initial search backend implementation

This shall allow us to search for replies/threads more easily.

2 files changed, 644 insertions, 0 deletions

diff --git a/lib/PublicInbox/Search.pm b/lib/PublicInbox/Search.pm
new file mode 100644
index 00000000..fe4984e5
--- /dev/null
+++ b/lib/PublicInbox/Search.pm
@@ -0,0 +1,539 @@
+# 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::Search;
+use strict;
+use warnings;
+use PublicInbox::SearchMsg;
+use base qw/Exporter/;
+use Digest::SHA qw//;
+use Search::Xapian qw/:standard/;
+require PublicInbox::View;
+use Date::Parse qw/str2time/;
+use POSIX qw//;
+use Email::MIME;
+
+our @EXPORT = qw/xpfx mid_compressed/;
+
+use constant {
+        TS => 0,
+        SHA1HEX_LEN => 40,
+        SCHEMA_VERSION => 0,
+        LANG => 'english',
+        QP_FLAGS => FLAG_PHRASE|FLAG_BOOLEAN|FLAG_LOVEHATE|FLAG_WILDCARD,
+};
+
+use constant MID_MAX => SHA1HEX_LEN;
+
+# setup prefixes
+my %bool_pfx_internal = (
+        type => 'T', # "mail" or "ghost"
+        mid => 'Q', # uniQue id (Message-ID or mid_compressed)
+);
+
+my %bool_pfx_external = (
+        path => 'XPATH',
+        thread => 'G', # newsGroup (or similar entity - e.g. a web forum name)
+        references => 'XREFS',
+        inreplyto => 'XIRT',
+);
+
+my %prob_prefix = (
+        subject => 'S',
+);
+
+my %all_pfx = (%bool_pfx_internal, %bool_pfx_external, %prob_prefix);
+
+sub xpfx { $all_pfx{$_[0]} }
+
+our %PFX2TERM_RMAP;
+while (my ($k, $v) = each %all_pfx) {
+        next if $prob_prefix{$k};
+        $PFX2TERM_RMAP{$v} = $k;
+}
+
+my $mail_query = Search::Xapian::Query->new(xpfx('type') . 'mail');
+
+# this is idempotent
+sub mid_compressed {
+        my ($mid) = @_;
+        return $mid if (length($mid) <= MID_MAX);
+        Digest::SHA::sha1_hex($mid);
+}
+
+sub new {
+        my ($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;
+                require File::Path;
+                File::Path::mkpath($dir);
+                $db = Search::Xapian::WritableDatabase->new($dir,
+                                        Search::Xapian::DB_CREATE_OR_OPEN);
+        } else {
+                $db = Search::Xapian::Database->new($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 $mid = clean_mid($mime->header('Message-ID'));
+        $mid = mid_compressed($mid);
+        my $was_ghost = 0;
+        my $ct_msg = $mime->header('Content-Type') || 'text/plain';
+        my $enc_msg = PublicInbox::View::enc_for($ct_msg);
+
+        $db->begin_transaction;
+        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 = $mime->header('Subject');
+                $subj = '' unless defined $subj;
+
+                if (length $subj) {
+                        $doc->add_term(xpfx('subject') . $subj);
+
+                        my $path = subject_path($subj);
+                        $doc->add_term(xpfx('path') . $path);
+                }
+
+                my $from = $mime->header('From') || '';
+                my @from;
+
+                if ($from) {
+                        @from = Email::Address->parse($from);
+                        $from = $from[0]->name;
+                }
+
+                my $ts = eval { str2time($mime->header('Date')) } || 0;
+                my $date = POSIX::strftime('%Y-%m-%d %H:%M', gmtime($ts));
+                $ts = Search::Xapian::sortable_serialise($ts);
+                $doc->add_value(PublicInbox::Search::TS, $ts);
+
+                # this is what we show in index results:
+                $subj =~ tr/\n/ /;
+                $from =~ tr/\n/ /;
+                $doc->set_data("$mid\n$subj\n$from\n$date");
+
+                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;
+
+                if (@from) {
+                        $tg->index_text($from[0]->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 $enc = PublicInbox::View::enc_for($ct, $enc_msg);
+                        my (@orig, @quot);
+                        foreach my $l (split(/\n/, $enc->decode($part->body))) {
+                                if ($l =~ /^\s*>/) {
+                                        push @quot, $l;
+                                } else {
+                                        push @orig, $l;
+                                }
+                        }
+                        if (@quot) {
+                                $tg->index_text(join("\n", @quot), 0);
+                                $tg->increase_termpos;
+                        }
+                        if (@orig) {
+                                $tg->index_text(join("\n", @orig));
+                                $tg->increase_termpos;
