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substitute-binary: Increase lookup concurrency to reduce latency. 

* guix/scripts/substitute-binary.scm (%lookup-threads): New variable.
  (guix-substitute-binary): Use 'n-par-map' instead of 'par-map' for
  batch 'lookup-narinfo' calls.
This commit is contained in:
Ludovic Courtès 2013-11-08 22:47:02 +01:00
parent 6a9957545c
commit 50dc48922c
1 changed files with 12 additions and 4 deletions
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16
guix/scripts/substitute-binary.scm
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@ -290,6 +290,12 @@ reading PORT."
(time>? (subtract-duration now (make-time time-duration 0 ttl))
(make-time time-monotonic 0 date)))
(define %lookup-threads
;; Number of threads spawned to perform lookup operations. This means we
;; can have this many simultaneous HTTP GET requests to the server, which
;; limits the impact of connection latency.
20)
(define (lookup-narinfo cache path)
"Check locally if we have valid info about PATH, otherwise go to CACHE and
check what it has."
@ -489,8 +495,9 @@ Internal tool to substitute a pre-built binary to a local build.\n"))
;; Return the subset of PATHS available in CACHE.
(let ((substitutable
(if cache
(par-map (cut lookup-narinfo cache <>)
paths)
(n-par-map %lookup-threads
(cut lookup-narinfo cache <>)
paths)
'())))
(for-each (lambda (narinfo)
(when narinfo
@ -501,8 +508,9 @@ Internal tool to substitute a pre-built binary to a local build.\n"))
;; Reply info about PATHS if it's in CACHE.
(let ((substitutable
(if cache
(par-map (cut lookup-narinfo cache <>)
paths)
(n-par-map %lookup-threads
(cut lookup-narinfo cache <>)
paths)
'())))
(for-each (lambda (narinfo)
(format #t "~a\n~a\n~a\n"