Subject: bug#26225: [PATCH] guix: Compress and decompress xz archives in parallel.

From: Efraim Flashner <[email-masked]>
Date: Thu, 23 Mar 2017 11:47:32 +0200

* guix/scripts/pack.scm (%compressors): Add flag '-T0' when calling "xz".
* guix/utils.scm (decompressed-port, compressed-port,
compressed-output-port): Same.
---
 guix/scripts/pack.scm | 3 ++-
 guix/utils.scm        | 7 ++++---
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/guix/scripts/pack.scm b/guix/scripts/pack.scm
index 626c592e1..9e91bc22a 100644
--- a/guix/scripts/pack.scm
+++ b/guix/scripts/pack.scm
@@ -1,5 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2015, 2017 Ludovic Courtès <[email-masked]>
+;;; Copyright © 2017 Efraim Flashner <[email-masked]>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -59,7 +60,7 @@
         (compressor "lzip"  "lz"
                     #~(#+(file-append lzip "/bin/lzip") "-9"))
         (compressor "xz"    "xz"
-                    #~(#+(file-append xz "/bin/xz") "-e"))
+                    #~(#+(file-append xz "/bin/xz") "-e -T0"))
         (compressor "bzip2" "bz2"
                     #~(#+(file-append bzip2 "/bin/bzip2") "-9"))))
 
diff --git a/guix/utils.scm b/guix/utils.scm
index bc90686de..fb962df8b 100644
--- a/guix/utils.scm
+++ b/guix/utils.scm
@@ -5,6 +5,7 @@
 ;;; Copyright © 2014 Ian Denhardt <[email-masked]>
 ;;; Copyright © 2016 Mathieu Lirzin <[email-masked]>
 ;;; Copyright © 2015 David Thompson <[email-masked]>
+;;; Copyright © 2017 Efraim Flashner <[email-masked]>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -154,7 +155,7 @@ a symbol such as 'xz."
   (match compression
     ((or #f 'none) (values input '()))
     ('bzip2        (filtered-port `(,%bzip2 "-dc") input))
-    ('xz           (filtered-port `(,%xz "-dc") input))
+    ('xz           (filtered-port `(,%xz "-dc -T0") input))
     ('gzip         (filtered-port `(,%gzip "-dc") input))
     (else          (error "unsupported compression scheme" compression))))
 
@@ -164,7 +165,7 @@ a symbol such as 'xz."
   (match compression
     ((or #f 'none) (values input '()))
     ('bzip2        (filtered-port `(,%bzip2 "-c") input))
-    ('xz           (filtered-port `(,%xz "-c") input))
+    ('xz           (filtered-port `(,%xz "-c -T0") input))
     ('gzip         (filtered-port `(,%gzip "-c") input))
     (else          (error "unsupported compression scheme" compression))))
 
@@ -221,7 +222,7 @@ program--e.g., '(\"--fast\")."
   (match compression
     ((or #f 'none) (values output '()))
     ('bzip2        (filtered-output-port `(,%bzip2 "-c" ,@options) output))
-    ('xz           (filtered-output-port `(,%xz "-c" ,@options) output))
+    ('xz           (filtered-output-port `(,%xz "-c -T0" ,@options) output))
     ('gzip         (filtered-output-port `(,%gzip "-c" ,@options) output))
     (else          (error "unsupported compression scheme" compression))))
 
-- 
2.12.1