nacos源码阅读--服务注册

秒速五厘米 2022-10-29 01:58 62阅读 0赞

## 一、springboot启动日志报`NacosServiceRegistry` ##

**springboot+nacos启动时，log会有一条nacos注册信息如下：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5ODk4MTkx_size_16_color_FFFFFF_t_70]  
\*\*很显然，启动注册服务的操作便在`NacosServiceRegistry`当中。

**`NacosServiceRegistry`可以通过查找所有类直接寻找，也可以从以下springboot自动装配的角度去寻找**

通过查看`spring.factories`文件也可以看到，nacos自动装配的类如下，nacos按照了springboot的约定进行了自动装配：\*\*  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5ODk4MTkx_size_16_color_FFFFFF_t_70 1]  
**进入到`NacosDiscoveryAutoConfiguration`发现，前两个Bean都是作为最后一个Bean的参数，猜想第三个bean是主要的注册方法。**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5ODk4MTkx_size_16_color_FFFFFF_t_70 2]  
\*\*\*\*点进去发现他继承了`AbstractAutoServiceRegistration.class`**，并且`AbstractAutoServiceRegistration.class`实现了ApplicationContextAware以及ApplicationListener，果然下方有一个`onApplicationEvent`的方法**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5ODk4MTkx_size_16_color_FFFFFF_t_70 3]  
**监听器中有一个bind方法，bind方法中又有一个start方法：**

public void start() { 
            if (!this.isEnabled()) { 
                if (logger.isDebugEnabled()) { 
                    logger.debug("Discovery Lifecycle disabled. Not starting");
                }
    
            } else { 
                if (!this.running.get()) { 
                    this.context.publishEvent(new InstancePreRegisteredEvent(this, this.getRegistration()));
                    this.register();
                    if (this.shouldRegisterManagement()) { 
                        this.registerManagement();
                    }
    
                    this.context.publishEvent(new InstanceRegisteredEvent(this, this.getConfiguration()));
                    this.running.compareAndSet(false, true);
                }
    
            }
        }

**其中的register便是注册方法。由此便找到了`NacosServiceRegistry.class`**

## 二、`register`剖析 ##

**register方法如下：**

public void register(Registration registration) { 
            if (StringUtils.isEmpty(registration.getServiceId())) { 
                log.warn("No service to register for nacos client...");
            } else { 
                String serviceId = registration.getServiceId();
                Instance instance = this.getNacosInstanceFromRegistration(registration);
    
                try { 
                    this.namingService.registerInstance(serviceId, instance);
                    log.info("nacos registry, {} {}:{} register finished", new Object[]{ serviceId, instance.getIp(), instance.getPort()});
                } catch (Exception var5) { 
                    log.error("nacos registry, {} register failed...{},", new Object[]{ serviceId, registration.toString(), var5});
                }
    
            }
        }

**2.1 `getServiceId`查看源码最终发现读取了配置文件的spring项目的name**  
![在这里插入图片描述][20210207184033800.png]  
**2.2 `getNacosInstanceFromRegistration`方法获取了本地客户端的一些信息，然后生成实例**

private Instance getNacosInstanceFromRegistration(Registration registration) { 
            Instance instance = new Instance();
            instance.setIp(registration.getHost());
            instance.setPort(registration.getPort());
            instance.setWeight((double)this.nacosDiscoveryProperties.getWeight());
            instance.setClusterName(this.nacosDiscoveryProperties.getClusterName());
            instance.setMetadata(registration.getMetadata());
            return instance;
        }

**那么注册的主要方法便是`this.namingService.registerInstance(serviceId, instance);`**

**2.3 `registerInstance`方法设置了注册需要的一些基础信息，其中groupname默认为`DEFAULT_GROUP`**

public void registerInstance(String serviceName, String groupName, Instance instance) throws NacosException { 
            if (instance.isEphemeral()) { 
                BeatInfo beatInfo = new BeatInfo();
                beatInfo.setServiceName(NamingUtils.getGroupedName(serviceName, groupName));
                beatInfo.setIp(instance.getIp());
                beatInfo.setPort(instance.getPort());
                beatInfo.setCluster(instance.getClusterName());
                beatInfo.setWeight(instance.getWeight());
                beatInfo.setMetadata(instance.getMetadata());
                beatInfo.setScheduled(false);
                long instanceInterval = instance.getInstanceHeartBeatInterval();
                beatInfo.setPeriod(instanceInterval == 0L ? DEFAULT_HEART_BEAT_INTERVAL : instanceInterval);
                this.beatReactor.addBeatInfo(NamingUtils.getGroupedName(serviceName, groupName), beatInfo);
            }
    
            this.serverProxy.registerService(NamingUtils.getGroupedName(serviceName, groupName), groupName, instance);
        }

