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, 6 insertions, 8 deletions

diff --git a/lib/PublicInbox/LeiSearch.pm b/lib/PublicInbox/LeiSearch.pm
index 66c16e04..0b962b11 100644
--- a/lib/PublicInbox/LeiSearch.pm
+++ b/lib/PublicInbox/LeiSearch.pm
@@ -7,20 +7,18 @@ use v5.10.1;
 use parent qw(PublicInbox::ExtSearch);
 use PublicInbox::Search;
 
-sub combined_docid ($$) {
+# get combined docid from over.num:
+# (not generic Xapian, only works with our sharding scheme)
+sub num2docid ($$) {
         my ($self, $num) = @_;
-        ($num - 1) * $self->{nshard} + 1;
+        my $nshard = $self->{nshard};
+        ($num - 1) * $nshard + $num % $nshard + 1;
 }
 
 sub msg_keywords {
         my ($self, $num) = @_; # num_or_mitem
         my $xdb = $self->xdb; # set {nshard};
-        my $docid = ref($num) ? $num->get_docid : do {
-                # get combined docid from over.num:
-                # (not generic Xapian, only works with our sharding scheme)
-                my $nshard = $self->{nshard};
-                ($num - 1) * $nshard + $num % $nshard + 1;
-        };
+        my $docid = ref($num) ? $num->get_docid : num2docid($self, $num);
         my %kw;
         eval {
                 my $end = $xdb->termlist_end($docid);