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spring cloud @RefreshScope 刷新机制_[fixed-10.51.11.38_8848-uat] [data-received] datai

作者：羊村懒王 | 2024-02-25 05:27:14

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[fixed-10.51.11.38_8848-uat] [data-received] dataid=orderplycloudservice-uat

在学习 nacos 的配置修改发现用到了 @RefreshScope 注解，将 spring boot 的日志调整如下

  1.  
  2. logging:
  3.   level:
  4.     com:
  5.       alibaba:
  6.         cloud: debug
  7.     org:
  8.       springframework:
  9.         context: debug
  10.         cloud: debug

调用 nacos 的配置修改，看到如下信息

  1.  
  2. 2023-03-10 15:48:15.332 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] com.alibaba.nacos.client.config.impl.ClientWorker Caller+0     at com.alibaba.nacos.client.config.impl.ClientWorker.parseUpdateDataIdResponse(ClientWorker.java:486)
  3.  - [fixed-node1.hahaou.cn_8848] [polling-resp] config changed. dataId=soft-jraft-apache-derby-config-test.yaml, group=DEFAULT_GROUP
  4. 2023-03-10 15:48:15.333 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] com.alibaba.nacos.client.config.impl.ClientWorker Caller+0     at com.alibaba.nacos.client.config.impl.ClientWorker$LongPollingRunnable.run(ClientWorker.java:598)
  5.  - get changedGroupKeys:[soft-jraft-apache-derby-config-test.yaml+DEFAULT_GROUP]
  6. 2023-03-10 15:48:15.400 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] com.alibaba.nacos.client.config.impl.ClientWorker Caller+0     at com.alibaba.nacos.client.config.impl.ClientWorker$LongPollingRunnable.run(ClientWorker.java:616)
  7.  - [fixed-node1.hahaou.cn_8848] [data-received] dataId=soft-jraft-apache-derby-config-test.yaml, group=DEFAULT_GROUP, tenant=null, md5=5f214678315ac83144e77f4c4b3b3416, content=spring:
  8.   youxia:
  9.     config:
  10.       name: test, type=
  11. 2023-03-10 15:48:15.400 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] com.alibaba.nacos.client.config.impl.CacheData Caller+0     at com.alibaba.nacos.client.config.impl.CacheData$1.run(CacheData.java:199)
  12.  - [fixed-node1.hahaou.cn_8848] [notify-context] dataId=soft-jraft-apache-derby-config-test.yaml, group=DEFAULT_GROUP, md5=5f214678315ac83144e77f4c4b3b3416
  13. 2023-03-10 15:48:15.401 DEBUG [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] o.s.cloud.endpoint.event.RefreshEventListener Caller+0     at org.springframework.cloud.endpoint.event.RefreshEventListener.handle(RefreshEventListener.java:71)
  14.  - Event received Refresh Nacos config
  15. 2023-03-10 15:48:17.002 DEBUG [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] o.s.c.a.AnnotationConfigApplicationContext Caller+0     at org.springframework.context.support.AbstractApplicationContext.prepareRefresh(AbstractApplicationContext.java:596)
  16.  - Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@653cd99a
  17. 2023-03-10 15:48:18.632 DEBUG [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] c.a.cloud.nacos.client.NacosPropertySourceBuilder Caller+0     at com.alibaba.cloud.nacos.client.NacosPropertySourceBuilder.loadNacosData(NacosPropertySourceBuilder.java:93)
  18.  - Loading nacos data, dataId: 'soft-jraft-apache-derby-config-test.yaml', group: 'DEFAULT_GROUP', data: spring:
  19.   youxia:
  20.     config:
  21.       name: test
  22. 2023-03-10 15:48:18.706 WARN [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] c.a.cloud.nacos.client.NacosPropertySourceBuilder Caller+0     at com.alibaba.cloud.nacos.client.NacosPropertySourceBuilder.loadNacosData(NacosPropertySourceBuilder.java:87)
  23.  - Ignore the empty nacos configuration and get it based on dataId[soft-jraft-apache-derby-config] & group[DEFAULT_GROUP]
  24. 2023-03-10 15:48:18.789 WARN [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] c.a.cloud.nacos.client.NacosPropertySourceBuilder Caller+0     at com.alibaba.cloud.nacos.client.NacosPropertySourceBuilder.loadNacosData(NacosPropertySourceBuilder.java:87)
  25.  - Ignore the empty nacos configuration and get it based on dataId[soft-jraft-apache-derby-config.properties] & group[DEFAULT_GROUP]
  26. 2023-03-10 15:48:18.790 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] o.s.c.b.c.PropertySourceBootstrapConfiguration Caller+0     at org.springframework.cloud.bootstrap.config.PropertySourceBootstrapConfiguration.initialize(PropertySourceBootstrapConfiguration.java:112)
  27.  - Located property source: [BootstrapPropertySource@1783236684 {name='bootstrapProperties-soft-jraft-apache-derby-config.properties,DEFAULT_GROUP', properties={}}, BootstrapPropertySource@942001677 {name='bootstrapProperties-soft-jraft-apache-derby-config,DEFAULT_GROUP', properties={}}, BootstrapPropertySource@1637255792 {name='bootstrapProperties-soft-jraft-apache-derby-config-test.yaml,DEFAULT_GROUP', properties={spring.youxia.config.name=test}}]
  28. 2023-03-10 15:48:18.800 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] org.springframework.boot.SpringApplication Caller+0     at org.springframework.boot.SpringApplication.logStartupProfileInfo(SpringApplication.java:651)
  29.  - No active profile set, falling back to default profiles: default
  30. 2023-03-10 15:48:18.801 DEBUG [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] o.s.c.a.AnnotationConfigApplicationContext Caller+0     at org.springframework.context.support.AbstractApplicationContext.prepareRefresh(AbstractApplicationContext.java:596)
  31.  - Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@6709b8b
  32. 2023-03-10 15:48:18.806 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] org.springframework.boot.SpringApplication Caller+0     at org.springframework.boot.StartupInfoLogger.logStarted(StartupInfoLogger.java:61)
  33.  - Started application in 3.403 seconds (JVM running for 54.758)
  34. 2023-03-10 15:48:18.807 DEBUG [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] o.s.c.a.AnnotationConfigApplicationContext Caller+0     at org.springframework.context.support.AbstractApplicationContext.doClose(AbstractApplicationContext.java:1006)
  35.  - Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@6709b8b, started on Fri Mar 10 15:48:18 CST 2023, parent: org.springframework.context.annotation.AnnotationConfigApplicationContext@653cd99a
  36. 2023-03-10 15:48:18.808 DEBUG [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] o.s.c.a.AnnotationConfigApplicationContext Caller+0     at org.springframework.context.support.AbstractApplicationContext.doClose(AbstractApplicationContext.java:1006)
  37.  - Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@653cd99a, started on Fri Mar 10 15:48:17 CST 2023
  38. 2023-03-10 15:48:18.819 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] o.s.cloud.endpoint.event.RefreshEventListener Caller+0     at org.springframework.cloud.endpoint.event.RefreshEventListener.handle(RefreshEventListener.java:73)
  39.  - Refresh keys changed: [spring.youxia.config.name]
  40. 2023-03-10 15:48:18.820 DEBUG [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] c.a.cloud.nacos.refresh.NacosContextRefresher Caller+0     at com.alibaba.cloud.nacos.refresh.NacosContextRefresher$1.innerReceive(NacosContextRefresher.java:136)
  41.  - Refresh Nacos config group=DEFAULT_GROUP,dataId=soft-jraft-apache-derby-config-test.yaml,configInfo=spring:
  42.   youxia:
  43.     config:
  44.       name: test
  45. 2023-03-10 15:48:18.820 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] com.alibaba.nacos.client.config.impl.CacheData Caller+0     at com.alibaba.nacos.client.config.impl.CacheData$1.run(CacheData.java:222)
  46.  - [fixed-node1.hahaou.cn_8848] [notify-ok] dataId=soft-jraft-apache-derby-config-test.yaml, group=DEFAULT_GROUP, md5=5f214678315ac83144e77f4c4b3b3416, listener=com.alibaba.cloud.nacos.refresh.NacosContextRefresher$1@59af462e 
  47. 2023-03-10 15:48:18.820 INFO [com.alibaba.nacos.client.Worker.longPolling.fixed-node1.hahaou.cn_8848] com.alibaba.nacos.client.config.impl.CacheData Caller+0     at com.alibaba.nacos.client.config.impl.CacheData.safeNotifyListener(CacheData.java:248)
  48.  - [fixed-node1.hahaou.cn_8848] [notify-listener] time cost=3420ms in ClientWorker, dataId=soft-jraft-apache-derby-config-test.yaml, group=DEFAULT_GROUP, md5=5f214678315ac83144e77f4c4b3b3416, listener=com.alibaba.cloud.nacos.refresh.NacosContextRefresher$1@59af462e 
  49. 使用Spring Cloud Alibaba接入Nacos配置中心，获取配置信息name为：test
  50. 使用Spring Cloud Alibaba接入Nacos配置中心，获取配置信息value为：null

