search: split search indexing to a separate file

This makes organization easier and reduces the amount of code
loaded for a PSGI, mod_perl or CGI instance.

6 files changed, 379 insertions, 363 deletions

diff --git a/lib/PublicInbox/Search.pm b/lib/PublicInbox/Search.pm
index 580b79fc..753f5f3f 100644
--- a/lib/PublicInbox/Search.pm
+++ b/lib/PublicInbox/Search.pm
@@ -57,160 +57,20 @@ while (my ($k, $v) = each %all_pfx) {
 
 my $mail_query = Search::Xapian::Query->new(xpfx('type') . 'mail');
 
+sub xdir {
+        my (undef, $git_dir) = @_;
+        "$git_dir/public-inbox/xapian" . SCHEMA_VERSION;
+}
+
 sub new {
-        my ($class, $git_dir, $writable) = @_;
-        # allow concurrent versions for easier rollback:
-        my $dir = "$git_dir/public-inbox/xapian" . SCHEMA_VERSION;
-        my $db;
-
-        if ($writable) { # not used by the WWW interface
-                require Search::Xapian::WritableDatabase;
-                my $flag = Search::Xapian::DB_OPEN;
-                if ($writable == 1) {
-                        require File::Path;
-                        File::Path::mkpath($dir);
-                        $flag = Search::Xapian::DB_CREATE_OR_OPEN;
-                }
-                $db = Search::Xapian::WritableDatabase->new($dir, $flag);
-        } else {
-                $db = Search::Xapian::Database->new($dir);
-        }
+        my ($class, $git_dir) = @_;
+        my $dir = $class->xdir($git_dir);
+        my $db = Search::Xapian::Database->new($dir);
         bless { xdb => $db, git_dir => $git_dir }, $class;
 }
 
 sub reopen { $_[0]->{xdb}->reopen }
 
-sub add_message {
-        my ($self, $mime) = @_; # mime = Email::MIME object
-        my $db = $self->{xdb};
-
-        my $doc_id;
-        my $mid_orig = mid_clean($mime->header_obj->header('Message-ID'));
-        my $mid = mid_compressed($mid_orig);
-        my $was_ghost = 0;
-        my $ct_msg = $mime->header('Content-Type') || 'text/plain';
-
-        eval {
-                my $smsg = $self->lookup_message($mid);
-                my $doc;
-
-                if ($smsg) {
-                        $smsg->ensure_metadata;
-                        # convert a ghost to a regular message
-                        # it will also clobber any existing regular message
-                        $smsg->mime($mime);
-                        $doc = $smsg->{doc};
-
-                        my $type = xpfx('type');
-                        eval {
-                                $doc->remove_term($type . 'ghost');
-                                $was_ghost = 1;
-                        };
-
-                        # probably does not exist:
-                        eval { $doc->remove_term($type . 'mail') };
-                        $doc->add_term($type . 'mail');
-                }  else {
-                        $smsg = PublicInbox::SearchMsg->new($mime);
-                        $doc = $smsg->{doc};
-                        $doc->add_term(xpfx('mid') . $mid);
-                }
-
-                my $subj = $smsg->subject;
-
-                if (length $subj) {
-                        $doc->add_term(xpfx('subject') . $subj);
-
-                        my $path = subject_path($subj);
-                        $doc->add_term(xpfx('path') . mid_compressed($path));
-                }
-
-                my $from = $smsg->from_name;
-                my $date = $smsg->date;
-                my $ts = Search::Xapian::sortable_serialise($smsg->ts);
-                $doc->add_value(PublicInbox::Search::TS, $ts);
-
-                my $tg = $self->term_generator;
-
-                $tg->set_document($doc);
-                $tg->index_text($subj, 1, 'S') if $subj;
-                $tg->increase_termpos;
-                $tg->index_text($subj) if $subj;
-                $tg->increase_termpos;
-
-                $tg->index_text($smsg->from->format);
-                $tg->increase_termpos;
-
-                $mime->walk_parts(sub {
-                        my ($part) = @_;
-                        return if $part->subparts; # walk_parts already recurses
-                        my $ct = $part->content_type || $ct_msg;
-
-                        # account for filter bugs...
-                        $ct =~ m!\btext/plain\b!i or return;
-
-                        my (@orig, @quot);
-                        my $body = $part->body;
-                        $part->body_set('');
-                        my @lines = split(/\n/, $body);
-                        while (defined(my $l = shift @lines)) {
-                                if ($l =~ /^\s*>/) {
-                                        push @quot, $l;
-                                } else {
-                                        push @orig, $l;
-                                }
-                        }
-                        if (@quot) {
-                                $tg->index_text(join("\n", @quot), 0);
-                                @quot = ();
-                                $tg->increase_termpos;
-                        }
-                        if (@orig) {
-                                $tg->index_text(join("\n", @orig));
-                                @orig = ();
-                                $tg->increase_termpos;
-                        }
-                });
-
-                if ($was_ghost) {
-                        $doc_id = $smsg->doc_id;
-                        $self->link_message($smsg, 0);
-                        $doc->set_data($smsg->to_doc_data);
-                        $db->replace_document($doc_id, $doc);
-                } else {
-                        $self->link_message($smsg, 0);
-                        $doc->set_data($smsg->to_doc_data);
-                        $doc_id = $db->add_document($doc);
-                }
-        };
-
-        if ($@) {
-                warn "failed to index message <$mid_orig>: $@\n";
-                return undef;
-        }
-        $doc_id;
-}
-
-# returns deleted doc_id on success, undef on missing
-sub remove_message {
-        my ($self, $mid_orig) = @_;
-        my $db = $self->{xdb};
-        my $doc_id;
-        $mid_orig = mid_clean($mid_orig);
-        my $mid = mid_compressed($mid_orig);
-
-        eval {
-                $doc_id = $self->find_unique_doc_id('mid', $mid);
-                $db->delete_document($doc_id) if defined $doc_id;
-        };
-
-        if ($@) {
-                warn "failed to remove message <$mid_orig>: $@\n";
-                return undef;
-        }
-        $doc_id;
-}
-
 # read-only
 sub query {
         my ($self, $query_string, $opts) = @_;
@@ -300,32 +160,6 @@ sub qp {
         $self->{query_parser} = $qp;
 }
 
