nacos中ServerStatusManager的作用是什么

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ServerStatusManager

nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/cluster/ServerStatusManager.java

@Servicepublic class ServerStatusManager {    @Resource(name = "consistencyDelegate")    private ConsistencyService consistencyService;    @Autowired    private SwitchDomain switchDomain;    private ServerStatus serverStatus = ServerStatus.STARTING;    @PostConstruct    public void init() {        GlobalExecutor.registerServerStatusUpdater(new ServerStatusUpdater());    }    private void refreshServerStatus() {        if (StringUtils.isNotBlank(switchDomain.getOverriddenServerStatus())) {            serverStatus = ServerStatus.valueOf(switchDomain.getOverriddenServerStatus());            return;        }        if (consistencyService.isAvailable()) {            serverStatus = ServerStatus.UP;        } else {            serverStatus = ServerStatus.DOWN;        }    }    public ServerStatus getServerStatus() {        return serverStatus;    }    public class ServerStatusUpdater implements Runnable {        @Override        public void run() {            refreshServerStatus();        }    }}

• ServerStatusManager的init方法注册了ServerStatusUpdater，它实现了Runnable接口，其run方法执行refreshServerStatus；refreshServerStatus会判断consistencyService是否是available，如果是更新serverStatus为ServerStatus.UP，否则为ServerStatus.DOWN

ServerStatus

nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/cluster/ServerStatus.java

public enum ServerStatus {    /**     * server is up and ready for request     */    UP,    /**     * server is out of service, something abnormal happened     */    DOWN,    /**     * server is preparing itself for request, usually 'UP' is the next status     */    STARTING,    /**     * server is manually paused     */    PAUSED,    /**     * only write operation is permitted.     */    WRITE_ONLY,    /**     * only read operation is permitted.     */    READ_ONLY}

• ServerStatus有UP、DOWN、STARTING、PAUSED、WRITE_ONLY、READ_ONLY这几种状态

TrafficReviseFilter

nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/web/TrafficReviseFilter.java

public class TrafficReviseFilter implements Filter {    @Autowired    private ServerStatusManager serverStatusManager;    @Autowired    private SwitchDomain switchDomain;    @Override    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException {        HttpServletRequest req = (HttpServletRequest) request;        HttpServletResponse resp = (HttpServletResponse) response;        // request limit if exist:        String urlString = req.getRequestURI() + "?" + req.getQueryString();        Map limitedUrlMap = switchDomain.getLimitedUrlMap();        if (limitedUrlMap != null && limitedUrlMap.size() > 0) {            for (Map.Entry entry : limitedUrlMap.entrySet()) {                String limitedUrl = entry.getKey();                if (StringUtils.startsWith(urlString, limitedUrl)) {                    resp.setStatus(entry.getValue());                    return;                }            }        }        // if server is UP:        if (serverStatusManager.getServerStatus() == ServerStatus.UP) {            filterChain.doFilter(req, resp);            return;        }        // requests from peer server should be let pass:        String agent = req.getHeader("Client-Version");        if (StringUtils.isBlank(agent)) {            agent = req.getHeader("User-Agent");        }        if (StringUtils.startsWith(agent, UtilsAndCommons.NACOS_SERVER_HEADER)) {            filterChain.doFilter(req, resp);            return;        }        // write operation should be let pass in WRITE_ONLY status:        if (serverStatusManager.getServerStatus() == ServerStatus.WRITE_ONLY && !HttpMethod.GET.equals(req.getMethod())) {            filterChain.doFilter(req, resp);            return;        }        // read operation should be let pass in READ_ONLY status:        if (serverStatusManager.getServerStatus() == ServerStatus.READ_ONLY && HttpMethod.GET.equals(req.getMethod())) {            filterChain.doFilter(req, resp);            return;        }        resp.getWriter().write("server is " + serverStatusManager.getServerStatus().name() + " now, please try again later!");        resp.setStatus(HttpServletResponse.SC_SERVICE_UNAVAILABLE);    }}

• TrafficReviseFilter会根据status及httpMethod进行读写路由，路由的不到的返回HttpServletResponse.SC_SERVICE_UNAVAILABLE

小结

ServerStatusManager的init方法注册了ServerStatusUpdater，它实现了Runnable接口，其run方法执行refreshServerStatus；refreshServerStatus会判断consistencyService是否是available，如果是更新serverStatus为ServerStatus.UP，否则为ServerStatus.DOWN

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