三 nacos注册中心源码解析--心跳机制一客户端心跳机制处理二服务端处理心跳机制

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我是靠谱客的博主孤独奇异果，最近开发中收集的这篇文章主要介绍三 nacos注册中心源码解析--心跳机制一客户端心跳机制处理二服务端处理心跳机制，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

Nacos 默认的CAP理论的AP，只能保证最终一致性，所以需要通过心跳机制来感知服务的上下线状态

一客户端心跳机制处理

在前面我们分析服务注册的时候就发现,在客户端注册时就会触发心跳机制,源码如下:
com.alibaba.nacos.client.naming.NacosNamingService#registerInstance

@Override
public void registerInstance(String serviceName, String groupName, Instance instance) throws NacosException {
    NamingUtils.checkInstanceIsLegal(instance);
    String groupedServiceName = NamingUtils.getGroupedName(serviceName, groupName);
    // 判断是否为临时实例
    if (instance.isEphemeral()) {
    	// 构建心跳信息
        BeatInfo beatInfo = beatReactor.buildBeatInfo(groupedServiceName, instance);
        // 触发心跳发送
        beatReactor.addBeatInfo(groupedServiceName, beatInfo);
    }
    serverProxy.registerService(groupedServiceName, groupName, instance);
}

1.1 构建心跳基础信息

public BeatInfo buildBeatInfo(String groupedServiceName, Instance instance) {
    BeatInfo beatInfo = new BeatInfo();
    beatInfo.setServiceName(groupedServiceName);
    beatInfo.setIp(instance.getIp());
    beatInfo.setPort(instance.getPort());
    beatInfo.setCluster(instance.getClusterName());
    beatInfo.setWeight(instance.getWeight());
    // 元数据
    beatInfo.setMetadata(instance.getMetadata());
    beatInfo.setScheduled(false);
    // 配置心跳间隔 默认为5s发起一次心跳
    beatInfo.setPeriod(instance.getInstanceHeartBeatInterval());
    return beatInfo;
}

1.2 开启定时心跳任务

public void addBeatInfo(String serviceName, BeatInfo beatInfo) {
    NAMING_LOGGER.info("[BEAT] adding beat: {} to beat map.", beatInfo);
    String key = buildKey(serviceName, beatInfo.getIp(), beatInfo.getPort());
    BeatInfo existBeat = null;
    //fix #1733
    if ((existBeat = dom2Beat.remove(key)) != null) {
        existBeat.setStopped(true);
    }
    dom2Beat.put(key, beatInfo);
    // 开启定时心跳任务
    executorService.schedule(new BeatTask(beatInfo), beatInfo.getPeriod(), TimeUnit.MILLISECONDS);
    MetricsMonitor.getDom2BeatSizeMonitor().set(dom2Beat.size());
}

1.3 间隔五秒发送心跳信息

@Override
public void run() {
    if (beatInfo.isStopped()) {
        return;
    }
    long nextTime = beatInfo.getPeriod();
    try {
        // 向服务端发送心跳
        JsonNode result = serverProxy.sendBeat(beatInfo, BeatReactor.this.lightBeatEnabled);
        long interval = result.get("clientBeatInterval").asLong();
        boolean lightBeatEnabled = false;
        if (result.has(CommonParams.LIGHT_BEAT_ENABLED)) {
            lightBeatEnabled = result.get(CommonParams.LIGHT_BEAT_ENABLED).asBoolean();
        }
        BeatReactor.this.lightBeatEnabled = lightBeatEnabled;
        if (interval > 0) {
            nextTime = interval;
        }
        int code = NamingResponseCode.OK;
        if (result.has(CommonParams.CODE)) {
            code = result.get(CommonParams.CODE).asInt();
        }
        if (code == NamingResponseCode.RESOURCE_NOT_FOUND) {
            Instance instance = new Instance();
            instance.setPort(beatInfo.getPort());
            instance.setIp(beatInfo.getIp());
            instance.setWeight(beatInfo.getWeight());
            instance.setMetadata(beatInfo.getMetadata());
            instance.setClusterName(beatInfo.getCluster());
            instance.setServiceName(beatInfo.getServiceName());
            instance.setInstanceId(instance.getInstanceId());
            instance.setEphemeral(true);
            try {
                serverProxy.registerService(beatInfo.getServiceName(),
                        NamingUtils.getGroupName(beatInfo.getServiceName()), instance);
            } catch (Exception ignore) {
            }
        }
    } catch (NacosException ex) {
        NAMING_LOGGER.error("[CLIENT-BEAT] failed to send beat: {}, code: {}, msg: {}",
                JacksonUtils.toJson(beatInfo), ex.getErrCode(), ex.getErrMsg());
        
    }
    // 嵌套调用心跳任务(和前面的定时服务发现逻辑相类似)
    executorService.schedule(new BeatTask(beatInfo), nextTime, TimeUnit.MILLISECONDS);
}

二服务端处理心跳机制

2.1 处理客户端心跳请求,如果实例不存在会进行实例的注册

com.alibaba.nacos.naming.controllers.InstanceController#beat

@CanDistro
    @PutMapping("/beat")
    @Secured(parser = NamingResourceParser.class, action = ActionTypes.WRITE)
    public ObjectNode beat(HttpServletRequest request) throws Exception {
        
        ObjectNode result = JacksonUtils.createEmptyJsonNode();
        result.put(SwitchEntry.CLIENT_BEAT_INTERVAL, switchDomain.getClientBeatInterval());
        