得知保存配置后进行了 jvm 重启。

梳理过程如下

@RefreshScope

  1.  
  2. package org.springframework.cloud.context.config.annotation;
  3.  
  4. import java.lang.annotation.Documented;
  5. import java.lang.annotation.ElementType;
  6. import java.lang.annotation.Retention;
  7. import java.lang.annotation.RetentionPolicy;
  8. import java.lang.annotation.Target;
  9.  
  10. import org.springframework.context.annotation.Scope;
  11. import org.springframework.context.annotation.ScopedProxyMode;
  12.  
  13. /**
  14.  * Convenience annotation to put a <code>@Bean</code> definition in
  15.  * {@link org.springframework.cloud.context.scope.refresh.RefreshScope refresh scope}.
  16.  * Beans annotated this way can be refreshed at runtime and any components that are using
  17.  * them will get a new instance on the next method call, fully initialized and injected
  18.  * with all dependencies.
  19.  *
  20.  * @author Dave Syer
  21.  *
  22.  */
  23. @Target({ ElementType.TYPE, ElementType.METHOD })
  24. @Retention(RetentionPolicy.RUNTIME)
  25. @Scope("refresh")
  26. @Documented
  27. public @interface RefreshScope {
  28.  
  29.     /**
  30.      * @see Scope#proxyMode()
  31.      * @return proxy mode
  32.      */
  33.     ScopedProxyMode proxyMode() default ScopedProxyMode.TARGET_CLASS;
  34.  
  35. }

