/*
* Copyright 2013 The Netty Project
*
* The Netty Project licenses this file to you 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.netty.util.concurrent;
import io.netty.util.Signal;
import io.netty.util.internal.EmptyArrays;
import io.netty.util.internal.InternalThreadLocalMap;
import io.netty.util.internal.PlatformDependent;
import io.netty.util.internal.StringUtil;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;
import java.util.ArrayDeque;
import java.util.concurrent.CancellationException;
import java.util.concurrent.TimeUnit;
import static java.util.concurrent.TimeUnit.*;
public class DefaultPromise<V> extends AbstractFuture<V> implements Promise<V> {
private static final InternalLogger logger = InternalLoggerFactory.getInstance(DefaultPromise.class);
private static final InternalLogger rejectedExecutionLogger =
InternalLoggerFactory.getInstance(DefaultPromise.class.getName() + ".rejectedExecution");
private static final int MAX_LISTENER_STACK_DEPTH = 8;
private static final Signal SUCCESS = Signal.valueOf(DefaultPromise.class.getName() + ".SUCCESS");
private static final Signal UNCANCELLABLE = Signal.valueOf(DefaultPromise.class.getName() + ".UNCANCELLABLE");
private static final CauseHolder CANCELLATION_CAUSE_HOLDER = new CauseHolder(new CancellationException());
static {
CANCELLATION_CAUSE_HOLDER.cause.setStackTrace(EmptyArrays.EMPTY_STACK_TRACE);
}
private final EventExecutor executor;
private volatile Object result;
/**
* One or more listeners. Can be a {@link GenericFutureListener} or a {@link DefaultFutureListeners}.
* If {@code null}, it means either 1) no listeners were added yet or 2) all listeners were notified.
*/
private Object listeners;
/**
* The list of the listeners that were added after the promise is done. Initially {@code null} and lazily
* instantiated when the late listener is scheduled to be notified later. Also used as a cached {@link Runnable}
* that performs the notification of the listeners it contains.
*/
private LateListeners lateListeners;
private short waiters;
/**
* Creates a new instance.
*
* It is preferable to use {@link EventExecutor#newPromise()} to create a new promise
*
* @param executor
* the {@link EventExecutor} which is used to notify the promise once it is complete
*/
public DefaultPromise(EventExecutor executor) {
if (executor == null) {
throw new NullPointerException("executor");
}
this.executor = executor;
}
protected DefaultPromise() {
// only for subclasses
executor = null;
}
protected EventExecutor executor() {
return executor;
}
@Override
public boolean isCancelled() {
return isCancelled0(result);
}
private static boolean isCancelled0(Object result) {
return result instanceof CauseHolder && ((CauseHolder) result).cause instanceof CancellationException;
}
@Override
public boolean isCancellable() {
return result == null;
}
@Override
public boolean isDone() {
return isDone0(result);
}
private static boolean isDone0(Object result) {
return result != null && result != UNCANCELLABLE;
}
@Override
public boolean isSuccess() {
Object result = this.result;
if (result == null || result == UNCANCELLABLE) {
return false;
}
return !(result instanceof CauseHolder);
}
@Override
public Throwable cause() {
Object result = this.result;
if (result instanceof CauseHolder) {
return ((CauseHolder) result).cause;
}
return null;
}
@Override
public Promise<V> addListener(GenericFutureListener<? extends Future<? super V>> listener) {
if (listener == null) {
throw new NullPointerException("listener");
}
if (isDone()) {
notifyLateListener(listener);
return this;
}
synchronized (this) {
if (!isDone()) {
if (listeners == null) {
listeners = listener;
} else {
if (listeners instanceof DefaultFutureListeners) {
((DefaultFutureListeners) listeners).add(listener);
} else {
final GenericFutureListener<? extends Future<V>> firstListener =
(GenericFutureListener<? extends Future<V>>) listeners;
listeners = new DefaultFutureListeners(firstListener, listener);
}
}
return this;
}
}
notifyLateListener(listener);
return this;
}
@Override
public Promise<V> addListeners(GenericFutureListener<? extends Future<? super V>>... listeners) {
if (listeners == null) {
throw new NullPointerException("listeners");
}
for (GenericFutureListener<? extends Future<? super V>> l: listeners) {
if (l == null) {
break;
}
addListener(l);
}
return this;
}
@Override