+                        }
+                });
+
+                if ($was_ghost) {
+                        $doc_id = $smsg->doc_id;
+                        $self->link_message($smsg, 0);
+                        $db->replace_document($doc_id, $doc);
+                } else {
+                        $self->link_message($smsg, 0);
+                        $doc_id = $db->add_document($doc);
+                }
+        };
+
+        if ($@) {
+                warn "failed to index message <$mid>: $@\n";
+                $db->cancel_transaction;
+        } else {
+                $db->commit_transaction;
+        }
+        $doc_id;
+}
+
+# returns deleted doc_id on success, undef on missing
+sub remove_message {
+        my ($self, $mid) = @_;
+        my $db = $self->{xdb};
+        my $doc_id;
+        $mid = clean_mid($mid);
+        $mid = mid_compressed($mid);
+
+        $db->begin_transaction;
+        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>: $@\n";
+                $db->cancel_transaction;
+        } else {
+                $db->commit_transaction;
+        }
+        $db->commit;
+        $doc_id;
+}
+
+# read-only
+sub query {
+        my ($self, $query_string, $opts) = @_;
+        my $query = $self->qp->parse_query($query_string, QP_FLAGS);
+
+        $query = Search::Xapian::Query->new(OP_AND, $mail_query, $query);
+        $self->do_enquire($query, $opts);
+}
+
+# given a message ID, get replies to a message
+sub get_replies {
+        my ($self, $mid, $opts) = @_;
+        $mid = clean_mid($mid);
+        $mid = mid_compressed($mid);
+        my $qp = $self->qp;
+        my $irt = $qp->parse_query("inreplyto:$mid", 0);
+        my $ref = $qp->parse_query("references:$mid", 0);
+        my $query = Search::Xapian::Query->new(OP_OR, $irt, $ref);
+
+        $self->do_enquire($query);
+}
+
+sub get_thread {
+        my ($self, $mid, $opts) = @_;
+        my $smsg = eval { $self->lookup_message($mid) };
+
+        return { count => 0, msgs => [] } unless $smsg;
+        my $qp = $self->qp;
+        my $qtid = $qp->parse_query('thread:'.$smsg->thread_id);
+        my $qsub = $qp->parse_query('path:'.$smsg->path);
+        my $query = Search::Xapian::Query->new(OP_OR, $qtid, $qsub);
+        $self->do_enquire($query);
+}
+
+# private subs below
+
+sub do_enquire {
+        my ($self, $query, $opts) = @_;
+        my $enquire = $self->enquire;
+
+        $enquire->set_query($query);
+        $enquire->set_sort_by_relevance_then_value(TS, 0);
+        $opts ||= {};
+        my $offset = $opts->{offset} || 0;
+        my $limit = $opts->{limit} || 50;
+        my $mset = $enquire->get_mset($offset, $limit);
+        my @msgs = map { $_->get_document->get_data } $mset->items;
+
+        { count => $mset->get_matches_estimated, msgs => \@msgs }
+}
+
+# read-write
+sub stemmer { Search::Xapian::Stem->new(LANG) }
+
+# read-only
+sub qp {
+        my ($self) = @_;
+
+        my $qp = $self->{query_parser};
+        return $qp if $qp;
+
+        # new parser
+        $qp = Search::Xapian::QueryParser->new;
+        $qp->set_default_op(OP_AND);
+        $qp->set_database($self->{xdb});
+        $qp->set_stemmer($self->stemmer);
+        $qp->set_stemming_strategy(STEM_SOME);
+        $qp->add_valuerangeprocessor($self->ts_range_processor);
+        $qp->add_valuerangeprocessor($self->date_range_processor);
+
+        while (my ($name, $prefix) = each %bool_pfx_external) {
+                $qp->add_boolean_prefix($name, $prefix);
+        }
+
+        while (my ($name, $prefix) = each %prob_prefix) {
+                $qp->add_prefix($name, $prefix);
+        }
+
+        $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);
+}
+
+sub date_range_processor {
+        $_[0]->{drp} ||= Search::Xapian::DateValueRangeProcessor->new(TS);
+}
+
+sub clean_mid {
+        my ($mid) = @_;
+        defined($mid) or die "no Message-ID";
+        # MDA->precheck did more checking for us
+        $mid =~ s/\A\s*<?//;
+        $mid =~ s/>?\s*\z//;
+        $mid;
+}
+
+sub link_message {
+        my ($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('References');
+        my @refs = $refs ? ($refs =~ /<([^>]+)>/g) : ();
+        my $irt = $mime->header('In-Reply-To');
+        if ($irt) {
+                if ($irt =~ /<([^>]+)>/) {
+                        $irt = $1;
+                }
+                push @refs, $irt;
+        }
+
+        my $tid;
+        if (@refs) {
+                @refs = map { mid_compressed($_) } @refs;
+                my %uniq;