可以得知，@RefreshScope 是一个 scopeName 为 refresh 的 @Scope。

ScopedProxyMode

  1.  
  2. package org.springframework.context.annotation;
  3.  
  4. /**
  5.  * Enumerates the various scoped-proxy options.
  6.  *
  7.  * <p>For a more complete discussion of exactly what a scoped proxy is, see the
  8.  * section of the Spring reference documentation entitled '<em>Scoped beans as
  9.  * dependencies</em>'.
  10.  *
  11.  * @author Mark Fisher
  12.  * @since 2.5
  13.  * @see ScopeMetadata
  14.  */
  15. public enum ScopedProxyMode {
  16.  
  17.     /**
  18.      * Default typically equals {@link #NO}, unless a different default
  19.      * has been configured at the component-scan instruction level.
  20.      */
  21.     DEFAULT,
  22.  
  23.     /**
  24.      * Do not create a scoped proxy.
  25.      * <p>This proxy-mode is not typically useful when used with a
  26.      * non-singleton scoped instance, which should favor the use of the
  27.      * {@link #INTERFACES} or {@link #TARGET_CLASS} proxy-modes instead if it
  28.      * is to be used as a dependency.
  29.      */
  30.     NO,
  31.  
  32.     /**
  33.      * Create a JDK dynamic proxy implementing <i>all</i> interfaces exposed by
  34.      * the class of the target object.
  35.      */
  36.     INTERFACES,
  37.  
  38.     /**
  39.      * Create a class-based proxy (uses CGLIB).
  40.      */
  41.     TARGET_CLASS
  42.  
  43. }

由枚举 ScopedProxyMode 得知，ScopedProxyMode.TARGET_CLASS 通过 cglib 生成一个代理类进行字节码增强

RefreshAutoConfiguration

部分源码如下

  1.  
  2. package org.springframework.cloud.autoconfigure;
  3.  
  4. import java.util.HashSet;
  5. import java.util.Set;
  6.  
  7. import javax.annotation.PostConstruct;
  8.  
  9. import org.springframework.aop.scope.ScopedProxyUtils;
  10. import org.springframework.beans.BeansException;
  11. import org.springframework.beans.factory.BeanFactory;
  12. import org.springframework.beans.factory.ListableBeanFactory;
  13. import org.springframework.beans.factory.annotation.Autowired;
  14. import org.springframework.beans.factory.config.BeanDefinition;
  15. import org.springframework.beans.factory.config.BeanDefinitionHolder;
  16. import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
  17. import org.springframework.beans.factory.support.BeanDefinitionRegistry;
  18. import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;
  19. import org.springframework.boot.autoconfigure.AutoConfigureBefore;
  20. import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
  21. import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
  22. import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
  23. import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration;
  24. import org.springframework.boot.context.properties.bind.Bindable;
  25. import org.springframework.boot.context.properties.bind.Binder;
  26. import org.springframework.cloud.context.refresh.ContextRefresher;
  27. import org.springframework.cloud.context.scope.refresh.RefreshScope;
  28. import org.springframework.cloud.endpoint.event.RefreshEventListener;
  29. import org.springframework.cloud.logging.LoggingRebinder;
  30. import org.springframework.context.ConfigurableApplicationContext;
  31. import org.springframework.context.EnvironmentAware;
  32. import org.springframework.context.annotation.Bean;
  33. import org.springframework.context.annotation.Configuration;
  34. import org.springframework.context.weaving.LoadTimeWeaverAware;
  35. import org.springframework.core.env.Environment;
  36. import org.springframework.core.env.StandardEnvironment;
  37. import org.springframework.instrument.classloading.LoadTimeWeaver;
  38. import org.springframework.stereotype.Component;
  39. import org.springframework.util.StringUtils;
  40.  
  41. /**
  42.  * Autoconfiguration for the refresh scope and associated features to do with changes in
  43.  * the Environment (e.g. rebinding logger levels).
  44.  *
  45.  * @author Dave Syer
  46.  * @author Venil Noronha
  47.  */
  48. @Configuration(proxyBeanMethods = false)
  49. @ConditionalOnClass(RefreshScope.class)
  50. @ConditionalOnProperty(name = RefreshAutoConfiguration.REFRESH_SCOPE_ENABLED,
  51.         matchIfMissing = true)
  52. @AutoConfigureBefore(HibernateJpaAutoConfiguration.class)
  53. public class RefreshAutoConfiguration {
  54.  
  55.     /**
  56.      * Name of the refresh scope name.
  57.      */
  58.     public static final String REFRESH_SCOPE_NAME = "refresh";
  59.  
  60.     /**
  61.      * Name of the prefix for refresh scope.
  62.      */
  63.     public static final String REFRESH_SCOPE_PREFIX = "spring.cloud.refresh";
  64.  
  65.     /**
  66.      * Name of the enabled prefix for refresh scope.
  67.      */
  68.     public static final String REFRESH_SCOPE_ENABLED = REFRESH_SCOPE_PREFIX + ".enabled";
  69.  
  70.     @Bean
  71.     @ConditionalOnMissingBean(RefreshScope.class)
  72.     public static RefreshScope refreshScope() {
  73.         return new RefreshScope();
  74.     }
  75.  
  76.     @Bean
  77.     @ConditionalOnMissingBean
  78.     public static LoggingRebinder loggingRebinder() {
  79.         return new LoggingRebinder();
  80.     }
  81.  
  82.     @Bean
  83.     @ConditionalOnMissingBean
  84.     public ContextRefresher contextRefresher(ConfigurableApplicationContext context,
  85.             RefreshScope scope) {
  86.         return new ContextRefresher(context, scope);
  87.     }
  88.  
  89.     @Bean
  90.     public RefreshEventListener refreshEventListener(ContextRefresher contextRefresher) {
  91.         return new RefreshEventListener(contextRefresher);
  92.     }
  93.  
  94. }

