[PATCH 3/5] searchidx: sync Msgmap database along with Xapian

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

We can avoid duplicating work of extracting messages from git if we
tie this to Xapian.  Of course, this ties the two features together,
but it's probably reasonable to expect that anybody who wants to use
public-inbox to serve messages to front-end users will have both.
---
 lib/PublicInbox/SearchIdx.pm | 84 ++++++++++++++++++++++++++++++++++----------
 1 file changed, 66 insertions(+), 18 deletions(-)

diff --git a/lib/PublicInbox/SearchIdx.pm b/lib/PublicInbox/SearchIdx.pm
index 44f6bc1..351450c 100644
--- a/lib/PublicInbox/SearchIdx.pm
+++ b/lib/PublicInbox/SearchIdx.pm
@@ -247,18 +247,36 @@ sub link_message_to_parents {
 }
 
 sub index_blob {
-	my ($self, $git, $blob) = @_;
-	my $mime = do_cat_mail($git, $blob) or return;
-	eval { $self->add_message($mime) };
-	warn "W: index_blob $blob: $@\n" if $@;
+	my ($self, $git, $mime) = @_;
+	$self->add_message($mime);
 }
 
 sub unindex_blob {
-	my ($self, $git, $blob) = @_;
-	my $mime = do_cat_mail($git, $blob) or return;
-	my $mid = $mime->header('Message-ID');
-	eval { $self->remove_message($mid) } if defined $mid;
-	warn "W: unindex_blob $blob: $@\n" if $@;
+	my ($self, $git, $mime) = @_;
+	my $mid = mid_clean($mime->header('Message-ID'));
+	$self->remove_message($mid) if defined $mid;
+}
+
+sub index_mm {
+	my ($self, $git, $mime) = @_;
+	$self->{mm}->mid_insert(mid_clean($mime->header('Message-ID')));
+}
+
+sub unindex_mm {
+	my ($self, $git, $mime) = @_;
+	$self->{mm}->mid_delete(mid_clean($mime->header('Message-ID')));
+}
+
+sub index_both {
+	my ($self, $git, $mime) = @_;
+	index_blob($self, $git, $mime);
+	index_mm($self, $git, $mime);
+}
+
+sub unindex_both {
+	my ($self, $git, $mime) = @_;
+	unindex_blob($self, $git, $mime);
+	unindex_mm($self, $git, $mime);
 }
 
 sub do_cat_mail {
@@ -292,9 +310,11 @@ sub rlog {
 		die('open` '.join(' ', @cmd) . " pipe failed: $!\n");
 	while (my $line = <$log>) {
 		if ($line =~ /$addmsg/o) {
-			$add_cb->($self, $git, $1);
+			my $mime = do_cat_mail($git, $1) or next;
+			$add_cb->($self, $git, $mime);
 		} elsif ($line =~ /$delmsg/o) {
-			$del_cb->($self, $git, $1);
+			my $mime = do_cat_mail($git, $1) or next;
+			$del_cb->($self, $git, $mime);
 		} elsif ($line =~ /^commit ($h40)/o) {
 			$latest = $1;
 		}
@@ -308,17 +328,45 @@ sub _index_sync {
 	my ($self, $head) = @_;
 	my $db = $self->{xdb};
 	$head ||= 'HEAD';
+	my $mm = $self->{mm} = eval {
+		require PublicInbox::Msgmap;
+		PublicInbox::Msgmap->new($self->{git_dir}, 1);
+	};
 
 	$db->begin_transaction;
-	eval {
-		my $latest = $db->get_metadata('last_commit');
-		my $range = $latest eq '' ? $head : "$latest..$head";
-		$latest = $self->rlog($range, *index_blob, *unindex_blob);
-		$db->set_metadata('last_commit', $latest) if defined $latest;
-	};
+	my $lx = $db->get_metadata('last_commit');
+	my $range = $lx eq '' ? $head : "$lx..$head";
+	if ($mm) {
+		$mm->{dbh}->begin_work;
+		my $lm = $mm->last_commit || '';
+		if ($lm eq $lx) {
+			# Common case is the indexes are synced,
+			# we only need to run git-log once:
+			$lx = $self->rlog($range, *index_both, *unindex_both);
+			$mm->{dbh}->commit;
+			if (defined $lx) {
+				$db->set_metadata('last_commit', $lx);
+				$mm->last_commit($lx);
+			}
+		} else {
+			# dumb case, msgmap and xapian are out-of-sync
+			# do not care for performance:
+			my $r = $lm eq '' ? $head : "$lm..$head";
+			$lm = $self->rlog($r, *index_mm, *unindex_mm);
+			$mm->{dbh}->commit;
+			$mm->last_commit($lm) if defined $lm;
+
+			goto xapian_only;
+		}
+	} else {
+		# user didn't install DBD::SQLite and DBI
+xapian_only:
+		$lx = $self->rlog($range, *index_blob, *unindex_blob);
+		$db->set_metadata('last_commit', $lx) if defined $lx;
+	}
 	if ($@) {
-		warn "indexing failed: $@\n";
 		$db->cancel_transaction;
+		$mm->{dbh}->rollback if $mm;
 	} else {
 		$db->commit_transaction;
 	}
-- 
EW