+                @refs = grep { !$uniq{$_}++ } @refs; # uniq
+
+                $doc->add_term(xpfx('inreplyto') . $refs[-1]);
+
+                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) = @_;
+        $mid = clean_mid($mid);
+        $mid = mid_compressed($mid);
+
+        my $doc_id = $self->find_unique_doc_id('mid', $mid);
+        my $smsg;
+        if (defined $doc_id) {
+                # raises on error:
+                my $doc = $self->{xdb}->get_document($doc_id);
+                $smsg = PublicInbox::SearchMsg->wrap($doc, $mid);
+                $smsg->doc_id($doc_id);
+        }
+        $smsg;
+}
+
+sub find_unique_doc_id {
+        my ($self, $term, $value) = @_;
+
+        my ($begin, $end) = $self->find_doc_ids($term, $value);
+
+        return undef if $begin->equal($end); # not found
+
+        my $rv = $begin->get_docid;
+
+        # sanity check
+        $begin->inc;
+        $begin->equal($end) or die "Term '$term:$value' is not unique\n";
+        $rv;
+}
+
+# returns begin and end PostingIterator
+sub find_doc_ids {
+        my ($self, $term, $value) = @_;
+
+        $self->find_doc_ids_for_term(xpfx($term) . $value);
+}
+
+# returns begin and end PostingIterator
+sub find_doc_ids_for_term {
+        my ($self, $term) = @_;
+        my $db = $self->{xdb};
+
+        ($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) = @_;
+
+        $subj =~ s/\A\s+//;
+        $subj =~ s/\s+\z//;
+        $subj =~ s/^(?:re|aw):\s*//i; # remove reply prefix (aw: German)
+        $subj =~ s![^a-zA-Z0-9_\.~/\-]+!_!g;
+        $subj;
+}
+
+sub do_cat_mail {
+        my ($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('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});
+}
+
+1;
diff --git a/lib/PublicInbox/SearchMsg.pm b/lib/PublicInbox/SearchMsg.pm
new file mode 100644
index 00000000..920804ac
--- /dev/null
+++ b/lib/PublicInbox/SearchMsg.pm
@@ -0,0 +1,105 @@
+# Copyright (C) 2015, all contributors <meta@public-inbox.org>
+# License: GPLv3 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::SearchMsg;
+use strict;
+use warnings;
+use Search::Xapian;
+our $PFX2TERM_RE = undef;
+
+sub new {
+        my ($class, $mime) = @_;
+        my $doc = Search::Xapian::Document->new;
+        $doc->add_term(PublicInbox::Search::xpfx('type') . 'mail');
+
+        bless { type => 'mail', doc => $doc, mime => $mime }, $class;
+}
+
+sub wrap {
+        my ($class, $doc, $mid) = @_;
+        bless { doc => $doc, mime => undef, mid => $mid }, $class;
+}
+
+sub ensure_metadata {
+        my ($self) = @_;
+        my $doc = $self->{doc};
+        my $i = $doc->termlist_begin;
+        my $end = $doc->termlist_end;
+
+        unless (defined $PFX2TERM_RE) {
+                my $or = join('|', keys %PublicInbox::Search::PFX2TERM_RMAP);
+                $PFX2TERM_RE = qr/\A($or)/;
+        }
+
+        for (; $i != $end; $i->inc) {
+                my $val = $i->get_termname;
+
+                if ($val =~ s/$PFX2TERM_RE//o) {
+                        my $field = $PublicInbox::Search::PFX2TERM_RMAP{$1};
+                        if ($field eq 'references') {
+                                my $refs = $self->{references} ||= [];
+                                push @$refs, $val;
+                        } else {
+                                $self->{$field} = $val;
+                        }
+                }
+        }
+}
+
+sub mid {
+        my ($self, $mid) = @_;
+
+        if (defined $mid) {
+            $self->{mid} = $mid;
+        } else {
+            $self->{mid} ||= $self->_extract_mid;
+        }
+}
+
+sub _extract_mid {
+        my ($self) = @_;
+
+        my $mid = $self->mime->header('Message-ID');
+        if ($mid && $mid =~ /<([^>]+)>/) {
+                return $1;
+        }
+        return $mid;
+}
+
+sub mime {
+        my ($self, $mime) = @_;
+        if (defined $mime) {
+                $self->{mime} = $mime;
+        } else {
+                # TODO load from git
+                $self->{mime};
+        }
+}
+
+sub doc_id {
+        my ($self, $doc_id) = @_;
+        if (defined $doc_id) {
+                $self->{doc_id} = $doc_id;
+        } else {
+                # TODO load from xapian
+                $self->{doc_id};
+        }
+}
+
+sub thread_id {
+        my ($self) = @_;
+        my $tid = $self->{thread};
+        return $tid if defined $tid;
+        $self->ensure_metadata;
+        $self->{thread};
+}
+
+sub path {
+        my ($self) = @_;
+        my $path = $self->{path};
+        return $path if defined $path;
+        $self->ensure_metadata;
+        $self->{path};
+}
+
+1;