/*
* JBoss, Home of Professional Open Source
*
* Copyright 2008 Red Hat, Inc. and/or its affiliates.
*
* 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 org.xnio;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.CancellationException;
import java.util.concurrent.Executor;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.locks.LockSupport;
import static org.xnio._private.Messages.futureMsg;
/**
* An abstract base class for {@code IoFuture} objects. Used to easily produce implementations.
*
* @param <T> the type of result that this operation produces
*/
public abstract class AbstractIoFuture<T> implements IoFuture<T> {
@SuppressWarnings("unchecked")
private final AtomicReference<State<T>> stateRef = new AtomicReference<>((State<T>) ST_INITIAL);
private static final State<?> ST_INITIAL = new InitialState<>();
private static final State<?> ST_CANCELLED = new CancelledState<>();
static abstract class State<T> {
abstract Status getStatus();
abstract void notifyDone(AbstractIoFuture<T> future, T result);
abstract void notifyFailed(AbstractIoFuture<T> future, IOException exception);
abstract void notifyCancelled(AbstractIoFuture<T> future);
abstract void cancel();
abstract boolean cancelRequested();
State<T> withWaiter(final Thread thread) {
return new WaiterState<T>(this, thread);
}
<A> State<T> withNotifier(final Executor executor, final AbstractIoFuture<T> future, final Notifier<? super T, A> notifier, final A attachment) {
return new NotifierState<T, A>(this, notifier, attachment);
}
State<T> withCancelHandler(final Cancellable cancellable) {
return new CancellableState<T>(this, cancellable);
}
T getResult() {
throw new IllegalStateException();
}
IOException getException() {
throw new IllegalStateException();
}
}
static final class InitialState<T> extends State<T> {
Status getStatus() {
return Status.WAITING;
}
void notifyDone(final AbstractIoFuture<T> future, final T result) {
}
void notifyFailed(final AbstractIoFuture<T> future, final IOException exception) {
}
void notifyCancelled(final AbstractIoFuture<T> future) {
}
void cancel() {
}
boolean cancelRequested() {
return false;
}
}
static final class CompleteState<T> extends State<T> {
private final T result;
CompleteState(final T result) {
this.result = result;
}
Status getStatus() {
return Status.DONE;
}
void notifyDone(final AbstractIoFuture<T> future, final T result) {
}
void notifyFailed(final AbstractIoFuture<T> future, final IOException exception) {
}
void notifyCancelled(final AbstractIoFuture<T> future) {
}
void cancel() {
}
State<T> withCancelHandler(final Cancellable cancellable) {
return this;
}
State<T> withWaiter(final Thread thread) {
return this;
}
<A> State<T> withNotifier(final Executor executor, final AbstractIoFuture<T> future, final Notifier<? super T, A> notifier, final A attachment) {
future.runNotifier(new NotifierRunnable<T, A>(notifier, future, attachment));
return this;
}
T getResult() {
return result;
}
boolean cancelRequested() {
return false;
}
}
static final class FailedState<T> extends State<T> {
private final IOException exception;
FailedState(final IOException exception) {
this.exception = exception;
}
Status getStatus() {
return Status.FAILED;
}
void notifyDone(final AbstractIoFuture<T> future, final T result) {
}
void notifyFailed(final AbstractIoFuture<T> future, final IOException exception) {
}
void notifyCancelled(final AbstractIoFuture<T> future) {
}
void cancel() {
}
State<T> withCancelHandler(final Cancellable cancellable) {
return this;
}
State<T> withWaiter(final Thread thread) {
return this;
}
<A> State<T> withNotifier(final Executor executor, final AbstractIoFuture<T> future, final Notifier<? super T, A> notifier, final A attachment) {
future.runNotifier(new NotifierRunnable<T, A>(notifier, future, attachment));
return this;
}
IOException getException() {
return exception;
}
boolean cancelRequested() {
return false;
