[signals] Minor performance optimization

- Minor performance optimization to speed up signal handlers; substitutes
  call_user_func for call_user_func_array for finite numbers of arguments.

Author: weierophinney

src/SignalHandler.php

@@ -117,7 +117,24 @@ public function getCallback()
     public function call(array $args = array())
     {
         $callback = $this->getCallback();
-        return call_user_func_array($callback, $args);
+
+        // Following is a performance optimization hack. call_user_func() is up 
+        // to 6x faster than call_user_func_array(), and since signal handlers 
+        // will be called potentially dozens to hundreds of times in an 
+        // application, this optimization makes sense.
+        //
+        // We can potentially expand the number of case statements if we find 
+        // many instances where we're using more arguments.
+        switch (count($args)) {
+            case 1:
+                return call_user_func($callback, $args[0]);
+            case 2:
+                return call_user_func($callback, $args[0], $args[1]);
+            case 3:
+                return call_user_func($callback, $args[0], $args[1], $args[2]);
+            default:
+                return call_user_func_array($callback, $args);
+        }
     }
 
     /**