04、Registry

dubbo-registry-api
dubbo-registry-consul
dubbo-registry-default  
dubbo-registry-etcd3
dubbo-registry-eureka
dubbo-registry-multicast
dubbo-registry-multiple
dubbo-registry-nacos
dubbo-registry-redis
dubbo-registry-sofa
dubbo-registry-zookeeper

看来是要向ServiceMesh发展
dubbo-registry-default
dubbo=org.apache.dubbo.registry.dubbo.DubboRegistryFactory

ListenerRegistryWrapper

@Override
    public void register(URL url) {
        try {
            registry.register(url);
        } finally {
            if (CollectionUtils.isNotEmpty(listeners)) {
                RuntimeException exception = null;
                for (RegistryServiceListener listener : listeners) {
                    if (listener != null) {
                        try {
                            listener.onRegister(url);
                        } catch (RuntimeException t) {
                            logger.error(t.getMessage(), t);
                            exception = t;
                        }
                    }
                }
                if (exception != null) {
                    throw exception;
                }
            }
        }
    }

FailbackRegistry

@Override
    public void register(URL url) {
        if (!acceptable(url)) {
            logger.info("URL " + url + " will not be registered to Registry. Registry " + url + " does not accept service of this protocol type.");
            return;
        }
        super.register(url);
        removeFailedRegistered(url);
        removeFailedUnregistered(url);
        try {
            // Sending a registration request to the server side
            doRegister(url);
        } catch (Exception e) {
            Throwable t = e;

            // If the startup detection is opened, the Exception is thrown directly.
            boolean check = getUrl().getParameter(Constants.CHECK_KEY, true)
                    && url.getParameter(Constants.CHECK_KEY, true)
                    && !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
            addFailedRegistered(url);
        }
    }

ZookeeperRegistry

@Override
    public void doRegister(URL url) {
        try {
            zkClient.create(toUrlPath(url), url.getParameter(DYNAMIC_KEY, true));
        } catch (Throwable e) {
            throw new RpcException("Failed to register " + url + " to zookeeper " + getUrl() + ", cause: " + e.getMessage(), e);
        }
    }

FailbackRegistry

zk 根据zk长连接机制 保持

public ZookeeperRegistry(URL url, ZookeeperTransporter zookeeperTransporter) {
        super(url);
        if (url.isAnyHost()) {
            throw new IllegalStateException("registry address == null");
        }
        String group = url.getParameter(GROUP_KEY, DEFAULT_ROOT);
        if (!group.startsWith(PATH_SEPARATOR)) {
            group = PATH_SEPARATOR + group;
        }
        this.root = group;
        zkClient = zookeeperTransporter.connect(url);
        zkClient.addStateListener((state) -> {
            if (state == StateListener.RECONNECTED) {
                logger.warn("Trying to fetch the latest urls, in case there're provider changes during connection loss.\n" +
                        " Since ephemeral ZNode will not get deleted for a connection lose, " +
                        "there's no need to re-register url of this instance.");
                ZookeeperRegistry.this.fetchLatestAddresses();
            } else if (state == StateListener.NEW_SESSION_CREATED) {
                logger.warn("Trying to re-register urls and re-subscribe listeners of this instance to registry...");
                try {
                    ZookeeperRegistry.this.recover();
                } catch (Exception e) {
                    logger.error(e.getMessage(), e);
                }
            } else if (state == StateListener.SESSION_LOST) {
                logger.warn("Url of this instance will be deleted from registry soon. " +
                        "Dubbo client will try to re-register once a new session is created.");
            } else if (state == StateListener.SUSPENDED) {

            } else if (state == StateListener.CONNECTED) {

            }
        });
    }

NacosRegistry

/**
     * The interval in second of lookup Nacos service names(only for Dubbo-OPS)
     */
private static final long LOOKUP_INTERVAL = Long.getLong("nacos.service.names.lookup.interval", 30);
    
private void scheduleServiceNamesLookup(final URL url, final NotifyListener listener) {
        if (scheduledExecutorService == null) {
            scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
            scheduledExecutorService.scheduleAtFixedRate(() -> {
                Set<String> serviceNames = getAllServiceNames();
                filterData(serviceNames, serviceName -> {
                    boolean accepted = false;
                    for (String category : ALL_SUPPORTED_CATEGORIES) {
                        String prefix = category + SERVICE_NAME_SEPARATOR;
                        if (serviceName != null && serviceName.startsWith(prefix)) {
                            accepted = true;
                            break;
                        }
                    }
                    return accepted;
                });
                doSubscribe(url, listener, serviceNames);
            }, LOOKUP_INTERVAL, LOOKUP_INTERVAL, TimeUnit.SECONDS);
        }
    }