content: package org.apache.lucene.util;
  
  /**
   * 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.
   */
  
  import java.util.concurrent.Executors;
  import java.util.concurrent.ThreadFactory;
  import java.util.concurrent.atomic.AtomicInteger;
  
  /**
   * A default {@link ThreadFactory} implementation that accepts the name prefix
   * of the created threads as a constructor argument. Otherwise, this factory
   * yields the same semantics as the thread factory returned by
   * {@link Executors#defaultThreadFactory()}.
   */
  public class NamedThreadFactory implements ThreadFactory {
    private static final AtomicInteger threadPoolNumber = new AtomicInteger(1);
    private final ThreadGroup group;
    private final AtomicInteger threadNumber = new AtomicInteger(1);
    private static final String NAME_PATTERN = "%s-%d-thread";
    private final String threadNamePrefix;
  
    /**
     * Creates a new {@link NamedThreadFactory} instance
     * 
     * @param threadNamePrefix the name prefix assigned to each thread created.
     */
    public NamedThreadFactory(String threadNamePrefix) {
      final SecurityManager s = System.getSecurityManager();
      group = (s != null) ? s.getThreadGroup() : Thread.currentThread()
          .getThreadGroup();
      this.threadNamePrefix = String.format(NAME_PATTERN,
          checkPrefix(threadNamePrefix), threadPoolNumber.getAndIncrement());
    }
  
    private static String checkPrefix(String prefix) {
      return prefix == null || prefix.length() == 0 ? "Lucene" : prefix;
    }
  
    /**
     * Creates a new {@link Thread}
     * 
     * @see java.util.concurrent.ThreadFactory#newThread(java.lang.Runnable)
     */
    public Thread newThread(Runnable r) {
      final Thread t = new Thread(group, r, String.format("%s-%d",
          this.threadNamePrefix, threadNumber.getAndIncrement()), 0);
      t.setDaemon(false);
      t.setPriority(Thread.NORM_PRIORITY);
      return t;
    }
  
  }
  