db-db2/foreign-resources.lisp

   1 ;;;; -*- Mode: LISP; Syntax: ANSI-Common-Lisp; Base: 10 -*-
   2 ;;;; *************************************************************************
   3 ;;;; FILE IDENTIFICATION
   4 ;;;;
   5 ;;;; $Id$
   6 ;;;;
   7 ;;;; This file is part of CLSQL.
   8 ;;;;
   9 ;;;; CLSQL users are granted the rights to distribute and use this software
  10 ;;;; as governed by the terms of the Lisp Lesser GNU Public License
  11 ;;;; (http://opensource.franz.com/preamble.html), also known as the LLGPL.
  12 ;;;; *************************************************************************
  13
  14 (in-package #:clsql-db2)
  15
  16 (defparameter *foreign-resource-hash* (make-hash-table :test #'equal))
  17
  18 (defstruct (foreign-resource)
  19   (type (error "Missing TYPE.")
  20         :read-only t)
  21   (sizeof (error "Missing SIZEOF.")
  22           :read-only t)
  23   (buffer (error "Missing BUFFER.")
  24           :read-only t)
  25   (in-use nil :type boolean))
  26
  27
  28 (defun %get-resource (type sizeof)
  29   (let ((resources (gethash type *foreign-resource-hash*)))
  30     (car (member-if
  31           #'(lambda (res)
  32               (and (= (foreign-resource-sizeof res) sizeof)
  33                    (not (foreign-resource-in-use res))))
  34           resources))))
  35
  36 (defun %insert-foreign-resource (type res)
  37   (let ((resource (gethash type *foreign-resource-hash*)))
  38     (setf (gethash type *foreign-resource-hash*)
  39           (cons res resource))))
  40
  41 (defmacro acquire-foreign-resource (type &optional size)
  42   `(let ((res (%get-resource ,type ,size)))
  43      (unless res
  44        (setf res (make-foreign-resource
  45                   :type ,type :sizeof ,size
  46                   :buffer (uffi:allocate-foreign-object ,type ,size)))
  47        (%insert-foreign-resource ',type res))
  48      (claim-foreign-resource res)))
  49
  50 (defun free-foreign-resource (ares)
  51   (setf (foreign-resource-in-use ares) nil)
  52   ares)
  53
  54 (defun claim-foreign-resource (ares)
  55   (setf (foreign-resource-in-use ares) t)
  56   ares)
  57
  58
  59