lei_mirror: further reduce `git config' calls

We can parse the config at once and avoid clobbering variables
which do not need changing.  We'll also do some prep work for
fetch.hideRefs proposal being discussed at
<https://public-inbox.org/git/20230209122857.M669733@dcvr/>

1 files changed, 36 insertions, 26 deletions

diff --git a/lib/PublicInbox/LeiMirror.pm b/lib/PublicInbox/LeiMirror.pm
index d959b6b6..dd6356bb 100644
--- a/lib/PublicInbox/LeiMirror.pm
+++ b/lib/PublicInbox/LeiMirror.pm
@@ -401,23 +401,42 @@ sub fgrp_fetch_all {
         my $opt = {};
         my @fetch = do {
                 local $self->{lei}->{opt}->{jobs} = 1;
-                (fetch_args($self->{lei}, $opt),
-                        qw(--no-tags --multiple));
+                (fetch_args($self->{lei}, $opt), qw(--no-tags --multiple));
         };
         push(@fetch, "-j$j") if $j;
         while (my ($osdir, $fgrpv) = each %$todo) {
                 my $f = "$osdir/config";
                 return if !keep_going($self);
 
+                my $cmd = ['git', "--git-dir=$osdir", qw(config -f), $f ];
                 # clobber group from previous run atomically
-                my $cmd = ['git', "--git-dir=$osdir", qw(config -f),
-                                $f, '--unset-all', "remotes.$grp"];
-                $self->{lei}->qerr("# @$cmd");
-                if (!$self->{dry_run}) {
-                        my $pid = spawn($cmd, undef, { 2 => $self->{lei}->{2} });
+                for ("remotes.$grp") { # TODO: hideRefs
+                        my $c = [ @$cmd, '--unset-all', $_ ];
+                        $self->{lei}->qerr("# @$c");
+                        next if $self->{dry_run};
+                        my $pid = spawn($c, undef, $opt);
                         waitpid($pid, 0) // die "waitpid: $!";
-                        die "E: @$cmd: \$?=$?" if ($? && ($? >> 8) != 5);
+                        die "E: @$c \$?=$?" if ($? && ($? >> 8) != 5);
+                }
 
+                # permanent configs:
+                my $cfg = PublicInbox::Config->git_config_dump($f);
+                for my $fgrp (@$fgrpv) {
+                        my $u = $fgrp->{-uri} // die 'BUG: no {-uri}';
+                        my $rn = $fgrp->{-remote} // die 'BUG: no {-remote}';
+                        for ("url=$u", "fetch=+refs/*:refs/remotes/$rn/*",
+                                        'tagopt=--no-tags') {
+                                my ($k, $v) = split(/=/, $_, 2);
+                                $k = "remote.$rn.$k";
+                                next if ($cfg->{$k} // '') eq $v;
+                                my $c = [@$cmd, $k, $v];
+                                $fgrp->{lei}->qerr("# @$c");
+                                next if $fgrp->{dry_run};
+                                run_die($c, undef, $opt);
+                        }
+                }
+
+                if (!$self->{dry_run}) {
                         # update the config atomically via O_APPEND while
                         # respecting git-config locking
                         sysopen(my $lk, "$f.lock", O_CREAT|O_EXCL|O_WRONLY)
@@ -430,7 +449,6 @@ sub fgrp_fetch_all {
                         close $fh or die "close($f): $!";
                         unlink("$f.lock") or die "unlink($f.lock): $!";
                 }
-
                 $cmd = [ @git, "--git-dir=$osdir", @fetch, $grp ];
                 my $end = PublicInbox::OnDestroy->new($$, \&fgrpv_done, $fgrpv);
                 start_cmd($self, $cmd, $opt, $end);
@@ -446,12 +464,15 @@ sub forkgroup_prep {
         my $dir = "$os/$fg.git";
         if (!-d $dir && !$self->{dry_run}) {
                 PublicInbox::Import::init_bare($dir);
-                my @cmd = ('git', "--git-dir=$dir", 'config');
-                my $opt = { 2 => $self->{lei}->{2} };
-                for ('repack.useDeltaIslands=true',
-                                'pack.island=refs/remotes/([^/]+)/') {
-                        run_die([@cmd, split(/=/, $_, 2)], undef, $opt);
-                }
+                my $f = "$dir/config";
+                open my $fh, '+>>', $f or die "open:($f): $!";
+                print $fh <<EOM or die "print($f): $!";
+[repack]
+        useDeltaIslands = true
+[pack]
+        island = refs/remotes/([^/]+)/
+EOM
+                close $fh or die "close($f): $!";
         }
         my $key = $self->{-key} // die 'BUG: no -key';
         my $rn = substr(sha256_hex($key), 0, 16);
@@ -546,17 +567,6 @@ sub resume_fetch {
 sub fgrp_enqueue {
         my ($fgrp, $end) = @_; # $end calls fgrp_fetch_all
         return if !keep_going($fgrp);
-        my $opt = { 2 => $fgrp->{lei}->{2} };
-        # --no-tags is required to avoid conflicts
-        my $u = $fgrp->{-uri} // die 'BUG: no {-uri}';
-        my $rn = $fgrp->{-remote} // die 'BUG: no {-remote}';
-        my @cmd = ('git', "--git-dir=$fgrp->{-osdir}", 'config');
-        for ("url=$u", "fetch=+refs/*:refs/remotes/$rn/*", 'tagopt=--no-tags') {
-                my @kv = split(/=/, $_, 2);
-                $kv[0] = "remote.$rn.$kv[0]";
-                $fgrp->{dry_run} ? $fgrp->{lei}->qerr("# @cmd @kv") :
-                                run_die([@cmd, @kv], undef, $opt);
-        }
         ++$fgrp->{chg}->{nr_chg};
         push @{$FGRP_TODO->{$fgrp->{-osdir}}}, $fgrp;
 }