buffer: little improve for Buffer.concat method

When buffer list less than 2, no need to calculate the length. The change's benchmark result is here: https://gist.github.com/JacksonTian/2c9e2bdec00018e010e6 It improve 15% ~ 25% speed when list only have one buffer, to other cases no effect. PR-URL: #1437 Reviewed-By: Trevor Norris <[email protected]> Reviewed-By: Brendan Ashworth <[email protected]>
nodejs · Apr 23, 2015 · 3d3083b · 3d3083b
1 parent bb254b5
commit 3d3083b
Showing 1 changed file with 5 additions and 5 deletions.
diff --git a/lib/buffer.js b/lib/buffer.js
@@ -247,6 +247,11 @@ Buffer.concat = function(list, length) {
   if (!Array.isArray(list))
     throw new TypeError('list argument must be an Array of Buffers.');
 
+  if (list.length === 0)
+    return new Buffer(0);
+  else if (list.length === 1)
+    return list[0];
+
   if (length === undefined) {
     length = 0;
     for (var i = 0; i < list.length; i++)
@@ -255,11 +260,6 @@ Buffer.concat = function(list, length) {
     length = length >>> 0;
   }
 
-  if (list.length === 0)
-    return new Buffer(0);
-  else if (list.length === 1)
-    return list[0];
-
   var buffer = new Buffer(length);
   var pos = 0;
   for (var i = 0; i < list.length; i++) {