extmsg: add note about the deficiency of the implementation

ref: http://public-inbox.org/meta/20150905091457.GA27857@dcvr.yhbt.net/

diff --git a/lib/PublicInbox/ExtMsg.pm b/lib/PublicInbox/ExtMsg.pm
index 243b6bad4ccd9d1e990972d828c5bf05ef3539bb..77537c2cd9f1bd4a8f070e0ada83f515b9f12268 100644 (file)
--- a/lib/PublicInbox/ExtMsg.pm
+++ b/lib/PublicInbox/ExtMsg.pm
@@ -95,6 +95,8 @@ sub ext_msg {
                unshift @pfx, { srch => $ctx->{srch}, url => $url };
                foreach my $pfx (@pfx) {
                        my $srch = delete $pfx->{srch} or next;
+
+                       # FIXME we may need a proper prefix trie here...
                        if (my $res = $srch->mid_prefix($mid)) {
                                $n_partial += scalar(@$res);
                                $pfx->{res} = $res;