public Promise<V> removeListener(GenericFutureListener<? extends Future<? super V>> listener) {
if (listener == null) {
throw new NullPointerException("listener");
}
if (isDone()) {
return this;
}
synchronized (this) {
if (!isDone()) {
if (listeners instanceof DefaultFutureListeners) {
((DefaultFutureListeners) listeners).remove(listener);
} else if (listeners == listener) {
listeners = null;
}
}
}
return this;
}
@Override
public Promise<V> removeListeners(GenericFutureListener<? extends Future<? super V>>... listeners) {
if (listeners == null) {
throw new NullPointerException("listeners");
}
for (GenericFutureListener<? extends Future<? super V>> l: listeners) {
if (l == null) {
break;
}
removeListener(l);
}
return this;
}
@Override
public Promise<V> sync() throws InterruptedException {
await();
rethrowIfFailed();
return this;
}
@Override
public Promise<V> syncUninterruptibly() {
awaitUninterruptibly();
rethrowIfFailed();
return this;
}
private void rethrowIfFailed() {
Throwable cause = cause();
if (cause == null) {
return;
}
PlatformDependent.throwException(cause);
}
@Override
public Promise<V> await() throws InterruptedException {
if (isDone()) {
return this;
}
if (Thread.interrupted()) {
throw new InterruptedException(toString());
}
synchronized (this) {
while (!isDone()) {
checkDeadLock();
incWaiters();
try {
wait();
} finally {
decWaiters();
}
}
}
return this;
}
@Override
public boolean await(long timeout, TimeUnit unit)
throws InterruptedException {
return await0(unit.toNanos(timeout), true);
}
@Override
public boolean await(long timeoutMillis) throws InterruptedException {
return await0(MILLISECONDS.toNanos(timeoutMillis), true);
}
@Override
public Promise<V> awaitUninterruptibly() {
if (isDone()) {
return this;
}
boolean interrupted = false;
synchronized (this) {
while (!isDone()) {
checkDeadLock();
incWaiters();
try {
wait();
} catch (InterruptedException e) {
// Interrupted while waiting.
interrupted = true;
} finally {
decWaiters();
}
}
}
if (interrupted) {
Thread.currentThread().interrupt();
}
return this;
}
@Override
public boolean awaitUninterruptibly(long timeout, TimeUnit unit) {
try {
return await0(unit.toNanos(timeout), false);
} catch (InterruptedException e) {
// Should not be raised at all.
throw new InternalError();
}
}
@Override
public boolean awaitUninterruptibly(long timeoutMillis) {
try {
return await0(MILLISECONDS.toNanos(timeoutMillis), false);
} catch (InterruptedException e) {
// Should not be raised at all.
throw new InternalError();
}
}
private boolean await0(long timeoutNanos, boolean interruptable) throws InterruptedException {
if (isDone()) {
return true;
}
if (timeoutNanos <= 0) {
return isDone();
}
if (interruptable && Thread.interrupted()) {
throw new InterruptedException(toString());
}
long startTime = System.nanoTime();
long waitTime = timeoutNanos;
boolean interrupted = false;
try {
synchronized (this) {
if (isDone()) {
return true;
}
if (waitTime <= 0) {
return isDone();
}
checkDeadLock();
incWaiters();
try {
for (;;) {
try {
wait(waitTime / 1000000, (int) (waitTime % 1000000));
} catch (InterruptedException e) {
if (interruptable) {
throw e;
} else {
interrupted = true;
}
}
if (isDone()) {
return true;
} else {
waitTime = timeoutNanos - (System.nanoTime() - startTime);
if (waitTime <= 0) {
return isDone();
}
}
}
} finally {
decWaiters();
}
}
} finally {
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
/**
* Do deadlock checks
*/
protected void checkDeadLock() {
EventExecutor e = executor();
if (e != null && e.inEventLoop()) {
throw new BlockingOperationException(toString());
}
}
@Override
public Promise<V> setSuccess(V result) {
if (setSuccess0(result)) {
notifyListeners();
return this;
}
throw new IllegalStateException("complete already: " + this);
}
@Override
public boolean trySuccess(V result) {
if (setSuccess0(result)) {
notifyListeners();
return true;
}
return false;
}
@Override
public Promise<V> setFailure(Throwable cause) {
if (setFailure0(cause)) {
notifyListeners();
return this;
}
throw new IllegalStateException("complete already: " + this, cause);
}
@Override
public boolean tryFailure(Throwable cause) {
if (setFailure0(cause)) {
notifyListeners();
return true;
}
return false;
}
@Override
public boolean cancel(boolean mayInterruptIfRunning) {
Object result = this.result;
if (isDone0(result) || result == UNCANCELLABLE) {
return false;
}
synchronized (this) {
// Allow only once.
