sockets/namedb/file-monitor.lisp

   1 ;;;; -*- Mode: Lisp; Syntax: ANSI-Common-Lisp; Indent-tabs-mode: NIL -*-
   2 ;;;
   3 ;;; file-monitor.lisp --- Monitor files on disk.
   4 ;;;
   5 ;;; Copyright (C) 2007, Stelian Ionescu  <sionescu@common-lisp.net>
   6 ;;;
   7 ;;; This code is free software; you can redistribute it and/or
   8 ;;; modify it under the terms of the version 2.1 of
   9 ;;; the GNU Lesser General Public License as published by
  10 ;;; the Free Software Foundation, as clarified by the
  11 ;;; preamble found here:
  12 ;;;     http://opensource.franz.com/preamble.html
  13 ;;;
  14 ;;; This program is distributed in the hope that it will be useful,
  15 ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 ;;; GNU General Public License for more details.
  18 ;;;
  19 ;;; You should have received a copy of the GNU Lesser General
  20 ;;; Public License along with this library; if not, write to the
  21 ;;; Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
  22 ;;; Boston, MA 02110-1301, USA
  23
  24 (in-package :net.sockets)
  25
  26 (defclass file-monitor ()
  27   ((file :initform (error "Must supply a file name")
  28          :initarg :file :accessor file-of)
  29    (timestamp :initarg :timestamp :accessor timestamp-of)
  30    (update-fn :initarg :update-fn :accessor update-fn-of))
  31   (:default-initargs :timestamp 0))
  32
  33 (defgeneric oldp (monitor)
  34   (:method ((monitor file-monitor))
  35     (let ((mtime (file-write-date (file-of monitor))))
  36       (values (< (timestamp-of monitor) mtime)
  37               mtime))))
  38
  39 (defgeneric update-monitor (monitor)
  40   (:method ((monitor file-monitor))
  41     (multiple-value-bind (oldp mtime) (oldp monitor)
  42       (when oldp
  43         (funcall (update-fn-of monitor) (file-of monitor))
  44         (multiple-value-prog1
  45             (values (timestamp-of monitor) mtime)
  46           (setf (timestamp-of monitor) mtime))))))