change OpenStream to accept a context

[marten-seemann]

Depends on libp2p/go-libp2p-core#172.

[willscott]

should there be an issue for shutting down the stream when the context expires as a follow-on to this?

[Stebalien]

should there be an issue for shutting down the stream when the context expires as a follow-on to this?

The context is just for opening the stream. This is actually how contexts are supposed to be used, we just tend to abuse them.

[willscott]

should there be an issue for shutting down the stream when the context expires as a follow-on to this?

The context is just for opening the stream. This is actually how contexts are supposed to be used, we just tend to abuse them.

Am i correct in reading it that OpenStream does block on a network send of a window update indicating the new stream exists:
https://github.com/libp2p/go-yamux/blob/master/session.go#L201

If so, do we need to thread context down to the sending loop to be able to fail out of that blocking?

[marten-seemann]

@willscott is right here in that we should not ignore the context entirely, as this PR (which just intends to satisfy the new interface) does. @Stebalien is right that the context should only apply to opening the stream, i.e. it applies only for the duration of OpenStream, everything that happens after OpenStream has returned doesn't matter.

I opened #30 to track this.

[raulk]

The context deadline might need to percolate down to the actual network write over the transport, potentially through SetDeadline...