Disconnecting peers causes yamux::connection errors.

[shamil-gadelshin]

It seems that disconnecting peers using swarm.disconnect_peer_id leads to yamux errors sometimes which is not expected. I would expect errors related to connections instead or some other warnings.

I wonder whether it's a bug or normal behaviour?

2023-03-15T10:02:38.795218Z ERROR yamux::connection: a3c01b98: socket error: decode error: i/o error: unexpected end of file    
2023-03-15T10:02:38.797169Z ERROR yamux::connection: 9e4fe70c: socket error: decode error: i/o error: unexpected end of file    
2023-03-15T10:02:38.797208Z ERROR yamux::connection: 6151b6cc: socket error: decode error: i/o error: unexpected end of file    
2023-03-15T10:02:38.797254Z ERROR yamux::connection: cb968a02: socket error: decode error: i/o error: unexpected end of file    
2023-03-15T10:02:39.149592Z ERROR yamux::connection: c01ebf5e: socket error: decode error: i/o error: unexpected end of file    
2023-03-15T10:02:38.797284Z ERROR yamux::connection: 463b602e: socket error: decode error: i/o error: Broken pipe (os error 32)    
2023-03-15T10:02:39.149719Z ERROR yamux::connection: 1c3eaf30: socket error: decode error: i/o error: unexpected end of file    
2023-03-15T10:02:39.149889Z ERROR yamux::connection: b4ad7c8d: socket error: decode error: i/o error: unexpected end of file    
2023-03-15T10:02:39.149992Z ERROR yamux::connection: 7cd18774: socket error: decode error: i/o error: unexpected end of file    
2023-03-15T10:02:39.150068Z ERROR yamux::connection: 03c93599: socket error: decode error: i/o error: unexpected end of file    
2023-03-15T10:02:39.152475Z ERROR yamux::connection: 0b76ffc7: socket error: decode error: i/o error: unexpected end of file    

[thomaseizinger]

The relevant code is - I think - here:

rust-libp2p/swarm/src/connection/pool/task.rs

Line 192 in 0e46865

let error = closing_muxer.await.err().map(ConnectionError::IO);

Currently we report errors that happen during closing as part of the ConnectionClosed event. Perhaps we should not do that?

[shamil-gadelshin]

It seems this error ends up here with a debug message. Did you mean an inner code from this line?

[thomaseizinger]

Ah, I didn't realise that the messages you are pointing out are from yamux itself. Those should definitely be downgraded from an error.

yamux has undergone a big refactoring a while ago but it is not included in libp2p yet. That new version no longer has the above log line. At least I don't think so: https://github.com/libp2p/rust-yamux/blob/master/yamux/src/connection.rs

Once we upgrade to that, this log line should go away.

[shamil-gadelshin]

Great! We'll wait for the upgrade then. Thank you!

[thomaseizinger]

There are still a number of non-breaking things merging but I expect us to want to merge #3651 or something like that soon which will then be a breaking change and allow us to bundle a few things like the yamux upgrade with it.