www: support cloning individual v2 git partitions

This will require multiple client invocations, but should reduce
load on the server and make it easier for readers to only clone
the latest data.

Unfortunately, supporting a cloneurl file for externally-hosted
repos will be more difficult as we cannot easily know if the
clones use v1 or v2 repositories, or how many git partitions
they have.

1 files changed, 36 insertions, 1 deletions

diff --git a/lib/PublicInbox/Inbox.pm b/lib/PublicInbox/Inbox.pm
index b1ea8dc7..30977514 100644
--- a/lib/PublicInbox/Inbox.pm
+++ b/lib/PublicInbox/Inbox.pm
@@ -82,6 +82,18 @@ sub new {
         bless $opts, $class;
 }
 
+sub git_part {
+        my ($self, $part) = @_;
+        ($self->{version} || 1) == 2 or return;
+        $self->{"$part.git"} ||= eval {
+                my $git_dir = "$self->{mainrepo}/git/$part.git";
+                my $g = PublicInbox::Git->new($git_dir);
+                $g->{-httpbackend_limiter} = $self->{-httpbackend_limiter};
+                # no cleanup needed, we never cat-file off this, only clone
+                $g;
+        };
+}
+
 sub git {
         my ($self) = @_;
         $self->{git} ||= eval {
@@ -94,6 +106,29 @@ sub git {
         };
 }
 
+sub max_git_part {
+        my ($self) = @_;
+        my $v = $self->{version};
+        return unless defined($v) && $v == 2;
+        my $part = $self->{-max_git_part};
+        my $changed = git($self)->alternates_changed;
+        if (!defined($part) || $changed) {
+                $self->git->cleanup if $changed;
+                my $gits = "$self->{mainrepo}/git";
+                if (opendir my $dh, $gits) {
+                        my $max = -1;
+                        while (defined(my $git_dir = readdir($dh))) {
+                                $git_dir =~ m!\A(\d+)\.git\z! or next;
+                                $max = $1 if $1 > $max;
+                        }
+                        $part = $self->{-max_git_part} = $max if $max >= 0;
+                } else {
+                        warn "opendir $gits failed: $!\n";
+                }
+        }
+        $part;
+}
+
 sub mm {
         my ($self) = @_;
         $self->{mm} ||= eval {
@@ -133,7 +168,7 @@ sub description {
         local $/ = "\n";
         chomp $desc;
         $desc =~ s/\s+/ /smg;
-        $desc = '($GIT_DIR/description missing)' if $desc eq '';
+        $desc = '($REPO_DIR/description missing)' if $desc eq '';
         $self->{description} = $desc;
 }