packages, scripts, utils: Enable multi-threaded xz compression.

xz compression is slow; using the multi-thread mode of xz can make it more
than 6 times faster, for example when compressing the large linux-libre
source.

* guix/build/utils.scm (%xz-parallel-args): New procedure.
* guix/packages.scm (patch-and-repack): Specify the required above xz
arguments by setting the XZ_DEFAULTS environment variable.
* guix/scripts/pack.scm (%compressors, bootstrap-xz): Modify the commands
Gexps so they do not need to be quoted.  This allows lazily evaluating the
arguments on the builder's side.  Specify the required xz arguments.
(self-contained-tarball): Do not quote the compressor command value.
(docker-image): Likewise.
* guix/utils.scm (decompressed-port, compressed-port)
(compressed-output-port): Specify the required above xz arguments.

1 files changed, 18 insertions, 9 deletions

diff --git a/guix/scripts/pack.scm b/guix/scripts/pack.scm
index 379e6a3ac6..a0112162e3 100644
--- a/guix/scripts/pack.scm
+++ b/guix/scripts/pack.scm
@@ -5,6 +5,7 @@
 ;;; Copyright © 2018 Chris Marusich <cmmarusich@gmail.com>
 ;;; Copyright © 2018 Efraim Flashner <efraim@flashner.co.il>
 ;;; Copyright © 2020 Tobias Geerinckx-Rice <me@tobias.gr>
+;;; Copyright © 2020 Maxim Cournoyer <maxim.cournoyer@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -25,6 +26,7 @@
   #:use-module (guix scripts)
   #:use-module (guix ui)
   #:use-module (guix gexp)
+  #:use-module ((guix build utils) #:select (%xz-parallel-args))
   #:use-module (guix utils)
   #:use-module (guix store)
   #:use-module ((guix status) #:select (with-status-verbosity))
@@ -70,29 +72,34 @@
   compressor?
   (name       compressor-name)      ;string (e.g., "gzip")
   (extension  compressor-extension) ;string (e.g., ".lz")
-  (command    compressor-command))  ;gexp (e.g., #~("/gnu/store/…/gzip" "-9n"))
+  (command    compressor-command))  ;gexp (e.g., #~(list "/gnu/store/…/gzip"
+                                    ;                    "-9n" ))
 
 (define %compressors
   ;; Available compression tools.
   (list (compressor "gzip"  ".gz"
-                    #~(#+(file-append gzip "/bin/gzip") "-9n"))
+                    #~(list #+(file-append gzip "/bin/gzip") "-9n"))
         (compressor "lzip"  ".lz"
-                    #~(#+(file-append lzip "/bin/lzip") "-9"))
+                    #~(list #+(file-append lzip "/bin/lzip") "-9"))
         (compressor "xz"    ".xz"
-                    #~(#+(file-append xz "/bin/xz") "-e"))
+                    #~(append (list #+(file-append xz "/bin/xz")
+                                    "-e")
+                              (%xz-parallel-args)))
         (compressor "bzip2" ".bz2"
-                    #~(#+(file-append bzip2 "/bin/bzip2") "-9"))
+                    #~(list #+(file-append bzip2 "/bin/bzip2") "-9"))
         (compressor "zstd" ".zst"
                     ;; The default level 3 compresses better than gzip in a
                     ;; fraction of the time, while the highest level 19
                     ;; (de)compresses more slowly and worse than xz.
-                    #~(#+(file-append zstd "/bin/zstd") "-3"))
+                    #~(list #+(file-append zstd "/bin/zstd") "-3"))
         (compressor "none" "" #f)))
 
 ;; This one is only for use in this module, so don't put it in %compressors.
 (define bootstrap-xz
   (compressor "bootstrap-xz" ".xz"
-              #~(#+(file-append %bootstrap-coreutils&co "/bin/xz") "-e")))
+              #~(append (list #+(file-append %bootstrap-coreutils&co "/bin/xz")
+                              "-e")
+                        (%xz-parallel-args))))
 
 (define (lookup-compressor name)
   "Return the compressor object called NAME.  Error out if it could not be
@@ -269,7 +276,7 @@ added to the pack."
                            #+@(if (compressor-command compressor)
                                   #~("-I"
                                      (string-join
-                                      '#+(compressor-command compressor)))
+                                      #+(compressor-command compressor)))
                                   #~())
                            "--format=gnu"
 
@@ -541,11 +548,13 @@ the image."
                                ,@(source-module-closure
                                   `((guix docker)
                                     (guix build store-copy)
+                                    (guix build utils) ;for %xz-parallel-args
                                     (guix profiles)
                                     (guix search-paths))
                                   #:select? not-config?))
         #~(begin
             (use-modules (guix docker) (guix build store-copy)
+                         (guix build utils)
                          (guix profiles) (guix search-paths)
                          (srfi srfi-1) (srfi srfi-19)
                          (ice-9 match))
@@ -602,7 +611,7 @@ the image."
                                        #~(list (string-append #$profile "/"
                                                               #$entry-point)))
                                 #:extra-files directives
-                                #:compressor '#+(compressor-command compressor)
+                                #:compressor #+(compressor-command compressor)
                                 #:creation-time (make-time time-utc 0 1))))))
 
   (gexp->derivation (string-append name ".tar"