/*
* Copyright 2002-2009 the original author or authors.
*
* 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.springframework.scheduling.backportconcurrent;
import java.util.concurrent.Callable;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;
import edu.emory.mathcs.backport.java.util.concurrent.Executor;
import edu.emory.mathcs.backport.java.util.concurrent.Executors;
import edu.emory.mathcs.backport.java.util.concurrent.RejectedExecutionException;
import org.springframework.core.task.TaskRejectedException;
import org.springframework.scheduling.SchedulingTaskExecutor;
/**
* Adapter that takes a JSR-166 backport
* <code>edu.emory.mathcs.backport.java.util.concurrent.Executor</code> and
* exposes a Spring {@link org.springframework.core.task.TaskExecutor} for it.
*
* <p><b>NOTE:</b> This class implements Spring's
* {@link org.springframework.core.task.TaskExecutor} interface (and hence implicitly
* the standard Java 5 {@link java.util.concurrent.Executor} interface) as well as
* the JSR-166 {@link edu.emory.mathcs.backport.java.util.concurrent.Executor}
* interface, with the former being the primary interface, the other just
* serving as secondary convenience. For this reason, the exception handling
* follows the TaskExecutor contract rather than the backport Executor contract, in
* particular regarding the {@link org.springframework.core.task.TaskRejectedException}.
*
* <p>Note that there is a pre-built {@link ThreadPoolTaskExecutor} that allows for
* defining a JSR-166 backport
* {@link edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor} in bean
* style, exposing it as a Spring {@link org.springframework.core.task.TaskExecutor}
* directly. This is a convenient alternative to a raw ThreadPoolExecutor
* definition with a separate definition of the present adapter class.
*
* @author Juergen Hoeller
* @since 2.0.3
* @see edu.emory.mathcs.backport.java.util.concurrent.Executor
* @see edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor
* @see edu.emory.mathcs.backport.java.util.concurrent.Executors
* @see ThreadPoolTaskExecutor
*/
public class ConcurrentTaskExecutor implements SchedulingTaskExecutor, Executor {
private Executor concurrentExecutor;
/**
* Create a new ConcurrentTaskExecutor,
* using a single thread executor as default.
* @see edu.emory.mathcs.backport.java.util.concurrent.Executors#newSingleThreadExecutor()
*/
public ConcurrentTaskExecutor() {
setConcurrentExecutor(null);
}
/**
* Create a new ConcurrentTaskExecutor,
* using the given JSR-166 backport concurrent executor.
* @param concurrentExecutor the JSR-166 backport concurrent executor to delegate to
*/
public ConcurrentTaskExecutor(Executor concurrentExecutor) {
setConcurrentExecutor(concurrentExecutor);
}
/**
* Specify the JSR-166 backport concurrent executor to delegate to.
*/
public final void setConcurrentExecutor(Executor concurrentExecutor) {
this.concurrentExecutor =
(concurrentExecutor != null ? concurrentExecutor : Executors.newSingleThreadExecutor());
}
/**
* Return the JSR-166 backport concurrent executor that this adapter
* delegates to.
*/
public final Executor getConcurrentExecutor() {
return this.concurrentExecutor;
}
/**
* Delegates to the specified JSR-166 backport concurrent executor.
* @see edu.emory.mathcs.backport.java.util.concurrent.Executor#execute(Runnable)
*/
public void execute(Runnable task) {
try {
this.concurrentExecutor.execute(task);
}
catch (RejectedExecutionException ex) {
throw new TaskRejectedException(
"Executor [" + this.concurrentExecutor + "] did not accept task: " + task, ex);
}
}
public void execute(Runnable task, long startTimeout) {
execute(task);
}
public Future<?> submit(Runnable task) {
FutureTask<Object> future = new FutureTask<Object>(task, null);
execute(future);
return future;
}
public <T> Future<T> submit(Callable<T> task) {
FutureTask<T> future = new FutureTask<T>(task);
execute(future);
return future;
}
/**
* This task executor prefers short-lived work units.
*/
public boolean prefersShortLivedTasks() {
return true;
}
}