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derivations: Avoid uses of 'write' in 'write-derivation'.

This leads a 4% improvement on the wall-clock time of:

  guix build -e '(@@ (gnu packages libreoffice) libreoffice)' --no-grafts -d

* guix/derivations.scm (escaped-string): New procedure.
(write-derivation)[write-escaped-string]: New procedure.
[write-string-list, write-output, write-env-var]: Use it.
master
Ludovic Courtès 2020-08-28 19:19:04 +02:00
parent 3e339c4410
commit 4ec66950f0
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GPG Key ID: 090B11993D9AEBB5
1 changed files with 40 additions and 7 deletions

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@ -579,15 +579,48 @@ things as appropriate and is thus more efficient."
(write-sequence lst write-item port)
(put-char port #\)))
(define %escape-char-set
;; Characters that need to be escaped.
(char-set #\" #\\ #\newline #\return #\tab))
(define (escaped-string str)
"Escape double quote characters found in STR, if any."
(define escape
(match-lambda
(#\" "\\\"")
(#\\ "\\\\")
(#\newline "\\n")
(#\return "\\r")
(#\tab "\\t")))
(let loop ((str str)
(result '()))
(let ((index (string-index str %escape-char-set)))
(if index
(let ((rest (string-drop str (+ 1 index))))
(loop rest
(cons* (escape (string-ref str index))
(string-take str index)
result)))
(if (null? result)
str
(string-concatenate-reverse (cons str result)))))))
(define (write-derivation drv port)
"Write the ATerm-like serialization of DRV to PORT. See Section 2.4 of
Eelco Dolstra's PhD dissertation for an overview of a previous version of
that form."
;; Use 'put-string', which does less work and is faster than 'display'.
;; Likewise, 'write-escaped-string' is faster than 'write'.
(define (write-escaped-string str port)
(put-char port #\")
(put-string port (escaped-string str))
(put-char port #\"))
(define (write-string-list lst)
(write-list lst write port))
(write-list lst write-escaped-string port))
(define (write-output output port)
(match output
@ -599,7 +632,7 @@ that form."
"")
(or (and=> hash bytevector->base16-string)
""))
write
write-escaped-string
port))))
(define (write-input input port)
@ -619,11 +652,11 @@ that form."
(define (write-env-var env-var port)
(match env-var
((name . value)
(put-string port "(")
(write name port)
(put-string port ",")
(write value port)
(put-string port ")"))))
(put-char port #\()
(write-escaped-string name port)
(put-char port #\,)
(write-escaped-string value port)
(put-char port #\)))))
;; Assume all the lists we are writing are already sorted.
(match drv