  1.  
  2. @ConditionalOnProperty(name = RefreshAutoConfiguration.REFRESH_SCOPE_ENABLED,
  3.         matchIfMissing = true)

通过上面的注解得知，自动刷新在 spring cloud 中默认启用

nacos中添加配置

NacosConfigService

  1.  
  2. public NacosConfigService(Properties properties) throws NacosException {
  3.     ValidatorUtils.checkInitParam(properties);
  4.     String encodeTmp = properties.getProperty(PropertyKeyConst.ENCODE);
  5.     if (StringUtils.isBlank(encodeTmp)) {
  6.         this.encode = Constants.ENCODE;
  7.     } else {
  8.         this.encode = encodeTmp.trim();
  9.     }
  10.     initNamespace(properties);
  11.     
  12.     this.agent = new MetricsHttpAgent(new ServerHttpAgent(properties));
  13.     this.agent.start();
  14.     this.worker = new ClientWorker(this.agent, this.configFilterChainManager, properties);
  15. }

NacosConfigService 构造器创建 ClientWorker 对象

ClientWorker

  1.  
  2. public ClientWorker(final HttpAgent agent, final ConfigFilterChainManager configFilterChainManager,
  3.         final Properties properties) {
  4.     this.agent = agent;
  5.     this.configFilterChainManager = configFilterChainManager;
  6.     
  7.     // Initialize the timeout parameter
  8.     
  9.     init(properties);
  10.     
  11.     this.executor = Executors.newScheduledThreadPool(1, new ThreadFactory() {
  12.         @Override
  13.         public Thread newThread(Runnable r) {
  14.             Thread t = new Thread(r);
  15.             t.setName("com.alibaba.nacos.client.Worker." + agent.getName());
  16.             t.setDaemon(true);
  17.             return t;
  18.         }
  19.     });
  20.     
  21.     this.executorService = Executors
  22.             .newScheduledThreadPool(Runtime.getRuntime().availableProcessors(), new ThreadFactory() {
  23.                 @Override
  24.                 public Thread newThread(Runnable r) {
  25.                     Thread t = new Thread(r);
  26.                     t.setName("com.alibaba.nacos.client.Worker.longPolling." + agent.getName());
  27.                     t.setDaemon(true);
  28.                     return t;
  29.                 }
  30.             });
  31.     
  32.     this.executor.scheduleWithFixedDelay(new Runnable() {
  33.         @Override
  34.         public void run() {
  35.             try {
  36.                 checkConfigInfo();
  37.             } catch (Throwable e) {
  38.                 LOGGER.error("[" + agent.getName() + "] [sub-check] rotate check error", e);
  39.             }
  40.         }
  41.     }, 1L, 10L, TimeUnit.MILLISECONDS);
  42. }
  43.  
  44. public void checkConfigInfo() {
  45.     // Dispatch taskes.
  46.     int listenerSize = cacheMap.size();
  47.     // Round up the longingTaskCount.
  48.     int longingTaskCount = (int) Math.ceil(listenerSize / ParamUtil.getPerTaskConfigSize());
  49.     if (longingTaskCount > currentLongingTaskCount) {
  50.         for (int i = (int) currentLongingTaskCount; i < longingTaskCount; i++) {
  51.             // The task list is no order.So it maybe has issues when changing.
  52.             executorService.execute(new LongPollingRunnable(i));
  53.         }
  54.         currentLongingTaskCount = longingTaskCount;
  55.     }
  56. }
  57.  
  58. class LongPollingRunnable implements Runnable {
  59.     
  60.     private final int taskId;
  61.     
  62.     public LongPollingRunnable(int taskId) {
  63.         this.taskId = taskId;
  64.     }
  65.     
  66.     @Override
  67.     public void run() {
  68.         
  69.         List<CacheData> cacheDatas = new ArrayList<CacheData>();
  70.         List<String> inInitializingCacheList = new ArrayList<String>();
  71.         try {
  72.             // check failover config
  73.             for (CacheData cacheData : cacheMap.values()) {
  74.                 if (cacheData.getTaskId() == taskId) {
  75.                     cacheDatas.add(cacheData);
  76.                     try {
  77.                         checkLocalConfig(cacheData);
  78.                         if (cacheData.isUseLocalConfigInfo()) {
  79.                             cacheData.checkListenerMd5();
  80.                         }
  81.                     } catch (Exception e) {
  82.                         LOGGER.error("get local config info error", e);
  83.                     }
  84.                 }
  85.             }
  86.             
  87.             // check server config
  88.             List<String> changedGroupKeys = checkUpdateDataIds(cacheDatas, inInitializingCacheList);
  89.             if (!CollectionUtils.isEmpty(changedGroupKeys)) {
  90.                 LOGGER.info("get changedGroupKeys:" + changedGroupKeys);
  91.             }
  92.             
  93.             for (String groupKey : changedGroupKeys) {
  94.                 String[] key = GroupKey.parseKey(groupKey);
  95.                 String dataId = key[0];
  96.                 String group = key[1];
  97.                 String tenant = null;
  98.                 if (key.length == 3) {
  99.                     tenant = key[2];
  100.                 }
  101.                 try {
  102.                     String[] ct = getServerConfig(dataId, group, tenant, 3000L);
  103.                     CacheData cache = cacheMap.get(GroupKey.getKeyTenant(dataId, group, tenant));
  104.                     cache.setContent(ct[0]);
  105.                     if (null != ct[1]) {
  106.                         cache.setType(ct[1]);
  107.                     }
  108.                     LOGGER.info("[{}] [data-received] dataId={}, group={}, tenant={}, md5={}, content={}, type={}",
  109.                             agent.getName(), dataId, group, tenant, cache.getMd5(),
  110.                             ContentUtils.truncateContent(ct[0]), ct[1]);
  111.                 } catch (NacosException ioe) {
  112.                     String message = String
  113.                             .format("[%s] [get-update] get changed config exception. dataId=%s, group=%s, tenant=%s",
  114.                                     agent.getName(), dataId, group, tenant);
  115.                     LOGGER.error(message, ioe);
  116.                 }
  117.             }
  118.             for (CacheData cacheData : cacheDatas) {
  119.                 if (!cacheData.isInitializing() || inInitializingCacheList
  120.                         .contains(GroupKey.getKeyTenant(cacheData.dataId, cacheData.group, cacheData.tenant))) {
  121.                     cacheData.checkListenerMd5();
  122.                     cacheData.setInitializing(false);
  123.                 }
  124.             }
  125.             inInitializingCacheList.clear();
  126.             
  127.             executorService.execute(this);
  128.             
  129.         } catch (Throwable e) {
  130.             
  131.             // If the rotation training task is abnormal, the next execution time of the task will be punished
  132.             LOGGER.error("longPolling error : ", e);
  133.             executorService.schedule(this, taskPenaltyTime, TimeUnit.MILLISECONDS);
  134.         }
  135.     }
  136. }

