Using inside tokio::spawn

[mzigan]

Hello everyone!

How to avoid mistakes when using inside tokio::spawn?

use xrpl::asynch::clients::AsyncJsonRpcClient;
use xrpl::asynch::transaction::sign_and_submit;
use xrpl::asynch::wallet::generate_faucet_wallet;
use xrpl::models::transactions::account_set::AccountSet;

#[tokio::main]
async fn main() {
    tokio::spawn(async {
        let client = AsyncJsonRpcClient::connect("https://testnet.xrpl-labs.com/".parse().unwrap());
        // Create a new wallet we can use to sign the transaction
        let wallet = generate_faucet_wallet(&client, None, None, None, None)
            .await
            .unwrap();
        // Define the transaction we want to sign
        let mut account_set = AccountSet::new(
            wallet.classic_address.clone().into(),
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            Some("6578616d706c652e636f6d".into()), // example.com
            None,
            None,
            None,
            None,
            None,
            None,
        );
        println!("AccountSet transaction before signing: {:?}", account_set);
        // Sign and submit the transaction
        sign_and_submit(&mut account_set, &client, &wallet, true, true)
            .await
            .unwrap();
        println!("AccountSet transaction after signing: {:?}", account_set);
    });
}

error: implementation of `Send` is not general enough
  --> src/main.rs:8:5
   |
8  | /     tokio::spawn(async {
9  | |         let client = AsyncJsonRpcClient::connect("https://testnet.xrpl-labs.com/".parse().unwrap());
10 | |         // Create a new wallet we can use to sign the transaction
11 | |         let wallet = generate_faucet_wallet(&client, None, None, None, None)
...  |
40 | |         println!("AccountSet transaction after signing: {:?}", account_set);
41 | |     });
   | |______^ implementation of `Send` is not general enough
   |
   = note: `Send` would have to be implemented for the type `&AsyncJsonRpcClient`
   = note: ...but `Send` is actually implemented for the type `&'0 AsyncJsonRpcClient`, for some specific lifetime `'0`

error: implementation of `Send` is not general enough
  --> src/main.rs:8:5
   |
8  | /     tokio::spawn(async {
9  | |         let client = AsyncJsonRpcClient::connect("https://testnet.xrpl-labs.com/".parse().unwrap());
10 | |         // Create a new wallet we can use to sign the transaction
11 | |         let wallet = generate_faucet_wallet(&client, None, None, None, None)
...  |
40 | |         println!("AccountSet transaction after signing: {:?}", account_set);
41 | |     });
   | |______^ implementation of `Send` is not general enough
   |
   = note: `Send` would have to be implemented for the type `&std::string::String`
   = note: ...but `Send` is actually implemented for the type `&'0 std::string::String`, for some specific lifetime `'0`

error: implementation of `Send` is not general enough
  --> src/main.rs:8:5
   |
8  | /     tokio::spawn(async {
9  | |         let client = AsyncJsonRpcClient::connect("https://testnet.xrpl-labs.com/".parse().unwrap());
10 | |         // Create a new wallet we can use to sign the transaction
11 | |         let wallet = generate_faucet_wallet(&client, None, None, None, None)
...  |
40 | |         println!("AccountSet transaction after signing: {:?}", account_set);
41 | |     });
   | |______^ implementation of `Send` is not general enough
   |
   = note: `Send` would have to be implemented for the type `&str`
   = note: ...but `Send` is actually implemented for the type `&'0 str`, for some specific lifetime `'0`

error: lifetime bound not satisfied
  --> src/main.rs:8:5
   |
8  | /     tokio::spawn(async {
9  | |         let client = AsyncJsonRpcClient::connect("https://testnet.xrpl-labs.com/".parse().unwrap());
10 | |         // Create a new wallet we can use to sign the transaction
11 | |         let wallet = generate_faucet_wallet(&client, None, None, None, None)
...  |
40 | |         println!("AccountSet transaction after signing: {:?}", account_set);
41 | |     });
   | |______^
   |
   = note: this is a known limitation that will be removed in the future (see issue #100013 <https://github.com/rust-lang/rust/issues/100013> for more information)

[mzigan]

Hi! Can you please tell me how long it will take to fix the bug? Or maybe there is some workaround that allows using the library in async multithreaded mode?

[sephynox]

We are looking at ways to handle this but for now, can you keep the client on the main thread and use channels to send data back and forth to the main thread for RPC calls?