From f09aea1b58b3ef961d3cc712f116fe4617bc8f90 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Mon, 14 Mar 2016 16:53:38 +0100
Subject: [PATCH] store: 'references/substitutes' caches its results.
* guix/store.scm (%reference-cache): New variable.
(references/substitutes): Use it.
---
guix/store.scm | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/guix/store.scm b/guix/store.scm
index a220b6e6f9a..01248738dc7 100644
--- a/guix/store.scm
+++ b/guix/store.scm
@@ -726,14 +726,23 @@ (define references
"Return the list of references of PATH."
store-path-list))
+(define %reference-cache
+ ;; Brute-force cache mapping store items to their list of references.
+ ;; Caching matters because when building a profile in the presence of
+ ;; grafts, we keep calling 'graft-derivation', which in turn calls
+ ;; 'references/substitutes' many times with the same arguments. Ideally we
+ ;; would use a cache associated with the daemon connection instead (XXX).
+ (make-hash-table 100))
+
(define (references/substitutes store items)
"Return the list of list of references of ITEMS; the result has the same
length as ITEMS. Query substitute information for any item missing from the
store at once. Raise a '&nix-protocol-error' exception if reference
information for one of ITEMS is missing."
(let* ((local-refs (map (lambda (item)
- (guard (c ((nix-protocol-error? c) #f))
- (references store item)))
+ (or (hash-ref %reference-cache item)
+ (guard (c ((nix-protocol-error? c) #f))
+ (references store item))))
items))
(missing (fold-right (lambda (item local-ref result)
(if local-ref
@@ -757,7 +766,10 @@ (define (references/substitutes store items)
(result '()))
(match items
(()
- (reverse result))
+ (let ((result (reverse result)))
+ (for-each (cut hash-set! %reference-cache <> <>)
+ items result)
+ result))
((item items ...)
(match local-refs
((#f tail ...)
--
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