--- /dev/null
+;;;; -*- Mode: LISP; Syntax: ANSI-Common-Lisp; Base: 10 -*-
+;;;; *************************************************************************
+;;;; FILE IDENTIFICATION
+;;;;
+;;;; Name: pool.lisp
+;;;; Purpose: Support function for connection pool
+;;;; Programmers: Kevin M. Rosenberg, Marc Battyani
+;;;; Date Started: Apr 2002
+;;;;
+;;;; $Id$
+;;;;
+;;;; This file, part of CLSQL, is Copyright (c) 2002-2003 by Kevin M. Rosenberg
+;;;;
+;;;; CLSQL users are granted the rights to distribute and use this software
+;;;; as governed by the terms of the Lisp Lesser GNU Public License
+;;;; (http://opensource.franz.com/preamble.html), also known as the LLGPL.
+;;;; *************************************************************************
+
+(in-package #:clsql-sys)
+
+(defvar *db-pool* (make-hash-table :test #'equal))
+(defvar *db-pool-lock* (make-process-lock "DB Pool lock"))
+
+(defclass conn-pool ()
+ ((connection-spec :accessor connection-spec :initarg :connection-spec)
+ (database-type :accessor pool-database-type :initarg :pool-database-type)
+ (free-connections :accessor free-connections
+ :initform (make-array 5 :fill-pointer 0 :adjustable t))
+ (all-connections :accessor all-connections
+ :initform (make-array 5 :fill-pointer 0 :adjustable t))
+ (lock :accessor conn-pool-lock
+ :initform (make-process-lock "Connection pool"))))
+
+(defun acquire-from-conn-pool (pool)
+ (or (with-process-lock ((conn-pool-lock pool) "Acquire from pool")
+ (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)))))
+ (let ((conn (connect (connection-spec pool)
+ :database-type (pool-database-type pool)
+ :if-exists :new
+ :make-default nil)))
+ (with-process-lock ((conn-pool-lock pool) "Acquire from pool")
+ (vector-push-extend conn (all-connections pool))
+ (setf (conn-pool conn) pool))
+ conn)))
+
+(defun release-to-conn-pool (conn)
+ (let ((pool (conn-pool conn)))
+ (with-process-lock ((conn-pool-lock pool) "Release to pool")
+ (vector-push-extend conn (free-connections pool)))))
+
+(defun clear-conn-pool (pool)
+ (with-process-lock ((conn-pool-lock pool) "Clear pool")
+ (loop for conn across (all-connections pool)
+ do (setf (conn-pool conn) nil)
+ ;; disconnect may error if remote side closed connection
+ (ignore-errors (disconnect :database conn)))
+ (setf (fill-pointer (free-connections pool)) 0)
+ (setf (fill-pointer (all-connections pool)) 0))
+ nil)
+
+(defun find-or-create-connection-pool (connection-spec database-type)
+ "Find connection pool in hash table, creates a new connection pool
+if not found"
+ (with-process-lock (*db-pool-lock* "Find-or-create connection")
+ (let* ((key (list connection-spec database-type))
+ (conn-pool (gethash key *db-pool*)))
+ (unless conn-pool
+ (setq conn-pool (make-instance 'conn-pool
+ :connection-spec connection-spec
+ :pool-database-type database-type))
+ (setf (gethash key *db-pool*) conn-pool))
+ conn-pool)))
+
+(defun acquire-from-pool (connection-spec database-type &optional pool)
+ (unless (typep pool 'conn-pool)
+ (setf pool (find-or-create-connection-pool connection-spec database-type)))
+ (acquire-from-conn-pool pool))
+
+(defun release-to-pool (database)
+ (release-to-conn-pool database))
+
+(defun disconnect-pooled (&optional clear)
+ "Disconnects all connections in the pool."
+ (with-process-lock (*db-pool-lock* "Disconnect pooled")
+ (maphash
+ #'(lambda (key conn-pool)
+ (declare (ignore key))
+ (clear-conn-pool conn-pool))
+ *db-pool*)
+ (when clear (clrhash *db-pool*)))
+ t)
+
+;(defun pool-start-sql-recording (pool &key (types :command))
+; "Start all stream in the pool recording actions of TYPES"
+; (dolist (con (pool-connections pool))
+; (start-sql-recording :type types
+; :database (connection-database con))))
+
+;(defun pool-stop-sql-recording (pool &key (types :command))
+; "Start all stream in the pool recording actions of TYPES"
+; (dolist (con (pool-connections pool))
+; (stop-sql-recording :type types
+; :database (connection-database con))))
+
+;(defmacro with-database-connection (pool &body body)
+; `(let ((connection (obtain-connection ,pool))
+; (results nil))
+; (unwind-protect
+; (with-database ((connection-database connection))
+; (setq results (multiple-value-list (progn ,@body))))
+; (release-connection connection))
+; (values-list results)))