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1 ;;; itimer-autosave.el --- Autosave functions with itimers
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2
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3 ;; Copyright status unknown
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4
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5 ;; This file is part of XEmacs.
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6
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7 ;; XEmacs is free software; you can redistribute it and/or modify it
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8 ;; under the terms of the GNU General Public License as published by
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9 ;; the Free Software Foundation; either version 2, or (at your option)
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10 ;; any later version.
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11
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12 ;; XEmacs is distributed in the hope that it will be useful, but
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13 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
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14 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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15 ;; General Public License for more details.
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16
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17 ;; You should have received a copy of the GNU General Public License
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18 ;; along with XEmacs; see the file COPYING. If not, write to the Free
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19 ;; Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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20 ;; 02111-1307, USA.
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21
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22 ;;; Synched up with: Not in FSF.
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23
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24 ;;; Commentary:
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25
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26 ;; itimer-driven auto-saves
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27
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28 ;;; Code:
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29
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30 ;jwz: this is preloaded so don't ;;;###autoload
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31 (defvar auto-save-timeout 960
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32 "*Number of seconds idle time before auto-save.
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33 Zero or nil means disable auto-saving due to idleness.
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34
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35 The actual amount of idle time between auto-saves is logarithmically related
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36 to the size of the current buffer. This variable is the number of seconds
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37 after which an auto-save will happen when the current buffer is 50k or less;
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38 the timeout will be 2 1/4 times this in a 200k buffer, 3 3/4 times this in a
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39 1000k buffer, and 4 1/2 times this in a 2000k buffer.
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40
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41 See also the variable `auto-save-interval', which controls auto-saving based
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42 on the number of characters typed.")
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43
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44 ;jwz: this is preloaded so don't ;;;###autoload
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45 (defvar auto-gc-threshold (/ gc-cons-threshold 3)
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46 "*GC when this many bytes have been consed since the last GC,
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47 and the user has been idle for `auto-save-timeout' seconds.")
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48
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49 (defun auto-save-itimer ()
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50 "For use as a itimer callback function.
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51 Auto-saves and garbage-collects based on the size of the current buffer
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52 and the value of `auto-save-timeout', `auto-gc-threshold', and the current
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53 keyboard idle-time."
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54 (if (or (null auto-save-timeout)
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55 (<= auto-save-timeout 0)
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56 (eq (minibuffer-window) (selected-window)))
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57 nil
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58 (let ((buf-size (1+ (ash (buffer-size) -8)))
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59 (delay-level 0)
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60 (now (current-time))
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61 delay)
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62 (while (> buf-size 64)
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63 (setq delay-level (1+ delay-level)
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64 buf-size (- buf-size (ash buf-size -2))))
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65 (if (< delay-level 4)
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66 (setq delay-level 4))
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67 ;; delay_level is 4 for files under around 50k, 7 at 100k, 9 at 200k,
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68 ;; 11 at 300k, and 12 at 500k, 15 at 1 meg, and 17 at 2 meg.
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69 (setq delay (/ (* delay-level auto-save-timeout) 4))
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70 (let ((idle-time (if (or (not (consp last-input-time))
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71 (/= (car now) (car last-input-time)))
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72 (1+ delay)
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73 (- (car (cdr now)) (cdr last-input-time)))))
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74 (and (> idle-time delay)
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75 (do-auto-save))
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76 (and (> idle-time auto-save-timeout)
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77 (> (consing-since-gc) auto-gc-threshold)
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78 (garbage-collect)))))
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79 ;; Look at the itimer that's currently running; if the user has changed
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80 ;; the value of auto-save-timeout, modify this itimer to have the correct
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81 ;; restart time. There will be some latency between when the user changes
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82 ;; this variable and when it takes effect, but it will happen eventually.
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83 (let ((self (get-itimer "auto-save")))
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84 (or self (error "auto-save-itimer can't find itself"))
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85 (if (and auto-save-timeout (> auto-save-timeout 4))
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86 (or (= (itimer-restart self) (/ auto-save-timeout 4))
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87 (set-itimer-restart self (/ auto-save-timeout 4)))))
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88 nil)
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89
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90 (defun itimer-init-auto-gc ()
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91 (or noninteractive ; may be being run from after-init-hook in -batch mode.
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92 (get-itimer "auto-save")
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93 ;; the time here is just the first interval; if the user changes it
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94 ;; later, it will adjust.
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95 (let ((time (max 2 (/ (or auto-save-timeout 30) 4))))
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96 (start-itimer "auto-save" 'auto-save-itimer time time))))
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97
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98 (cond (purify-flag
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99 ;; This file is being preloaded into an emacs about to be dumped.
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100 ;; So arrange for the auto-save itimer to be started once emacs
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101 ;; is launched.
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102 (add-hook 'after-init-hook 'itimer-init-auto-gc))
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103 (t
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104 ;; Otherwise, this file is being loaded into a normal, interactive
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105 ;; emacs. Start the auto-save timer now.
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106 (itimer-init-auto-gc)))
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107
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108
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109 ;;; itimer-autosave.el ends here
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