From 909dd9561a40daea507dfe5155c31c273918e2b5 Mon Sep 17 00:00:00 2001
From: xiaoc <hustcoolboy@gmail.com>
Date: Sat, 25 Oct 2014 13:08:14 +0800
Subject: [PATCH 1/2] add cache for module with same version

In a large project  developed with node.Js, some modulex are used frequently, let's say ```underscore``` or ```lodash```,  module A is depended on it,and module B is  depended on it too, and they are depended on the same version. So module ```underscore``` is loaded twice , right?  and that may cost more memory, so why don't we set the cache for the same module with the same version. Thanks!
---
 lib/module.js | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/lib/module.js b/lib/module.js
index 564f6c49d6cb..c70602321560 100644
--- a/lib/module.js
+++ b/lib/module.js
@@ -25,7 +25,7 @@ var runInThisContext = require('vm').runInThisContext;
 var runInNewContext = require('vm').runInNewContext;
 var assert = require('assert').ok;
 var fs = NativeModule.require('fs');
-
+var moduleVersionCache = {},
 
 // If obj.hasOwnProperty has been overridden, then calling
 // obj.hasOwnProperty(prop) will break.
@@ -104,7 +104,7 @@ function readPackage(requestPath) {
   }
 
   try {
-    var pkg = packageMainCache[requestPath] = JSON.parse(json).main;
+    var pkg = packageMainCache[requestPath] = JSON.parse(json);
   } catch (e) {
     e.path = jsonPath;
     e.message = 'Error parsing ' + jsonPath + ': ' + e.message;
@@ -116,9 +116,24 @@ function readPackage(requestPath) {
 function tryPackage(requestPath, exts) {
   var pkg = readPackage(requestPath);
 
-  if (!pkg) return false;
+  if (!(pkg && pkg.main)) return false;
+
+  var name = pkg.name,
+      version = pkg.version,
+      main = pkg.main;
+
+  var cache = moduleVersionCache[name];
+  if(!cache){
+    cache = moduleVersionCache[name] = {};
+  }
+
+  var filename =  cache[version];
+
+  if(!filename) {
+     filename = path.resolve(requestPath, main);
+     cache[version] = filename;
+  }
 
-  var filename = path.resolve(requestPath, pkg);
   return tryFile(filename) || tryExtensions(filename, exts) ||
          tryExtensions(path.resolve(filename, 'index'), exts);
 }

From 167aedca9989b3bd051a70f9f95f3f16b7273ad8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=B7=98=E5=B0=8F=E6=9D=B0?= <hustcoolboy@gmail.com>
Date: Sat, 25 Oct 2014 16:21:10 +0800
Subject: [PATCH 2/2] sorry, stupid mistake

---
 lib/module.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/module.js b/lib/module.js
index c70602321560..a2f70ca380ca 100644
--- a/lib/module.js
+++ b/lib/module.js
@@ -25,7 +25,7 @@ var runInThisContext = require('vm').runInThisContext;
 var runInNewContext = require('vm').runInNewContext;
 var assert = require('assert').ok;
 var fs = NativeModule.require('fs');
-var moduleVersionCache = {},
+var moduleVersionCache = {};
 
 // If obj.hasOwnProperty has been overridden, then calling
 // obj.hasOwnProperty(prop) will break.