main.rs

mod framework;

use actix_web::rt::Runtime;
use mongodb::Client;

fn main() {
    framework::log::init_logger();
    framework::config::init_config("app.conf");
    framework::mongo::init_mongo_client();

    log::info!("1111");
    Runtime::new().unwrap().block_on(aa());
    log::info!("1112");
    Runtime::new().unwrap().block_on(bb());
    log::info!("11113");

    log::info!("over");
}

async fn aa() {
    log::info!("aa1");
    let client = framework::mongo::get_mongo_client();
    let rs = client.list_database_names(None, None).await;
    log::info!("aa2, {:?}", rs);
}

async fn bb() {
    log::info!("bb1");
    let client = Client::with_uri_str("mongodb://localhost:27017").await;
    log::info!("bb2");

    match client {
        Ok(v) => {
            let rs = v.list_database_names(None, None).await;
            log::info!("4441 {:?}", rs);
        }
        Err(e) => {
            log::info!("4442 {:?}", e);
        }
    }
    log::info!("9999");
}

mongo.rs

use crate::framework::config;

use actix_web::rt::Runtime;

use mongodb::Client;

use once_cell::sync::OnceCell;

static INSTANCE: OnceCell<Client> = OnceCell::new();

pub fn init_mongo_client() -> &'static Client {
    INSTANCE.get_or_init(|| {
        let config = config::get_config();
        let mmongodb_uri = config.get("mondo_uri").unwrap();

        let client = Runtime::new()
            .unwrap()
            .block_on(Client::with_uri_str(&mmongodb_uri));

        log::info!("build mongodb client, uri={}", mmongodb_uri);
        // log::info!(" ### {:#?}", client);
        client.ok().unwrap()
    })
}

pub fn get_mongo_client() -> &'static Client {
    INSTANCE.get().unwrap()
}

输出

2021-05-17 16:32:46 INFO [demo3::framework::log] env_logger initialized.
2021-05-17 16:32:46 INFO [demo3::framework::mongo] build mongodb client, uri=mongodb://localhost:27017
2021-05-17 16:32:46 INFO [demo3] 1111
2021-05-17 16:32:46 INFO [demo3] aa1
2021-05-17 16:33:16 INFO [demo3] aa2, Err(Error { kind: ServerSelectionError { message: "Server selection timeout: No available servers. Topology: { Type: Unknown, Servers: [ { Address: localhost:27017, Type: Unknown }, ] }" }, labels: [] })
2021-05-17 16:33:16 INFO [demo3] 1112
2021-05-17 16:33:16 INFO [demo3] bb1
2021-05-17 16:33:16 INFO [demo3] bb2
2021-05-17 16:33:16 INFO [demo3] 4441 Ok(["admin", "config", "local", "table"])
2021-05-17 16:33:16 INFO [demo3] 999
2021-05-17 16:33:16 INFO [demo3] 11113
2021-05-17 16:33:16 INFO [demo3] over

问题：为啥用aa的方式连接mongodb成功，但是一执行操作就报超时，bb的方式就没问题？