}
}
static final class CancelledState<T> extends State<T> {
CancelledState() {
}
Status getStatus() {
return Status.CANCELLED;
}
void notifyDone(final AbstractIoFuture<T> future, final T result) {
}
void notifyFailed(final AbstractIoFuture<T> future, final IOException exception) {
}
void notifyCancelled(final AbstractIoFuture<T> future) {
}
void cancel() {
}
State<T> withCancelHandler(final Cancellable cancellable) {
try {
cancellable.cancel();
} catch (Throwable ignored) {}
return this;
}
<A> State<T> withNotifier(final Executor executor, final AbstractIoFuture<T> future, final Notifier<? super T, A> notifier, final A attachment) {
future.runNotifier(new NotifierRunnable<T, A>(notifier, future, attachment));
return this;
}
State<T> withWaiter(final Thread thread) {
return this;
}
boolean cancelRequested() {
return true;
}
}
static final class NotifierState<T, A> extends State<T> {
final State<T> next;
final Notifier<? super T, A> notifier;
final A attachment;
NotifierState(final State<T> next, final Notifier<? super T, A> notifier, final A attachment) {
this.next = next;
this.notifier = notifier;
this.attachment = attachment;
}
Status getStatus() {
return Status.WAITING;
}
void notifyDone(final AbstractIoFuture<T> future, final T result) {
doNotify(future);
next.notifyDone(future, result);
}
void notifyFailed(final AbstractIoFuture<T> future, final IOException exception) {
doNotify(future);
next.notifyFailed(future, exception);
}
void notifyCancelled(final AbstractIoFuture<T> future) {
doNotify(future);
next.notifyCancelled(future);
}
void cancel() {
next.cancel();
}
private void doNotify(final AbstractIoFuture<T> future) {
future.runNotifier(new NotifierRunnable<T, A>(notifier, future, attachment));
}
boolean cancelRequested() {
return next.cancelRequested();
}
}
static final class WaiterState<T> extends State<T> {
final State<T> next;
final Thread waiter;
WaiterState(final State<T> next, final Thread waiter) {
this.next = next;
this.waiter = waiter;
}
Status getStatus() {
return Status.WAITING;
}
void notifyDone(final AbstractIoFuture<T> future, final T result) {
LockSupport.unpark(waiter);
next.notifyDone(future, result);
}
void notifyFailed(final AbstractIoFuture<T> future, final IOException exception) {
LockSupport.unpark(waiter);
next.notifyFailed(future, exception);
}
void notifyCancelled(final AbstractIoFuture<T> future) {
LockSupport.unpark(waiter);
next.notifyCancelled(future);
}
void cancel() {
next.cancel();
}
boolean cancelRequested() {
return next.cancelRequested();
}
}
static final class CancellableState<T> extends State<T> {
final State<T> next;
final Cancellable cancellable;
CancellableState(final State<T> next, final Cancellable cancellable) {
this.next = next;
this.cancellable = cancellable;
}
Status getStatus() {
return Status.WAITING;
}
void notifyDone(final AbstractIoFuture<T> future, final T result) {
next.notifyDone(future, result);
}
void notifyFailed(final AbstractIoFuture<T> future, final IOException exception) {
next.notifyFailed(future, exception);
}
void notifyCancelled(final AbstractIoFuture<T> future) {
next.notifyCancelled(future);
}
void cancel() {
try {
cancellable.cancel();
} catch (Throwable ignored) {}
next.cancel();
}
boolean cancelRequested() {
return next.cancelRequested();
}
}
static final class CancelRequestedState<T> extends State<T> {
final State<T> next;
CancelRequestedState(final State<T> next) {
this.next = next;
}
Status getStatus() {
return Status.WAITING;
}
void notifyDone(final AbstractIoFuture<T> future, final T result) {
next.notifyDone(future, result);
}
void notifyFailed(final AbstractIoFuture<T> future, final IOException exception) {
next.notifyFailed(future, exception);
}
void notifyCancelled(final AbstractIoFuture<T> future) {
next.notifyCancelled(future);
}
void cancel() {
// terminate
}
boolean cancelRequested() {
return true;
}
}
/**
* Construct a new instance.
