聊聊nacos的ConfigDataChangeEvent

序

本文主要研究一下nacos的ConfigDataChangeEvent

Event

nacos-1.1.3/config/src/main/java/com/alibaba/nacos/config/server/utils/event/EventDispatcher.java

    public interface Event {
    }

• Event是个空接口，仅仅用于标名事件

ConfigDataChangeEvent

nacos-1.1.3/config/src/main/java/com/alibaba/nacos/config/server/service/ConfigDataChangeEvent.java

public class ConfigDataChangeEvent implements Event {

    final public boolean isBeta;
    final public String dataId;
    final public String group;
    final public String tenant;
    final public String tag;
    final public long lastModifiedTs;

    public ConfigDataChangeEvent(String dataId, String group, long gmtModified) {
        this(false, dataId, group, gmtModified);
    }

    public ConfigDataChangeEvent(boolean isBeta, String dataId, String group, String tenant, long gmtModified) {
        if (null == dataId || null == group) {
            throw new IllegalArgumentException();
        }
        this.isBeta = isBeta;
        this.dataId = dataId;
        this.group = group;
        this.tenant = tenant;
        this.tag = null;
        this.lastModifiedTs = gmtModified;
    }

    public ConfigDataChangeEvent(boolean isBeta, String dataId, String group, long gmtModified) {
        this(isBeta, dataId, group, StringUtils.EMPTY, gmtModified);
    }

    public ConfigDataChangeEvent(boolean isBeta, String dataId, String group, String tenant, String tag,
                                 long gmtModified) {
        if (null == dataId || null == group) {
            throw new IllegalArgumentException();
        }
        this.isBeta = isBeta;
        this.dataId = dataId;
        this.group = group;
        this.tenant = tenant;
        this.tag = tag;
        this.lastModifiedTs = gmtModified;
    }

}

• ConfigDataChangeEvent实现了Event接口，它包含有isBeta、dataId、group、tenant、tag、lastModifiedTs属性

AbstractEventListener

nacos-1.1.3/config/src/main/java/com/alibaba/nacos/config/server/utils/event/EventDispatcher.java

    static public abstract class AbstractEventListener {

        public AbstractEventListener() {
            /**
             * automatic register
             */
            EventDispatcher.addEventListener(this);
        }

        /**
         * 感兴趣的事件列表
         *
         * @return event list
         */
        abstract public List<Class<? extends Event>> interest();

        /**
         * 处理事件
         *
         * @param event event
         */
        abstract public void onEvent(Event event);
    }

• AbstractEventListener接口定义了interest、onEvent两个抽象方法

AsyncNotifyService

nacos-1.1.3/config/src/main/java/com/alibaba/nacos/config/server/service/notify/AsyncNotifyService.java

@Service
public class AsyncNotifyService extends AbstractEventListener {

    @Override
    public List<Class<? extends Event>> interest() {
        List<Class<? extends Event>> types = new ArrayList<Class<? extends Event>>();
        // 触发配置变更同步通知
        types.add(ConfigDataChangeEvent.class);
        return types;
    }

    @Override
    public void onEvent(Event event) {

        // 并发产生 ConfigDataChangeEvent
        if (event instanceof ConfigDataChangeEvent) {
            ConfigDataChangeEvent evt = (ConfigDataChangeEvent) event;
            long dumpTs = evt.lastModifiedTs;
            String dataId = evt.dataId;
            String group = evt.group;
            String tenant = evt.tenant;
            String tag = evt.tag;
            List<?> ipList = serverListService.getServerList();

            // 其实这里任何类型队列都可以
            Queue<NotifySingleTask> queue = new LinkedList<NotifySingleTask>();
            for (int i = 0; i < ipList.size(); i++) {
                queue.add(new NotifySingleTask(dataId, group, tenant, tag, dumpTs, (String) ipList.get(i), evt.isBeta));
            }
            EXECUTOR.execute(new AsyncTask(httpclient, queue));
        }
    }

    @Autowired
    public AsyncNotifyService(ServerListService serverListService) {
        this.serverListService = serverListService;
        httpclient.start();
    }

    //......
}

• AsyncNotifyService继承了AbstractEventListener接口，其interest返回的列表包含了ConfigDataChangeEvent；其onEvent方法判断是ConfigDataChangeEvent，则会通过serverListService.getServerList()获取ipList，然后遍历该列表往queue添加NotifySingleTask，然后使用该queue创建AsyncTask并提交线程池执行

AsyncTask

nacos-1.1.3/config/src/main/java/com/alibaba/nacos/config/server/service/notify/AsyncNotifyService.java

    class AsyncTask implements Runnable {

        public AsyncTask(CloseableHttpAsyncClient httpclient, Queue<NotifySingleTask> queue) {
            this.httpclient = httpclient;
            this.queue = queue;
        }