-sub term_generator { # write-only
-        my ($self) = @_;
-
-        my $tg = $self->{term_generator};
-        return $tg if $tg;
-
-        $tg = Search::Xapian::TermGenerator->new;
-        $tg->set_stemmer($self->stemmer);
-
-        $self->{term_generator} = $tg;
-}
-
-sub next_doc_id { $_[0]->{xdb}->get_lastdocid + 1 }
-
-# increments last_thread_id counter
-# returns a 64-bit integer represented as a hex string
-sub next_thread_id {
-        my ($self) = @_;
-        my $db = $self->{xdb};
-        my $last_thread_id = int($db->get_metadata('last_thread_id') || 0);
-
-        $db->set_metadata('last_thread_id', ++$last_thread_id);
-
-        $last_thread_id;
-}
-
 sub ts_range_processor {
         $_[0]->{tsrp} ||= Search::Xapian::NumberValueRangeProcessor->new(TS);
 }
@@ -334,76 +168,6 @@ sub date_range_processor {
         $_[0]->{drp} ||= Search::Xapian::DateValueRangeProcessor->new(TS);
 }
 
-sub link_message {
-        my ($self, $smsg, $is_ghost) = @_;
-
-        if ($is_ghost) {
-                $smsg->ensure_metadata;
-        } else {
-                $self->link_message_to_parents($smsg);
-        }
-}
-
-sub link_message_to_parents {
-        my ($self, $smsg) = @_;
-        my $doc = $smsg->{doc};
-        my $mid = mid_compressed($smsg->mid);
-        my $mime = $smsg->mime;
-        my $refs = $mime->header_obj->header('References');
-        my @refs = $refs ? ($refs =~ /<([^>]+)>/g) : ();
-        my $irt = $mime->header_obj->header('In-Reply-To');
-        if ($irt) {
-                $irt = mid_compressed(mid_clean($irt));
-
-                # maybe some crazies will try to make a circular reference:
-                if ($irt eq $mid) {
-                        $irt = undef;
-                } else {
-                        # last References should be $irt
-                        # we will de-dupe later
-                        push @refs, $irt;
-                }
-        }
-
-        my $tid;
-        if (@refs) {
-                my @crefs = map { mid_compressed($_) } @refs;
-                my %uniq = ($mid => 1);
-
-                # prevent circular references via References: here:
-                @refs = ();
-                foreach my $ref (@crefs) {
-                        next if $uniq{$ref};
-                        $uniq{$ref} = 1;
-                        push @refs, $ref;
-                }
-        }
-        if (@refs) {
-                $doc->add_term(xpfx('inreplyto') . $irt) if defined $irt;
-                $smsg->{references_sorted} = '<'.join('><', @refs).'>';
-
-                my $ref_pfx = xpfx('references');
-
-                # first ref *should* be the thread root,
-                # but we can never trust clients to do the right thing
-                my $ref = shift @refs;
-                $doc->add_term($ref_pfx . $ref);
-                $tid = $self->_resolve_mid_to_tid($ref);
-
-                # the rest of the refs should point to this tid:
-                foreach $ref (@refs) {
-                        $doc->add_term($ref_pfx . $ref);
-                        my $ptid = $self->_resolve_mid_to_tid($ref);
-                        if ($tid ne $ptid) {
-                                $self->merge_threads($tid, $ptid);
-                        }
-                }
-        } else {
-                $tid = $self->next_thread_id;
-        }
-        $doc->add_term(xpfx('thread') . $tid);
-}
-
 sub lookup_message {
         my ($self, $mid) = @_;
         $mid = mid_clean($mid);
@@ -450,47 +214,6 @@ sub find_doc_ids_for_term {
         ($db->postlist_begin($term), $db->postlist_end($term));
 }
 
