001package org.eclipse.aether.util.concurrency;
002
003/*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements.  See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership.  The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License.  You may obtain a copy of the License at
011 * 
012 *  http://www.apache.org/licenses/LICENSE-2.0
013 * 
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied.  See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022import java.util.concurrent.Executors;
023import java.util.concurrent.ThreadFactory;
024import java.util.concurrent.atomic.AtomicInteger;
025
026/**
027 * A factory to create worker threads with a given name prefix.
028 */
029public final class WorkerThreadFactory
030    implements ThreadFactory
031{
032
033    private final ThreadFactory factory;
034
035    private final String namePrefix;
036
037    private final AtomicInteger threadIndex;
038
039    private static final AtomicInteger POOL_INDEX = new AtomicInteger();
040
041    /**
042     * Creates a new thread factory whose threads will have names using the specified prefix.
043     * 
044     * @param namePrefix The prefix for the thread names, may be {@code null} or empty to derive the prefix from the
045     *            caller's simple class name.
046     */
047    public WorkerThreadFactory( String namePrefix )
048    {
049        this.factory = Executors.defaultThreadFactory();
050        this.namePrefix =
051            ( ( namePrefix != null && namePrefix.length() > 0 ) ? namePrefix : getCallerSimpleClassName() + '-' )
052                + POOL_INDEX.getAndIncrement() + '-';
053        threadIndex = new AtomicInteger();
054    }
055
056    private static String getCallerSimpleClassName()
057    {
058        StackTraceElement[] stack = new Exception().getStackTrace();
059        if ( stack == null || stack.length <= 2 )
060        {
061            return "Worker-";
062        }
063        String name = stack[2].getClassName();
064        name = name.substring( name.lastIndexOf( '.' ) + 1 );
065        return name;
066    }
067
068    public Thread newThread( Runnable r )
069    {
070        Thread thread = factory.newThread( r );
071        thread.setName( namePrefix + threadIndex.getAndIncrement() );
072        thread.setDaemon( true );
073        return thread;
074    }
075
076}