        String beat = WebUtils.optional(request, "beat", StringUtils.EMPTY);
        RsInfo clientBeat = null;
        if (StringUtils.isNotBlank(beat)) {
            clientBeat = JacksonUtils.toObj(beat, RsInfo.class);
        }
        String clusterName = WebUtils
                .optional(request, CommonParams.CLUSTER_NAME, UtilsAndCommons.DEFAULT_CLUSTER_NAME);
        String ip = WebUtils.optional(request, "ip", StringUtils.EMPTY);
        int port = Integer.parseInt(WebUtils.optional(request, "port", "0"));
        if (clientBeat != null) {
            if (StringUtils.isNotBlank(clientBeat.getCluster())) {
                clusterName = clientBeat.getCluster();
            } else {
                // fix #2533
                clientBeat.setCluster(clusterName);
            }
            ip = clientBeat.getIp();
            port = clientBeat.getPort();
        }
        String namespaceId = WebUtils.optional(request, CommonParams.NAMESPACE_ID, Constants.DEFAULT_NAMESPACE_ID);
        String serviceName = WebUtils.required(request, CommonParams.SERVICE_NAME);
        NamingUtils.checkServiceNameFormat(serviceName);
        Loggers.SRV_LOG.debug("[CLIENT-BEAT] full arguments: beat: {}, serviceName: {}", clientBeat, serviceName);
        // 获取实例
        Instance instance = serviceManager.getInstance(namespaceId, serviceName, clusterName, ip, port);
        // 如果实例不存在会进行注册
        if (instance == null) {
            if (clientBeat == null) {
                result.put(CommonParams.CODE, NamingResponseCode.RESOURCE_NOT_FOUND);
                return result;
            }
            
            Loggers.SRV_LOG.warn("[CLIENT-BEAT] The instance has been removed for health mechanism, "
                    + "perform data compensation operations, beat: {}, serviceName: {}", clientBeat, serviceName);
            
            instance = new Instance();
            instance.setPort(clientBeat.getPort());
            instance.setIp(clientBeat.getIp());
            instance.setWeight(clientBeat.getWeight());
            instance.setMetadata(clientBeat.getMetadata());
            instance.setClusterName(clusterName);
            instance.setServiceName(serviceName);
            instance.setInstanceId(instance.getInstanceId());
            instance.setEphemeral(clientBeat.isEphemeral());
            
            serviceManager.registerInstance(namespaceId, serviceName, instance);
        }
        
        Service service = serviceManager.getService(namespaceId, serviceName);
        
        if (service == null) {
            throw new NacosException(NacosException.SERVER_ERROR,
                    "service not found: " + serviceName + "@" + namespaceId);
        }
        if (clientBeat == null) {
            clientBeat = new RsInfo();
            clientBeat.setIp(ip);
            clientBeat.setPort(port);
            clientBeat.setCluster(clusterName);
        }
        // 处理客户端心跳请求
        service.processClientBeat(clientBeat);
        
        result.put(CommonParams.CODE, NamingResponseCode.OK);
        if (instance.containsMetadata(PreservedMetadataKeys.HEART_BEAT_INTERVAL)) {
            result.put(SwitchEntry.CLIENT_BEAT_INTERVAL, instance.getInstanceHeartBeatInterval());
        }
        result.put(SwitchEntry.LIGHT_BEAT_ENABLED, switchDomain.isLightBeatEnabled());
        return result;
    }

2.2 开启一个定时任务,更新实例的最后心跳时间

com.alibaba.nacos.naming.core.Service#processClientBeat

 public void processClientBeat(final RsInfo rsInfo) {
        ClientBeatProcessor clientBeatProcessor = new ClientBeatProcessor();
        clientBeatProcessor.setService(this);
        clientBeatProcessor.setRsInfo(rsInfo);
        HealthCheckReactor.scheduleNow(clientBeatProcessor);
    }

com.alibaba.nacos.naming.healthcheck.ClientBeatProcessor#run

@Override
    public void run() {
        Service service = this.service;
        if (Loggers.EVT_LOG.isDebugEnabled()) {
            Loggers.EVT_LOG.debug("[CLIENT-BEAT] processing beat: {}", rsInfo.toString());
        }
        
        String ip = rsInfo.getIp();
        String clusterName = rsInfo.getCluster();
        int port = rsInfo.getPort();
        // 获取集群
        Cluster cluster = service.getClusterMap().get(clusterName);
        // 获取集群下全部实例
        List<Instance> instances = cluster.allIPs(true);
        
        for (Instance instance : instances) {
            if (instance.getIp().equals(ip) && instance.getPort() == port) {
                if (Loggers.EVT_LOG.isDebugEnabled()) {
                    Loggers.EVT_LOG.debug("[CLIENT-BEAT] refresh beat: {}", rsInfo.toString());
                }
                // 更新最后心跳时间
                instance.setLastBeat(System.currentTimeMillis());
                if (!instance.isMarked()) {
                    if (!instance.isHealthy()) {
                        instance.setHealthy(true);
                        Loggers.EVT_LOG
                                .info("service: {} {POS} {IP-ENABLED} valid: {}:{}@{}, region: {}, msg: client beat ok",
                                        cluster.getService().getName(), ip, port, cluster.getName(),
                                        UtilsAndCommons.LOCALHOST_SITE);
                        // 发布服务变动事件
                        getPushService().serviceChanged(service);
                    }
                }
            }
        }
    }