-# this will create a ghost as necessary
-sub _resolve_mid_to_tid {
-        my ($self, $mid) = @_;
-
-        my $smsg = $self->lookup_message($mid) || $self->create_ghost($mid);
-        $smsg->thread_id;
-}
-
-sub create_ghost {
-        my ($self, $mid, $tid) = @_;
-
-        $mid = mid_compressed($mid);
-        $tid = $self->next_thread_id unless defined $tid;
-
-        my $doc = Search::Xapian::Document->new;
-        $doc->add_term(xpfx('mid') . $mid);
-        $doc->add_term(xpfx('thread') . $tid);
-        $doc->add_term(xpfx('type') . 'ghost');
-
-        my $smsg = PublicInbox::SearchMsg->wrap($doc, $mid);
-        $self->link_message($smsg, 1);
-        $self->{xdb}->add_document($doc);
-
-        $smsg;
-}
-
-sub merge_threads {
-        my ($self, $winner_tid, $loser_tid) = @_;
-        my ($head, $tail) = $self->find_doc_ids('thread', $loser_tid);
-        my $thread_pfx = xpfx('thread');
-        my $db = $self->{xdb};
-
-        for (; $head != $tail; $head->inc) {
-                my $docid = $head->get_docid;
-                my $doc = $db->get_document($docid);
-                $doc->remove_term($thread_pfx . $loser_tid);
-                $doc->add_term($thread_pfx . $winner_tid);
-                $db->replace_document($docid, $doc);
-        }
-}
-
 # normalize subjects so they are suitable as pathnames for URLs
 sub subject_path {
         my $subj = pop;
@@ -509,79 +232,9 @@ sub subject_normalized {
         $subj;
 }
 
-sub do_cat_mail {
-        my ($git, $blob) = @_;
-        my $mime = eval {
-                my $str = $git->cat_file($blob);
-                Email::MIME->new($str);
-        };
-        $@ ? undef : $mime;
-}
-
-sub index_blob {
-        my ($self, $git, $blob) = @_;
-        my $mime = do_cat_mail($git, $blob) or return;
-        eval { $self->add_message($mime) };
-        warn "W: index_blob $blob: $@\n" if $@;
-}
-
-sub unindex_blob {
-        my ($self, $git, $blob) = @_;
-        my $mime = do_cat_mail($git, $blob) or return;
-        my $mid = $mime->header_obj->header('Message-ID');
-        eval { $self->remove_message($mid) } if defined $mid;
-        warn "W: unindex_blob $blob: $@\n" if $@;
-}
-
 sub enquire {
         my ($self) = @_;
         $self->{enquire} ||= Search::Xapian::Enquire->new($self->{xdb});
 }
 
