imap: speed up HEADER.FIELDS[.NOT] range fetches

While we can't memoize the regexp forever like we do with other
Eml users, we can still benefit from caching regexp compilation
on a per-request basis.

A FETCH request from mutt on a 4K message inbox is around 8%
faster after this.  Since regexp compilation via qr// isn't
unbearably slow, a shared cache probably isn't worth the
trouble of implementing.  A per-request cache seems enough.

diff --git a/lib/PublicInbox/IMAP.pm b/lib/PublicInbox/IMAP.pm
index 0852ffab868dc61bfba42d9ca8f1858911ddcfd0..3966719908016c0c9f4c64b67a9d88908a652b25 100644 (file)
--- a/lib/PublicInbox/IMAP.pm
+++ b/lib/PublicInbox/IMAP.pm
@@ -544,25 +544,23 @@ sub hdrs_regexp ($) {
 
 # BODY[($SECTION_IDX.)?HEADER.FIELDS.NOT ($HDRS)]<$offset.$bytes>
 sub partial_hdr_not {
-       my ($eml, $section_idx, $hdrs) = @_;
+       my ($eml, $section_idx, $hdrs_re) = @_;
        if (defined $section_idx) {
                $eml = eml_body_idx($eml, $section_idx) or return;
        }
        my $str = $eml->header_obj->as_string;
-       my $re = hdrs_regexp($hdrs);
-       $str =~ s/$re//g;
+       $str =~ s/$hdrs_re//g;
        $str .= "\r\n";
 }
 
 # BODY[($SECTION_IDX.)?HEADER.FIELDS ($HDRS)]<$offset.$bytes>
 sub partial_hdr_get {
-       my ($eml, $section_idx, $hdrs) = @_;
+       my ($eml, $section_idx, $hdrs_re) = @_;
        if (defined $section_idx) {
                $eml = eml_body_idx($eml, $section_idx) or return;
        }
        my $str = $eml->header_obj->as_string;
-       my $re = hdrs_regexp($hdrs);
-       join('', ($str =~ m/($re)/g), "\r\n");
+       join('', ($str =~ m/($hdrs_re)/g), "\r\n");
 }
 
 sub partial_prepare ($$$) {
@@ -583,9 +581,10 @@ sub partial_prepare ($$$) {
                                (?:HEADER\.FIELDS(\.NOT)?)\x20 # 2
                                \(([A-Z0-9\-\x20]+)\) # 3 - hdrs
                        \](?:<([0-9]+)(?:\.([0-9]+))?>)?\z/sx) { # 4 5
-               $partial->{$att} = [ $2 ? \&partial_hdr_not
-                                       : \&partial_hdr_get,
-                                       $1, $3, $4, $5 ];
+               my $tmp = $partial->{$att} = [ $2 ? \&partial_hdr_not
+                                               : \&partial_hdr_get,
+                                               $1, undef, $4, $5 ];
+               $tmp->[2] = hdrs_regexp($3);
        } else {
                undef;
        }

diff --git a/t/imap.t b/t/imap.t
index fe6352b678c32fe59a810a5f87d98df1382e926b..451b6596bf9f8d08df021a385d597fcb8eebb807 100644 (file)
--- a/t/imap.t
+++ b/t/imap.t
@@ -46,17 +46,21 @@ use PublicInbox::IMAPD;
        my $partial_body = \&PublicInbox::IMAP::partial_body;
        my $partial_hdr_get = \&PublicInbox::IMAP::partial_hdr_get;
        my $partial_hdr_not = \&PublicInbox::IMAP::partial_hdr_not;
+       my $hdrs_regexp = \&PublicInbox::IMAP::hdrs_regexp;
        is_deeply($x, {
                'BODY[9]' => [ $partial_body, 9, undef, undef, undef ],
                'BODY[9]<5>' => [ $partial_body, 9, undef, 5, undef ],
                'BODY[9]<5.1>' => [ $partial_body, 9, undef, 5, 1 ],
                'BODY[1.1]' => [ $partial_body, '1.1', undef, undef, undef ],
                'BODY[HEADER.FIELDS (DATE FROM)]' => [ $partial_hdr_get,
-                                       undef, 'DATE FROM', undef, undef ],
+                                       undef, $hdrs_regexp->('DATE FROM'),
+                                       undef, undef ],
                'BODY[HEADER.FIELDS.NOT (TO)]' => [ $partial_hdr_not,
-                                               undef, 'TO', undef, undef ],
+                                               undef, $hdrs_regexp->('TO'),
+                                               undef, undef ],
                'BODY[1.1.HEADER.FIELDS (TO)]' => [ $partial_hdr_get,
-                                               '1.1', 'TO', undef, undef ],
+                                               '1.1', $hdrs_regexp->('TO'),
+                                               undef, undef ],
        }, 'structure matches expected');
 }