lib: don't penalize setTimeout() common case

The common case is where setTimeout() is called with two arguments, the callback and the timeout. Specifying optional arguments in the parameter list forces common case calls to go through an arguments adaptor stack frame. PR-URL: #1221 Reviewed-By: Trevor Norris <[email protected]>
nodejs · Mar 20, 2015 · 31da975 · 31da975
1 parent b64983d
commit 31da975
Showing 1 changed file with 13 additions and 23 deletions.
diff --git a/lib/timers.js b/lib/timers.js
@@ -173,51 +173,41 @@ exports.active = function(item) {
  */
 
 
-exports.setTimeout = function(callback, after, arg1, arg2, arg3) {
-  var timer, i, args;
-  var len = arguments.length;
-
+exports.setTimeout = function(callback, after) {
   after *= 1; // coalesce to number or NaN
 
   if (!(after >= 1 && after <= TIMEOUT_MAX)) {
     after = 1; // schedule on next tick, follows browser behaviour
   }
 
-  timer = new Timeout(after);
-
-  switch (len) {
+  var timer = new Timeout(after);
+  var length = arguments.length;
+  var ontimeout = callback;
+  switch (length) {
     // fast cases
     case 0:
     case 1:
     case 2:
-      timer._onTimeout = callback;
       break;
     case 3:
-      timer._onTimeout = function() {
-        callback.call(timer, arg1);
-      };
+      ontimeout = callback.bind(timer, arguments[2]);
       break;
     case 4:
-      timer._onTimeout = function() {
-        callback.call(timer, arg1, arg2);
-      };
+      ontimeout = callback.bind(timer, arguments[2], arguments[3]);
       break;
     case 5:
-      timer._onTimeout = function() {
-        callback.call(timer, arg1, arg2, arg3);
-      };
+      ontimeout =
+          callback.bind(timer, arguments[2], arguments[3], arguments[4]);
       break;
     // slow case
     default:
-      args = new Array(len - 2);
-      for (i = 2; i < len; i++)
+      var args = new Array(length - 2);
+      for (var i = 2; i < length; i++)
         args[i - 2] = arguments[i];
-
-      timer._onTimeout = function() {
-        callback.apply(timer, args);
-      };
+      ontimeout = callback.apply.bind(callback, timer, args);
       break;
   }
+  timer._onTimeout = ontimeout;
 
   if (process.domain) timer.domain = process.domain;