[PATCH 4/4] git: reduce early bare-bones memory use

[Eric Wong <e@80x24.org>]

The {-git_path} cache can rely on auto-vivification, and
{alt_st} may not be needed for short-lived repos.  So don't
populate those fields until they're needed, since we can
expect to handle thousands of git repos, too.
---
 lib/PublicInbox/Git.pm | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index b2ae75c8..9140caea 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -66,7 +66,7 @@ sub new {
 	$git_dir =~ tr!/!/!s;
 	$git_dir =~ s!/*\z!!s;
 	# may contain {-tmp} field for File::Temp::Dir
-	bless { git_dir => $git_dir, alt_st => '', -git_path => {} }, $class
+	bless { git_dir => $git_dir }, $class
 }
 
 sub git_path ($$) {
@@ -90,7 +90,7 @@ sub alternates_changed {
 
 	# can't rely on 'q' on some 32-bit builds, but `d' works
 	my $st = pack('dd', $st[10], $st[7]); # 10: ctime, 7: size
-	return 0 if $self->{alt_st} eq $st;
+	return 0 if ($self->{alt_st} // '') eq $st;
 	$self->{alt_st} = $st; # always a true value
 }