ClientWorker checkConfigInfo() 中通过线程池创建 LongPollingRunnable 对象，线程池名称前缀为 com.alibaba.nacos.client.Worker.longPolling

CacheData

  1.  
  2. void checkListenerMd5() {
  3.     for (ManagerListenerWrap wrap : listeners) {
  4.         if (!md5.equals(wrap.lastCallMd5)) {
  5.             safeNotifyListener(dataId, group, content, type, md5, wrap);
  6.         }
  7.     }
  8. }
  9.  
  10. private void safeNotifyListener(final String dataId, final String group, final String content, final String type,
  11.         final String md5, final ManagerListenerWrap listenerWrap) {
  12.     final Listener listener = listenerWrap.listener;
  13.     
  14.     Runnable job = new Runnable() {
  15.         @Override
  16.         public void run() {
  17.             ClassLoader myClassLoader = Thread.currentThread().getContextClassLoader();
  18.             ClassLoader appClassLoader = listener.getClass().getClassLoader();
  19.             try {
  20.                 if (listener instanceof AbstractSharedListener) {
  21.                     AbstractSharedListener adapter = (AbstractSharedListener) listener;
  22.                     adapter.fillContext(dataId, group);
  23.                     LOGGER.info("[{}] [notify-context] dataId={}, group={}, md5={}", name, dataId, group, md5);
  24.                 }
  25.                 // 执行回调之前先将线程classloader设置为具体webapp的classloader，以免回调方法中调用spi接口是出现异常或错用（多应用部署才会有该问题）。
  26.                 Thread.currentThread().setContextClassLoader(appClassLoader);
  27.                 
  28.                 ConfigResponse cr = new ConfigResponse();
  29.                 cr.setDataId(dataId);
  30.                 cr.setGroup(group);
  31.                 cr.setContent(content);
  32.                 configFilterChainManager.doFilter(null, cr);
  33.                 String contentTmp = cr.getContent();
  34.                 listener.receiveConfigInfo(contentTmp);
  35.                 
  36.                 // compare lastContent and content
  37.                 if (listener instanceof AbstractConfigChangeListener) {
  38.                     Map data = ConfigChangeHandler.getInstance()
  39.                             .parseChangeData(listenerWrap.lastContent, content, type);
  40.                     ConfigChangeEvent event = new ConfigChangeEvent(data);
  41.                     ((AbstractConfigChangeListener) listener).receiveConfigChange(event);
  42.                     listenerWrap.lastContent = content;
  43.                 }
  44.                 
  45.                 listenerWrap.lastCallMd5 = md5;
  46.                 LOGGER.info("[{}] [notify-ok] dataId={}, group={}, md5={}, listener={} ", name, dataId, group, md5,
  47.                         listener);
  48.             } catch (NacosException ex) {
  49.                 LOGGER.error("[{}] [notify-error] dataId={}, group={}, md5={}, listener={} errCode={} errMsg={}",
  50.                         name, dataId, group, md5, listener, ex.getErrCode(), ex.getErrMsg());
  51.             } catch (Throwable t) {
  52.                 LOGGER.error("[{}] [notify-error] dataId={}, group={}, md5={}, listener={} tx={}", name, dataId,
  53.                         group, md5, listener, t.getCause());
  54.             } finally {
  55.                 Thread.currentThread().setContextClassLoader(myClassLoader);
  56.             }
  57.         }
  58.     };
  59.     
  60.     final long startNotify = System.currentTimeMillis();
  61.     try {
  62.         if (null != listener.getExecutor()) {
  63.             listener.getExecutor().execute(job);
  64.         } else {
  65.             job.run();
  66.         }
  67.     } catch (Throwable t) {
  68.         LOGGER.error("[{}] [notify-error] dataId={}, group={}, md5={}, listener={} throwable={}", name, dataId,
  69.                 group, md5, listener, t.getCause());
  70.     }
  71.     final long finishNotify = System.currentTimeMillis();
  72.     LOGGER.info("[{}] [notify-listener] time cost={}ms in ClientWorker, dataId={}, group={}, md5={}, listener={} ",
  73.             name, (finishNotify - startNotify), dataId, group, md5, listener);
  74. }

