Migration from mplex to yamux

[odesenfans]

Hello,

I just upgraded my P2P stack to Rust libp2p v0.51.3. One of the big changes in that release is the deprecation of mplex in favor of yamux, which seems to make sense. However, I am now confronted with the difficulty of upgrading the P2P network from mplex to yamux smoothly, meaning that new peers running with v0.51.3 should be able to dial up-to-date peers using yamux and outdated peers using mplex.

What would be the best way to achieve this? Is this possible at all?

[thomaseizinger]

You can use SelectUpgrade where you list yamux first, meaning it will be the preferred muxer.

We will continue to maintain libp2p-mplex but you'll have to depend on it yourself, the reexport from libp2p will be gone in the next release :)

[dariusc93]

Pretty much like @thomaseizinger said, you could use SelectUpgrade, with yamux listed first. If this stack is configurable by the end user, you could use Either to use just yamux or both muxers. Eg https://github.com/dariusc93/rust-ipfs/blob/libp2p-next/src/p2p/transport.rs#L172-L177 .

[odesenfans]

Great, I figured the mechanism was there somewhere but I couldn't find it. It seems to work! Thanks for the example @dariusc93.