profiles: Build the man database only if 'man-db' is in the profile.

This allows us to skip the expensive man-db profile hook in most cases.

Suggested by Liliana Marie Prikler <liliana.prikler@gmail.com>.

* guix/profiles.scm (manual-database/optional): New procedure.
(%default-profile-hooks): Use it instead of 'manual-database'.
* doc/guix.texi (Documentation): Add footnote about 'man -k' database
creation.
This commit is contained in:
Ludovic Courtès 2021-10-26 16:01:40 +02:00
parent d21353adea
commit 3c1158ac4e
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2 changed files with 14 additions and 2 deletions

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@ -36611,7 +36611,9 @@ $ info -k TLS
@end example
@noindent
The command below searches for the same keyword in man pages:
The command below searches for the same keyword in man
pages@footnote{The database searched by @command{man -k} is only created
in profiles that contain the @code{man-db} package.}:
@example
$ man -k TLS

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@ -1682,6 +1682,16 @@ (define man-directory
`((type . profile-hook)
(hook . manual-database))))
(define (manual-database/optional manifest)
"Return a derivation to build the manual database of MANIFEST, but only if
MANIFEST contains the \"man-db\" package. Otherwise, return #f."
;; Building the man database (for "man -k") is expensive and rarely used.
;; Build it only if the profile also contains "man-db".
(mlet %store-monad ((man-db (manifest-lookup-package manifest "man-db")))
(if man-db
(manual-database manifest)
(return #f))))
(define (texlive-configuration manifest)
"Return a derivation that builds a TeXlive configuration for the entries in
MANIFEST."
@ -1784,7 +1794,7 @@ (define %default-profile-hooks
;; This is the list of derivation-returning procedures that are called by
;; default when making a non-empty profile.
(list info-dir-file
manual-database
manual-database/optional
fonts-dir-file
ghc-package-cache-file
ca-certificate-bundle