content: /*
   * Copyright 2013-2023 the original author or authors.
   *
   * Licensed 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
   *
   *      https://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.cloud.nacos.discovery;
  
  import java.time.Duration;
  import java.util.concurrent.ScheduledFuture;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.concurrent.atomic.AtomicLong;
  
  import com.alibaba.cloud.nacos.NacosDiscoveryProperties;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.springframework.cloud.client.discovery.event.HeartbeatEvent;
  import org.springframework.context.ApplicationEventPublisher;
  import org.springframework.context.ApplicationEventPublisherAware;
  import org.springframework.context.SmartLifecycle;
  import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
  
  
  /**
   * @author yuhuangbin
   * @author ruansheng
   */
  public class NacosDiscoveryHeartBeatPublisher implements ApplicationEventPublisherAware, SmartLifecycle {
  
  	private static final Logger log = LoggerFactory.getLogger(NacosDiscoveryHeartBeatPublisher.class);
  
  	private final NacosDiscoveryProperties nacosDiscoveryProperties;
  
  	private final ThreadPoolTaskScheduler taskScheduler;
  	private final AtomicLong nacosHeartBeatIndex = new AtomicLong(0);
  	private final AtomicBoolean running = new AtomicBoolean(false);
  	private ApplicationEventPublisher publisher;
  	private ScheduledFuture<?> heartBeatFuture;
  
  	public NacosDiscoveryHeartBeatPublisher(NacosDiscoveryProperties nacosDiscoveryProperties) {
  		this.nacosDiscoveryProperties = nacosDiscoveryProperties;
  		this.taskScheduler = getTaskScheduler();
  	}
  
  	private static ThreadPoolTaskScheduler getTaskScheduler() {
  		ThreadPoolTaskScheduler taskScheduler = new ThreadPoolTaskScheduler();
  		taskScheduler.setBeanName("HeartBeat-Task-Scheduler");
  		taskScheduler.initialize();
  		return taskScheduler;
  	}
  
  	@Override
  	public void start() {
  		if (this.running.compareAndSet(false, true)) {
  			log.info("Start nacos heartBeat task scheduler.");
  			this.heartBeatFuture = this.taskScheduler.scheduleWithFixedDelay(
  					this::publishHeartBeat, Duration.ofMillis(this.nacosDiscoveryProperties.getWatchDelay()));
  		}
  	}
  
  	@Override
  	public void stop() {
  		if (this.running.compareAndSet(true, false)) {
  			if (this.heartBeatFuture != null) {
  				// shutdown current user-thread,
  				// then the other daemon-threads will terminate automatic.
  				this.taskScheduler.shutdown();
  				this.heartBeatFuture.cancel(true);
  			}
  		}
  	}
  
  	@Override
  	public boolean isAutoStartup() {
  		return true;
  	}
  
  	@Override
  	public boolean isRunning() {
  		return this.running.get();
  	}
  
  	@Override
  	public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {
  		this.publisher = applicationEventPublisher;
  	}
  
  	/**
  	 * nacos doesn't support watch now , publish an event every 30 seconds.
  	 */
  	public void publishHeartBeat() {
  		HeartbeatEvent event = new HeartbeatEvent(this, nacosHeartBeatIndex.getAndIncrement());
  		this.publisher.publishEvent(event);
  	}
  }
  