-# indexes all unindexed messages
-sub index_sync {
-        my ($self, $head) = @_;
-        require PublicInbox::GitCatFile;
-        my $db = $self->{xdb};
-        my $hex = '[a-f0-9]';
-        my $h40 = $hex .'{40}';
-        my $addmsg = qr!^:000000 100644 \S+ ($h40) A\t${hex}{2}/${hex}{38}$!;
-        my $delmsg = qr!^:100644 000000 ($h40) \S+ D\t${hex}{2}/${hex}{38}$!;
-        $head ||= 'HEAD';
-
-        $db->begin_transaction;
-        eval {
-                my $git = PublicInbox::GitCatFile->new($self->{git_dir});
-
-                my $latest = $db->get_metadata('last_commit');
-                my $range = length $latest ? "$latest..$head" : $head;
-                $latest = undef;
-
-                # get indexed messages
-                my @cmd = ('git', "--git-dir=$self->{git_dir}", "log",
-                            qw/--reverse --no-notes --no-color --raw -r
-                               --no-abbrev/, $range);
-                my $pid = open(my $log, '-|', @cmd) or
-                        die('open` '.join(' ', @cmd) . " pipe failed: $!\n");
-
-                while (my $line = <$log>) {
-                        if ($line =~ /$addmsg/o) {
-                                $self->index_blob($git, $1);
-                        } elsif ($line =~ /$delmsg/o) {
-                                $self->unindex_blob($git, $1);
-                        } elsif ($line =~ /^commit ($h40)/o) {
-                                $latest = $1;
-                        }
-                }
-                close $log;
-                $db->set_metadata('last_commit', $latest) if defined $latest;
-        };
-        if ($@) {
-                warn "indexing failed: $@\n";
-                $db->cancel_transaction;
-        } else {
-                $db->commit_transaction;
-        }
-}
-
 1;
diff --git a/lib/PublicInbox/SearchIdx.pm b/lib/PublicInbox/SearchIdx.pm
new file mode 100644
index 00000000..408b21fd
--- /dev/null
+++ b/lib/PublicInbox/SearchIdx.pm
@@ -0,0 +1,363 @@
+# Copyright (C) 2015, all contributors <meta@public-inbox.org>
+# License: AGPLv3 or later (https://www.gnu.org/licenses/agpl-3.0.txt)
+# based on notmuch, but with no concept of folders, files or flags
+package PublicInbox::SearchIdx;
+use strict;
+use warnings;
+use base qw(PublicInbox::Search);
+use PublicInbox::MID qw/mid_clean mid_compressed/;
+*xpfx = *PublicInbox::Search::xpfx;
+
+sub new {
+        my ($class, $git_dir, $writable) = @_;
+        my $dir = $class->xdir($git_dir);
+        require Search::Xapian::WritableDatabase;
+        my $flag = Search::Xapian::DB_OPEN;
+        if ($writable == 1) {
+                require File::Path;
+                File::Path::mkpath($dir);
+                $flag = Search::Xapian::DB_CREATE_OR_OPEN;
+        }
+        my $db = Search::Xapian::WritableDatabase->new($dir, $flag);
+        bless { xdb => $db, git_dir => $git_dir }, $class;
+}
+
+sub add_message {
+        my ($self, $mime) = @_; # mime = Email::MIME object
+        my $db = $self->{xdb};
+
+        my $doc_id;
+        my $mid_orig = mid_clean($mime->header_obj->header('Message-ID'));
+        my $mid = mid_compressed($mid_orig);
+        my $was_ghost = 0;
+        my $ct_msg = $mime->header('Content-Type') || 'text/plain';
+
+        eval {
+                my $smsg = $self->lookup_message($mid);
+                my $doc;
+
+                if ($smsg) {
+                        $smsg->ensure_metadata;
+                        # convert a ghost to a regular message
+                        # it will also clobber any existing regular message
+                        $smsg->mime($mime);
+                        $doc = $smsg->{doc};
+
+                        my $type = xpfx('type');
+                        eval {
+                                $doc->remove_term($type . 'ghost');
+                                $was_ghost = 1;
+                        };
+
+                        # probably does not exist:
+                        eval { $doc->remove_term($type . 'mail') };
+                        $doc->add_term($type . 'mail');
+                }  else {
+                        $smsg = PublicInbox::SearchMsg->new($mime);
+                        $doc = $smsg->{doc};
+                        $doc->add_term(xpfx('mid') . $mid);
+                }
+
+                my $subj = $smsg->subject;
+
+                if (length $subj) {
+                        $doc->add_term(xpfx('subject') . $subj);
+
+                        my $path = $self->subject_path($subj);
+                        $doc->add_term(xpfx('path') . mid_compressed($path));
+                }
+
+                my $from = $smsg->from_name;
+                my $date = $smsg->date;
+                my $ts = Search::Xapian::sortable_serialise($smsg->ts);
+                $doc->add_value(PublicInbox::Search::TS, $ts);
+
+                my $tg = $self->term_generator;
+
+                $tg->set_document($doc);
+                $tg->index_text($subj, 1, 'S') if $subj;
+                $tg->increase_termpos;
+                $tg->index_text($subj) if $subj;
+                $tg->increase_termpos;
+
+                $tg->index_text($smsg->from->format);
+                $tg->increase_termpos;
+
+                $mime->walk_parts(sub {
