Server should accept a context

[Drew Wells]

If I wanted to be notified via a channel that the server has shutdown, I can't currently doing this. Accepting a context and exposing a listening context would make this possible. This way I could write the following code

client code using smux

// Session will be closed by server after 10 seconds
ctx := context.WithTimeout(context.TODO(), 10 * time.Second)
session, err := smux.Server(conn, &smux.Config{Ctx: ctx})

go func() {
  // Get a reference to the server's context, to be notified that the server is complete
  <-session.Context().Done()
  // server has shutdown

  // The convention for returning errors is to expose .Err() method
  err := session.Err()
  if err != nil {
    log.Error(session.Err())
  }
}()

Inside server code, you would create a WithCancel context. Call this cancel when the server shuts down after updating Err()'s return.
smux/server

ctx, cancel := context.WithCancel(config.Ctx)
// cancel() when the server shuts down, notifying those listening to server context
session.ctx = ctx
session.cancel = cancel

func (*s session) Close() {
  session.cancel()
}

[xtaci]

there are 2 ways to shutdown the server

1. to Close() the session manually
2. the underlying connection passively closed, then AcceptStream() will return error