Middleware::pending_transaction hangs or panics

[vakond]

Version
873cf09
ethers = { git = "https://github.com/gakonst/ethers-rs", features = ["full"] }

Platform
5.4.0-58-generic #64-Ubuntu SMP Wed Dec 9 08:16:25 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

Description
Call of pending_transaction(tx_hash) after send_transaction(tx) hangs or panics.

I tried this code:

let tx_hash = client.send_transaction(tx, None).await?;
let receipt = client.pending_transaction(tx_hash).await?;
dbg!(receipt);

I expected to see the contents of the receipt.

Instead, the program hangs or panics with following message:
thread 'tokio-runtime-worker' panicked at 'WS Server panic: NoResponse'

I've prepared two mininal projects to reproduce this behaviour (please see corresponding README files):
https://github.com/vakond/ethers-ganache-pending
https://github.com/vakond/ethers-geth-pending
The bug (if it's a bug) can also be observed with the Kovan testnet.

It seems only one variant panics: Ganache+Ws. Ganache+Http just hangs. Other variants: {Geth, Kovan}+{Ws, Http} all hang.

[gakonst]

@vakond thank you for the detailed bug report. Wish everyone did it this way. I opened #103 as a fix. I've verified it fixes the issue in ganache with both Http and Ws, could you confirm if it fixes it with Geth/Kovan? You can try it by importing as ethers = { git = "https://github.com/gakonst/ethers-rs", branch = "fix/pending-tx-hang", features = ["full"] }

[vakond]

@gakonst thank you for your excellent library. I gladly confirm the Ganache test has passed with the fix branch. But unfortunately the Geth test still hangs, as well as Kovan. In case you want to try Kovan first, I'm attaching the main.rs template file here (Cargo.toml the same as in ganache-pending).
kovan-main-rs.zip

[gakonst]

@vakond OK should be fixed now in #104. It's merged to master now. I've tested on Kovan & Rinkeby via Infura with both HTTP and WS and it seems to work. Thank you for surfacing this, I should've been more diligent with my testing. In case you want to share more about what you're working, feel free to join t.me/ethers_rs!