v2writable: reindex handles 3-headered monsters

And maybe 8-headered ones, too...

I noticed --reindex failing on the linux-renesas-soc mirror due
one 3-headed monster of a message having 3 sets of headers;
while another normal message had a Message-ID that matched one
of the 3 IDs of the 3-headed monster.

We still try to do the majority of indexing backwards, but we
defer indexing multi-Message-ID'd messages until the end to
ensure we get all the "good" messages in before we process the
multi-headered ones.

Link: https://public-inbox.org/meta/20191016211415.GA6084@dcvr/

4 files changed, 236 insertions, 60 deletions

diff --git a/TODO b/TODO
index a327ca06..61c44a84 100644
--- a/TODO
+++ b/TODO
@@ -133,3 +133,6 @@ all need to be considered for everything we introduce)
   for coderepos
 
 * configurable diff output for solver-generated blobs
+
+* fix search for messages with multiple Subject:/To:/From:/Date:
+  headers (some wacky examples out there...)
diff --git a/lib/PublicInbox/OverIdx.pm b/lib/PublicInbox/OverIdx.pm
index 7fd1905d..64277342 100644
--- a/lib/PublicInbox/OverIdx.pm
+++ b/lib/PublicInbox/OverIdx.pm
@@ -343,6 +343,20 @@ sub remove_oid {
         $nr;
 }
 
+sub num_mid0_for_oid {
+        my ($self, $oid, $mid) = @_;
+        my ($num, $mid0);
+        $self->begin_lazy;
+        each_by_mid($self, $mid, ['ddd'], sub {
+                my ($smsg) = @_;
+                my $blob = $smsg->{blob};
+                return 1 if (!defined($blob) || $blob ne $oid); # continue;
+                ($num, $mid0) = ($smsg->{num}, $smsg->{mid});
+                0; # done
+        });
+        ($num, $mid0);
+}
+
 sub create_tables {
         my ($dbh) = @_;
 
diff --git a/lib/PublicInbox/V2Writable.pm b/lib/PublicInbox/V2Writable.pm
index 9d507828..7ece6b01 100644
--- a/lib/PublicInbox/V2Writable.pm
+++ b/lib/PublicInbox/V2Writable.pm
@@ -841,81 +841,157 @@ sub mark_deleted ($$$$) {
         }
 }
 
-sub reindex_oid ($$$$) {
+sub reindex_checkpoint ($$$) {
+        my ($self, $sync, $git) = @_;
+
+        $git->cleanup;
+        $sync->{mm_tmp}->atfork_prepare;
+        $self->done; # release lock
+
+        if (my $pr = $sync->{-opt}->{-progress}) {
+                my ($bn) = (split('/', $git->{git_dir}))[-1];
+                $pr->("$bn ".sprintf($sync->{-regen_fmt}, $sync->{nr}));
+        }
+
+        # allow -watch or -mda to write...
+        $self->idx_init; # reacquire lock
+        $sync->{mm_tmp}->atfork_parent;
+}
+
+# only for a few odd messages with multiple Message-IDs
+sub reindex_oid_m ($$$$) {
         my ($self, $sync, $git, $oid) = @_;
-        my $len;
+        my ($num, $mid0, $len);
         my $msgref = $git->cat_file($oid, \$len);
         my $mime = PublicInbox::MIME->new($$msgref);
         my $mids = mids($mime->header_obj);
         my $cid = content_id($mime);
+        die "BUG: reindex_oid_m called for <=1 mids" if scalar(@$mids) <= 1;
 
