如何用dubbo源碼解析export 遠程服務

本篇文章給大家分享的是有關如何用dubbo源碼解析export 遠程服務，小編覺得挺實用的，因此分享給大家學習，希望大家閱讀完這篇文章后可以有所收獲，話不多說，跟著小編一起來看看吧。

服務注冊信息恢復com.alibaba.dubbo.registry.support.FailbackRegistry#recover

@Override    protected void recover() throws Exception {        // 獲取服務注冊的url集合        Set<URL> recoverRegistered = new HashSet<URL>(getRegistered());        if (!recoverRegistered.isEmpty()) {            if (logger.isInfoEnabled()) {                logger.info("Recover register url " + recoverRegistered);            }            for (URL url : recoverRegistered) {//                保存注冊失敗的服務注冊url                failedRegistered.add(url);            }        }        // 獲取訂閱的服務url集合        Map<URL, Set<NotifyListener>> recoverSubscribed = new HashMap<URL, Set<NotifyListener>>(getSubscribed());        if (!recoverSubscribed.isEmpty()) {            if (logger.isInfoEnabled()) {                logger.info("Recover subscribe url " + recoverSubscribed.keySet());            }            for (Map.Entry<URL, Set<NotifyListener>> entry : recoverSubscribed.entrySet()) {                URL url = entry.getKey();                for (NotifyListener listener : entry.getValue()) {//                    添加訂閱失敗的服務url                    addFailedSubscribed(url, listener);                }            }        }    }

進入這個方法com.alibaba.dubbo.registry.support.FailbackRegistry#register服務注冊

@Override    public void register(URL url) {//        添加注冊服務url=》        super.register(url);        failedRegistered.remove(url);        failedUnregistered.remove(url);        try {            // Sending a registration request to the server side 向服務器端發送注冊請求=》ZookeeperRegistry            doRegister(url);        } catch (Exception e) {            Throwable t = e;            // If the startup detection is opened, the Exception is thrown directly. 如果打開啟動檢測，則直接拋出異常            boolean check = getUrl().getParameter(Constants.CHECK_KEY, true)                    && url.getParameter(Constants.CHECK_KEY, true)                    && !Constants.CONSUMER_PROTOCOL.equals(url.getProtocol());            boolean skipFailback = t instanceof SkipFailbackWrapperException;            if (check || skipFailback) {                if (skipFailback) {                    t = t.getCause();                }                throw new IllegalStateException("Failed to register " + url + " to registry " + getUrl().getAddress() + ", cause: " + t.getMessage(), t);            } else {                logger.error("Failed to register " + url + ", waiting for retry, cause: " + t.getMessage(), t);            }            // Record a failed registration request to a failed list, retry regularly 將失敗的注冊請求記錄到失敗的列表中，定期重試            failedRegistered.add(url);        }    }

進入這個方法com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistry#doRegister進行zk服務注冊，這里的邏輯就是創建zk臨時節點

@Override    protected void doRegister(URL url) {        try {//            服務注冊，創建zk節點，如果dynamic配置的是true，創建的就是zk臨時節點=》            zkClient.create(toUrlPath(url), url.getParameter(Constants.DYNAMIC_KEY, true));        } catch (Throwable e) {            throw new RpcException("Failed to register " + url + " to zookeeper " + getUrl() + ", cause: " + e.getMessage(), e);        }    }

這里默認創建的是臨時節點，這也就是zk注冊的服務所在節點掛了之后其他客戶端節點本地的服務列表會更新的原因，不會調用到不存在的服務，當然也存在zk臨時節點刪除，通知其他訂閱這個節點的客戶端時候出現網絡抖動，zk會做處理確保一定能通知到，這種中間處理也能要業務邏輯要做處理了

/dubbo/com.alibaba.dubbo.demo.DemoService/providers/dubbo://172.28.84.147:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&bean.name=com.alibaba.dubbo.demo.DemoService&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=76579&side=provider&timestamp=1569898563184 服務注冊的zk path是這樣的

