v2: fill alternates with old epochs on init from mirrors

For v2 repositories with multiple epochs, we must not forget
about earlier epochs in clones.  Ensure we update the alternates
file with all known epochs up to the current one.

Reported-by: Eric W. Biederman <ebiederm@xmission.com>
  https://public-inbox.org/meta/871scj2vzi.fsf@xmission.com/

2 files changed, 33 insertions, 11 deletions

diff --git a/lib/PublicInbox/V2Writable.pm b/lib/PublicInbox/V2Writable.pm
index d8d75ec2..412eb6a9 100644
--- a/lib/PublicInbox/V2Writable.pm
+++ b/lib/PublicInbox/V2Writable.pm
@@ -495,15 +495,21 @@ sub git_init {
         PublicInbox::Import::run_die(\@cmd);
 
         my $alt = "$all/objects/info/alternates";
-        my $new_obj_dir = "../../git/$epoch.git/objects";
         my %alts;
+        my @add;
         if (-e $alt) {
                 open(my $fh, '<', $alt) or die "open < $alt: $!\n";
                 %alts = map { chomp; $_ => 1 } (<$fh>);
         }
-        return $git_dir if $alts{$new_obj_dir};
+        foreach my $i (0..$epoch) {
+                my $dir = "../../git/$i.git/objects";
+                push @add, $dir if !$alts{$dir} && -d "$pfx/$i.git";
+        }
+        return $git_dir unless @add;
         open my $fh, '>>', $alt or die "open >> $alt: $!\n";
-        print $fh "$new_obj_dir\n" or die "print >> $alt: $!\n";
+        foreach my $dir (@add) {
+                print $fh "$dir\n" or die "print >> $alt: $!\n";
+        }
         close $fh or die "close $alt: $!\n";
         $git_dir
 }
diff --git a/t/v2mirror.t b/t/v2mirror.t
index 4cd369bd..c0c329ca 100644
--- a/t/v2mirror.t
+++ b/t/v2mirror.t
@@ -45,11 +45,16 @@ To: You <you@example.com>
 Subject: a
 Date: Thu, 01 Jan 1970 00:00:00 +0000
 
+my $old_rotate_bytes = $v2w->{rotate_bytes};
+$v2w->{rotate_bytes} = 500; # force rotating
 for my $i (1..9) {
         $mime->header_set('Message-ID', "<$i\@example.com>");
         $mime->header_set('Subject', "subject = $i");
         ok($v2w->add($mime), "add msg $i OK");
 }
+
+my $epoch_max = $v2w->{epoch_max};
+ok($epoch_max > 0, "multiple epochs");
 $v2w->done;
 
 my %opts = (
@@ -79,11 +84,14 @@ ok(defined $pid, 'forked httpd process successfully');
 my ($host, $port) = ($sock->sockhost, $sock->sockport);
 $sock = undef;
 
-my @cmd = (qw(git clone --mirror -q), "http://$host:$port/v2/0",
-        "$tmpdir/m/git/0.git");
+my @cmd;
+foreach my $i (0..$epoch_max) {
+        @cmd = (qw(git clone --mirror -q), "http://$host:$port/v2/$i",
+                "$tmpdir/m/git/$i.git");
 
-is(system(@cmd), 0, 'cloned OK');
-ok(-d "$tmpdir/m/git/0.git", 'mirror OK');;
+        is(system(@cmd), 0, 'cloned OK');
+        ok(-d "$tmpdir/m/git/$i.git", 'mirror OK');
+}
 
 @cmd = ("$script-init", '-V2', 'm', "$tmpdir/m", 'http://example.com/m',
         'alt@example.com');
@@ -94,14 +102,23 @@ my $mibx = { mainrepo => "$tmpdir/m", address => 'alt@example.com' };
 $mibx = PublicInbox::Inbox->new($mibx);
 is_deeply([$mibx->mm->minmax], [$ibx->mm->minmax], 'index synched minmax');
 
+$v2w->{rotate_bytes} = $old_rotate_bytes;
 for my $i (10..15) {
         $mime->header_set('Message-ID', "<$i\@example.com>");
         $mime->header_set('Subject', "subject = $i");
         ok($v2w->add($mime), "add msg $i OK");
 }
 $v2w->barrier;
-is(system('git', "--git-dir=$tmpdir/m/git/0.git", 'fetch', '-q'), 0,
-        'fetch successful');
+
+sub fetch_each_epoch {
+        foreach my $i (0..$epoch_max) {
+                my $dir = "$tmpdir/m/git/$i.git";
+                is(system('git', "--git-dir=$dir", 'fetch', '-q'), 0,
+                        'fetch successful');
+        }
+}
+
+fetch_each_epoch();
 
 my $mset = $mibx->search->reopen->query('m:15@example.com', {mset => 1});
 is(scalar($mset->items), 0, 'new message not found in mirror, yet');
@@ -131,8 +148,7 @@ like($to_purge, qr/\A[a-f0-9]{40,}\z/, 'read blob to be purged');
 $mset = $ibx->search->reopen->query('m:10@example.com', {mset => 1});
 is(scalar($mset->items), 0, 'purged message gone from origin');
 
-is(system('git', "--git-dir=$tmpdir/m/git/0.git", 'fetch', '-q'), 0,
-        'fetch successful');
+fetch_each_epoch();
 {
         open my $err, '+>', "$tmpdir/index-err" or die "open: $!";
         my $ipid = fork;