调用 CacheData 的 checkListenerMd5()

AbstractSharedListener

  1.  
  2. public abstract class AbstractSharedListener implements Listener {
  3.     
  4.     private volatile String dataId;
  5.     
  6.     private volatile String group;
  7.     
  8.     public final void fillContext(String dataId, String group) {
  9.         this.dataId = dataId;
  10.         this.group = group;
  11.     }
  12.     
  13.     @Override
  14.     public final void receiveConfigInfo(String configInfo) {
  15.         innerReceive(dataId, group, configInfo);
  16.     }
  17.     
  18.     @Override
  19.     public Executor getExecutor() {
  20.         return null;
  21.     }
  22.     
  23.     /**
  24.      * receive.
  25.      *
  26.      * @param dataId     data ID
  27.      * @param group      group
  28.      * @param configInfo content
  29.      */
  30.     public abstract void innerReceive(String dataId, String group, String configInfo);
  31. }

调用 AbstractSharedListener 的 receiveConfigInfo()，在 NacosContextRefresher 的 registerNacosListener() 中进行实现

NacosContextRefresher

  1.  
  2. private void registerNacosListener(final String groupKey, final String dataKey) {
  3.     String key = NacosPropertySourceRepository.getMapKey(dataKey, groupKey);
  4.     Listener listener = listenerMap.computeIfAbsent(key,
  5.             lst -> new AbstractSharedListener() {
  6.                 @Override
  7.                 public void innerReceive(String dataId, String group,
  8.                         String configInfo) {
  9.                     refreshCountIncrement();
  10.                     nacosRefreshHistory.addRefreshRecord(dataId, group, configInfo);
  11.                     // todo feature: support single refresh for listening
  12.                     applicationContext.publishEvent(
  13.                             new RefreshEvent(this, null, "Refresh Nacos config"));
  14.                     if (log.isDebugEnabled()) {
  15.                         log.debug(String.format(
  16.                                 "Refresh Nacos config group=%s,dataId=%s,configInfo=%s",
  17.                                 group, dataId, configInfo));
  18.                     }
  19.                 }
  20.             });
  21.     try {
  22.         configService.addListener(dataKey, groupKey, listener);
  23.     }
  24.     catch (NacosException e) {
  25.         log.warn(String.format(
  26.                 "register fail for nacos listener ,dataId=[%s],group=[%s]", dataKey,
  27.                 groupKey), e);
  28.     }
  29. }

最终通过 ApplicationContext 发布事件 RefreshEvent

至此，nacos 逻辑执行完毕。

RefreshEventListener

  1.  
  2. public class RefreshEventListener implements SmartApplicationListener {
  3.  
  4.     private static Log log = LogFactory.getLog(RefreshEventListener.class);
  5.  
  6.     private ContextRefresher refresh;
  7.  
  8.     private AtomicBoolean ready = new AtomicBoolean(false);
  9.  
  10.     public RefreshEventListener(ContextRefresher refresh) {
  11.         this.refresh = refresh;
  12.     }
  13.  
  14.     @Override
  15.     public boolean supportsEventType(Class<? extends ApplicationEvent> eventType) {
  16.         return ApplicationReadyEvent.class.isAssignableFrom(eventType)
  17.                 || RefreshEvent.class.isAssignableFrom(eventType);
  18.     }
  19.  
  20.     @Override
  21.     public void onApplicationEvent(ApplicationEvent event) {
  22.         if (event instanceof ApplicationReadyEvent) {
  23.             handle((ApplicationReadyEvent) event);
  24.         }
  25.         else if (event instanceof RefreshEvent) {
  26.             handle((RefreshEvent) event);
  27.         }
  28.     }
  29.  
  30.     public void handle(ApplicationReadyEvent event) {
  31.         this.ready.compareAndSet(false, true);
  32.     }
  33.  
  34.     public void handle(RefreshEvent event) {
  35.         if (this.ready.get()) { // don't handle events before app is ready
  36.             log.debug("Event received " + event.getEventDesc());
  37.             Set<String> keys = this.refresh.refresh();
  38.             log.info("Refresh keys changed: " + keys);
  39.         }
  40.     }
  41.  
  42. }

调用 RefreshEventListener 的 onApplicationEvent()，事件对象为 RefreshEvent。

执行完可以看到打印了日志

  1.  
  2. Event received Refresh Nacos config

后面调用 ContextRefresher 的 refresh()

