[bug#50814] [PATCH 4/5] guix: Prepare the UI for continuable &warning exceptions.

[Attila Lendvai]

> Do we really need to close and open the connection again every time
> a continuation is made and resumed? This seems inefficient if a threading
> mechanism implemented by continuations is used (such as guile-fibers),
> and there are two threads (‘fibers’) communicating and waiting with/for
> each other in a loop, causing many ‘context switches’ (i.e., many captured
> and resumed continuations).
>
> Also note that a connection has some state: to the guix-daemon, it acts as
> a GC root for everything built with the connection, and everything added to
> the store (with add-to-store & friends) with that connection ... Simply
> reconnecting isn't sufficient.

pardon my ignorance wrt dynamic-wind and call/cc, but does that^ mean
that 1) i should simply leave the wind part of the dynamic-wind empty
and move back the open-connection call into the let... or that 2) the
entire idea of replacing the exception handler with an unwind-protect
is flawed?

if 2) then i'll try to smarten up the handler to use raise-continuable
if the exception is of type &warning.

or any better ideas?

- attila
PGP: 5D5F 45C7 DFCD 0A39