'Inline' set in Set, and do time checks before the lock

cache.go

@@ -49,8 +49,19 @@ type cache struct {
 // (DefaultExpiration), the cache's default expiration time is used. If it is -1
 // (NoExpiration), the item never expires.
 func (c *cache) Set(k string, x interface{}, d time.Duration) {
+	// "Inlining" of set
+	var e int64
+	if d == DefaultExpiration {
+		d = c.defaultExpiration
+	}
+	if d > 0 {
+		e = time.Now().Add(d).UnixNano()
+	}
 	c.mu.Lock()
-	c.set(k, x, d)
+	c.items[k] = Item{
+		Object:     x,
+		Expiration: e,
+	}
 	// TODO: Calls to mu.Unlock are currently not deferred because defer
 	// adds ~200 ns (as of go1.)
 	c.mu.Unlock()