io.netty.util.concurrent.PromiseTask Maven / Gradle / Ivy
/*
* 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:
*
* https://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 java.util.concurrent.Callable;
import java.util.concurrent.RunnableFuture;
class PromiseTask extends DefaultPromise implements RunnableFuture {
private static final class RunnableAdapter implements Callable {
final Runnable task;
final T result;
RunnableAdapter(Runnable task, T result) {
this.task = task;
this.result = result;
}
@Override
public T call() {
task.run();
return result;
}
@Override
public String toString() {
return "Callable(task: " + task + ", result: " + result + ')';
}
}
private static final Runnable COMPLETED = new SentinelRunnable("COMPLETED");
private static final Runnable CANCELLED = new SentinelRunnable("CANCELLED");
private static final Runnable FAILED = new SentinelRunnable("FAILED");
private static class SentinelRunnable implements Runnable {
private final String name;
SentinelRunnable(String name) {
this.name = name;
}
@Override
public void run() { } // no-op
@Override
public String toString() {
return name;
}
}
// Strictly of type Callable or Runnable
private Object task;
PromiseTask(EventExecutor executor, Runnable runnable, V result) {
super(executor);
task = result == null ? runnable : new RunnableAdapter(runnable, result);
}
PromiseTask(EventExecutor executor, Runnable runnable) {
super(executor);
task = runnable;
}
PromiseTask(EventExecutor executor, Callable callable) {
super(executor);
task = callable;
}
@Override
public final int hashCode() {
return System.identityHashCode(this);
}
@Override
public final boolean equals(Object obj) {
return this == obj;
}
@SuppressWarnings("unchecked")
V runTask() throws Throwable {
final Object task = this.task;
if (task instanceof Callable) {
return ((Callable) task).call();
}
((Runnable) task).run();
return null;
}
@Override
public void run() {
try {
if (setUncancellableInternal()) {
V result = runTask();
setSuccessInternal(result);
}
} catch (Throwable e) {
setFailureInternal(e);
}
}
private boolean clearTaskAfterCompletion(boolean done, Runnable result) {
if (done) {
// The only time where it might be possible for the sentinel task
// to be called is in the case of a periodic ScheduledFutureTask,
// in which case it's a benign race with cancellation and the (null)
// return value is not used.
task = result;
}
return done;
}
@Override
public final Promise setFailure(Throwable cause) {
throw new IllegalStateException();
}
protected final Promise setFailureInternal(Throwable cause) {
super.setFailure(cause);
clearTaskAfterCompletion(true, FAILED);
return this;
}
@Override
public final boolean tryFailure(Throwable cause) {
return false;
}
protected final boolean tryFailureInternal(Throwable cause) {
return clearTaskAfterCompletion(super.tryFailure(cause), FAILED);
}
@Override
public final Promise setSuccess(V result) {
throw new IllegalStateException();
}
protected final Promise setSuccessInternal(V result) {
super.setSuccess(result);
clearTaskAfterCompletion(true, COMPLETED);
return this;
}
@Override
public final boolean trySuccess(V result) {
return false;
}
protected final boolean trySuccessInternal(V result) {
return clearTaskAfterCompletion(super.trySuccess(result), COMPLETED);
}
@Override
public final boolean setUncancellable() {
throw new IllegalStateException();
}
protected final boolean setUncancellableInternal() {
return super.setUncancellable();
}
@Override
public boolean cancel(boolean mayInterruptIfRunning) {
return clearTaskAfterCompletion(super.cancel(mayInterruptIfRunning), CANCELLED);
}
@Override
protected StringBuilder toStringBuilder() {
StringBuilder buf = super.toStringBuilder();
buf.setCharAt(buf.length() - 1, ',');
return buf.append(" task: ")
.append(task)
.append(')');
}
}
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