[dpkg] 65/192: dpkg-shlibdeps: Cache get_control_path() calls

[Ximin Luo]

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infinity0 pushed a commit to branch pu/reproducible_builds
in repository dpkg.

commit 08ceaf0dd829aa1cee5382974ce29540955a25df
Author: Guillem Jover <guillem at debian.org>
Date:   Sat Apr 1 16:49:48 2017 +0000

    dpkg-shlibdeps: Cache get_control_path() calls
    
    It is basically a thin-wrapper around «dpkg-query --control-path» and
    the repeated calls add up to quite a sum.
    
    Results from a poor-mans performance test on ~90 ELF binaries from
    piglit:
    
      * BEFORE:
        real    0m35.892s
        user    0m15.652s
        sys     0m18.584s
    
      * AFTER:
        real    0m10.884s
        user    0m7.316s
        sys     0m3.296s
    
    Closes: #846405
    Based-on-patch-by: Niels Thykier <niels at thykier.net>
    Signed-off-by: Guillem Jover <guillem at debian.org>
---
 debian/changelog          | 2 ++
 scripts/dpkg-shlibdeps.pl | 8 +++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/debian/changelog b/debian/changelog
index 0efc23c..79a1cfd 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -5,6 +5,8 @@ dpkg (1.19.0) UNRELEASED; urgency=medium
     Thanks to Niels Thykier <niels at thykier.net>.
   * Parse start-stop-daemon usernames and groupnames starting with digits in
     -u and -c correctly. Reported by Bodo Eggert <7eggert at online.de>.
+  * Cache the result of «dpkg-query --control-path» calls in dpkg-shlibdeps.
+    Based on a patch by Niels Thykier <niels at thykier.net>. Closes: #846405
   * Perl modules:
     - Switch from Dpkg::Util to List::Util, now that the module in the
       new required Perl contains the needed functions.
diff --git a/scripts/dpkg-shlibdeps.pl b/scripts/dpkg-shlibdeps.pl
index 0dbb572..2ca35ba 100755
--- a/scripts/dpkg-shlibdeps.pl
+++ b/scripts/dpkg-shlibdeps.pl
@@ -23,6 +23,7 @@
 
 use strict;
 use warnings;
+use feature qw(state);
 
 use List::Util qw(any none);
 use POSIX qw(:errno_h);
@@ -782,7 +783,12 @@ sub find_symbols_file {
     } else {
 	push @files, "$Dpkg::CONFDIR/symbols/$pkg.symbols.$host_arch",
 	    "$Dpkg::CONFDIR/symbols/$pkg.symbols";
-	my $control_file = get_control_path($pkg, 'symbols');
+
+	state %control_file_cache;
+	if (not exists $control_file_cache{$pkg}) {
+	    $control_file_cache{$pkg} = get_control_path($pkg, 'symbols');
+	}
+	my $control_file = $control_file_cache{$pkg};
 	push @files, $control_file if defined $control_file;
     }
 

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