ContextRefresher

  1.  
  2. public synchronized Set<String> refresh() {
  3.     Set<String> keys = refreshEnvironment();
  4.     this.scope.refreshAll();
  5.     return keys;
  6. }
  7.  
  8. public synchronized Set<String> refreshEnvironment() {
  9.     Map<String, Object> before = extract(
  10.             this.context.getEnvironment().getPropertySources());
  11.     addConfigFilesToEnvironment();
  12.     Set<String> keys = changes(before,
  13.             extract(this.context.getEnvironment().getPropertySources())).keySet();
  14.     this.context.publishEvent(new EnvironmentChangeEvent(this.context, keys));
  15.     return keys;
  16. }
  17.  
  18. /* For testing. */ ConfigurableApplicationContext addConfigFilesToEnvironment() {
  19.     ConfigurableApplicationContext capture = null;
  20.     try {
  21.         StandardEnvironment environment = copyEnvironment(
  22.                 this.context.getEnvironment());
  23.         SpringApplicationBuilder builder = new SpringApplicationBuilder(Empty.class)
  24.                 .bannerMode(Mode.OFF).web(WebApplicationType.NONE)
  25.                 .environment(environment);
  26.         // Just the listeners that affect the environment (e.g. excluding logging
  27.         // listener because it has side effects)
  28.         builder.application()
  29.                 .setListeners(Arrays.asList(new BootstrapApplicationListener(),
  30.                         new ConfigFileApplicationListener()));
  31.         capture = builder.run();
  32.         if (environment.getPropertySources().contains(REFRESH_ARGS_PROPERTY_SOURCE)) {
  33.             environment.getPropertySources().remove(REFRESH_ARGS_PROPERTY_SOURCE);
  34.         }
  35.         MutablePropertySources target = this.context.getEnvironment()
  36.                 .getPropertySources();
  37.         String targetName = null;
  38.         for (PropertySource<?> source : environment.getPropertySources()) {
  39.             String name = source.getName();
  40.             if (target.contains(name)) {
  41.                 targetName = name;
  42.             }
  43.             if (!this.standardSources.contains(name)) {
  44.                 if (target.contains(name)) {
  45.                     target.replace(name, source);
  46.                 }
  47.                 else {
  48.                     if (targetName != null) {
  49.                         target.addAfter(targetName, source);
  50.                         // update targetName to preserve ordering
  51.                         targetName = name;
  52.                     }
  53.                     else {
  54.                         // targetName was null so we are at the start of the list
  55.                         target.addFirst(source);
  56.                         targetName = name;
  57.                     }
  58.                 }
  59.             }
  60.         }
  61.     }
  62.     finally {
  63.         ConfigurableApplicationContext closeable = capture;
  64.         while (closeable != null) {
  65.             try {
  66.                 closeable.close();
  67.             }
  68.             catch (Exception e) {
  69.                 // Ignore;
  70.             }
  71.             if (closeable.getParent() instanceof ConfigurableApplicationContext) {
  72.                 closeable = (ConfigurableApplicationContext) closeable.getParent();
  73.             }
  74.             else {
  75.                 break;
  76.             }
  77.         }
  78.     }
  79.     return capture;
  80. }

refreshEnvironment() 中执行如下操作

addConfigFilesToEnvironment() 添加到配置文件到环境中，发布一系列事件 BootstrapApplicationListener、ConfigFileApplicationListener

调用 EventPublishingRunListener 的发布一系列事件进行 jvm 的重启相关操作，其中 EventPublishingRunListener 是默认的监听器，在 spring boot 的 META-INF/spring.factories 中进行了指定

  1.  
  2. # Run Listeners
  3. org.springframework.boot.SpringApplicationRunListener=\
  4. org.springframework.boot.context.event.EventPublishingRunListener

EventPublishingRunListener

  1.  
  2. public class EventPublishingRunListener implements SpringApplicationRunListener, Ordered {
  3.  
  4.     private final SpringApplication application;
  5.  
  6.     private final String[] args;
  7.  
  8.     private final SimpleApplicationEventMulticaster initialMulticaster;
  9.  
  10.     public EventPublishingRunListener(SpringApplication application, String[] args) {
  11.         this.application = application;
  12.         this.args = args;
  13.         this.initialMulticaster = new SimpleApplicationEventMulticaster();
  14.         for (ApplicationListener<?> listener : application.getListeners()) {
  15.             this.initialMulticaster.addApplicationListener(listener);
  16.         }
  17.     }
  18.  
  19.     @Override
  20.     public int getOrder() {
  21.         return 0;
  22.     }
  23.  
  24.     @Override
  25.     public void starting() {
  26.         this.initialMulticaster.multicastEvent(new ApplicationStartingEvent(this.application, this.args));
  27.     }
  28.  
  29.     @Override
  30.     public void environmentPrepared(ConfigurableEnvironment environment) {
  31.         this.initialMulticaster
  32.                 .multicastEvent(new ApplicationEnvironmentPreparedEvent(this.application, this.args, environment));
  33.     }
  34.  
  35.     @Override
  36.     public void contextPrepared(ConfigurableApplicationContext context) {
  37.         this.initialMulticaster
  38.                 .multicastEvent(new ApplicationContextInitializedEvent(this.application, this.args, context));
  39.     }
  40.  
  41.     @Override
  42.     public void contextLoaded(ConfigurableApplicationContext context) {
  43.         for (ApplicationListener<?> listener : this.application.getListeners()) {
  44.             if (listener instanceof ApplicationContextAware) {
  45.                 ((ApplicationContextAware) listener).setApplicationContext(context);
  46.             }
  47.             context.addApplicationListener(listener);
  48.         }
  49.         this.initialMulticaster.multicastEvent(new ApplicationPreparedEvent(this.application, this.args, context));
  50.     }
  51.  
  52.     @Override
  53.     public void started(ConfigurableApplicationContext context) {
  54.         context.publishEvent(new ApplicationStartedEvent(this.application, this.args, context));
  55.     }
  56.  
  57.     @Override
  58.     public void running(ConfigurableApplicationContext context) {
  59.         context.publishEvent(new ApplicationReadyEvent(this.application, this.args, context));
  60.     }
  61.  
  62.     @Override
  63.     public void failed(ConfigurableApplicationContext context, Throwable exception) {
  64.         ApplicationFailedEvent event = new ApplicationFailedEvent(this.application, this.args, context, exception);
  65.         if (context != null && context.isActive()) {
  66.             // Listeners have been registered to the application context so we should
  67.             // use it at this point if we can
  68.             context.publishEvent(event);
  69.         }
  70.         else {
  71.             // An inactive context may not have a multicaster so we use our multicaster to
  72.             // call all of the context's listeners instead
  73.             if (context instanceof AbstractApplicationContext) {
  74.                 for (ApplicationListener<?> listener : ((AbstractApplicationContext) context)
  75.                         .getApplicationListeners()) {
  76.                     this.initialMulticaster.addApplicationListener(listener);
  77.                 }
  78.             }
  79.             this.initialMulticaster.setErrorHandler(new LoggingErrorHandler());
  80.             this.initialMulticaster.multicastEvent(event);
  81.         }
  82.     }
  83.  
  84.     private static class LoggingErrorHandler implements ErrorHandler {
  85.  
  86.         private static final Log logger = LogFactory.getLog(EventPublishingRunListener.class);
  87.  
  88.         @Override
  89.         public void handleError(Throwable throwable) {
  90.             logger.warn("Error calling ApplicationEventListener", throwable);
  91.         }
  92.  
  93.     }
  94.  
  95. }

