From e32425bfcd55497cdad4982908d6fcba9a0e033c Mon Sep 17 00:00:00 2001
From: Brian White <mscdex@mscdex.net>
Date: Fri, 13 Jan 2017 05:19:54 -0500
Subject: [PATCH] module: avoid JSON.stringify() for cache key
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By avoiding JSON.stringify() and simply joining the strings with a
delimiter that does not appear in paths, we can improve cached
require() performance by at least 50%.

Additionally, this commit removes the last source of permanent
function deoptimization (const) for _findPath().

PR-URL: https://github.com/nodejs/node/pull/10789
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
---
 lib/module.js | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/lib/module.js b/lib/module.js
index 1b9c2413b7..77675fcd98 100644
--- a/lib/module.js
+++ b/lib/module.js
@@ -165,10 +165,11 @@ Module._findPath = function(request, paths, isMain) {
     return false;
   }
 
-  const cacheKey = JSON.stringify({request: request, paths: paths});
-  if (Module._pathCache[cacheKey]) {
-    return Module._pathCache[cacheKey];
-  }
+  var cacheKey = request + '\x00' +
+                (paths.length === 1 ? paths[0] : paths.join('\x00'));
+  var entry = Module._pathCache[cacheKey];
+  if (entry)
+    return entry;
 
   var exts;
   var trailingSlash = request.length > 0 &&