Dubbo源碼解析-Dubbo-Register-RedisRegister

1.Redis註冊中心

redis支持很多的數據結構類型，key_value模式，內存存儲數據，因此速度很快，效率很高；

dubbo利用JRedis來連接到Redis分佈式哈希鍵-值數據庫，JedisPool是一個線程安全的網絡連接池。可以用JedisPool創建一些可靠Jedis實例，可以從池中獲取Jedis實例，使用完後再把Jedis實例還回JedisPool。這種方式可以避免創建大量socket連接並且會實現高效的性能。

2.RedisRegistry

繼承FailbackRegistry,基於redis實現註冊，取消註冊，訂閱，取消訂閱，時間通知等行爲；

類基本屬性：

public class RedisRegistry extends FailbackRegistry {

    // 日誌輸出
    private static final Logger logger = LoggerFactory.getLogger(RedisRegistry.class);

    // redis默認port 6379
    private static final int DEFAULT_REDIS_PORT = 6379;

    private final static String DEFAULT_ROOT = "dubbo";

    // 過其調度器
    private final ScheduledExecutorService expireExecutor = Executors.newScheduledThreadPool(1, new NamedThreadFactory("DubboRegistryExpireTimer", true));

    // 過期執行器
    private final ScheduledFuture<?> expireFuture;

    // port
    private final String root;

    // jedisPolol ip:port集合
    private final Map<String, JedisPool> jedisPools = new ConcurrentHashMap<>();

    // 通知器 key root+service
    private final ConcurrentMap<String, Notifier> notifiers = new ConcurrentHashMap<>();

    private final int reconnectPeriod;

    private final int expirePeriod;

    private volatile boolean admin = false;

    private boolean replicate;

初始化方法:

    public RedisRegistry(URL url) {
        // 父類方法
        super(url);
        if (url.isAnyHost()) {
            throw new IllegalStateException("registry address == null");
        }
        // 全局配置加載
        GenericObjectPoolConfig config = new GenericObjectPoolConfig();
        config.setTestOnBorrow(url.getParameter("test.on.borrow", true));
        config.setTestOnReturn(url.getParameter("test.on.return", false));
        config.setTestWhileIdle(url.getParameter("test.while.idle", false));
        if (url.getParameter("max.idle", 0) > 0) {
            config.setMaxIdle(url.getParameter("max.idle", 0));
        }
        if (url.getParameter("min.idle", 0) > 0) {
            config.setMinIdle(url.getParameter("min.idle", 0));
        }
        if (url.getParameter("max.active", 0) > 0) {
            config.setMaxTotal(url.getParameter("max.active", 0));
        }
        if (url.getParameter("max.total", 0) > 0) {
            config.setMaxTotal(url.getParameter("max.total", 0));
        }
        if (url.getParameter("max.wait", url.getParameter("timeout", 0)) > 0) {
            config.setMaxWaitMillis(url.getParameter("max.wait", url.getParameter("timeout", 0)));
        }
        if (url.getParameter("num.tests.per.eviction.run", 0) > 0) {
            config.setNumTestsPerEvictionRun(url.getParameter("num.tests.per.eviction.run", 0));
        }
        if (url.getParameter("time.between.eviction.runs.millis", 0) > 0) {
            config.setTimeBetweenEvictionRunsMillis(url.getParameter("time.between.eviction.runs.millis", 0));
        }
        if (url.getParameter("min.evictable.idle.time.millis", 0) > 0) {
            config.setMinEvictableIdleTimeMillis(url.getParameter("min.evictable.idle.time.millis", 0));
        }

        String cluster = url.getParameter("cluster", "failover");
        if (!"failover".equals(cluster) && !"replicate".equals(cluster)) {
            throw new IllegalArgumentException("Unsupported redis cluster: " + cluster + ". The redis cluster only supported failover or replicate.");
        }
        replicate = "replicate".equals(cluster);
        // 地址集合
        List<String> addresses = new ArrayList<>();
        addresses.add(url.getAddress());
        // 備用地址
        String[] backups = url.getParameter(RemotingConstants.BACKUP_KEY, new String[0]);
        if (ArrayUtils.isNotEmpty(backups)) {
            addresses.addAll(Arrays.asList(backups));
        }

        // 創建JedisPool加入連接池
        for (String address : addresses) {
            int i = address.indexOf(':');
            String host;
            int port;
            if (i > 0) {
                host = address.substring(0, i);
                port = Integer.parseInt(address.substring(i + 1));
            } else {
                host = address;
                port = DEFAULT_REDIS_PORT;
            }
            // 創建jedisPools
            this.jedisPools.put(address, new JedisPool(config, host, port,
                    url.getParameter(TIMEOUT_KEY, DEFAULT_TIMEOUT), StringUtils.isEmpty(url.getPassword()) ? null : url.getPassword(),
                    url.getParameter("db.index", 0)));
        }

