Threadsafe slot access

(defclass my-object ()
  ((lock :initform (bt:make-recursive-lock)
         :accessor lock)
   (slot :initarg :slot
         ...)
   (another-slot ...)
   ...))

(defmethod set-slot ((obj my-objectt) (new-value string))
  (bt:with-recursive-lock-held ((lock obj))
    (setf ((slot-value obj 'slot)) new-value)))

(defmethod do-something ((obj my-objectt))
  (bt:with-recursive-lock-held ((lock obj))
    (do-something-with-obj
      ...)))

(defmethod do-something-else ((obj my-objectt))
  (bt:with-recursive-lock-held ((lock obj))
    (do-something-else-with-obj
      ...)))

...