*/
protected AbstractIoFuture() {
}
/**
* {@inheritDoc}
*/
public Status getStatus() {
return getState().getStatus();
}
private State<T> getState() {
return stateRef.get();
}
private boolean compareAndSetState(State<T> expect, State<T> update) {
return stateRef.compareAndSet(expect, update);
}
/**
* {@inheritDoc}
*/
public Status await() {
final Thread thread = Thread.currentThread();
State<T> state;
for (;;) {
state = getState();
if (state.getStatus() != Status.WAITING) {
return state.getStatus();
}
Xnio.checkBlockingAllowed();
State<T> withWaiter = state.withWaiter(thread);
if (compareAndSetState(state, withWaiter)) {
boolean intr = Thread.interrupted();
try {
do {
LockSupport.park(this);
if (Thread.interrupted()) intr = true;
state = getState();
} while (state.getStatus() == Status.WAITING);
return state.getStatus();
} finally {
if (intr) thread.interrupt();
}
}
// retry
}
}
/**
* {@inheritDoc}
*/
public Status await(long time, final TimeUnit timeUnit) {
if (time < 0L) {
time = 0L;
}
long duration = timeUnit.toNanos(time);
long now = System.nanoTime();
long tick;
final Thread thread = Thread.currentThread();
State<T> state;
for (;;) {
state = getState();
if (state.getStatus() != Status.WAITING || duration == 0L) {
return state.getStatus();
}
Xnio.checkBlockingAllowed();
State<T> withWaiter = state.withWaiter(thread);
if (compareAndSetState(state, withWaiter)) {
boolean intr = Thread.interrupted();
try {
do {
LockSupport.parkNanos(this, duration);
if (Thread.interrupted()) intr = true;
state = getState();
duration -= (tick = System.nanoTime()) - now;
now = tick;
} while (state.getStatus() == Status.WAITING && duration > 0L);
return state.getStatus();
} finally {
if (intr) thread.interrupt();
}
}
// retry
}
}
/**
* {@inheritDoc}
*/
public Status awaitInterruptibly() throws InterruptedException {
final Thread thread = Thread.currentThread();
State<T> state;
for (;;) {
state = getState();
if (state.getStatus() != Status.WAITING) {
return state.getStatus();
}
Xnio.checkBlockingAllowed();
if (Thread.interrupted()) throw new InterruptedException();
State<T> withWaiter = state.withWaiter(thread);
if (compareAndSetState(state, withWaiter)) {
do {
LockSupport.park(this);
if (Thread.interrupted()) throw new InterruptedException();
state = getState();
} while (state.getStatus() == Status.WAITING);
return state.getStatus();
}
// retry
}
}
/**
* {@inheritDoc}
*/
public Status awaitInterruptibly(long time, final TimeUnit timeUnit) throws InterruptedException {
if (time < 0L) {
time = 0L;
}
long duration = timeUnit.toNanos(time);
long now = System.nanoTime();
long tick;
final Thread thread = Thread.currentThread();
State<T> state;
for (;;) {
state = getState();
if (state.getStatus() != Status.WAITING || duration == 0L) {
return state.getStatus();
}
Xnio.checkBlockingAllowed();
if (Thread.interrupted()) throw new InterruptedException();
State<T> withWaiter = state.withWaiter(thread);
if (compareAndSetState(state, withWaiter)) {
do {
LockSupport.parkNanos(this, duration);
if (Thread.interrupted()) throw new InterruptedException();
state = getState();
duration -= (tick = System.nanoTime()) - now;
now = tick;
} while (state.getStatus() == Status.WAITING && duration > 0L);
return state.getStatus();
}
// retry
}
}
/**
* {@inheritDoc}
*/
@SuppressWarnings({"unchecked"})
public T get() throws IOException, CancellationException {
switch (await()) {
case DONE: return getState().getResult();
case FAILED: throw getState().getException();
case CANCELLED: throw futureMsg.opCancelled();
default: throw new IllegalStateException();
}
}
/**
* {@inheritDoc}
*/
@SuppressWarnings({"unchecked"})
public T getInterruptibly() throws IOException, InterruptedException, CancellationException {
switch (awaitInterruptibly()) {
case DONE: return getState().getResult();
case FAILED: throw getState().getException();
case CANCELLED: throw futureMsg.opCancelled();
default: throw new IllegalStateException();
}
}
/**
* {@inheritDoc}
*/
public IOException getException() throws IllegalStateException {
return getState().getException();
}
/**
* {@inheritDoc}
*/
public <A> IoFuture<T> addNotifier(final Notifier<? super T, A> notifier, final A attachment) {
State<T> oldState, newState;
do {
oldState = getState();
newState = oldState.withNotifier(getNotifierExecutor(), this, notifier, attachment);
if (oldState == newState) {
return this;
}
} while (! compareAndSetState(oldState, newState));
return this;
}
/**
* Set the exception for this operation. Any threads blocking on this instance will be unblocked.