result = this.result;
if (isDone0(result) || result == UNCANCELLABLE) {
return false;
}
this.result = CANCELLATION_CAUSE_HOLDER;
if (hasWaiters()) {
notifyAll();
}
}
notifyListeners();
return true;
}
@Override
public boolean setUncancellable() {
Object result = this.result;
if (isDone0(result)) {
return !isCancelled0(result);
}
synchronized (this) {
// Allow only once.
result = this.result;
if (isDone0(result)) {
return !isCancelled0(result);
}
this.result = UNCANCELLABLE;
}
return true;
}
private boolean setFailure0(Throwable cause) {
if (cause == null) {
throw new NullPointerException("cause");
}
if (isDone()) {
return false;
}
synchronized (this) {
// Allow only once.
if (isDone()) {
return false;
}
result = new CauseHolder(cause);
if (hasWaiters()) {
notifyAll();
}
}
return true;
}
private boolean setSuccess0(V result) {
if (isDone()) {
return false;
}
synchronized (this) {
// Allow only once.
if (isDone()) {
return false;
}
if (result == null) {
this.result = SUCCESS;
} else {
this.result = result;
}
if (hasWaiters()) {
notifyAll();
}
}
return true;
}
@Override
@SuppressWarnings("unchecked")
public V getNow() {
Object result = this.result;
if (result instanceof CauseHolder || result == SUCCESS) {
return null;
}
return (V) result;
}
private boolean hasWaiters() {
return waiters > 0;
}
private void incWaiters() {
if (waiters == Short.MAX_VALUE) {
throw new IllegalStateException("too many waiters: " + this);
}
waiters ++;
}
private void decWaiters() {
waiters --;
}
private void notifyListeners() {
// This method doesn't need synchronization because:
// 1) This method is always called after synchronized (this) block.
// Hence any listener list modification happens-before this method.
// 2) This method is called only when 'done' is true. Once 'done'
// becomes true, the listener list is never modified - see add/removeListener()
Object listeners = this.listeners;
if (listeners == null) {
return;
}
EventExecutor executor = executor();
if (executor.inEventLoop()) {
final InternalThreadLocalMap threadLocals = InternalThreadLocalMap.get();
final int stackDepth = threadLocals.futureListenerStackDepth();
if (stackDepth < MAX_LISTENER_STACK_DEPTH) {
threadLocals.setFutureListenerStackDepth(stackDepth + 1);
try {
if (listeners instanceof DefaultFutureListeners) {
notifyListeners0(this, (DefaultFutureListeners) listeners);
} else {
final GenericFutureListener<? extends Future<V>> l =
(GenericFutureListener<? extends Future<V>>) listeners;
notifyListener0(this, l);
}
} finally {
this.listeners = null;
threadLocals.setFutureListenerStackDepth(stackDepth);
}
return;
}
}
if (listeners instanceof DefaultFutureListeners) {
final DefaultFutureListeners dfl = (DefaultFutureListeners) listeners;
execute(executor, new Runnable() {
@Override
public void run() {
notifyListeners0(DefaultPromise.this, dfl);
DefaultPromise.this.listeners = null;
}
});
} else {
final GenericFutureListener<? extends Future<V>> l =
(GenericFutureListener<? extends Future<V>>) listeners;
execute(executor, new Runnable() {
@Override
public void run() {
notifyListener0(DefaultPromise.this, l);
DefaultPromise.this.listeners = null;
}
});
}
}
private static void notifyListeners0(Future<?> future, DefaultFutureListeners listeners) {
final GenericFutureListener<?>[] a = listeners.listeners();
final int size = listeners.size();
for (int i = 0; i < size; i ++) {
notifyListener0(future, a[i]);
}
}
/**
* Notifies the specified listener which were added after this promise is already done.
