Nacos-Config模块源码讲解
前言 我们知道Nacos其实是由两个重要的模块组成，一是 Naming 模块，另一个就是今天要讲的 Config 模块。
版本说明 Nacos：2.1.1 jdk：1.8 代码分支：develope
配置中心基本原理 配置中心有三个角色分别是是配置发布者、配置服务端、配置客户端。整个流程由配置发布者发起，先发布一条配置到服务端，然后客户端监听这条配置，当配置有变动时由服务端推送到客用户端。
配置发布 我们从web层着手，可以很快的发现入口为com.alibaba.nacos.config.server.controller.ConfigController#publishConfig，这个方法看上去很长，但其实大体逻辑很简单，示意代码如下所示。
public class ConfigController { /** * Adds or updates non-aggregated data. * <p> * request and response will be used in aspect, see * {@link com.alibaba.nacos.config.server.aspect.CapacityManagementAspect} and * {@link com.alibaba.nacos.config.server.aspect.RequestLogAspect}. * </p> * @throws NacosException NacosException. */ @PostMapping @Secured(action = ActionTypes.WRITE, signType = SignType.CONFIG) public Boolean publishConfig(HttpServletRequest request, HttpServletResponse response, @RequestParam(value = "dataId") String dataId, @RequestParam(value = "group") String group, @RequestParam(value = "tenant", required = false, defaultValue = StringUtils.EMPTY) String tenant, @RequestParam(value = "content") String content, @RequestParam(value = "tag", required = false) String tag, @RequestParam(value = "appName", required = false) String appName, @RequestParam(value = "src_user", required = false) String srcUser, @RequestParam(value = "config_tags", required = false) String configTags, @RequestParam(value = "desc", required = false) String desc, @RequestParam(value = "use", required = false) String use, @RequestParam(value = "effect", required = false) String effect, @RequestParam(value = "type", required = false) String type, @RequestParam(value = "schema", required = false) String schema) throws NacosException { final String srcIp = RequestUtil.getRemoteIp(request); final String requestIpApp = RequestUtil.getAppName(request); if (StringUtils.isBlank(srcUser)) { srcUser = RequestUtil.getSrcUserName(request); } //check type if (!ConfigType.isValidType(type)) { type = ConfigType.getDefaultType().getType(); } // encrypted Pair<String, String> pair = EncryptionHandler.encryptHandler(dataId, content); content = pair.getSecond(); // check tenant ParamUtils.checkTenant(tenant); ParamUtils.checkParam(dataId, group, "datumId", content); ParamUtils.checkParam(tag); Map<String, Object> configAdvanceInfo = new HashMap<>(10); MapUtil.putIfValNoNull(configAdvanceInfo, "config_tags", configTags); MapUtil.putIfValNoNull(configAdvanceInfo, "desc", desc); MapUtil.putIfValNoNull(configAdvanceInfo, "use", use); MapUtil.putIfValNoNull(configAdvanceInfo, "effect", effect); MapUtil.putIfValNoNull(configAdvanceInfo, "type", type); MapUtil.putIfValNoNull(configAdvanceInfo, "schema", schema); ParamUtils.checkParam(configAdvanceInfo); if (AggrWhitelist.isAggrDataId(dataId)) { LOGGER.warn("[aggr-conflict] {} attempt to publish single data, {}, {}", RequestUtil.getRemoteIp(request), dataId, group); throw new NacosException(NacosException.NO_RIGHT, "dataId:" + dataId + " is aggr"); } final Timestamp time = TimeUtils.getCurrentTime(); String betaIps = request.getHeader("betaIps"); ConfigInfo configInfo = new ConfigInfo(dataId, group, tenant, appName, content); configInfo.setType(type); String encryptedDataKey = pair.getFirst(); configInfo.setEncryptedDataKey(encryptedDataKey); if (StringUtils.isBlank(betaIps)) { if (StringUtils.isBlank(tag)) { persistService.insertOrUpdate(srcIp, srcUser, configInfo, time, configAdvanceInfo, false); ConfigChangePublisher.notifyConfigChange( new ConfigDataChangeEvent(false, dataId, group, tenant, time.getTime())); } else { persistService.insertOrUpdateTag(configInfo, tag, srcIp, srcUser, time, false); ConfigChangePublisher.notifyConfigChange( new ConfigDataChangeEvent(false, dataId, group, tenant, tag, time.getTime())); } } else { // beta publish configInfo.setEncryptedDataKey(encryptedDataKey); persistService.insertOrUpdateBeta(configInfo, betaIps, srcIp, srcUser, time, false); ConfigChangePublisher.notifyConfigChange( new ConfigDataChangeEvent(true, dataId, group, tenant, time.getTime())); } ConfigTraceService.logPersistenceEvent(dataId, group, tenant, requestIpApp, time.getTime(), InetUtils.getSelfIP(), ConfigTraceService.PERSISTENCE_EVENT_PUB, content); return true; } } 整个方法就是先组装ConfigInfo，然后委托com.alibaba.nacos.config.server.service.repository.PersistService#insertOrUpdateTag进行处理，这里如果使用的是mysql那么实现类就是com.alibaba.nacos.config.server.service.repository.extrnal.ExternalStoragePersistServiceImpl，这个是一个插入数据库的动作就不细讲了，只是要注意的是这个方法包含新增和更新，当插入失败时会变成更新操作。而操作完数据库之后会发送一个ConfigDataChangeEvent事件，这个事件的处理类是com.alibaba.nacos.config.server.service.notify.AsyncNotifyService，示意代码如下所示。
