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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

doc

• ConsulCatalogWatch