-        # get the NNTP article number we used before, highest number wins
-        # and gets deleted from sync->{mm_tmp};
-        my $mid0;
-        my $num = -1;
-        my $del = 0;
-        foreach my $mid (@$mids) {
-                $del += delete($sync->{D}->{"$mid\0$cid"}) ? 1 : 0;
-                my $n = $sync->{mm_tmp}->num_for($mid);
-                if (defined $n && $n > $num) {
+        for my $mid (reverse @$mids) {
+                delete($sync->{D}->{"$mid\0$cid"}) and
+                        die "BUG: reindex_oid should handle <$mid> delete";
+        }
+        for my $mid (reverse @$mids) {
+                ($num, $mid0) = $self->{over}->num_mid0_for_oid($oid, $mid);
+                last if defined $num;
+        }
+        unless (defined($num)) {
+                for my $mid (reverse @$mids) {
+                        # is this a number we got before?
+                        $num = $sync->{mm_tmp}->num_for($mid);
+                        next unless defined $num;
                         $mid0 = $mid;
-                        $num = $n;
-                        $self->{mm}->mid_set($num, $mid0);
+                        last;
                 }
         }
-        if (!defined($mid0) && !$del) {
+        if (defined($num)) {
+                $sync->{mm_tmp}->num_delete($num);
+        } else {
                 $num = $sync->{regen}--;
-                die "BUG: ran out of article numbers\n" if $num <= 0;
-                my $mm = $self->{mm};
-                foreach my $mid (reverse @$mids) {
-                        if ($mm->mid_set($num, $mid) == 1) {
+                if ($num <= 0) {
+                        # fixup bugs in old mirrors on reindex
+                        for my $mid (reverse @$mids) {
+                                $num = $self->{mm}->mid_insert($mid);
+                                next unless defined $num;
                                 $mid0 = $mid;
                                 last;
                         }
-                }
-                if (!defined($mid0)) {
-                        my $id = '<' . join('> <', @$mids) . '>';
-                        warn "Message-ID $id unusable for $num\n";
-                        foreach my $mid (@$mids) {
-                                defined(my $n = $mm->num_for($mid)) or next;
-                                warn "#$n previously mapped for <$mid>\n";
+                        if (defined $mid0) {
+                                if ($sync->{reindex}) {
+                                        warn "reindex added #$num <$mid0>\n";
+                                }
+                        } else {
+                                warn "E: cannot find article #\n";
+                                return;
+                        }
+                } else { # $num > 0, use the new article number
+                        for my $mid (reverse @$mids) {
+                                $self->{mm}->mid_set($num, $mid) == 1 or next;
+                                $mid0 = $mid;
+                                last;
+                        }
+                        unless (defined $mid0) {
+                                warn "E: cannot regen #$num\n";
+                                return;
                         }
                 }
         }
+        $sync->{nr}++;
+        if (do_idx($self, $msgref, $mime, $len, $num, $oid, $mid0)) {
+                reindex_checkpoint($self, $sync, $git);
+        }
+}
 
-        if (!defined($mid0) || $del) {
-                if (!defined($mid0) && $del) { # expected for deletes
-                        $num = $sync->{regen}--;
-                        $self->{mm}->num_highwater($num) if !$sync->{reindex};
-                        return
+sub check_unindexed ($$$) {
+        my ($self, $num, $mid0) = @_;
+        my $unindexed = $self->{unindexed} // {};
+        my $n = delete($unindexed->{$mid0});
+        defined $n or return;
+        if ($n != $num) {
+                die "BUG: unindexed $n != $num <$mid0>\n";
+        } else {
+                $self->{mm}->mid_set($num, $mid0);
+        }
+}
+
+sub reindex_oid ($$$$) {
+        my ($self, $sync, $git, $oid) = @_;
+        my ($num, $mid0, $len);
+        my $msgref = $git->cat_file($oid, \$len);
+        return if $len == 0; # purged
+        my $mime = PublicInbox::MIME->new($$msgref);
+        my $mids = mids($mime->header_obj);
+        my $cid = content_id($mime);
+
+        if (scalar(@$mids) == 0) {
+                warn "E: $oid has no Message-ID, skipping\n";
+                return;
+        } elsif (scalar(@$mids) == 1) {
+                my $mid = $mids->[0];
+
+                # was the file previously marked as deleted?, skip if so
+                if (delete($sync->{D}->{"$mid\0$cid"})) {
+                        if (!$sync->{reindex}) {
+                                $num = $sync->{regen}--;
+                                $self->{mm}->num_highwater($num);
+                        }
+                        return;
                 }
 
