Re: Tramp timeout for currently unreachable connections?

[Visuwesh <visuweshm@gmail.com>]

[வியாழன் செப்டம்பர் 12, 2024] Robert Pluim wrote:

>>>>>> On Thu, 12 Sep 2024 16:47:39 +0200, Michael Albinus <michael.albinus@gmx.de> said:
>
>     Michael> Visuwesh <visuweshm@gmail.com> writes:
>     >> Hello all,
>
>     Michael> Hi Visuwesh,
>
>     >> I know that non-essential=t prevents Tramp from establishing new
>     >> connections but is there a way to make Tramp use a very short timeout
>     >> when trying to connect to a previously established connection that is
>     >> now unreachable?  What I mean is: if I am connected to a remote host via
>     >> a ssh connection /ssh:user@remote: and my internet connection goes down,
>     >> I do not want Tramp trying to fetch remote resources forever.
>
>     Michael> Use 'M-x tramp-cleanup-connection'. Play with user option `tramp-connection-timeout'.
>
> Idle thought: would enabling 'ServerAliveInterval' help at all here?
> (my Tramp connections travel from one side of my desk to the other, so
> I canʼt tell ☺️)

I have it set to 100 but it doesn't help much.  I don't think I am
describing my problem well.  I have the following function

    (defun vz/stb--buffer-annotation (buffer)
      (let ((case-fold-search nil))
        (pcase (buffer-name buffer)
          ((rx bos (1+ anychar) "<" (+ (not ">")) ">")
              (let ((non-essential t))
                (vz/with-when (buffer-file-name buffer)
                  (abbreviate-file-name it)))
              ;; (let ((non-essential t))
              ;;   (vz/with-when (vz/file-visiting-buffer-p buffer)
              ;;     (abbreviate-file-name it)))
              )
          ((rx bos "*" (or "shell" "ssh") (? "-"))
              (let ((non-essential t))
                (abbreviate-file-name (buffer-local-value 'default-directory buffer))))
          (_ (vz/buffer-annotation buffer)))))

that returns an annotation string for my C-x b replacement.  If Tramp
already knows the connection is dead, non-essential=t signals Tramp to
not to bother to open a new connection.  I would like a similar variable
to make Tramp give up after a few seconds if it gets no reply from the
remote server in the case of connections that are no longer reachable.