/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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 org.apache.metamodel.util;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;
/**
* A shared {@link ExecutorService} for use on ad-hoc tasks that can be
* optimized by running operations in parallel.
*
* Note that since this {@link ExecutorService} is shared, it is not recommended
* to use it for dedicated tasks or daemon-like long-running tasks.
*/
public final class SharedExecutorService {
/**
* A custom thread factory that creates daemon threads.
*/
private static final class ThreadFactoryImpl implements ThreadFactory {
private static final AtomicInteger counter = new AtomicInteger(0);
private final ThreadGroup _threadGroup;
public ThreadFactoryImpl() {
SecurityManager s = System.getSecurityManager();
_threadGroup = (s != null) ? s.getThreadGroup() : Thread
.currentThread().getThreadGroup();
}
@Override
public Thread newThread(Runnable r) {
Thread thread = new Thread(_threadGroup, r,
"MetaModel.SharedExecutorService.Thread."
+ counter.incrementAndGet());
thread.setDaemon(true);
thread.setPriority(Thread.NORM_PRIORITY);
return thread;
}
}
private static final ExecutorService executor = Executors
.newCachedThreadPool(new ThreadFactoryImpl());
private SharedExecutorService() {
// prevent instantiation
}
/**
* Gets the shared {@link ExecutorService}.
*
* @return an {@link ExecutorService} for shared usage.
*/
public static final ExecutorService get() {
return executor;
}
}