* This method ensures that the specified listener is not notified until {@link #listeners} becomes {@code null}
* to avoid the case where the late listeners are notified even before the early listeners are notified.
*/
private void notifyLateListener(final GenericFutureListener<?> l) {
final EventExecutor executor = executor();
if (executor.inEventLoop()) {
if (listeners == null && lateListeners == null) {
final InternalThreadLocalMap threadLocals = InternalThreadLocalMap.get();
final int stackDepth = threadLocals.futureListenerStackDepth();
if (stackDepth < MAX_LISTENER_STACK_DEPTH) {
threadLocals.setFutureListenerStackDepth(stackDepth + 1);
try {
notifyListener0(this, l);
} finally {
threadLocals.setFutureListenerStackDepth(stackDepth);
}
return;
}
} else {
LateListeners lateListeners = this.lateListeners;
if (lateListeners == null) {
this.lateListeners = lateListeners = new LateListeners();
}
lateListeners.add(l);
execute(executor, lateListeners);
return;
}
}
// Add the late listener to lateListeners in the executor thread for thread safety.
// We could just make LateListeners extend ConcurrentLinkedQueue, but it's an overkill considering
// that most asynchronous applications won't execute this code path.
execute(executor, new LateListenerNotifier(l));
}
protected static void notifyListener(
final EventExecutor eventExecutor, final Future<?> future, final GenericFutureListener<?> l) {
if (eventExecutor.inEventLoop()) {
final InternalThreadLocalMap threadLocals = InternalThreadLocalMap.get();
final int stackDepth = threadLocals.futureListenerStackDepth();
if (stackDepth < MAX_LISTENER_STACK_DEPTH) {
threadLocals.setFutureListenerStackDepth(stackDepth + 1);
try {
notifyListener0(future, l);
} finally {
threadLocals.setFutureListenerStackDepth(stackDepth);
}
return;
}
}
execute(eventExecutor, new Runnable() {
@Override
public void run() {
notifyListener0(future, l);
}
});
}
private static void execute(EventExecutor executor, Runnable task) {
try {
executor.execute(task);
} catch (Throwable t) {
rejectedExecutionLogger.error("Failed to submit a listener notification task. Event loop shut down?", t);
}
}
@SuppressWarnings({ "unchecked", "rawtypes" })
static void notifyListener0(Future future, GenericFutureListener l) {
try {
l.operationComplete(future);
} catch (Throwable t) {
if (logger.isWarnEnabled()) {
logger.warn("An exception was thrown by " + l.getClass().getName() + ".operationComplete()", t);
}
}
}
/**
* Returns a {@link GenericProgressiveFutureListener}, an array of {@link GenericProgressiveFutureListener}, or
* {@code null}.
*/
private synchronized Object progressiveListeners() {
Object listeners = this.listeners;
if (listeners == null) {
// No listeners added
return null;
}
if (listeners instanceof DefaultFutureListeners) {
// Copy DefaultFutureListeners into an array of listeners.
DefaultFutureListeners dfl = (DefaultFutureListeners) listeners;
int progressiveSize = dfl.progressiveSize();
switch (progressiveSize) {
case 0:
return null;
case 1:
for (GenericFutureListener<?> l: dfl.listeners()) {
if (l instanceof GenericProgressiveFutureListener) {
return l;
}
}
return null;
}
GenericFutureListener<?>[] array = dfl.listeners();
GenericProgressiveFutureListener<?>[] copy = new GenericProgressiveFutureListener[progressiveSize];
for (int i = 0, j = 0; j < progressiveSize; i ++) {
GenericFutureListener<?> l = array[i];
if (l instanceof GenericProgressiveFutureListener) {
copy[j ++] = (GenericProgressiveFutureListener<?>) l;
}
}
return copy;
} else if (listeners instanceof GenericProgressiveFutureListener) {
return listeners;
} else {
// Only one listener was added and it's not a progressive listener.