**其中最后一行代码执行了注册动作，注册之前会通过`schedule`的方式添加定时心跳检测任务，默认五秒检测，而且会根据计算机可用资源核心数除以二分配检测资源（最小为1核心数），暂时不看**

**2.4 `registerService`方法进行了post请求，将本地的一些基础信息作为参数放入到请求体当中，进行post**

public void registerService(String serviceName, String groupName, Instance instance) throws NacosException { 
            LogUtils.NAMING_LOGGER.info("[REGISTER-SERVICE] {} registering service {} with instance: {}", new Object[]{ this.namespaceId, serviceName, instance});
            Map<String, String> params = new HashMap(9);
            params.put("namespaceId", this.namespaceId);
            params.put("serviceName", serviceName);
            params.put("groupName", groupName);
            params.put("clusterName", instance.getClusterName());
            params.put("ip", instance.getIp());
            params.put("port", String.valueOf(instance.getPort()));
            params.put("weight", String.valueOf(instance.getWeight()));
            params.put("enable", String.valueOf(instance.isEnabled()));
            params.put("healthy", String.valueOf(instance.isHealthy()));
            params.put("ephemeral", String.valueOf(instance.isEphemeral()));
            params.put("metadata", JSON.toJSONString(instance.getMetadata()));
            this.reqAPI(UtilAndComs.NACOS_URL_INSTANCE, params, (String)"POST");
        }

**最后通过callServer方法中的httpClient进行了http请求，请求地址为`http://127.0.0.1:8848/nacos/v1/ns/instance`**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5ODk4MTkx_size_16_color_FFFFFF_t_70 4]  
**而通过debug执行这一行代码之后，在nacos就能看到服务已经注册了上去。**

**客户端已经知道注册的流程是怎么样的了，接下来看服务端接收到http请求会有什么样的操作。**

## 三、服务端的处理 ##

**上面的http请求地址为`http://127.0.0.1:8848/nacos/v1/ns/instance`，对应的controller方法为`register`方法，位置如下：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5ODk4MTkx_size_16_color_FFFFFF_t_70 5]  
**3.1 点击去之后发现最终的实现方法为`registerInstance`**

public void registerInstance(String namespaceId, String serviceName, Instance instance) throws NacosException { 
            
            createEmptyService(namespaceId, serviceName, instance.isEphemeral());
            
            Service service = getService(namespaceId, serviceName);
            
            if (service == null) { 
                throw new NacosException(NacosException.INVALID_PARAM,
                        "service not found, namespace: " + namespaceId + ", service: " + serviceName);
            }
            
            addInstance(namespaceId, serviceName, instance.isEphemeral(), instance);
        }

**首先会去创建一个新的service，namespaceId为键，如果namespaceId不存在，则执行`createServiceIfAbsent`，服务第一次都会进行这个方法的执行，执行之后会保存在一个叫serviceMap的Map存储结构当中，相当于缓存**

public void createEmptyService(String namespaceId, String serviceName, boolean local) throws NacosException { 
        createServiceIfAbsent(namespaceId, serviceName, local, null);
    }

**3.2 接着是`addInstance`方法，这个方法会根据ip地址**

public void addInstance(String namespaceId, String serviceName, boolean ephemeral, Instance... ips)
                throws NacosException { 
            
            String key = KeyBuilder.buildInstanceListKey(namespaceId, serviceName, ephemeral);
            
            Service service = getService(namespaceId, serviceName);
            
            synchronized (service) { 
                List<Instance> instanceList = addIpAddresses(service, ephemeral, ips);
                
                Instances instances = new Instances();
                instances.setInstanceList(instanceList);
                
                consistencyService.put(key, instances);
            }
        }

**最后通过`consistencyService.put(key, instances);`做持久化，并没有持久到数据库当中。**

**`ConsistencyService`类会通过添加监听器的方式，当值进行变化时执行onchange方法来更改服务当前状态：**

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[20210207184033800.png]: /images/20221024/46b647a02b8e4de2b3349fcd431b304d.png
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