Subject: [PATCH] refresh: Account for overlapping updater coverage.

From: [email-masked]
Date: Tue, 27 Nov 2018 20:27:37 -0600

From: Eric Bavier <[email-masked]>

* guix/scripts/refresh.scm (list-updaters-and-exit): Do not assume updater
predicates are disjoint.  Track covered packages directly.
---
Hello Guix,

Some of our packages are covered by more than one of our updaters:

scheme@(guile-user)> ,use(gnu packages)(guix packages)(guix upstream)
scheme@(guile-user)> ,use(srfi srfi-1)(srfi srfi-26)
scheme@(guile-user)> (define updaters (force (@@ (guix upstream) %updaters)))
scheme@(guile-user)> (define predicates (map upstream-updater-predicate updaters))
scheme@(guile-user)> (define doubles
  (fold-packages
    (lambda (pkg result)
      (if (> (count (cut <> pkg) predicates) 1)
         (cons pkg result)
       result))
    '()))
scheme@(guile-user)> (length doubles)
$1 = 469
scheme@(guile-user)> (map package-name doubles)
$2 = ("agda" "emacs-agda2-mode" "fribidi" "raincat" "ghc-tasty-quickcheck" ... "ghc-hxt")

It seams mostly packages covered by both the "hackage" and "stackage"
updaters.  And Fribidi is a GNU package but hosted on github.

Currently this leads to double-counting while computing total package
coverage and a too optimistic result (by about 5.4%).

The below patch fixes it by tracking the (un)covered packages directly.

 guix/scripts/refresh.scm | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/guix/scripts/refresh.scm b/guix/scripts/refresh.scm
index 58fc64db1..f7d2cffb7 100644
--- a/guix/scripts/refresh.scm
+++ b/guix/scripts/refresh.scm
@@ -179,24 +179,24 @@ specified with `--select'.\n"))
 
   (let* ((packages (fold-packages cons '()))
          (total    (length packages)))
-    (define covered
-      (fold (lambda (updater covered)
-              (let ((matches (count (upstream-updater-predicate updater)
-                                    packages)))
+    (define uncovered
+      (fold (lambda (updater uncovered)
+              (let ((matches (filter (upstream-updater-predicate updater)
+                                     packages)))
                 ;; TRANSLATORS: The parenthetical expression here is rendered
                 ;; like "(42% coverage)" and denotes the fraction of packages
                 ;; covered by the given updater.
                 (format #t (G_ "  - ~a: ~a (~2,1f% coverage)~%")
                         (upstream-updater-name updater)
                         (G_ (upstream-updater-description updater))
-                        (* 100. (/ matches total)))
-                (+ covered matches)))
-            0
+                        (* 100. (/ (length matches) total)))
+                (lset-difference eq? uncovered matches)))
+            packages
             (force %updaters)))
 
     (newline)
     (format #t (G_ "~2,1f% of the packages are covered by these updaters.~%")
-            (* 100. (/ covered total))))
+            (* 100. (/ (- total (length uncovered)) total))))
   (exit 0))
 
 (define (warn-no-updater package)
-- 
2.19.1