+                        my ($part) = @_;
+                        return if $part->subparts; # walk_parts already recurses
+                        my $ct = $part->content_type || $ct_msg;
+
+                        # account for filter bugs...
+                        $ct =~ m!\btext/plain\b!i or return;
+
+                        my (@orig, @quot);
+                        my $body = $part->body;
+                        $part->body_set('');
+                        my @lines = split(/\n/, $body);
+                        while (defined(my $l = shift @lines)) {
+                                if ($l =~ /^\s*>/) {
+                                        push @quot, $l;
+                                } else {
+                                        push @orig, $l;
+                                }
+                        }
+                        if (@quot) {
+                                $tg->index_text(join("\n", @quot), 0);
+                                @quot = ();
+                                $tg->increase_termpos;
+                        }
+                        if (@orig) {
+                                $tg->index_text(join("\n", @orig));
+                                @orig = ();
+                                $tg->increase_termpos;
+                        }
+                });
+
+                if ($was_ghost) {
+                        $doc_id = $smsg->doc_id;
+                        $self->link_message($smsg, 0);
+                        $doc->set_data($smsg->to_doc_data);
+                        $db->replace_document($doc_id, $doc);
+                } else {
+                        $self->link_message($smsg, 0);
+                        $doc->set_data($smsg->to_doc_data);
+                        $doc_id = $db->add_document($doc);
+                }
+        };
+
+        if ($@) {
+                warn "failed to index message <$mid_orig>: $@\n";
+                return undef;
+        }
+        $doc_id;
+}
+
+# returns deleted doc_id on success, undef on missing
+sub remove_message {
+        my ($self, $mid_orig) = @_;
+        my $db = $self->{xdb};
+        my $doc_id;
+        $mid_orig = mid_clean($mid_orig);
+        my $mid = mid_compressed($mid_orig);
+
+        eval {
+                $doc_id = $self->find_unique_doc_id('mid', $mid);
+                $db->delete_document($doc_id) if defined $doc_id;
+        };
+
+        if ($@) {
+                warn "failed to remove message <$mid_orig>: $@\n";
+                return undef;
+        }
+        $doc_id;
+}
+
+sub term_generator { # write-only
+        my ($self) = @_;
+
+        my $tg = $self->{term_generator};
+        return $tg if $tg;
+
+        $tg = Search::Xapian::TermGenerator->new;
+        $tg->set_stemmer($self->stemmer);
+
+        $self->{term_generator} = $tg;
+}
+
+sub next_doc_id { $_[0]->{xdb}->get_lastdocid + 1 }
+
+# increments last_thread_id counter
+# returns a 64-bit integer represented as a hex string
+sub next_thread_id {
+        my ($self) = @_;
+        my $db = $self->{xdb};
+        my $last_thread_id = int($db->get_metadata('last_thread_id') || 0);
+
+        $db->set_metadata('last_thread_id', ++$last_thread_id);
+
+        $last_thread_id;
+}
+
+sub link_message {
+        my ($self, $smsg, $is_ghost) = @_;
+
+        if ($is_ghost) {
+                $smsg->ensure_metadata;
+        } else {
+                $self->link_message_to_parents($smsg);
+        }
+}
+
+sub link_message_to_parents {
+        my ($self, $smsg) = @_;
+        my $doc = $smsg->{doc};
+        my $mid = mid_compressed($smsg->mid);
+        my $mime = $smsg->mime;
+        my $refs = $mime->header_obj->header('References');
+        my @refs = $refs ? ($refs =~ /<([^>]+)>/g) : ();
+        my $irt = $mime->header_obj->header('In-Reply-To');
+        if ($irt) {
+                $irt = mid_compressed(mid_clean($irt));
+
+                # maybe some crazies will try to make a circular reference:
+                if ($irt eq $mid) {
+                        $irt = undef;
+                } else {
+                        # last References should be $irt
+                        # we will de-dupe later
+                        push @refs, $irt;
+                }
+        }
+
+        my $tid;
+        if (@refs) {
+                my @crefs = map { mid_compressed($_) } @refs;
+                my %uniq = ($mid => 1);
+
+                # prevent circular references via References: here:
+                @refs = ();
+                foreach my $ref (@crefs) {
+                        next if $uniq{$ref};
+                        $uniq{$ref} = 1;
+                        push @refs, $ref;
+                }
+        }
+        if (@refs) {
+                $doc->add_term(xpfx('inreplyto') . $irt) if defined $irt;
+                $smsg->{references_sorted} = '<'.join('><', @refs).'>';
+
+                my $ref_pfx = xpfx('references');
+
+                # first ref *should* be the thread root,
+                # but we can never trust clients to do the right thing
+                my $ref = shift @refs;
+                $doc->add_term($ref_pfx . $ref);
+                $tid = $self->_resolve_mid_to_tid($ref);
+
