remove release() pattern

common/common.go

@@ -13,19 +13,6 @@ var (
 	ErrDuplicatedName   = errors.New("Duplicated name.")
 )
 
-// Releasable interface is for those types that can release its members.
-type Releasable interface {
-	// Release releases all references to accelerate garbage collection.
-	Release()
-}
-
-// Release tries to release the given object.
-func Release(v interface{}) {
-	if releasable, ok := v.(Releasable); ok {
-		releasable.Release()
-	}
-}
-
 // Must panics if err is not nil.
 func Must(err error) {
 	if err != nil {