*
* @param exception the exception to set
* @return {@code false} if the operation was already completed, {@code true} otherwise
*/
protected boolean setException(IOException exception) {
State<T> oldState;
oldState = getState();
if (oldState.getStatus() != Status.WAITING) {
return false;
} else {
State<T> newState = new FailedState<T>(exception);
while (! compareAndSetState(oldState, newState)) {
oldState = getState();
if (oldState.getStatus() != Status.WAITING) {
return false;
}
}
}
oldState.notifyFailed(this, exception);
return true;
}
/**
* Set the result for this operation. Any threads blocking on this instance will be unblocked.
*
* @param result the result to set
* @return {@code false} if the operation was already completed, {@code true} otherwise
*/
protected boolean setResult(T result) {
State<T> oldState;
oldState = getState();
if (oldState.getStatus() != Status.WAITING) {
return false;
} else {
State<T> newState = new CompleteState<>(result);
while (! compareAndSetState(oldState, newState)) {
oldState = getState();
if (oldState.getStatus() != Status.WAITING) {
return false;
}
}
}
oldState.notifyDone(this, result);
return true;
}
/**
* Acknowledge the cancellation of this operation.
*
* @return {@code false} if the operation was already completed, {@code true} otherwise
*/
protected boolean setCancelled() {
State<T> oldState;
oldState = getState();
if (oldState.getStatus() != Status.WAITING) {
return false;
} else {
@SuppressWarnings("unchecked")
State<T> newState = (State<T>) ST_CANCELLED;
while (! compareAndSetState(oldState, newState)) {
oldState = getState();
if (oldState.getStatus() != Status.WAITING) {
return false;
}
}
}
oldState.notifyCancelled(this);
return true;
}
/**
* Cancel an operation. The actual cancel may be synchronous or asynchronous. Implementers will use this method
* to initiate the cancel; use the {@link #setCancelled()} method to indicate that the cancel was successful. The
* default implementation calls any registered cancel handlers.
*
* @return this {@code IoFuture} instance
*/
public IoFuture<T> cancel() {
State<T> state;
do {
state = getState();
if (state.getStatus() != Status.WAITING || state.cancelRequested()) return this;
} while (! compareAndSetState(state, new CancelRequestedState<T>(state)));
state.cancel();
return this;
}
/**
* Add a cancellation handler. The argument will be cancelled whenever this {@code IoFuture} is cancelled. If
* the {@code IoFuture} is already cancelled when this method is called, the handler will be called directly.
*
* @param cancellable the cancel handler
*/
protected void addCancelHandler(final Cancellable cancellable) {
State<T> oldState, newState;
do {
oldState = getState();
if (oldState.getStatus() != Status.WAITING || oldState.cancelRequested()) {
try {
cancellable.cancel();
} catch (Throwable ignored) {
}
return;
}
newState = oldState.withCancelHandler(cancellable);
if (oldState == newState) return;
} while (! compareAndSetState(oldState, newState));
}
/**
* Run a notifier. Implementors will run the notifier, preferably in another thread. The default implementation
* runs the notifier using the {@code Executor} retrieved via {@link #getNotifierExecutor()}.
*
* @param runnable the runnable task
*/
protected void runNotifier(final Runnable runnable) {
getNotifierExecutor().execute(runnable);
}
/**
* Get the executor used to run asynchronous notifiers. By default, this implementation simply returns the direct
* executor.
*
* @return the executor to use
*/
protected Executor getNotifierExecutor() {
return IoUtils.directExecutor();
}
static class NotifierRunnable<T, A> implements Runnable {
private final Notifier<? super T, A> notifier;
private final IoFuture<T> future;
private final A attachment;
NotifierRunnable(final Notifier<? super T, A> notifier, final IoFuture<T> future, final A attachment) {
this.notifier = notifier;
this.future = future;
this.attachment = attachment;
}
public void run() {
try {
notifier.notify(future, attachment);
} catch (Throwable t) {
futureMsg.notifierFailed(t, notifier);
}
}
}
}