调用了 contextLoaded()，在 RestartListener 的 onApplicationEvent() 中进行调用

RestartListener

  1.  
  2. public class RestartListener implements SmartApplicationListener {
  3.  
  4.     private ConfigurableApplicationContext context;
  5.  
  6.     private ApplicationPreparedEvent event;
  7.  
  8.     @Override
  9.     public int getOrder() {
  10.         return 0;
  11.     }
  12.  
  13.     @Override
  14.     public boolean supportsEventType(Class<? extends ApplicationEvent> eventType) {
  15.         return ApplicationPreparedEvent.class.isAssignableFrom(eventType)
  16.                 || ContextRefreshedEvent.class.isAssignableFrom(eventType)
  17.                 || ContextClosedEvent.class.isAssignableFrom(eventType);
  18.  
  19.     }
  20.  
  21.     @Override
  22.     public boolean supportsSourceType(Class<?> sourceType) {
  23.         return true;
  24.     }
  25.  
  26.     @Override
  27.     public void onApplicationEvent(ApplicationEvent input) {
  28.         if (input instanceof ApplicationPreparedEvent) {
  29.             this.event = (ApplicationPreparedEvent) input;
  30.             if (this.context == null) {
  31.                 this.context = this.event.getApplicationContext();
  32.             }
  33.         }
  34.         else if (input instanceof ContextRefreshedEvent) {
  35.             if (this.context != null && input.getSource().equals(this.context)
  36.                     && this.event != null) {
  37.                 this.context.publishEvent(this.event);
  38.             }
  39.         }
  40.         else {
  41.             if (this.context != null && input.getSource().equals(this.context)) {
  42.                 this.context = null;
  43.                 this.event = null;
  44.             }
  45.         }
  46.     }
  47.  
  48. }

RestartListener 的 onApplicationEvent() 传入 ApplicationPreparedEvent，调用 AbstractApplicationContext 的 refresh()，即进行 ioc 容器重启，此时是第一次

调用 EventPublishingRunListener 的 running()，进行新的配置加载

调用 PropertySourceBootstrapConfiguration 的 initialize()，间接调用 NacosPropertySourceLocator 的 locate() 进行文件加载

调用 RestartListener 的 onApplicationEvent()，参数为 ApplicationPreparedEvent，调用 AbstractApplicationContext 的 refresh() 进行 ioc 容器重启，此时是第二次

调用 RestartListener 的 onApplicationEvent()，参数为 ContextRefreshedEvent

至此，ContextRefresher 的 refreshEnvironment() 逻辑执行完毕

接下来调用 RefreshScope 的 refreshAll()，间接调用父类 GenericScope 的 destroy()，发布事件 RefreshScopeRefreshedEvent 到 ApplicationContext 中

java 连接 nacos 后会定时心跳连接

通过 NacosWatch 开启 ThreadPoolTaskScheduler 进行定时任务发起，事件为 HeartbeatEvent。

总结

nacos 的在页面上的配置信息的更新是通过 jvm 重启实现的。想到了 jvm 启动后，无法做热更新，这么做也是不错的选择。由于做了重启，这个适合在没有访问的情况下执行，如果在操作过程中有事务在执行会不好，但是在生产环境中是否有这样的应用目前还不清楚。

由此可以看到，spring 中大量使用了事件，联想到了观察者模式、消息队列、消息通知、web 请求响应、窗口点击事件等。

版本变化

从 spring boot 2.4.x 开始，代码逻辑发生了变化，如下

新加了注解 @ConditionalOnBootstrapEnabled 和 @ConditionalOnBootstrapDisabled 用于自动刷新处理。

新加 LegacyContextRefresher

将 ContextRefresher 修改为抽象类，添加抽象方法 updateEnvironment()，让子类继承并重写。
addConfigFilesToEnvironment() 的相关逻辑迁移到 LegacyContextRefresher。

将 ConfigFileApplicationListener 替换为 BootstrapConfigFileApplicationListener
重写 ConfigFileApplicationListener 的 onApplicationEvent() 禁用其中的异常。

参考链接

https://blog.csdn.net/luqiang81191293/article/details/106678065

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