[bug#71802] [PATCH 0/1] Avoid guix home reconfiguration when nothing is to be done.

[bug#71802] [PATCH 0/1] Avoid guix home reconfiguration when nothing is to be done.

[Nicolas Graves via Guix-patches via]

While experimenting with profile reconfigurations almost a year ago, a
thing that happened a lot was that I reconfigured a lot while often I
didn't need to. In the event a guix system / guix home wrapper comes
to life (I've experimented for that in RDE), such a reflex to avoid
switching to new profiles that already are existing profiles is
welcome IMO.

This is not a definitive proposal but rather an illustration of an
approach which could be implemented at other places too to avoid some
unecessary calculations / reconfigurations.

Nicolas Graves (1):
  guix: home: Avoid home reconfiguration when nothing is to be done.

 guix/scripts/home.scm | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

-- 
2.45.2

[bug#71802] [PATCH] guix: home: Avoid home reconfiguration when nothing is to be done.

[Nicolas Graves via Guix-patches via]

* guix/scripts/home.scm (perform-action): In case of 'reconfigure
action, when the output profile is the current profile, avoid
reconfiguration.

Change-Id: I9d4413df05455a1ebbe10773a851a61e1c8c9e66
---
 guix/scripts/home.scm | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/guix/scripts/home.scm b/guix/scripts/home.scm
index b4c82d275f1..f0b8251c435 100644
--- a/guix/scripts/home.scm
+++ b/guix/scripts/home.scm
@@ -446,12 +446,16 @@ (define println
                      (generation (generation-file-name
                                   %guix-home (+ 1 number))))
 
-                (switch-symlinks generation he-out-path)
-                (switch-symlinks %guix-home generation)
-                (setenv "GUIX_NEW_HOME" he-out-path)
-                (primitive-load (string-append he-out-path "/activate"))
-                (setenv "GUIX_NEW_HOME" #f)
-                (return he-out-path)))
+                (if (equal? he-out-path (readlink* %guix-home))
+                    (begin (info (G_ "Nothing to be done.~%"))
+                           (return #f))
+                    (begin
+                      (switch-symlinks generation he-out-path)
+                      (switch-symlinks %guix-home generation)
+                      (setenv "GUIX_NEW_HOME" he-out-path)
+                      (primitive-load (string-append he-out-path "/activate"))
+                      (setenv "GUIX_NEW_HOME" #f)
+                      (return he-out-path)))))
              ((container)
               (mlet %store-monad ((status (spawn-home-container
                                            he
-- 
2.45.2

[bug#71802] [PATCH 0/1] Avoid guix home reconfiguration when nothing is to be done.

[Richard Sent]

Hi Nicolas,

> While experimenting with profile reconfigurations almost a year ago, a
> thing that happened a lot was that I reconfigured a lot while often I
> didn't need to. In the event a guix system / guix home wrapper comes
> to life (I've experimented for that in RDE), such a reflex to avoid
> switching to new profiles that already are existing profiles is
> welcome IMO.
>
> This is not a definitive proposal but rather an illustration of an
> approach which could be implemented at other places too to avoid some
> unecessary calculations / reconfigurations.

I can't figure out exactly how this patch could apply, but I can see it
or something similar being useful when using guix-home-service. If we
can make oneshot service attempt to register a new generation on every
invocation /and/ use a patch like to avoid redundant generations, it may
solve many of the issues raised in [1].

[1]: https://issues.guix.gnu.org/69781#5

-- 
Take it easy,
Richard Sent
Making my computer weirder one commit at a time.