content: /**
   * Copyright The Apache Software Foundation
   *
   * 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 com.alibaba.wasp.metrics;
  
  import java.util.concurrent.ScheduledExecutorService;
  import java.util.concurrent.ScheduledThreadPoolExecutor;
  import java.util.concurrent.ThreadFactory;
  import java.util.concurrent.atomic.AtomicInteger;
  
  /**
   * Class to handle the ScheduledExecutorService{@link java.util.concurrent.ScheduledExecutorService}
   */
  public class MetricsExecutor {
  
  
    public static ScheduledExecutorService getExecutor() {
      return ExecutorSingleton.INSTANCE.scheduler;
    }
  
    public static void stop() {
      if (!getExecutor().isShutdown()) {
        getExecutor().shutdown();
      }
    }
  
    private enum ExecutorSingleton {
      INSTANCE;
  
      private final ScheduledExecutorService scheduler = new ScheduledThreadPoolExecutor(
          1, new ThreadPoolExecutorThreadFactory("Wasp-Metrics2-"));
    }
  
    private static class ThreadPoolExecutorThreadFactory implements ThreadFactory {
      private final String name;
      private final AtomicInteger threadNumber = new AtomicInteger(1);
  
      private ThreadPoolExecutorThreadFactory(String name) {
        this.name = name;
      }
  
      @Override
      public Thread newThread(Runnable runnable) {
        Thread t = new Thread(runnable, name + threadNumber.getAndIncrement());
        t.setDaemon(true);
        return t;
      }
    }
  }
  