+                # the rest of the refs should point to this tid:
+                foreach $ref (@refs) {
+                        $doc->add_term($ref_pfx . $ref);
+                        my $ptid = $self->_resolve_mid_to_tid($ref);
+                        if ($tid ne $ptid) {
+                                $self->merge_threads($tid, $ptid);
+                        }
+                }
+        } else {
+                $tid = $self->next_thread_id;
+        }
+        $doc->add_term(xpfx('thread') . $tid);
+}
+
+sub index_blob {
+        my ($self, $git, $blob) = @_;
+        my $mime = do_cat_mail($git, $blob) or return;
+        eval { $self->add_message($mime) };
+        warn "W: index_blob $blob: $@\n" if $@;
+}
+
+sub unindex_blob {
+        my ($self, $git, $blob) = @_;
+        my $mime = do_cat_mail($git, $blob) or return;
+        my $mid = $mime->header_obj->header('Message-ID');
+        eval { $self->remove_message($mid) } if defined $mid;
+        warn "W: unindex_blob $blob: $@\n" if $@;
+}
+
+sub do_cat_mail {
+        my ($git, $blob) = @_;
+        my $mime = eval {
+                my $str = $git->cat_file($blob);
+                Email::MIME->new($str);
+        };
+        $@ ? undef : $mime;
+}
+
+# indexes all unindexed messages
+sub index_sync {
+        my ($self, $head) = @_;
+        require PublicInbox::GitCatFile;
+        my $db = $self->{xdb};
+        my $hex = '[a-f0-9]';
+        my $h40 = $hex .'{40}';
+        my $addmsg = qr!^:000000 100644 \S+ ($h40) A\t${hex}{2}/${hex}{38}$!;
+        my $delmsg = qr!^:100644 000000 ($h40) \S+ D\t${hex}{2}/${hex}{38}$!;
+        $head ||= 'HEAD';
+
+        $db->begin_transaction;
+        eval {
+                my $git = PublicInbox::GitCatFile->new($self->{git_dir});
+
+                my $latest = $db->get_metadata('last_commit');
+                my $range = length $latest ? "$latest..$head" : $head;
+                $latest = undef;
+
+                # get indexed messages
+                my @cmd = ('git', "--git-dir=$self->{git_dir}", "log",
+                            qw/--reverse --no-notes --no-color --raw -r
+                               --no-abbrev/, $range);
+                my $pid = open(my $log, '-|', @cmd) or
+                        die('open` '.join(' ', @cmd) . " pipe failed: $!\n");
+
+                while (my $line = <$log>) {
+                        if ($line =~ /$addmsg/o) {
+                                $self->index_blob($git, $1);
+                        } elsif ($line =~ /$delmsg/o) {
+                                $self->unindex_blob($git, $1);
+                        } elsif ($line =~ /^commit ($h40)/o) {
+                                $latest = $1;
+                        }
+                }
+                close $log;
+                $db->set_metadata('last_commit', $latest) if defined $latest;
+        };
+        if ($@) {
+                warn "indexing failed: $@\n";
+                $db->cancel_transaction;
+        } else {
+                $db->commit_transaction;
+        }
+}
+
+# this will create a ghost as necessary
+sub _resolve_mid_to_tid {
+        my ($self, $mid) = @_;
+
+        my $smsg = $self->lookup_message($mid) || $self->create_ghost($mid);
+        $smsg->thread_id;
+}
+
+sub create_ghost {
+        my ($self, $mid, $tid) = @_;
+
+        $mid = mid_compressed($mid);
+        $tid = $self->next_thread_id unless defined $tid;
+
+        my $doc = Search::Xapian::Document->new;
+        $doc->add_term(xpfx('mid') . $mid);
+        $doc->add_term(xpfx('thread') . $tid);
+        $doc->add_term(xpfx('type') . 'ghost');
+
+        my $smsg = PublicInbox::SearchMsg->wrap($doc, $mid);
+        $self->link_message($smsg, 1);
+        $self->{xdb}->add_document($doc);
+
+        $smsg;
+}
+
+sub merge_threads {
+        my ($self, $winner_tid, $loser_tid) = @_;
+        my ($head, $tail) = $self->find_doc_ids('thread', $loser_tid);
+        my $thread_pfx = xpfx('thread');
+        my $db = $self->{xdb};
+
+        for (; $head != $tail; $head->inc) {
+                my $docid = $head->get_docid;
+                my $doc = $db->get_document($docid);
+                $doc->remove_term($thread_pfx . $loser_tid);
+                $doc->add_term($thread_pfx . $winner_tid);
+                $db->replace_document($docid, $doc);
+        }
+}
+
+1;
diff --git a/public-inbox-index b/public-inbox-index
index 1104bbc8..f39ad9e1 100755
--- a/public-inbox-index
+++ b/public-inbox-index
@@ -10,7 +10,7 @@ use strict;
 use warnings;
 my $usage = "public-inbox-index GIT_DIR";
 use PublicInbox::Config;
-eval { require PublicInbox::Search };
+eval { require PublicInbox::SearchIdx };
 if ($@) {
         print STDERR "Search::Xapian required for $0\n";
         exit 1;
@@ -26,6 +26,6 @@ foreach my $dir (@ARGV) {
 sub index_dir {
         my ($git_dir) = @_;
         -d $git_dir or die "$git_dir does not appear to be a git repository\n";
-        my $s = PublicInbox::Search->new($git_dir, 1);
+        my $s = PublicInbox::SearchIdx->new($git_dir, 1);
         $s->index_sync;
 }
diff --git a/public-inbox-learn b/public-inbox-learn
index bd592471..c89ffb54 100755
--- a/public-inbox-learn
+++ b/public-inbox-learn
@@ -78,9 +78,9 @@ foreach my $recipient (keys %dests) {
         }
 