        // URL中獲取屬性
        this.reconnectPeriod = url.getParameter(REGISTRY_RECONNECT_PERIOD_KEY, DEFAULT_REGISTRY_RECONNECT_PERIOD);
        String group = url.getParameter(GROUP_KEY, DEFAULT_ROOT);
        if (!group.startsWith(PATH_SEPARATOR)) {
            group = PATH_SEPARATOR + group;
        }
        if (!group.endsWith(PATH_SEPARATOR)) {
            group = group + PATH_SEPARATOR;
        }
        this.root = group;
        // 過期時間
        this.expirePeriod = url.getParameter(SESSION_TIMEOUT_KEY, DEFAULT_SESSION_TIMEOUT);
        // 過期key定時刪除
        this.expireFuture = expireExecutor.scheduleWithFixedDelay(() -> {
            try {
                deferExpired(); // Extend the expiration time
            } catch (Throwable t) { // Defensive fault tolerance
                logger.error("Unexpected exception occur at defer expire time, cause: " + t.getMessage(), t);
            }
        }, expirePeriod / 2, expirePeriod / 2, TimeUnit.MILLISECONDS);
    }


deferExpired過期前置處理:

對動態管理（人工刪除的節點）進行延期；

 // 過期前置操作：獲取動態節點，重新註冊
    private void deferExpired() {
        for (Map.Entry<String, JedisPool> entry : jedisPools.entrySet()) {
            JedisPool jedisPool = entry.getValue();
            try {
                try (Jedis jedis = jedisPool.getResource()) {
                    for (URL url : new HashSet<>(getRegistered())) {
                        if (url.getParameter(DYNAMIC_KEY, true)) {
                            String key = toCategoryPath(url);
                            // 對key進行延期
                            if (jedis.hset(key, url.toFullString(), String.valueOf(System.currentTimeMillis() + expirePeriod)) == 1) {
                                // 發佈註冊事件
                                jedis.publish(key, REGISTER);
                            }
                        }
                    }
                    // 如果中心管理
                    if (admin) {
                        clean(jedis);
                    }
                    // 如果不需要複製，則退出
                    if (!replicate) {
                        break;//  If the server side has synchronized data, just write a single machine
                    }
                }
            } catch (Throwable t) {
                logger.warn("Failed to write provider heartbeat to redis registry. registry: " + entry.getKey() + ", cause: " + t.getMessage(), t);
            }
        }
    }

Clean:核心請求過期數據的邏輯

// 清理過期數據
    private void clean(Jedis jedis) {
        Set<String> keys = jedis.keys(root + ANY_VALUE);
        if (CollectionUtils.isNotEmpty(keys)) {
            for (String key : keys) {
                // 查詢key,map:key:Provider,Consumer等 value 過期時間
                Map<String, String> values = jedis.hgetAll(key);
                if (CollectionUtils.isNotEmptyMap(values)) {
                    boolean delete = false;
                    long now = System.currentTimeMillis();
                    for (Map.Entry<String, String> entry : values.entrySet()) {
                        URL url = URL.valueOf(entry.getKey());
                        if (url.getParameter(DYNAMIC_KEY, true)) {
                            long expire = Long.parseLong(entry.getValue());
                            // 如果已經過期
                            if (expire < now) {
                                // 刪除key
                                jedis.hdel(key, entry.getKey());
                                delete = true;
                                if (logger.isWarnEnabled()) {
                                    logger.warn("Delete expired key: " + key + " -> value: " + entry.getKey() + ", expire: " + new Date(expire) + ", now: " + new Date(now));
                                }
                            }
                        }
                    }
                    // 發送取消註冊時間
                    if (delete) {
                        jedis.publish(key, UNREGISTER);
                    }
                }
            }
        }
    }

public boolean isAvailable() 存活方法:

// 如果一個連接正常，表示存活   
@Override
    public boolean isAvailable() {
        for (JedisPool jedisPool : jedisPools.values()) {
            try (Jedis jedis = jedisPool.getResource()) {
                if (jedis.isConnected()) {
                    return true; // At least one single machine is available.
                }
            } catch (Throwable t) {
            }
        }
        return false;
    }

銷燬方法：

    @Override
    public void destroy() {
        super.destroy();
        try {
            expireFuture.cancel(true);
        } catch (Throwable t) {
            logger.warn(t.getMessage(), t);
        }
        try {
            for (Notifier notifier : notifiers.values()) {
                notifier.shutdown();
            }
        } catch (Throwable t) {
            logger.warn(t.getMessage(), t);
        }
        for (Map.Entry<String, JedisPool> entry : jedisPools.entrySet()) {
            JedisPool jedisPool = entry.getValue();
            try {
                jedisPool.destroy();
            } catch (Throwable t) {
                logger.warn("Failed to destroy the redis registry client. registry: " + entry.getKey() + ", cause: " + t.getMessage(), t);
            }
        }
        ExecutorUtil.gracefulShutdown(expireExecutor, expirePeriod);
    }

