guix gc: Adjust size suffix based on the amount of data.

* guix/ui.scm (number->size): New procedure.
* guix/scripts/gc.scm (guix-gc)[actions]: Display the amount of
collected-garbage using more specific units.
[ensure-free-space]: Display the size using an appropriate size unit.
* nix/libstore/gc.cc (deletePathRecursive, removeUnusedLinks): Same.
* nix/libstore/optimise-store.cc (showBytes): Move function ...
* nix/libstore/misc.cc: ... to here.  Expand to adjust the output based
on the amount of bytes received.

Change-Id: Idceb1a13f8e45f959d327f53d1a8accb29d2678b

2 files changed, 35 insertions, 5 deletions

diff --git a/guix/scripts/gc.scm b/guix/scripts/gc.scm
index 58af827617..7663efe7f8 100644
--- a/guix/scripts/gc.scm
+++ b/guix/scripts/gc.scm
@@ -261,10 +261,10 @@ is deprecated; use '-D'~%"))
     ;; Attempt to have at least SPACE bytes available in STORE.
     (let ((free (free-disk-space (%store-prefix))))
       (if (> free space)
-          (info (G_ "already ~,2h MiBs available on ~a, nothing to do~%")
-                (/ free 1024. 1024.) (%store-prefix))
+          (info (G_ "already ~a available on ~a, nothing to do~%")
+                (number->size free) (%store-prefix))
           (let ((to-free (- space free)))
-            (info (G_ "freeing ~,2h MiBs~%") (/ to-free 1024. 1024.))
+            (info (G_ "freeing ~a~%") (number->size to-free))
             (collect-garbage store to-free)))))
 
   (define (delete-generations store pattern)
@@ -328,10 +328,10 @@ is deprecated; use '-D'~%"))
              (ensure-free-space store free-space))
             (min-freed
              (let-values (((paths freed) (collect-garbage store min-freed)))
-              (info (G_ "freed ~,2h MiBs~%") (/ freed 1024. 1024.))))
+              (info (G_ "freed ~a~%") (number->size freed))))
             (else
              (let-values (((paths freed) (collect-garbage store)))
-              (info (G_ "freed ~,2h MiBs~%") (/ freed 1024. 1024.)))))))
+              (info (G_ "freed ~a~%") (number->size freed)))))))
         ((list-roots)
          (assert-no-extra-arguments)
          (list-roots))
diff --git a/guix/ui.scm b/guix/ui.scm
index cd9eb1013d..d6d5eb9dcd 100644
--- a/guix/ui.scm
+++ b/guix/ui.scm
@@ -19,6 +19,7 @@
 ;;; Copyright © 2018 Steve Sprang <scs@stevesprang.com>
 ;;; Copyright © 2022 Taiju HIGASHI <higashi@taiju.info>
 ;;; Copyright © 2022 Liliana Marie Prikler <liliana.prikler@gmail.com>
+;;; Copyright © 2025 Efraim Flashner <efraim@flashner.co.il>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -99,6 +100,7 @@
             make-regexp*
             string->number*
             size->number
+            number->size
             show-derivation-outputs
             build-notifier
             show-what-to-build
@@ -695,6 +697,34 @@ interpreted."
           (x
            (leave (G_ "unknown unit: ~a~%") unit)))))))
 
+(define (number->size num)
+  "Convert NUM, an integer number of bytes, to a human readable string using
+common storage prefixes."
+  (define (pretty-print-number number exponent)
+    (number->string (inexact->exact (round (/ number (expt 2 exponent))))))
+
+  (unless (number? num)
+    (leave (G_ "invalid number: ~a~%") (object->string num)))
+
+  (cond
+    ((> num (expt 2 80))
+     (string-append (pretty-print-number num 80) " YiB"))
+    ((> num (expt 2 70))
+     (string-append (pretty-print-number num 70) " ZiB"))
+    ((> num (expt 2 60))
+     (string-append (pretty-print-number num 60) " EiB"))
+    ((> num (expt 2 50))
+     (string-append (pretty-print-number num 50) " PiB"))
+    ((> num (expt 2 40))
+     (string-append (pretty-print-number num 40) " TiB"))
+    ((> num (expt 2 30))
+     (string-append (pretty-print-number num 30) " GiB"))
+    ((> num (expt 2 20))
+     (string-append (pretty-print-number num 20) " MiB"))
+    ((> num (expt 2 10))
+     (string-append (pretty-print-number num 10) " KiB"))
+    (#t (string-append (number->string num) " bytes"))))
+
 (define (display-collision-resolution-hint collision)
   "Display hints on how to resolve COLLISION, a &profile-collistion-error."
   (define (top-most-entry entry)