-                my $id = '<' . join('> <', @$mids) . '>';
-                defined($mid0) or
-                        warn "Skipping $id, no article number found\n";
-                if ($del && defined($mid0)) {
-                        warn "$id was deleted $del " .
-                                "time(s) but mapped to article #$num\n";
+                # is this a number we got before?
+                $num = $sync->{mm_tmp}->num_for($mid);
+                if (defined $num) {
+                        $mid0 = $mid;
+                        check_unindexed($self, $num, $mid0);
+                } else {
+                        $num = $sync->{regen}--;
+                        die "BUG: ran out of article numbers\n" if $num <= 0;
+                        if ($self->{mm}->mid_set($num, $mid) != 1) {
+                                warn "E: unable to assign $num => <$mid>\n";
+                                return;
+                        }
+                        $mid0 = $mid;
+                }
+        } else { # multiple MIDs are a weird case:
+                my $del = 0;
+                for (@$mids) {
+                        $del += delete($sync->{D}->{"$_\0$cid"}) // 0;
+                }
+                if ($del) {
+                        unindex_oid_remote($self, $oid, $_) for @$mids;
+                        # do not delete from {mm_tmp}, since another
+                        # single-MID message may use it.
+                } else { # handle them at the end:
+                        push @{$sync->{multi_mid} //= []}, $oid;
                 }
                 return;
-
         }
         $sync->{mm_tmp}->mid_delete($mid0) or
                 die "failed to delete <$mid0> for article #$num\n";
         $sync->{nr}++;
         if (do_idx($self, $msgref, $mime, $len, $num, $oid, $mid0)) {
-                $git->cleanup;
-                $sync->{mm_tmp}->atfork_prepare;
-                $self->done; # release lock
-
-                if (my $pr = $sync->{-opt}->{-progress}) {
-                        my ($bn) = (split('/', $git->{git_dir}))[-1];
-                        $pr->("$bn ".sprintf($sync->{-regen_fmt}, $sync->{nr}));
-                }
-
-                # allow -watch or -mda to write...
-                $self->idx_init; # reacquire lock
-                $sync->{mm_tmp}->atfork_parent;
+                reindex_checkpoint($self, $sync, $git);
         }
 }
 
@@ -1047,8 +1123,9 @@ sub unindex_oid_remote ($$$) {
         $self->{over}->remove_oid($oid, $mid);
 }
 
-sub unindex_oid ($$$) {
-        my ($self, $git, $oid) = @_;
+sub unindex_oid ($$$;$) {
+        my ($self, $git, $oid, $unindexed) = @_;
+        my $mm = $self->{mm};
         my $msgref = $git->cat_file($oid);
         my $mime = PublicInbox::MIME->new($msgref);
         my $mids = mids($mime->header_obj);
@@ -1068,8 +1145,11 @@ sub unindex_oid ($$$) {
                                 join(',',sort keys %gone), "\n";
                 }
                 foreach my $num (keys %gone) {
-                        $self->{unindexed}->{$num}++;
-                        $self->{mm}->num_delete($num);
+                        if ($unindexed) {
+                                my $mid0 = $mm->mid_for($num);
+                                $unindexed->{$mid0} = $num;
+                        }
+                        $mm->num_delete($num);
                 }
                 unindex_oid_remote($self, $oid, $mid);
         }
@@ -1078,20 +1158,21 @@ sub unindex_oid ($$$) {
 my $x40 = qr/[a-f0-9]{40}/;
 sub unindex ($$$$) {
         my ($self, $sync, $git, $unindex_range) = @_;
-        my $un = $self->{unindexed} ||= {}; # num => removal count
-        my $before = scalar keys %$un;
+        my $unindexed = $self->{unindexed} ||= {}; # $mid0 => $num
+        my $before = scalar keys %$unindexed;
+        # order does not matter, here:
         my @cmd = qw(log --raw -r
                         --no-notes --no-color --no-abbrev --no-renames);
         my $fh = $self->{reindex_pipe} = $git->popen(@cmd, $unindex_range);
         while (<$fh>) {
                 /\A:\d{6} 100644 $x40 ($x40) [AM]\tm$/o or next;
-                unindex_oid($self, $git, $1);
+                unindex_oid($self, $git, $1, $unindexed);
         }
         delete $self->{reindex_pipe};
         $fh = undef;
 
         return unless $sync->{-opt}->{prune};
-        my $after = scalar keys %$un;
+        my $after = scalar keys %$unindexed;
         return if $before == $after;
 