註冊邏輯：

 @Override
    public void doRegister(URL url) {
        // /dubbo/org.apache.dubbo.test.injvmServie/providers
        String key = toCategoryPath(url);
        // redis://redis/org.apache.dubbo.test.injvmServie?methods=test1,test2&notify=false
        String value = url.toFullString();
        String expire = String.valueOf(System.currentTimeMillis() + expirePeriod);
        boolean success = false;
        RpcException exception = null;
        for (Map.Entry<String, JedisPool> entry : jedisPools.entrySet()) {
            JedisPool jedisPool = entry.getValue();
            try {
                // 存放redis, 發佈註冊信息
                try (Jedis jedis = jedisPool.getResource()) {
                    jedis.hset(key, value, expire);
                    jedis.publish(key, REGISTER);
                    success = true;
                    if (!replicate) {
                        break; //  If the server side has synchronized data, just write a single machine
                    }
                }
            } catch (Throwable t) {
                exception = new RpcException("Failed to register service to redis registry. registry: " + entry.getKey() + ", service: " + url + ", cause: " + t.getMessage(), t);
            }
        }
        if (exception != null) {
            if (success) {
                logger.warn(exception.getMessage(), exception);
            } else {
                throw exception;
            }
        }
    }

取消註冊:

@Override
    public void doUnregister(URL url) {
        // 獲取key1, key2
        String key = toCategoryPath(url);
        String value = url.toFullString();
        RpcException exception = null;
        boolean success = false;
        for (Map.Entry<String, JedisPool> entry : jedisPools.entrySet()) {
            JedisPool jedisPool = entry.getValue();
            try {
                // 刪除redis hash 發佈取消註冊事件
                try (Jedis jedis = jedisPool.getResource()) {
                    jedis.hdel(key, value);
                    jedis.publish(key, UNREGISTER);
                    success = true;
                    if (!replicate) {
                        break; //  If the server side has synchronized data, just write a single machine
                    }
                }
            } catch (Throwable t) {
                exception = new RpcException("Failed to unregister service to redis registry. registry: " + entry.getKey() + ", service: " + url + ", cause: " + t.getMessage(), t);
            }
        }
        if (exception != null) {
            if (success) {
                logger.warn(exception.getMessage(), exception);
            } else {
                throw exception;
            }
        }
    }

@Override
    public void doSubscribe(final URL url, final NotifyListener listener) {
        // 獲取service,/dubbo/org.apache.dubbo.test.injvmServie
        String service = toServicePath(url);
        Notifier notifier = notifiers.get(service);
        if (notifier == null) {
            Notifier newNotifier = new Notifier(service);
            notifiers.putIfAbsent(service, newNotifier);
            notifier = notifiers.get(service);
            // 保證只有一個啓動
            if (notifier == newNotifier) {
                notifier.start();
            }
        }
        boolean success = false;
        RpcException exception = null;
        for (Map.Entry<String, JedisPool> entry : jedisPools.entrySet()) {
            JedisPool jedisPool = entry.getValue();
            try {
                try (Jedis jedis = jedisPool.getResource()) {
                    // 如果訂閱所有服務
                    if (service.endsWith(ANY_VALUE)) {
                        admin = true;
                        // 獲取所有匹配到了key
                        // /dubbo/org.apache.dubbo.test.injvmServie/providers
                        Set<String> keys = jedis.keys(service);
                        if (CollectionUtils.isNotEmpty(keys)) {
                            Map<String, Set<String>> serviceKeys = new HashMap<>();
                            for (String key : keys) {
                                String serviceKey = toServicePath(key);
                                Set<String> sk = serviceKeys.computeIfAbsent(serviceKey, k -> new HashSet<>());
                                sk.add(key);
                            }
                            // /dubbo/org.apache.dubbo.test.injvmServie/providers
                            for (Set<String> sk : serviceKeys.values()) {
                                doNotify(jedis, sk, url, Collections.singletonList(listener));
                            }
                        }
                    } else {
                        doNotify(jedis, jedis.keys(service + PATH_SEPARATOR + ANY_VALUE), url, Collections.singletonList(listener));
                    }
                    success = true;
                    break; // Just read one server's data
                }
            } catch (Throwable t) { // Try the next server
                exception = new RpcException("Failed to subscribe service from redis registry. registry: " + entry.getKey() + ", service: " + url + ", cause: " + t.getMessage(), t);
            }
        }
        if (exception != null) {
            if (success) {
                logger.warn(exception.getMessage(), exception);
            } else {
                throw exception;
            }
        }
    }

