lei_mirror: avoid dir/file conflicts in update-ref

Using the files ref backend for git, `delete' and `create'
operations for `update-ref --stdin' need to be processed in
separate transactions to avoid conflicts in cases where a file
becomes a directory (or presumably, vice versa).

diff --git a/lib/PublicInbox/LeiMirror.pm b/lib/PublicInbox/LeiMirror.pm
index afe12bb30dd719e545224b348575ff52b82b3f92..d959b6b61ac4cd018b1142681d663261846596b6 100644 (file)
--- a/lib/PublicInbox/LeiMirror.pm
+++ b/lib/PublicInbox/LeiMirror.pm
@@ -288,6 +288,19 @@ sub upr { # feed `git update-ref --stdin -z' verbosely
        print $w "$op ", join("\0", @rest, '') or die "print(w): $!";
 }
 
+sub start_update_ref {
+       my ($fgrp) = @_;
+       pipe(my ($r, $w)) or die "pipe: $!";
+       my $cmd = [ 'git', "--git-dir=$fgrp->{cur_dst}",
+               qw(update-ref --stdin -z) ];
+       my $pack = PublicInbox::OnDestroy->new($$, \&satellite_done, $fgrp);
+       start_cmd($fgrp, $cmd, { 0 => $r, 2 => $fgrp->{lei}->{2} }, $pack);
+       close $r or die "close(r): $!";
+       $fgrp->{dry_run} ? undef : $w;
+}
+
+sub upref_warn { warn "E: close(update-ref --stdin): $! (need git 1.8.5+)\n" }
+
 sub fgrp_update {
        my ($fgrp) = @_;
        return if !keep_going($fgrp);
@@ -299,14 +312,9 @@ sub fgrp_update {
        close $srcfh;
        my %dst = map { chomp; split(/\0/) } (<$dstfh>);
        close $dstfh;
-       pipe(my ($r, $w)) or die "pipe: $!";
-       my $cmd = [ 'git', "--git-dir=$fgrp->{cur_dst}",
-               qw(update-ref --stdin -z) ];
+       my $w = start_update_ref($fgrp) or return;
        my $lei = $fgrp->{lei};
-       my $pack = PublicInbox::OnDestroy->new($$, \&satellite_done, $fgrp);
-       start_cmd($fgrp, $cmd, { 0 => $r, 2 => $lei->{2} }, $pack);
-       close $r or die "close(r): $!";
-       return if $fgrp->{dry_run};
+       my $ndel;
        for my $ref (keys %dst) {
                my $new = delete $src{$ref};
                my $old = $dst{$ref};
@@ -315,18 +323,33 @@ sub fgrp_update {
                                upr($lei, $w, 'update', $ref, $new, $old);
                } else {
                        upr($lei, $w, 'delete', $ref, $old);
+                       ++$ndel;
                }
        }
-       while (my ($ref, $oid) = each %src) {
-               upr($lei, $w, 'create', $ref, $oid);
+       # git's ref files backend doesn't allow directory/file conflicts
+       # between `delete' and `create' ops:
+       if ($ndel && scalar(keys %src)) {
+               $fgrp->{-create_refs} = \%src;
+       } else {
+               while (my ($ref, $oid) = each %src) {
+                       upr($lei, $w, 'create', $ref, $oid);
+               }
        }
-       close($w) or warn "E: close(update-ref --stdin): $! (need git 1.8.5+)\n";
+       close($w) or upref_warn();
 }
 
 sub satellite_done {
        my ($fgrp) = @_;
-       pack_refs($fgrp, $fgrp->{cur_dst});
-       run_puh($fgrp);
+       if (my $create = delete $fgrp->{-create_refs}) {
+               my $w = start_update_ref($fgrp) or return;
+               while (my ($ref, $oid) = each %$create) {
+                       upr($fgrp->{lei}, $w, 'create', $ref, $oid);
+               }
+               close($w) or upref_warn();
+       } else {
+               pack_refs($fgrp, $fgrp->{cur_dst});
+               run_puh($fgrp);
+       }
 }
 
 sub pack_refs {