return null;
}
}
@SuppressWarnings("unchecked")
void notifyProgressiveListeners(final long progress, final long total) {
final Object listeners = progressiveListeners();
if (listeners == null) {
return;
}
final ProgressiveFuture<V> self = (ProgressiveFuture<V>) this;
EventExecutor executor = executor();
if (executor.inEventLoop()) {
if (listeners instanceof GenericProgressiveFutureListener[]) {
notifyProgressiveListeners0(
self, (GenericProgressiveFutureListener<?>[]) listeners, progress, total);
} else {
notifyProgressiveListener0(
self, (GenericProgressiveFutureListener<ProgressiveFuture<V>>) listeners, progress, total);
}
} else {
if (listeners instanceof GenericProgressiveFutureListener[]) {
final GenericProgressiveFutureListener<?>[] array =
(GenericProgressiveFutureListener<?>[]) listeners;
execute(executor, new Runnable() {
@Override
public void run() {
notifyProgressiveListeners0(self, array, progress, total);
}
});
} else {
final GenericProgressiveFutureListener<ProgressiveFuture<V>> l =
(GenericProgressiveFutureListener<ProgressiveFuture<V>>) listeners;
execute(executor, new Runnable() {
@Override
public void run() {
notifyProgressiveListener0(self, l, progress, total);
}
});
}
}
}
private static void notifyProgressiveListeners0(
ProgressiveFuture<?> future, GenericProgressiveFutureListener<?>[] listeners, long progress, long total) {
for (GenericProgressiveFutureListener<?> l: listeners) {
if (l == null) {
break;
}
notifyProgressiveListener0(future, l, progress, total);
}
}
@SuppressWarnings({ "unchecked", "rawtypes" })
private static void notifyProgressiveListener0(
ProgressiveFuture future, GenericProgressiveFutureListener l, long progress, long total) {
try {
l.operationProgressed(future, progress, total);
} catch (Throwable t) {
if (logger.isWarnEnabled()) {
logger.warn("An exception was thrown by " + l.getClass().getName() + ".operationProgressed()", t);
}
}
}
private static final class CauseHolder {
final Throwable cause;
CauseHolder(Throwable cause) {
this.cause = cause;
}
}
@Override
public String toString() {
return toStringBuilder().toString();
}
protected StringBuilder toStringBuilder() {
StringBuilder buf = new StringBuilder(64)
.append(StringUtil.simpleClassName(this))
.append('@')
.append(Integer.toHexString(hashCode()));
Object result = this.result;
if (result == SUCCESS) {
buf.append("(success)");
} else if (result == UNCANCELLABLE) {
buf.append("(uncancellable)");
} else if (result instanceof CauseHolder) {
buf.append("(failure(")
.append(((CauseHolder) result).cause)
.append(')');
} else {
buf.append("(incomplete)");
}
return buf;
}
private final class LateListeners extends ArrayDeque<GenericFutureListener<?>> implements Runnable {
private static final long serialVersionUID = -687137418080392244L;
LateListeners() {
super(2);
}
@Override
public void run() {
if (listeners == null) {
for (;;) {
GenericFutureListener<?> l = poll();
if (l == null) {
break;
}
notifyListener0(DefaultPromise.this, l);
}
} else {
// Reschedule until the initial notification is done to avoid the race condition
// where the notification is made in an incorrect order.
execute(executor(), this);
}
}
}
private final class LateListenerNotifier implements Runnable {
private GenericFutureListener<?> l;
LateListenerNotifier(GenericFutureListener<?> l) {
this.l = l;
}
@Override
public void run() {
LateListeners lateListeners = DefaultPromise.this.lateListeners;
if (l != null) {
if (lateListeners == null) {
DefaultPromise.this.lateListeners = lateListeners = new LateListeners();
}
lateListeners.add(l);
l = null;
}
lateListeners.run();
}
}
}