         # ensure any blob can not longer be accessed via dumb HTTP
@@ -1184,10 +1265,22 @@ sub index_sync {
 
         # unindex is required for leftovers if "deletes" affect messages
         # in a previous fetch+index window:
+        my $git;
         if (my @leftovers = values %{delete $sync->{D}}) {
-                my $git = $self->{-inbox}->git;
-                unindex_oid($self, $git, $_) for @leftovers;
-                $git->cleanup;
+                $git = $self->{-inbox}->git;
+                for my $oid (@leftovers) {
+                        $self->{current_info} = "leftover $oid";
+                        unindex_oid($self, $git, $oid);
+                }
+        }
+        if (my $multi_mid = delete $sync->{multi_mid}) {
+                $git //= $self->{-inbox}->git;
+
+                while (defined(my $oid = pop(@$multi_mid))) {
+                        $self->{current_info} = "multi_mid $oid";
+                        reindex_oid_m($self, $sync, $git, $oid);
+                }
+                $git->cleanup if $git;
         }
         $self->done;
 
diff --git a/t/v2reindex.t b/t/v2reindex.t
index 7c5a6b07..52711f8f 100644
--- a/t/v2reindex.t
+++ b/t/v2reindex.t
@@ -431,4 +431,70 @@ ok(!-d $xap, 'Xapian directories removed again');
                   ], 'msgmap as expected' );
 }
 
+# A real example from linux-renesas-soc on lore where a 3-headed monster
+# of a message has 3 sets of common headers.  Another normal message
+# previously existed with a single Message-ID that conflicts with one
+# of the Message-IDs in the 3-headed monster.
+{
+        my @warn;
+        local $SIG{__WARN__} = sub { push @warn, @_ };
+        my %config = %$ibx_config;
+        $config{indexlevel} = 'basic';
+        my $ibx = PublicInbox::Inbox->new(\%config);
+        my $im = PublicInbox::V2Writable->new($ibx);
+        my $m3 = PublicInbox::MIME->new(<<'EOF');
+Date: Tue, 24 May 2016 14:34:22 -0700 (PDT)
+Message-Id: <20160524.143422.552507610109476444.d@example.com>
+To: t@example.com
+Cc: c@example.com
+Subject: Re: [PATCH v2 2/2]
+From: <f@example.com>
+In-Reply-To: <1463825855-7363-2-git-send-email-y@example.com>
+References: <1463825855-7363-1-git-send-email-y@example.com>
+        <1463825855-7363-2-git-send-email-y@example.com>
+Date: Wed, 25 May 2016 10:01:51 +0900
+From: h@example.com
+To: g@example.com
+Cc: m@example.com
+Subject: Re: [PATCH]
+Message-ID: <20160525010150.GD7292@example.com>
+References: <1463498133-23918-1-git-send-email-g+r@example.com>
+In-Reply-To: <1463498133-23918-1-git-send-email-g+r@example.com>
+From: s@example.com
+To: h@example.com
+Cc: m@example.com
+Subject: [PATCH 12/13]
+Date: Wed, 01 Jun 2016 01:32:35 +0300
+Message-ID: <1923946.Jvi0TDUXFC@wasted.example.com>
+In-Reply-To: <13205049.n7pM8utpHF@wasted.example.com>
+References: <13205049.n7pM8utpHF@wasted.example.com>
+
+Somehow we got a message with 3 sets of headers into one
+message, could've been something broken on the archiver side.
+EOF
+
+        my $m1 = PublicInbox::MIME->new(<<'EOF');
+From: a@example.com
+To: t@example.com
+Subject: [PATCH 12/13]
+Date: Wed, 01 Jun 2016 01:32:35 +0300
+Message-ID: <1923946.Jvi0TDUXFC@wasted.example.com>
+In-Reply-To: <13205049.n7pM8utpHF@wasted.example.com>
+References: <13205049.n7pM8utpHF@wasted.example.com>
+
+This is probably one of the original messages
+
+EOF
+        $im->add($m1);
+        $im->add($m3);
+        $im->done;
+        remove_tree($xap);
+        eval { $im->index_sync() };
+        is($@, '', 'no error from initial indexing');
+        is_deeply(\@warn, [], 'no warnings from initial index');
+        eval { $im->index_sync({reindex=>1}) };
+        is($@, '', 'no error from reindexing after reused Message-ID (x3)');
+        is_deeply(\@warn, [], 'no warnings on reindex');
+}
+
 done_testing();