perf: prevent multiple Buffer creation in res.send

Author: dougwilson

History.md

@@ -1,3 +1,8 @@
+unreleased
+==========
+
+  * perf: prevent multiple `Buffer` creation in `res.send`
+
 4.6.1 / 2014-07-12
 ==================
 

lib/response.js

@@ -145,17 +145,24 @@ res.send = function send(body) {
   }
 
   // populate Content-Length
-  if (chunk !== undefined && !this.get('Content-Length')) {
-    len = Buffer.isBuffer(chunk)
-      ? chunk.length
-      : Buffer.byteLength(chunk, encoding);
+  if (chunk !== undefined) {
+    if (!Buffer.isBuffer(chunk)) {
+      // convert chunk to Buffer; saves later double conversions
+      chunk = new Buffer(chunk, encoding);
+      encoding = undefined;
+    }
+
+    len = chunk.length;
     this.set('Content-Length', len);
   }
 
+  // method check
+  var isHead = req.method === 'HEAD';
+
   // ETag support
-  var etag = len !== undefined && app.get('etag fn');
-  if (etag && ('GET' === req.method || 'HEAD' === req.method)) {
-    if (!this.get('ETag')) {
+  if (len !== undefined && (isHead || req.method === 'GET')) {
+    var etag = app.get('etag fn');
+    if (etag && !this.get('ETag')) {
       etag = etag(chunk, encoding);
       etag && this.set('ETag', etag);
     }
@@ -173,7 +180,7 @@ res.send = function send(body) {
   }
 
   // skip body for HEAD
-  if (req.method === 'HEAD') {
+  if (isHead) {
     this.end();
   }
 

test/res.send.js

@@ -512,8 +512,10 @@ describe('res', function(){
         var app = express()
 
         app.set('etag', function(body, encoding){
-          body.should.equal('hello, world!')
-          encoding.should.equal('utf8')
+          var chunk = !Buffer.isBuffer(body)
+            ? new Buffer(body, encoding)
+            : body;
+          chunk.toString().should.equal('hello, world!')
           return '"custom"'
         });