From fd951cd543d9f4d3ecfa4570e51797f84e79068b Mon Sep 17 00:00:00 2001 From: Ludovic Courtès Date: Sun, 23 Jun 2019 11:40:16 +0200 Subject: derivations: 'derivation' preserves pointer equality. * guix/derivations.scm (derivation): Check if FILE is already in %DERIVATION-CACHE and return it if it is. --- guix/derivations.scm | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/guix/derivations.scm b/guix/derivations.scm index 5c568f223b..403e86749b 100644 --- a/guix/derivations.scm +++ b/guix/derivations.scm @@ -873,8 +873,12 @@ derivation. It is kept as-is, uninterpreted, in the derivation." (append (map derivation-input-path inputs) sources))) (drv* (set-field drv (derivation-file-name) file))) - (hash-set! %derivation-cache file drv*) - drv*))) + ;; Preserve pointer equality. This improves the performance of + ;; 'eq?'-memoization on derivations. + (or (hash-ref %derivation-cache file) + (begin + (hash-set! %derivation-cache file drv*) + drv*))))) (define (invalidate-derivation-caches!) "Invalidate internal derivation caches. This is mostly useful for -- cgit v1.2.3