聊聊nacos的DelegateConsistencyServiceImpl

序

本文主要研究一下nacos的DelegateConsistencyServiceImpl

ConsistencyService

nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/consistency/ConsistencyService.java

public interface ConsistencyService {

    /**
     * Put a data related to a key to Nacos cluster
     *
     * @param key   key of data, this key should be globally unique
     * @param value value of data
     * @throws NacosException
     * @see
     */
    void put(String key, Record value) throws NacosException;

    /**
     * Remove a data from Nacos cluster
     *
     * @param key key of data
     * @throws NacosException
     */
    void remove(String key) throws NacosException;

    /**
     * Get a data from Nacos cluster
     *
     * @param key key of data
     * @return data related to the key
     * @throws NacosException
     */
    Datum get(String key) throws NacosException;

    /**
     * Listen for changes of a data
     *
     * @param key      key of data
     * @param listener callback of data change
     * @throws NacosException
     */
    void listen(String key, RecordListener listener) throws NacosException;

    /**
     * Cancel listening of a data
     *
     * @param key      key of data
     * @param listener callback of data change
     * @throws NacosException
     */
    void unlisten(String key, RecordListener listener) throws NacosException;

    /**
     * Tell the status of this consistency service
     *
     * @return true if available
     */
    boolean isAvailable();
}

• ConsistencyService定义了put、remove、get、listen、unlisten、isAvailable方法

DelegateConsistencyServiceImpl

nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/consistency/DelegateConsistencyServiceImpl.java

@Service("consistencyDelegate")
public class DelegateConsistencyServiceImpl implements ConsistencyService {

    @Autowired
    private PersistentConsistencyService persistentConsistencyService;

    @Autowired
    private EphemeralConsistencyService ephemeralConsistencyService;

    @Override
    public void put(String key, Record value) throws NacosException {
        mapConsistencyService(key).put(key, value);
    }

    @Override
    public void remove(String key) throws NacosException {
        mapConsistencyService(key).remove(key);
    }

    @Override
    public Datum get(String key) throws NacosException {
        return mapConsistencyService(key).get(key);
    }

    @Override
    public void listen(String key, RecordListener listener) throws NacosException {

        // this special key is listened by both:
        if (KeyBuilder.SERVICE_META_KEY_PREFIX.equals(key)) {
            persistentConsistencyService.listen(key, listener);
            ephemeralConsistencyService.listen(key, listener);
            return;
        }

        mapConsistencyService(key).listen(key, listener);
    }

    @Override
    public void unlisten(String key, RecordListener listener) throws NacosException {
        mapConsistencyService(key).unlisten(key, listener);
    }

    @Override
    public boolean isAvailable() {
        return ephemeralConsistencyService.isAvailable() && persistentConsistencyService.isAvailable();
    }

    private ConsistencyService mapConsistencyService(String key) {
        return KeyBuilder.matchEphemeralKey(key) ? ephemeralConsistencyService : persistentConsistencyService;
    }
}

• DelegateConsistencyServiceImpl实现了ConsistencyService接口；其put、remove、get、listen、unlisten方法内部都使用了mapConsistencyService来判断是使用ephemeralConsistencyService还persistentConsistencyService；其isAvailable方法要求ephemeralConsistencyService及persistentConsistencyService都是available

小结

ConsistencyService定义了put、remove、get、listen、unlisten、isAvailable方法；DelegateConsistencyServiceImpl实现了ConsistencyService接口；其put、remove、get、listen、unlisten方法内部都使用了mapConsistencyService来判断是使用ephemeralConsistencyService还persistentConsistencyService；其isAvailable方法要求ephemeralConsistencyService及persistentConsistencyService都是available

doc

• DelegateConsistencyServiceImpl