From 4aa27d61cbf10fdad098b20ae4bcef8f4893e531 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@yhbt.net>
Date: Wed, 10 Jun 2020 07:05:10 +0000
Subject: [PATCH 1/1] imap: further speed up HEADER.FIELDS FETCH requests

Since headers are big and include a lot of lines MUAs don't
care about, we can skip the CRLF_HDR ops and just do the
CRLF conversion in partial_hdr_get and partial_hdr_not.
This is another 10-15% speedup for mutt w/o header caching.
---
 lib/PublicInbox/IMAP.pm | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/lib/PublicInbox/IMAP.pm b/lib/PublicInbox/IMAP.pm
index 3cc68e66..fe3c7d1a 100644
--- a/lib/PublicInbox/IMAP.pm
+++ b/lib/PublicInbox/IMAP.pm
@@ -792,6 +792,7 @@ sub partial_hdr_not {
 	}
 	my $str = $eml->header_obj->as_string;
 	$str =~ s/$hdrs_re//g;
+	$str =~ s/(?<!\r)\n/\r\n/sg;
 	$str .= "\r\n";
 }
 
@@ -802,7 +803,9 @@ sub partial_hdr_get {
 		$eml = eml_body_idx($eml, $section_idx) or return;
 	}
 	my $str = $eml->header_obj->as_string;
-	join('', ($str =~ m/($hdrs_re)/g), "\r\n");
+	$str = join('', ($str =~ m/($hdrs_re)/g));
+	$str =~ s/(?<!\r)\n/\r\n/sg;
+	$str .= "\r\n";
 }
 
 sub partial_prepare ($$$$) {
@@ -828,7 +831,11 @@ sub partial_prepare ($$$$) {
 						: \&partial_hdr_get,
 						$1, undef, $4, $5 ];
 		$tmp->[2] = hdrs_regexp($3);
-		$$need |= CRLF_HDR|EML_HDR;
+
+		# don't emit CRLF_HDR instruction, here, partial_hdr_*
+		# will do CRLF conversion with only the extracted result
+		# and not waste time converting lines we don't care about.
+		$$need |= EML_HDR;
 	} else {
 		undef;
 	}
-- 
2.44.0