spring cloud的ConsulCatalogWatch有什么作用

本篇内容主要讲解“spring cloud的ConsulCatalogWatch有什么作用”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“spring cloud的ConsulCatalogWatch有什么作用”吧!

序

本文主要研究一下spring cloud的ConsulCatalogWatch

ConsulCatalogWatch

spring-cloud-consul-discovery-2.1.2.RELEASE-sources.jar!/org/springframework/cloud/consul/discovery/ConsulCatalogWatch.java

public class ConsulCatalogWatch
		implements ApplicationEventPublisherAware, SmartLifecycle {

	private static final Log log = LogFactory.getLog(ConsulDiscoveryClient.class);

	private final ConsulDiscoveryProperties properties;

	private final ConsulClient consul;

	private final TaskScheduler taskScheduler;

	private final AtomicReference<BigInteger> catalogServicesIndex = new AtomicReference<>();

	private final AtomicBoolean running = new AtomicBoolean(false);

	private ApplicationEventPublisher publisher;

	private ScheduledFuture<?> watchFuture;

	public ConsulCatalogWatch(ConsulDiscoveryProperties properties, ConsulClient consul) {
		this(properties, consul, getTaskScheduler());
	}

	public ConsulCatalogWatch(ConsulDiscoveryProperties properties, ConsulClient consul,
			TaskScheduler taskScheduler) {
		this.properties = properties;
		this.consul = consul;
		this.taskScheduler = taskScheduler;
	}

	private static ThreadPoolTaskScheduler getTaskScheduler() {
		ThreadPoolTaskScheduler taskScheduler = new ThreadPoolTaskScheduler();
		taskScheduler.initialize();
		return taskScheduler;
	}

	@Override
	public void setApplicationEventPublisher(ApplicationEventPublisher publisher) {
		this.publisher = publisher;
	}

	@Override
	public boolean isAutoStartup() {
		return true;
	}

	@Override
	public void stop(Runnable callback) {
		this.stop();
		callback.run();
	}

	@Override
	public void start() {
		if (this.running.compareAndSet(false, true)) {
			this.watchFuture = this.taskScheduler.scheduleWithFixedDelay(
					this::catalogServicesWatch,
					this.properties.getCatalogServicesWatchDelay());
		}
	}

	@Override
	public void stop() {
		if (this.running.compareAndSet(true, false) && this.watchFuture != null) {
			this.watchFuture.cancel(true);
		}
	}

	@Override
	public boolean isRunning() {
		return false;
	}

	@Override
	public int getPhase() {
		return 0;
	}

	@Timed("consul.watch-catalog-services")
	public void catalogServicesWatch() {
		try {
			long index = -1;
			if (this.catalogServicesIndex.get() != null) {
				index = this.catalogServicesIndex.get().longValue();
			}

			Response<Map<String, List<String>>> response = this.consul.getCatalogServices(
					new QueryParams(this.properties.getCatalogServicesWatchTimeout(),
							index),
					this.properties.getAclToken());
			Long consulIndex = response.getConsulIndex();
			if (consulIndex != null) {
				this.catalogServicesIndex.set(BigInteger.valueOf(consulIndex));
			}

			if (log.isTraceEnabled()) {
				log.trace("Received services update from consul: " + response.getValue()
						+ ", index: " + consulIndex);
			}
			this.publisher.publishEvent(new HeartbeatEvent(this, consulIndex));
		}
		catch (Exception e) {
			log.error("Error watching Consul CatalogServices", e);
		}
	}

}

• ConsulCatalogWatch构造器接收ConsulDiscoveryProperties、ConsulClient、TaskScheduler；其start方法会使用taskScheduler.scheduleWithFixedDelay注册catalogServicesWatch的定时任务；stop方法则是cancel掉这个定时任务；catalogServicesWatch方法使用consul.getCatalogServices方法获取consulIndex然后更新本地的catalogServicesIndex，发布HeartbeatEvent

ConsulDiscoveryClientConfiguration

spring-cloud-consul-discovery-2.1.2.RELEASE-sources.jar!/org/springframework/cloud/consul/discovery/ConsulDiscoveryClientConfiguration.java

@Configuration
@ConditionalOnConsulEnabled
@ConditionalOnProperty(value = "spring.cloud.consul.discovery.enabled", matchIfMissing = true)
@ConditionalOnDiscoveryEnabled
@EnableConfigurationProperties
@AutoConfigureBefore({ SimpleDiscoveryClientAutoConfiguration.class,
		CommonsClientAutoConfiguration.class })
public class ConsulDiscoveryClientConfiguration {

	/**
	 * Name of the catalog watch task scheduler bean.
	 */
	public static final String CATALOG_WATCH_TASK_SCHEDULER_NAME = "catalogWatchTaskScheduler";

	@Autowired
	private ConsulClient consulClient;

	@Bean
	@ConditionalOnMissingBean
	@ConditionalOnProperty("spring.cloud.consul.discovery.heartbeat.enabled")
	// TODO: move to service-registry for Edgware
	public TtlScheduler ttlScheduler(HeartbeatProperties heartbeatProperties) {
		return new TtlScheduler(heartbeatProperties, this.consulClient);
	}

	@Bean
	@ConditionalOnMissingBean
	// TODO: move to service-registry for Edgware
	public HeartbeatProperties heartbeatProperties() {
		return new HeartbeatProperties();
	}

	@Bean
	@ConditionalOnMissingBean
	// TODO: Split appropriate values to service-registry for Edgware
	public ConsulDiscoveryProperties consulDiscoveryProperties(InetUtils inetUtils) {
		return new ConsulDiscoveryProperties(inetUtils);
	}

	@Bean
	@ConditionalOnMissingBean
	public ConsulDiscoveryClient consulDiscoveryClient(
			ConsulDiscoveryProperties discoveryProperties) {
		return new ConsulDiscoveryClient(this.consulClient, discoveryProperties);
	}

	@Bean
	@ConditionalOnMissingBean
	@ConditionalOnProperty(name = "spring.cloud.consul.discovery.catalog-services-watch.enabled", matchIfMissing = true)
	public ConsulCatalogWatch consulCatalogWatch(
			ConsulDiscoveryProperties discoveryProperties,
			@Qualifier(CATALOG_WATCH_TASK_SCHEDULER_NAME) TaskScheduler taskScheduler) {
		return new ConsulCatalogWatch(discoveryProperties, this.consulClient,
				taskScheduler);
	}

	@Bean(name = CATALOG_WATCH_TASK_SCHEDULER_NAME)
	@ConditionalOnProperty(name = "spring.cloud.consul.discovery.catalog-services-watch.enabled", matchIfMissing = true)
	public TaskScheduler catalogWatchTaskScheduler() {
		return new ThreadPoolTaskScheduler();
	}

}

• ConsulDiscoveryClientConfiguration会注册ConsulCatalogWatch，其使用了名为catalogWatchTaskScheduler的taskScheduler；这里创建的是ThreadPoolTaskScheduler

小结

ConsulCatalogWatch构造器接收ConsulDiscoveryProperties、ConsulClient、TaskScheduler；其start方法会使用taskScheduler.scheduleWithFixedDelay注册catalogServicesWatch的定时任务；stop方法则是cancel掉这个定时任务；catalogServicesWatch方法使用consul.getCatalogServices方法获取consulIndex然后更新本地的catalogServicesIndex，发布HeartbeatEvent

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