/*
* Copyright (c) 2011-2018 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.scheduler;
import java.util.concurrent.
Callable;
import java.util.concurrent.
ExecutorService;
import java.util.concurrent.
Future;
import java.util.concurrent.
FutureTask;
import java.util.concurrent.atomic.
AtomicReferenceFieldUpdater;
import reactor.core.
Disposable;
import reactor.util.annotation.
Nullable;
/**
* A runnable task for {@link Scheduler} Workers that can run periodically
**/
final class
InstantPeriodicWorkerTask implements
Disposable,
Callable<
Void> {
final
Runnable task;
final
ExecutorService executor;
static final
Composite DISPOSED = new
EmptyCompositeDisposable();
static final
Future<
Void>
CANCELLED = new
FutureTask<>(() -> null);
volatile
Future<?>
rest;
static final
AtomicReferenceFieldUpdater<
InstantPeriodicWorkerTask,
Future>
REST =
AtomicReferenceFieldUpdater.
newUpdater(
InstantPeriodicWorkerTask.class,
Future.class, "rest");
volatile
Future<?>
first;
static final
AtomicReferenceFieldUpdater<
InstantPeriodicWorkerTask,
Future>
FIRST =
AtomicReferenceFieldUpdater.
newUpdater(
InstantPeriodicWorkerTask.class,
Future.class, "first");
volatile
Composite parent;
static final
AtomicReferenceFieldUpdater<
InstantPeriodicWorkerTask,
Composite>
PARENT =
AtomicReferenceFieldUpdater.
newUpdater(
InstantPeriodicWorkerTask.class,
Composite.class, "parent");
Thread thread;
InstantPeriodicWorkerTask(
Runnable task,
ExecutorService executor,
Composite parent) {
this.
task =
task;
this.
executor =
executor;
PARENT.
lazySet(this,
parent);
}
@
Override
@
Nullable
public
Void call() {
thread =
Thread.
currentThread();
try {
try {
task.
run();
setRest(
executor.
submit(this));
}
catch (
Throwable ex) {
Schedulers.
handleError(
ex);
}
}
finally {
thread = null;
}
return null;
}
void
setRest(
Future<?>
f) {
for (;;) {
Future o =
rest;
if (
o ==
CANCELLED) {
f.
cancel(
thread !=
Thread.
currentThread());
return;
}
if (
REST.
compareAndSet(this,
o,
f)) {
return;
}
}
}
void
setFirst(
Future<?>
f) {
for (;;) {
Future o =
first;
if (
o ==
CANCELLED) {
f.
cancel(
thread !=
Thread.
currentThread());
return;
}
if (
FIRST.
compareAndSet(this,
o,
f)) {
return;
}
}
}
@
Override
public boolean
isDisposed() {
return
rest ==
CANCELLED;
}
@
Override
public void
dispose() {
for (;;) {
Future f =
first;
if (
f ==
CANCELLED) {
break;
}
if (
FIRST.
compareAndSet(this,
f,
CANCELLED)) {
if (
f != null) {
f.
cancel(
thread !=
Thread.
currentThread());
}
break;
}
}
for (;;) {
Future f =
rest;
if (
f ==
CANCELLED) {
break;
}
if (
REST.
compareAndSet(this,
f,
CANCELLED)) {
if (
f != null) {
f.
cancel(
thread !=
Thread.
currentThread());
}
break;
}
}
for (;;) {
Composite o =
parent;
if (
o ==
DISPOSED ||
o == null) {
return;
}
if (
PARENT.
compareAndSet(this,
o,
DISPOSED)) {
o.
remove(this);
return;
}
}
}
}