.
onError(
t);
}
@
Override
public void
onNext(T
t) {
if (
done) {
Operators.
onNextDropped(
t,
actual.
currentContext());
return;
}
R
r =
value;
try {
r =
Objects.
requireNonNull(
accumulator.
apply(
r,
t),
"The accumulator returned a null value");
}
catch (
Throwable e) {
onError(
Operators.
onOperatorError(
s,
e,
t,
actual.
currentContext()));
return;
}
actual.
onNext(
r);
value =
r;
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
validate(this.
s,
s)) {
this.
s =
s;
actual.
onSubscribe(this);
}
}
@
Override
public void
request(long
n) {
s.
request(
n);
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) {
return
s;
}
if (
key ==
Attr.
TERMINATED) {
return
done;
}
return
InnerOperator.super.scanUnsafe(
key);
}
}
}