         $err or eval {
-                require PublicInbox::Search;
+                require PublicInbox::SearchIdx;
                 umask 0022; # XXX FIXME use git config core.sharedRepository
-                my $s = PublicInbox::Search->new($git_dir, 2);
+                my $s = PublicInbox::SearchIdx->new($git_dir, 2);
                 $s->index_sync;
         };
 }
diff --git a/public-inbox-mda b/public-inbox-mda
index a3c959ac..630ffcb9 100755
--- a/public-inbox-mda
+++ b/public-inbox-mda
@@ -90,7 +90,7 @@ sub search_index_sync {
         eval {
                 require PublicInbox::Search;
                 umask 0022; # XXX FIXME use git config core.sharedRepository
-                my $s = PublicInbox::Search->new($git_dir, 2);
+                my $s = PublicInbox::SearchIdx->new($git_dir, 2);
                 $s->index_sync;
         };
 }
diff --git a/t/search.t b/t/search.t
index 89a28629..be39410f 100644
--- a/t/search.t
+++ b/t/search.t
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use Test::More;
-eval { require PublicInbox::Search; };
+eval { require PublicInbox::SearchIdx; };
 plan skip_all => "Xapian missing for search" if $@;
 use File::Temp qw/tempdir/;
 use Email::MIME;
@@ -16,11 +16,11 @@ is(0, system(qw(git init -q --bare), $git_dir), "git init (main)");
 eval { PublicInbox::Search->new($git_dir) };
 ok($@, "exception raised on non-existent DB");
 
-my $rw = PublicInbox::Search->new($git_dir, 1);
+my $rw = PublicInbox::SearchIdx->new($git_dir, 1);
 my $ro = PublicInbox::Search->new($git_dir);
 my $rw_commit = sub {
         $rw = undef;
-        $rw = PublicInbox::Search->new($git_dir, 1);
+        $rw = PublicInbox::SearchIdx->new($git_dir, 1);
 };
 
 {