pomo connection reuse

gistfile1.lisp

;;;
;;; Connection pooling
;;;
(defparameter *connection-pool-lock* (bt:make-lock))
(defparameter *max-pooled-connections* 50)
(defvar *connection-pool* (make-queue *max-pooled-connections*))

(defun get-connection ()
  (or (bt:with-lock-held (*connection-pool-lock*)
        (unless (queue-empty-p *connection-pool*)
          (dequeue *connection-pool*)))
      (apply #'connect (list *db-name* *db-user* *db-password* *db-host*))))

(defun done-with-connection (connection)
  (bt:with-lock-held (*connection-pool-lock*)
    (if (queue-full-p *connection-pool*)
        (disconnect connection)
        (enqueue connection *connection-pool*))))

(defun clear-pooled-connections ()
  (bt:with-lock-held (*connection-pool-lock*)
    (loop until (queue-empty-p *connection-pool*)
       for connection = (dequeue *connection-pool*)
       when (connected-p connection)
       do (disconnect connection))))

(defmacro with-db ((&key (reusep t)) &body body)
  `(let* ((reusing-connection-p (and *database* ,reusep))
          (*database* (or (when reusing-connection-p *database*)
                          (get-connection))))
     (unwind-protect (progn ,@body)
       (unless reusing-connection-p
         (done-with-connection *database*)))))