substitute-binary: Add a local cache.

* guix/scripts/substitute-binary.scm (%narinfo-cache-directory,
  %narinfo-ttl, %narinfo-negative-ttl): New variables.
  (with-atomic-file-output, object->fields, read-narinfo,
  write-narinfo, narinfo->string, string->narinfo, lookup-narinfo): New
  procedures.
  (fetch-narinfo): Adjust to use `read-narinfo'.
  (guix-substitute-binary): Ensure the existence of
  %NARINFO-CACHE-DIRECTORY.  Use `lookup-narinfo' instead of
  `fetch-narinfo'.

1 files changed, 6 insertions, 0 deletions

diff --git a/tests/store.scm b/tests/store.scm
index 4ee20a9352..677e39e75d 100644
--- a/tests/store.scm
+++ b/tests/store.scm
@@ -159,6 +159,12 @@ Deriver: ~a~%"
                 (%current-system)                   ; System
                 (basename d))))                     ; Deriver
 
+    ;; Remove entry from the local cache.
+    (false-if-exception
+     (delete-file (string-append (getenv "XDG_CACHE_HOME")
+                                 "/guix/substitute-binary/"
+                                 (store-path-hash-part o))))
+
     ;; Make sure `substitute-binary' correctly communicates the above data.
     (set-build-options s #:use-substitutes? #t)
     (and (has-substitutes? s o)