+ (when (plusp (length (free-connections pool)))
+ (let ((pconn (vector-pop (free-connections pool))))
+ ;; test if connection still valid.
+ ;; Currently, on supported on MySQL
+ (cond
+ ((eq :mysql (database-type pconn))
+ (handler-case
+ (database-query "SHOW ERRORS LIMIT 1" pconn nil nil)
+ (error (e)
+ ;; we could check for error type 2006 for "SERVER GONE AWAY",
+ ;; but, it's safer just to disconnect the pooled conn for any error
+ (warn "Database connection ~S had an error when attempted to be acquired from the pool:
+ ~S
+Disconnecting.~%"
+ pconn e)
+ (ignore-errors (database-disconnect pconn))
+ nil)
+ (:no-error (res fields)
+ (declare (ignore res fields))
+ pconn)))
+ (t
+ pconn)))))