Apollo自动更新配置源码分析

心已赠人 2023-05-30 09:06 10阅读 0赞

# 源码阅读—定时拉取配置 #

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### AbstractConfigRepository ###

*  提供模板方法trySync(),具体实现交由子类
 *  管理监听者集合(添加,删除)
 *  fire!!通知监听者拉取配置改变状态

protected void fireRepositoryChange(String namespace, Properties newProperties) { 
        for (RepositoryChangeListener listener : m_listeners) { 
          try { 
            listener.onRepositoryChange(namespace, newProperties);
          } catch (Throwable ex) { 
            Tracer.logError(ex);
            logger.error("Failed to invoke repository change listener {}", listener.getClass(), ex);
          }
        }
      }

### RemoteConfigRepository ###

static { 
        m_executorService = Executors.newScheduledThreadPool(1,
            ApolloThreadFactory.create("RemoteConfigRepository", true));
      }

单线程维持调用

if (!m_loadConfigRateLimiter.tryAcquire(5, TimeUnit.SECONDS)) { 
          //wait at most 5 seconds
          try { 
            TimeUnit.SECONDS.sleep(5);
          } catch (InterruptedException e) { 
          }
        }

很有意思防止快速重试设置了等待时间  
==assembleQueryConfigUrl()==组装请求的URL(根据appid,cluster,namespace)

Transaction transaction = Tracer.newTransaction("Apollo.ConfigService", "queryConfig");
            transaction.addData("Url", url);

开启事务,完成查询之后返回结果

if (previous != current) { 
            logger.debug("Remote Config refreshed!");
            m_configCache.set(current);
            this.fireRepositoryChange(m_namespace, this.getConfig());
          }
    
          if (current != null) { 
            Tracer.logEvent(String.format("Apollo.Client.Configs.%s", current.getNamespaceName()),
                current.getReleaseKey());
          }

将结果和本地的数据进行比较如果不同,出发fire!!将配置更新到所有监听者.

#### 长轮询 ####

长轮询的开启入口在构造方法,调用下面的方法进入长轮询

private void scheduleLongPollingRefresh() { 
        remoteConfigLongPollService.submit(m_namespace, this);
      }

完成长轮询之后执行通知继续新一轮的长轮询

for (RemoteConfigRepository remoteConfigRepository : toBeNotified) { 
            try { 
              remoteConfigRepository.onLongPollNotified(lastServiceDto, remoteMessages);
            } catch (Throwable ex) { 
              Tracer.logError(ex);
            }
          }

[format_png]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly93czIuc2luYWltZy5jbi9sYXJnZS8wMDZ0TmM3OWx5MWcyNHZtbnhkMHhqMzBwMTA2Zm14ZS5qcGc?x-oss-process=image/format,png