如果注冊失敗的話怎么辦呢，在創建com.alibaba.dubbo.registry.support.FailbackRegistry#FailbackRegistry對象的時候構造方法邏輯中，重試參數retry.period 默認值是每5秒鐘會做重試處理，這里也可以自定義修改

public FailbackRegistry(URL url) {        super(url);//        每5秒中會重試注冊失敗的服務信息，可以修改這個參數retry.period        this.retryPeriod = url.getParameter(Constants.REGISTRY_RETRY_PERIOD_KEY, Constants.DEFAULT_REGISTRY_RETRY_PERIOD);        this.retryFuture = retryExecutor.scheduleWithFixedDelay(new Runnable() {            @Override            public void run() {                // Check and connect to the registry                try {                    retry();                } catch (Throwable t) { // Defensive fault tolerance                    logger.error("Unexpected error occur at failed retry, cause: " + t.getMessage(), t);                }            }        }, retryPeriod, retryPeriod, TimeUnit.MILLISECONDS);    }

進入這個方法服務注冊失敗重試邏輯，com.alibaba.dubbo.registry.support.FailbackRegistry#retry

protected void retry() {        if (!failedRegistered.isEmpty()) {            Set<URL> failed = new HashSet<URL>(failedRegistered);            if (failed.size() > 0) {                if (logger.isInfoEnabled()) {                    logger.info("Retry register " + failed);                }                try {                    for (URL url : failed) {                        try {//                            zk服務注冊                            doRegister(url);                            failedRegistered.remove(url);                        } catch (Throwable t) { // Ignore all the exceptions and wait for the next retry 這里異常不做處理等待下次重試                            logger.warn("Failed to retry register " + failed + ", waiting for again, cause: " + t.getMessage(), t);                        }                    }                } catch (Throwable t) { // Ignore all the exceptions and wait for the next retry                    logger.warn("Failed to retry register " + failed + ", waiting for again, cause: " + t.getMessage(), t);                }            }        }        if (!failedUnregistered.isEmpty()) {            Set<URL> failed = new HashSet<URL>(failedUnregistered);            if (!failed.isEmpty()) {                if (logger.isInfoEnabled()) {                    logger.info("Retry unregister " + failed);                }                try {                    for (URL url : failed) {                        try {//                            取消服務注冊失敗重試                            doUnregister(url);                            failedUnregistered.remove(url);                        } catch (Throwable t) { // Ignore all the exceptions and wait for the next retry                            logger.warn("Failed to retry unregister  " + failed + ", waiting for again, cause: " + t.getMessage(), t);                        }                    }                } catch (Throwable t) { // Ignore all the exceptions and wait for the next retry                    logger.warn("Failed to retry unregister  " + failed + ", waiting for again, cause: " + t.getMessage(), t);                }            }        }        if (!failedSubscribed.isEmpty()) {            Map<URL, Set<NotifyListener>> failed = new HashMap<URL, Set<NotifyListener>>(failedSubscribed);            for (Map.Entry<URL, Set<NotifyListener>> entry : new HashMap<URL, Set<NotifyListener>>(failed).entrySet()) {                if (entry.getValue() == null || entry.getValue().size() == 0) {                    failed.remove(entry.getKey());                }            }            if (failed.size() > 0) {                if (logger.isInfoEnabled()) {                    logger.info("Retry subscribe " + failed);                }                try {                    for (Map.Entry<URL, Set<NotifyListener>> entry : failed.entrySet()) {                        URL url = entry.getKey();                        Set<NotifyListener> listeners = entry.getValue();                        for (NotifyListener listener : listeners) {                            try {//                                服務訂閱失敗的進行重新訂閱                                doSubscribe(url, listener);                                listeners.remove(listener);                            } catch (Throwable t) { // Ignore all the exceptions and wait for the next retry                                logger.warn("Failed to retry subscribe " + failed + ", waiting for again, cause: " + t.getMessage(), t);                            }                        }                    }                } catch (Throwable t) { // Ignore all the exceptions and wait for the next retry                    logger.warn("Failed to retry subscribe " + failed + ", waiting for again, cause: " + t.getMessage(), t);                }            }        }        if (!failedUnsubscribed.isEmpty()) {            Map<URL, Set<NotifyListener>> failed = new HashMap<URL, Set<NotifyListener>>(failedUnsubscribed);            for (Map.Entry<URL, Set<NotifyListener>> entry : new HashMap<URL, Set<NotifyListener>>(failed).entrySet()) {                if (entry.getValue() == null || entry.getValue().isEmpty()) {                    failed.remove(entry.getKey());                }            }            if (failed.size() > 0) {                if (logger.isInfoEnabled()) {                    logger.info("Retry unsubscribe " + failed);                }                try {                    for (Map.Entry<URL, Set<NotifyListener>> entry : failed.entrySet()) {                        URL url = entry.getKey();                        Set<NotifyListener> listeners = entry.getValue();                        for (NotifyListener listener : listeners) {                            try {//                                取消訂閱                                doUnsubscribe(url, listener);                                listeners.remove(listener);                            } catch (Throwable t) { // Ignore all the exceptions and wait for the next retry                                logger.warn("Failed to retry unsubscribe " + failed + ", waiting for again, cause: " + t.getMessage(), t);                            }                        }                    }                } catch (Throwable t) { // Ignore all the exceptions and wait for the next retry                    logger.warn("Failed to retry unsubscribe " + failed + ", waiting for again, cause: " + t.getMessage(), t);                }            }        }        if (!failedNotified.isEmpty()) {            Map<URL, Map<NotifyListener, List<URL>>> failed = new HashMap<URL, Map<NotifyListener, List<URL>>>(failedNotified);            for (Map.Entry<URL, Map<NotifyListener, List<URL>>> entry : new HashMap<URL, Map<NotifyListener, List<URL>>>(failed).entrySet()) {                if (entry.getValue() == null || entry.getValue().size() == 0) {                    failed.remove(entry.getKey());                }            }            if (failed.size() > 0) {                if (logger.isInfoEnabled()) {                    logger.info("Retry notify " + failed);                }                try {                    for (Map<NotifyListener, List<URL>> values : failed.values()) {                        for (Map.Entry<NotifyListener, List<URL>> entry : values.entrySet()) {                            try {                                NotifyListener listener = entry.getKey();                                List<URL> urls = entry.getValue();                                listener.notify(urls);                                values.remove(listener);                            } catch (Throwable t) { // Ignore all the exceptions and wait for the next retry                                logger.warn("Failed to retry notify " + failed + ", waiting for again, cause: " + t.getMessage(), t);                            }                        }                    }                } catch (Throwable t) { // Ignore all the exceptions and wait for the next retry                    logger.warn("Failed to retry notify " + failed + ", waiting for again, cause: " + t.getMessage(), t);                }            }        }    }

com.alibaba.dubbo.registry.support.FailbackRegistry#failedRegistered對服務注冊失敗的重新注冊

對服務取消注冊失敗的進行重新取消服務注冊com.alibaba.dubbo.registry.support.FailbackRegistry#failedUnregistered，進入這個方法com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistry#doUnregister，這里的操作就是刪除刪除zk臨時節點，刪除zk臨時節點后其他訂閱服務的服務節點會收到zk的監聽器重新刷新已經生成的代理invoker對象，客戶端在進行負載均衡的時候是直接路由到具體的invoker

 @Override    protected void doUnregister(URL url) {        try {            zkClient.delete(toUrlPath(url));        } catch (Throwable e) {            throw new RpcException("Failed to unregister " + url + " to zookeeper " + getUrl() + ", cause: " + e.getMessage(), e);        }    }

以上就是如何用dubbo源碼解析export 遠程服務，小編相信有部分知識點可能是我們日常工作會見到或用到的。希望你能通過這篇文章學到更多知識。更多詳情敬請關注億速云行業資訊頻道。