        @Override
        public void run() {
            executeAsyncInvoke();
        }

        private void executeAsyncInvoke() {
            while (!queue.isEmpty()) {
                NotifySingleTask task = queue.poll();
                String targetIp = task.getTargetIP();
                if (serverListService.getServerList().contains(
                    targetIp)) {
                    // 启动健康检查且有不监控的ip则直接把放到通知队列，否则通知
                    if (serverListService.isHealthCheck()
                        && ServerListService.getServerListUnhealth().contains(targetIp)) {
                        // target ip 不健康，则放入通知列表中
                        ConfigTraceService.logNotifyEvent(task.getDataId(), task.getGroup(), task.getTenant(), null,
                            task.getLastModified(),
                            LOCAL_IP, ConfigTraceService.NOTIFY_EVENT_UNHEALTH, 0, task.target);
                        // get delay time and set fail count to the task
                        asyncTaskExecute(task);
                    } else {
                        HttpGet request = new HttpGet(task.url);
                        request.setHeader(NotifyService.NOTIFY_HEADER_LAST_MODIFIED,
                            String.valueOf(task.getLastModified()));
                        request.setHeader(NotifyService.NOTIFY_HEADER_OP_HANDLE_IP, LOCAL_IP);
                        if (task.isBeta) {
                            request.setHeader("isBeta", "true");
                        }
                        httpclient.execute(request, new AsyncNotifyCallBack(httpclient, task));
                    }
                }
            }
        }

        private Queue<NotifySingleTask> queue;
        private CloseableHttpAsyncClient httpclient;

    }

• AsyncTask实现了Runnable接口，其run方法执行executeAsyncInvoke方法；该方法会不断从queue取出NotifySingleTask，然后判断目标ip是否健康不健康则延迟再次执行该task；如果是健康的话则使用httpclient向目标地址发送get请求，然后注册AsyncNotifyCallBack

AsyncNotifyCallBack

nacos-1.1.3/config/src/main/java/com/alibaba/nacos/config/server/service/notify/AsyncNotifyService.java

    class AsyncNotifyCallBack implements FutureCallback<HttpResponse> {

        public AsyncNotifyCallBack(CloseableHttpAsyncClient httpClient, NotifySingleTask task) {
            this.task = task;
            this.httpClient = httpClient;
        }

        @Override
        public void completed(HttpResponse response) {

            long delayed = System.currentTimeMillis() - task.getLastModified();

            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                ConfigTraceService.logNotifyEvent(task.getDataId(),
                    task.getGroup(), task.getTenant(), null, task.getLastModified(),
                    LOCAL_IP,
                    ConfigTraceService.NOTIFY_EVENT_OK, delayed,
                    task.target);
            } else {
                log.error("[notify-error] target:{} dataId:{} group:{} ts:{} code:{}",
                    task.target, task.getDataId(), task.getGroup(), task.getLastModified(), response.getStatusLine().getStatusCode());
                ConfigTraceService.logNotifyEvent(task.getDataId(),
                    task.getGroup(), task.getTenant(), null, task.getLastModified(),
                    LOCAL_IP,
                    ConfigTraceService.NOTIFY_EVENT_ERROR, delayed,
                    task.target);

                //get delay time and set fail count to the task
                asyncTaskExecute(task);

                LogUtil.notifyLog.error("[notify-retry] target:{} dataId:{} group:{} ts:{}",
                    task.target, task.getDataId(), task.getGroup(), task.getLastModified());

                MetricsMonitor.getConfigNotifyException().increment();
            }
            HttpClientUtils.closeQuietly(response);
        }

        @Override
        public void failed(Exception ex) {

            long delayed = System.currentTimeMillis() - task.getLastModified();
            log.error("[notify-exception] target:{} dataId:{} group:{} ts:{} ex:{}",
                task.target, task.getDataId(), task.getGroup(), task.getLastModified(), ex.toString());
            ConfigTraceService.logNotifyEvent(task.getDataId(),
                task.getGroup(), task.getTenant(), null, task.getLastModified(),
                LOCAL_IP,
                ConfigTraceService.NOTIFY_EVENT_EXCEPTION, delayed,
                task.target);

            //get delay time and set fail count to the task
            asyncTaskExecute(task);
            LogUtil.notifyLog.error("[notify-retry] target:{} dataId:{} group:{} ts:{}",
                task.target, task.getDataId(), task.getGroup(), task.getLastModified());

            MetricsMonitor.getConfigNotifyException().increment();
        }

        @Override
        public void cancelled() {

            LogUtil.notifyLog.error("[notify-exception] target:{} dataId:{} group:{} ts:{} method:{}",
                task.target, task.getDataId(), task.getGroup(), task.getLastModified(), "CANCELED");

            //get delay time and set fail count to the task
            asyncTaskExecute(task);
            LogUtil.notifyLog.error("[notify-retry] target:{} dataId:{} group:{} ts:{}",
                task.target, task.getDataId(), task.getGroup(), task.getLastModified());

            MetricsMonitor.getConfigNotifyException().increment();
        }

        private NotifySingleTask task;
        private CloseableHttpAsyncClient httpClient;
    }

• AsyncNotifyCallBack实现了FutureCallback接口，其completed方法判断请求是否是HttpStatus.SC_OK，不是的话会再次延迟调度该任务；其failed、cancelled方法也是会再次延时调度该任务

小结

ConfigDataChangeEvent实现了Event接口，它包含有isBeta、dataId、group、tenant、tag、lastModifiedTs属性；AsyncNotifyService继承了AbstractEventListener接口，其interest返回的列表包含了ConfigDataChangeEvent；其onEvent方法判断是ConfigDataChangeEvent，则会通过serverListService.getServerList()获取ipList，然后遍历该列表往queue添加NotifySingleTask，然后使用该queue创建AsyncTask并提交线程池执行

doc

• ConfigDataChangeEvent