--- Memcached.php	2009-02-05 16:14:22.000000000 -0800
+++ Memcached_Modified.php	2009-02-05 16:26:59.000000000 -0800
@@ -190,10 +190,8 @@
         } else {
             $flag = 0;
         }
-        if ($this->test($id)) {
-            // because set and replace seems to have different behaviour
-            $result = $this->_memcache->replace($id, array($data, time(), $lifetime), $flag, $lifetime);
-        } else {
+        // set is required if the key already exists, but add is faster if it doesn't
+        if (! $result = $this->_memcache->add($id, array($data, time(), $lifetime), $flag, $lifetime)) {
             $result = $this->_memcache->set($id, array($data, time(), $lifetime), $flag, $lifetime);
         }
         if (count($tags) > 0) {
@@ -437,11 +435,12 @@
             if ($newLifetime <=0) {
                 return false;
             }
-            if ($this->test($id)) {
-                // because set and replace seems to have different behaviour
-                $result = $this->_memcache->replace($id, array($data, time(), $newLifetime), $flag, $newLifetime);
-            } else {
-                $result = $this->_memcache->set($id, array($data, time(), $newLifetime), $flag, $newLifetime);
+            /* 
+             * This add call will only succeed if the key has fallen out between the get call above 
+             * and here but the speed benefit of add is useful enough to run it regardless.
+             */
+            if (! $result = $this->_memcache->add($id, array($data, time(), $lifetime), $flag, $lifetime)) {
+              $result = $this->_memcache->set($id, array($data, time(), $lifetime), $flag, $lifetime);
             }
             return true;
         }