+ (when (plusp (length (free-connections pool)))
+ (let ((pconn (vector-pop (free-connections pool))))
+ ;; test if connection still valid.
+ ;; (e.g. db reboot -> invalid connection )
+ (handler-case
+ (case (database-underlying-type pconn)
+ (:postgresql
+ (database-execute-command "RESET ALL" pconn))
+ (:mysql
+ (database-query "SHOW ERRORS LIMIT 1" pconn nil nil))
+ (:mssql
+ ;; rpc escape sequence since this can't be called as a normal sp.
+ ;;http://msdn.microsoft.com/en-us/library/aa198358%28SQL.80%29.aspx
+ (database-execute-command "{rpc sp_reset_connection}" pconn))
+ (T
+ (database-query "SELECT 1;" pconn '(integer) nil)))
+ (sql-database-error (e)
+ ;; we could check for a specific error,
+ ;; 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 (&rest args)
+ (declare (ignore args))
+ pconn)))))