lei_mirror: support resuming multi-repo clones

This is actually a combination of clone and fetch, and I don't
think `public-inbox-fetch' will be used to update multiple git
repos (inbox or not).

Our use of `git update-ref --stdin -z' was broken for
incremental updates, but now fixed to properly NUL-terminate
commands.

1 files changed, 27 insertions, 7 deletions

diff --git a/lib/PublicInbox/LeiMirror.pm b/lib/PublicInbox/LeiMirror.pm
index 8b276336..f2111dd2 100644
--- a/lib/PublicInbox/LeiMirror.pm
+++ b/lib/PublicInbox/LeiMirror.pm
@@ -256,7 +256,7 @@ sub run_reap {
         $ret;
 }
 
-sub start_clone {
+sub start_cmd {
         my ($self, $cmd, $opt, $fini) = @_;
         do_reap($self);
         $self->{lei}->qerr("# @$cmd");
@@ -279,9 +279,9 @@ sub fetch_args ($$) {
 }
 
 sub upr { # feed `git update-ref --stdin -z' verbosely
-        my ($lei, $w, $op, $ref, $oid) = @_;
-        $lei->qerr("# $op $ref $oid") if $lei->{opt}->{verbose};
-        print $w "$op $ref\0$oid\0" or die "print(w): $!";
+        my ($lei, $w, $op, @rest) = @_; # ($ref, $oid) = @rest
+        $lei->qerr("# $op @rest") if $lei->{opt}->{verbose};
+        print $w "$op ", join("\0", @rest, '') or die "print(w): $!";
 }
 
 sub fgrp_update {
@@ -306,7 +306,8 @@ sub fgrp_update {
                 my $new = delete $src{$ref};
                 my $old = $dst{$ref};
                 if (defined $new) {
-                        upr($lei, $w, 'update', $ref, $new) if $new ne $old;
+                        $new eq $old or
+                                upr($lei, $w, 'update', $ref, $new, $old);
                 } else {
                         upr($lei, $w, 'delete', $ref, $old);
                 }
@@ -482,6 +483,23 @@ EOM
         bless { %$self, -osdir => $dir, -remote => $rn }, __PACKAGE__;
 }
 
+sub resume_fetch {
+        my ($self, $uri, $fini) = @_;
+        my $dst = $self->{cur_dst} // $self->{dst};
+        my @git = ('git', "--git-dir=$dst");
+        my $opt = +{ map { $_ => $self->{lei}->{$_} } (0..2) };
+        my $rn = 'origin'; # configurable?
+        for ("url=$uri", "fetch=+refs/*:refs/*", 'mirror=true') {
+                my @kv = split(/=/, $_, 2);
+                $kv[0] = "remote.$rn.$kv[0]";
+                next if $self->{dry_run};
+                run_die([@git, 'config', @kv], undef, $opt);
+        }
+        my $cmd = [ @{$self->{-torsocks}}, @git,
+                        fetch_args($self->{lei}, $opt), $rn ];
+        start_cmd($self, $cmd, $opt, $fini);
+}
+
 sub clone_v1 {
         my ($self, $nohang) = @_;
         my $lei = $self->{lei};
@@ -495,7 +513,9 @@ sub clone_v1 {
         if (my $fgrp = forkgroup_prep($self, $uri)) {
                 $fgrp->{-fini} = $fini;
                 push @{$self->{fgrp_todo}->{$fgrp->{-osdir}}}, $fgrp;
-        } else { # normal fetch
+        } elsif (-d $dst) {
+                resume_fetch($self, $uri, $fini);
+        } else { # normal clone
                 my $cmd = [ @{$self->{-torsocks}},
                                 clone_cmd($lei, my $opt = {}), "$uri", $dst ];
                 if (defined($self->{-ent})) {
@@ -505,7 +525,7 @@ sub clone_v1 {
                                                 "$self->{dst}$ref";
                         }
                 }
-                start_clone($self, $cmd, $opt, $fini);
+                start_cmd($self, $cmd, $opt, $fini);
         }
         if (!$self->{-is_epoch} && $lei->{opt}->{'inbox-config'} =~
                                 /\A(?:always|v1)\z/s) {