Notify:監聽

private void doNotify(Jedis jedis, String key) {
    // 遍歷所有的通知器，調用重載方法今天通知
    for (Map.Entry<URL, Set<NotifyListener>> entry : new HashMap<URL, Set<NotifyListener>>(getSubscribed()).entrySet()) {
        doNotify(jedis, Arrays.asList(key), entry.getKey(), new HashSet<NotifyListener>(entry.getValue()));
    }
}

private void doNotify(Jedis jedis, Collection<String> keys, URL url, Collection<NotifyListener> listeners) {
    if (keys == null || keys.isEmpty()
            || listeners == null || listeners.isEmpty()) {
        return;
    }
    long now = System.currentTimeMillis();
    List<URL> result = new ArrayList<URL>();
    // 獲得分類集合
    List<String> categories = Arrays.asList(url.getParameter(Constants.CATEGORY_KEY, new String[0]));
    // 通過url獲得服務接口
    String consumerService = url.getServiceInterface();
    // 遍歷分類路徑，例如/dubbo/com.alibaba.dubbo.demo.DemoService/providers
    for (String key : keys) {
        // 判斷服務是否匹配
        if (!Constants.ANY_VALUE.equals(consumerService)) {
            String prvoiderService = toServiceName(key);
            if (!prvoiderService.equals(consumerService)) {
                continue;
            }
        }
        // 從分類路徑上獲得分類名
        String category = toCategoryName(key);
        // 判斷訂閱的分類是否包含該分類
        if (!categories.contains(Constants.ANY_VALUE) && !categories.contains(category)) {
            continue;
        }
        List<URL> urls = new ArrayList<URL>();
        // 返回所有的URL集合
        Map<String, String> values = jedis.hgetAll(key);
        if (values != null && values.size() > 0) {
            for (Map.Entry<String, String> entry : values.entrySet()) {
                URL u = URL.valueOf(entry.getKey());
                // 判斷是否爲動態節點，因爲動態節點不受過期限制。並且判斷是否過期
                if (!u.getParameter(Constants.DYNAMIC_KEY, true)
                        || Long.parseLong(entry.getValue()) >= now) {
                    // 判斷url是否合法
                    if (UrlUtils.isMatch(url, u)) {
                        urls.add(u);
                    }
                }
            }
        }
        // 若不存在匹配的url，則創建 `empty://` 的 URL返回，用於清空該服務的該分類。
        if (urls.isEmpty()) {
            urls.add(url.setProtocol(Constants.EMPTY_PROTOCOL)
                    .setAddress(Constants.ANYHOST_VALUE)
                    .setPath(toServiceName(key))
                    .addParameter(Constants.CATEGORY_KEY, category));
        }
        result.addAll(urls);
        if (logger.isInfoEnabled()) {
            logger.info("redis notify: " + key + " = " + urls);
        }
    }
    if (result == null || result.isEmpty()) {
        return;
    }
    // 全部數據完成後，調用通知方法，來通知監聽器
    for (NotifyListener listener : listeners) {
        notify(url, listener, result);
    }
}

NotifyStub

private class NotifySub extends JedisPubSub {

        private final JedisPool jedisPool;

        public NotifySub(JedisPool jedisPool) {
            this.jedisPool = jedisPool;
        }

       // 時間通知行爲
        @Override
        public void onMessage(String key, String msg) {
            if (logger.isInfoEnabled()) {
                logger.info("redis event: " + key + " = " + msg);
            }
       // 註冊，取消註冊
            if (msg.equals(REGISTER)
                    || msg.equals(UNREGISTER)) {
                try {
                    Jedis jedis = jedisPool.getResource();
                   // 通知
                    try {
                        doNotify(jedis, key);
                    } finally {
                        jedis.close();
                    }
                } catch (Throwable t) { // TODO Notification failure does not restore mechanism guarantee
                    logger.error(t.getMessage(), t);
                }
            }
        }

        @Override
        public void onPMessage(String pattern, String key, String msg) {
           // 響應
            onMessage(key, msg);
        }

        // 自己可以擴展
        @Override
        public void onSubscribe(String key, int num) {
        }

        @Override
        public void onPSubscribe(String pattern, int num) {
        }

        @Override
        public void onUnsubscribe(String key, int num) {
        }

        @Override
        public void onPUnsubscribe(String pattern, int num) {
        }

    }

總結

Dubbo中使用Redis hashmap數據結構 key key1 value 形式，可以自己熟悉下這個結構的使用，key爲serivce,key1爲provider層等，value爲過期時間，提供給中心做過期刪除策略；

Dubbo源碼解析-Dubbo-Register-RedisRegister

1.Redis註冊中心

2.RedisRegistry

NotifyStub

總結

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https://yachay.unat.edu.pe/blog/index.php?comment_area=format_blog&comment_component=blog&comment_co

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