http: optimize checkInvalidHeaderChar()

This commit optimizes checkInvalidHeaderChar() by unrolling the
character checking loop a bit.

Additionally, some changes to the benchmark runner are needed in
order for the included benchmark to be run correctly. Specifically,
the regexp used to parse `key=value` parameters contained a greedy
quantifier that was causing the `key` to match part of the `value`
if `value` contained an equals sign.

PR-URL: https://github.com/nodejs/node/pull/6570
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>

1 files changed, 24 insertions, 5 deletions

diff --git a/lib/_http_common.js b/lib/_http_common.js
index 150d424261..ad0389ba21 100644
--- a/lib/_http_common.js
+++ b/lib/_http_common.js
@@ -301,13 +301,32 @@ exports._checkIsHttpToken = checkIsHttpToken;
  *  field-value    = *( field-content / obs-fold )
  *  field-content  = field-vchar [ 1*( SP / HTAB ) field-vchar ]
  *  field-vchar    = VCHAR / obs-text
+ *
+ * checkInvalidHeaderChar() is currently designed to be inlinable by v8,
+ * so take care when making changes to the implementation so that the source
+ * code size does not exceed v8's default max_inlined_source_size setting.
  **/
 function checkInvalidHeaderChar(val) {
-  val = '' + val;
-  for (var i = 0; i < val.length; i++) {
-    const ch = val.charCodeAt(i);
-    if (ch === 9) continue;
-    if (ch <= 31 || ch > 255 || ch === 127) return true;
+  val += '';
+  if (val.length < 1)
+    return false;
+  var c = val.charCodeAt(0);
+  if ((c <= 31 && c !== 9) || c > 255 || c === 127)
+    return true;
+  if (val.length < 2)
+    return false;
+  c = val.charCodeAt(1);
+  if ((c <= 31 && c !== 9) || c > 255 || c === 127)
+    return true;
+  if (val.length < 3)
+    return false;
+  c = val.charCodeAt(2);
+  if ((c <= 31 && c !== 9) || c > 255 || c === 127)
+    return true;
+  for (var i = 3; i < val.length; ++i) {
+    c = val.charCodeAt(i);
+    if ((c <= 31 && c !== 9) || c > 255 || c === 127)
+      return true;
   }
   return false;
 }