[RFC] inbox: add `modified' sub

[Eric Wong <e@80x24.org>]

For inboxes with SQLite enabled (all v2, and probably most v1);
stat-ing the msgmap.sqlite3 file is a much faster way of telling
when an inbox is modified compared to scanning git branches.
---
 RFC since I'm not so sure about this one.  It's probably fine,
 but mtime may be worth considering over ctime, too...
 (somebody could be using atomic-rsync on the SQLite and Xapian
  stuff because indexing is slow)

 lib/PublicInbox/Inbox.pm | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/lib/PublicInbox/Inbox.pm b/lib/PublicInbox/Inbox.pm
index cde4625..fa41ab6 100644
--- a/lib/PublicInbox/Inbox.pm
+++ b/lib/PublicInbox/Inbox.pm
@@ -333,4 +333,18 @@ sub recent {
 	search($self)->{over_ro}->recent($opts, $after, $before);
 }
 
+sub modified {
+	my ($self) = @_;
+	my $dir = $self->{mainrepo};
+	my @st;
+	if ($self->{version} >= 2) {
+		@st = stat("$dir/msgmap.sqlite3")
+	} elsif (-f "$dir/public-inbox/msgmap.sqlite3") { # v1
+		@st = stat(_);
+	} else { # v1 repos did not need sqlite3
+		return git($self)->modified;
+	}
+	@st ? $st[10] : time; # 10: ctime
+}
+
 1;
-- 
EW