/**
* Copyright (c) 2016-present, RxJava Contributors.
*
* 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 io.reactivex.internal.operators.completable;
import java.util.concurrent.atomic.*;
import io.reactivex.*;
import io.reactivex.disposables.
Disposable;
/**
* Consume the upstream source exactly once and cache its terminal event.
* <p>History: 2.0.4 - experimental
* @since 2.1
*/
public final class
CompletableCache extends
Completable implements
CompletableObserver {
static final
InnerCompletableCache[]
EMPTY = new
InnerCompletableCache[0];
static final
InnerCompletableCache[]
TERMINATED = new
InnerCompletableCache[0];
final
CompletableSource source;
final
AtomicReference<
InnerCompletableCache[]>
observers;
final
AtomicBoolean once;
Throwable error;
public
CompletableCache(
CompletableSource source) {
this.
source =
source;
this.
observers = new
AtomicReference<
InnerCompletableCache[]>(
EMPTY);
this.
once = new
AtomicBoolean();
}
@
Override
protected void
subscribeActual(
CompletableObserver observer) {
InnerCompletableCache inner = new
InnerCompletableCache(
observer);
observer.
onSubscribe(
inner);
if (
add(
inner)) {
if (
inner.
isDisposed()) {
remove(
inner);
}
if (
once.
compareAndSet(false, true)) {
source.
subscribe(this);
}
} else {
Throwable ex =
error;
if (
ex != null) {
observer.
onError(
ex);
} else {
observer.
onComplete();
}
}
}
@
Override
public void
onSubscribe(
Disposable d) {
// not used
}
@
Override
public void
onError(
Throwable e) {
error =
e;
for (
InnerCompletableCache inner :
observers.
getAndSet(
TERMINATED)) {
if (!
inner.
get()) {
inner.
downstream.
onError(
e);
}
}
}
@
Override
public void
onComplete() {
for (
InnerCompletableCache inner :
observers.
getAndSet(
TERMINATED)) {
if (!
inner.
get()) {
inner.
downstream.
onComplete();
}
}
}
boolean
add(
InnerCompletableCache inner) {
for (;;) {
InnerCompletableCache[]
a =
observers.
get();
if (
a ==
TERMINATED) {
return false;
}
int
n =
a.length;
InnerCompletableCache[]
b = new
InnerCompletableCache[
n + 1];
System.
arraycopy(
a, 0,
b, 0,
n);
b[
n] =
inner;
if (
observers.
compareAndSet(
a,
b)) {
return true;
}
}
}
void
remove(
InnerCompletableCache inner) {
for (;;) {
InnerCompletableCache[]
a =
observers.
get();
int
n =
a.length;
if (
n == 0) {
return;
}
int
j = -1;
for (int
i = 0;
i <
n;
i++) {
if (
a[
i] ==
inner) {
j =
i;
break;
}
}
if (
j < 0) {
return;
}
InnerCompletableCache[]
b;
if (
n == 1) {
b =
EMPTY;
} else {
b = new
InnerCompletableCache[
n - 1];
System.
arraycopy(
a, 0,
b, 0,
j);
System.
arraycopy(
a,
j + 1,
b,
j,
n -
j - 1);
}
if (
observers.
compareAndSet(
a,
b)) {
break;
}
}
}
final class
InnerCompletableCache
extends
AtomicBoolean
implements
Disposable {
private static final long
serialVersionUID = 8943152917179642732L;
final
CompletableObserver downstream;
InnerCompletableCache(
CompletableObserver downstream) {
this.
downstream =
downstream;
}
@
Override
public boolean
isDisposed() {
return
get();
}
@
Override
public void
dispose() {
if (
compareAndSet(false, true)) {
remove(this);
}
}
}
}