lei_xsearch: cross-(inbox|extindex) search

While a single extindex combines multiple inboxes into a single
search index, extindex still requires up-front indexing on items
which can be searched.  XSearch has no on-disk footprint itself
and uses Xapian DBs of existing publicinbox and extindex
("extinbox") exclusively.

XSearch still suffers from the multi-shard Xapian scalability
problems which led to the creation of extindex, but I expect the
number of shards to remain relatively low.

I envision users hosting public-inbox instances on their
workstations will only have two extindex combined by this, one
read-only extindex for serving public archives, and one
read-write extindex managed by LeiStore for private mail.

1 files changed, 7 insertions, 12 deletions

diff --git a/lib/PublicInbox/Search.pm b/lib/PublicInbox/Search.pm
index bbc5e32f..bca2036c 100644
--- a/lib/PublicInbox/Search.pm
+++ b/lib/PublicInbox/Search.pm
@@ -196,6 +196,7 @@ sub xdb_shards_flat ($) {
         my ($self) = @_;
         my $xpfx = $self->{xpfx};
         my (@xdb, $slow_phrase);
+        load_xapian();
         if ($xpfx =~ m/xapian${\SCHEMA_VERSION}\z/) {
                 @xdb = ($X{Database}->new($xpfx));
                 $self->{qp_flags} |= FLAG_PHRASE() if !-f "$xpfx/iamchert";
@@ -214,16 +215,6 @@ sub xdb_shards_flat ($) {
         @xdb;
 }
 
-sub _xdb {
-        my ($self) = @_;
-        $self->{qp_flags} //= $QP_FLAGS;
-        my @xdb = xdb_shards_flat($self) or return;
-        $self->{nshard} = scalar(@xdb);
-        my $xdb = shift @xdb;
-        $xdb->add_database($_) for @xdb;
-        $xdb;
-}
-
 # v2 Xapian docids don't conflict, so they're identical to
 # NNTP article numbers and IMAP UIDs.
 # https://trac.xapian.org/wiki/FAQ/MultiDatabaseDocumentID
@@ -242,8 +233,12 @@ sub mset_to_artnums {
 sub xdb ($) {
         my ($self) = @_;
         $self->{xdb} //= do {
-                load_xapian();
-                $self->_xdb;
+                $self->{qp_flags} //= $QP_FLAGS;
+                my @xdb = $self->xdb_shards_flat or return;
+                $self->{nshard} = scalar(@xdb);
+                my $xdb = shift @xdb;
+                $xdb->add_database($_) for @xdb;
+                $xdb;
         };
 }