/** * 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; } }