fn subscribe()

in registry/zookeeper/src/lib.rs [266:312]
44 lines of code
2 McCabe index (conditional complexity)

    fn subscribe(&self, url: Url, listener: RegistryNotifyListener) -> Result<(), StdError> {
        let service_name = url.get_service_name();
        let zk_path = format!("/{}/{}/{}", DUBBO_KEY, &service_name, PROVIDERS_KEY);
        if self
            .listeners
            .read()
            .unwrap()
            .get(service_name.as_str())
            .is_some()
        {
            return Ok(());
        }

        self.listeners
            .write()
            .unwrap()
            .insert(service_name.to_string(), listener.clone());

        let zk_listener =
            self.create_listener(zk_path.clone(), service_name.to_string(), listener.clone());

        let zk_changed_paths = self.zk_client.get_children_w(&zk_path, zk_listener);
        let result = match zk_changed_paths {
            Err(err) => {
                error!("zk subscribe error: {}", err);
                Vec::new()
            }
            Ok(urls) => urls
                .iter()
                .map(|node_key| {
                    let provider_url: Url = urlencoding::decode(node_key)
                        .unwrap()
                        .to_string()
                        .as_str()
                        .into();
                    provider_url
                })
                .collect(),
        };
        info!("notifying {}->{:?}", service_name, result);
        listener.notify(ServiceEvent {
            key: service_name,
            action: String::from("ADD"),
            service: result,
        });
        Ok(())
    }