dh_installman: Use man-recode(1) when present

It is a lot faster for any package with a non-trivial amount of
manpages-

Signed-off-by: Niels Thykier <niels@thykier.net>

2 files changed, 29 insertions, 13 deletions

diff --git a/debian/changelog b/debian/changelog
index d6806f4c..51edd7e2 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -4,6 +4,11 @@ debhelper (12.6.2) UNRELEASED; urgency=medium
   * dh_installman: Avoid error message when man-db is not unstalled
     (only occurs in debhelper's own buid as man-db is a mandatory
     dependency).
+  * dh_installman: Use man-recode(1) when available to massively
+    speed up re-encoding performance for any package with a non-
+    trivial amount of manpages.  Thanks to Robert Luberda for
+    reporting the issue and Colin Watson for writing man-recode
+    (Closes: #933576)
 
   [ Helmut Grohne ]:
   * cmake buildsystem: Fix CMAKE_SYSTEM_PROCESSOR for 32bit arms.
diff --git a/dh_installman b/dh_installman
index 55a13fa5..461764d0 100755
--- a/dh_installman
+++ b/dh_installman
@@ -272,6 +272,9 @@ on_items_in_parallel(\@all_packages, sub {
 });
 
 # Now utf-8 conversion.
+my $has_man_recode = 0;
+$has_man_recode = 1 if has_man_db_tool('man-recode');
+
 if (has_man_db_tool('man')) {
 	my (@manpages_to_reencode, @issues);
 	for my $package (@{$dh{DOPACKAGES}}) {
@@ -296,19 +299,7 @@ if (has_man_db_tool('man')) {
 		}
 	}
 	if (@manpages_to_reencode) {
-		on_items_in_parallel(\@manpages_to_reencode, sub {
-			for my $manpage (@_) {
-				my $manpage_tmp = "${manpage}.dh-new";
-				my $manpage_cmd = ($manpage =~ m{^/}) ? $manpage : "./${manpage}";
-				doit({ stdout => $manpage_tmp }, 'man', '-l', '--recode', 'UTF-8', $manpage_cmd);
-				# recode uncompresses compressed pages
-				my $orig = $manpage;
-				rm_files($orig) if $manpage =~ s/\.(gz|Z)$//;
-				rename_path($manpage_tmp, $manpage);
-			}
-			# Bulk reset permissions of all re-encoded files
-			xargs(\@_, 'chmod', '0644', '--');
-		});
+		on_items_in_parallel(\@manpages_to_reencode, \&reencode_manpages);
 	}
 } else {
 	# Should only occur during debhelper building itself (to avoid a B-D on man-db).
@@ -370,6 +361,26 @@ sub has_man_db_tool {
 	return $res;
 }
 
+sub reencode_manpages {
+	my (@manpages) = @_;
+	if ($has_man_recode) {
+		xargs(\@manpages, 'man-recode', '--to-code', 'UTF-8', '--suffix', '.dh-new');
+	}
+	for my $manpage (@manpages) {
+		my $manpage_tmp = "${manpage}.dh-new";
+		if (not $has_man_recode) {
+			my $manpage_cmd = ($manpage =~ m{^/}) ? $manpage : "./${manpage}";
+			doit({ stdout => $manpage_tmp }, 'man', '-l', '--recode', 'UTF-8', $manpage_cmd);
+		}
+		# recode uncompresses compressed pages
+		my $orig = $manpage;
+		rm_files($orig) if $manpage =~ s/\.(gz|Z)$//;
+		rename_path($manpage_tmp, $manpage);
+	}
+	# Bulk reset permissions of all re-encoded files
+	xargs(\@manpages, 'chmod', '0644', '--');
+}
+
 =head1 SEE ALSO
 
 L<debhelper(7)>