org.eclipse.jetty.util.thread.TryExecutor Maven / Gradle / Ivy
//
// ========================================================================
// Copyright (c) 1995-2018 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package org.eclipse.jetty.util.thread;
import java.util.concurrent.Executor;
import java.util.concurrent.RejectedExecutionException;
/**
* A variation of Executor that can confirm if a thread is available immediately
*/
public interface TryExecutor extends Executor
{
/**
* Attempt to execute a task.
* @param task The task to be executed
* @return True IFF the task has been given directly to a thread to execute. The task cannot be queued pending the later availability of a Thread.
*/
boolean tryExecute(Runnable task);
@Override
default void execute(Runnable task)
{
if (!tryExecute(task))
throw new RejectedExecutionException();
}
public static TryExecutor asTryExecutor(Executor executor)
{
if (executor instanceof TryExecutor)
return (TryExecutor)executor;
return new NoTryExecutor(executor);
}
public static class NoTryExecutor implements TryExecutor
{
private final Executor executor;
public NoTryExecutor(Executor executor)
{
this.executor = executor;
}
@Override
public void execute(Runnable task)
{
executor.execute(task);
}
@Override
public boolean tryExecute(Runnable task)
{
return false;
}
@Override
public String toString()
{
return String.format("%s@%x[%s]", getClass().getSimpleName(), hashCode(), executor);
}
}
public static final TryExecutor NO_TRY = task -> false;
}