1/*  Part of SWI-Prolog
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  2019, VU University Amsterdam
    7    All rights reserved.
    8
    9    Redistribution and use in source and binary forms, with or without
   10    modification, are permitted provided that the following conditions
   11    are met:
   12
   13    1. Redistributions of source code must retain the above copyright
   14       notice, this list of conditions and the following disclaimer.
   15
   16    2. Redistributions in binary form must reproduce the above copyright
   17       notice, this list of conditions and the following disclaimer in
   18       the documentation and/or other materials provided with the
   19       distribution.
   20
   21    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   22    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   23    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   24    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   25    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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   27    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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   33*/
   34
   35:- module(timed_call,
   36          [ timed_call/2
   37          ]).   38:- use_module(library(time)).   39:- use_module(library(debug)).   40:- use_module(library(error)).

 timed_call(:Goal, :Options)

Emulation for XSB timed_call/2. Runs Goal as once/1 with timed interrupts. The interrupt goals are called as interrupts using the semantics of ignore/1: possible choice points are cut and failure is ignored. If the interrupt throws an exception this is propagated.

Options is a list of the terms below. At least one of the terms max/2 or repeating/2 must be present.

max(+MaxInterval, :MaxHandler)

Schedule a single interrupt calling MaxHandler at MaxInterval milliseconds from now.

repeating(+RepInterval, :RepHandler)

Schedule a repeating interrupt calling RepHandler each RepInterval milliseconds.

nesting

Nested calls to timed_call/2 are transformed into calls to once/1. Without nesting, a nested call raises a permission_error exception.

See also

- call_with_time_limit/2, alarm/4, thread_signal/2.

Compatibility

- This predicate is a generalization of the SWI-Prolog library(time) interface. It is left in the XSB emulation because it uses non-standard option syntax and the time is in milliseconds where all SWI-Prolog time handling uses seconds.

   79:- meta_predicate
   80    timed_call(0, :).   81
   82timed_call(Goal, _Options) :-
   83    ok_nested(Goal),
   84    !,
   85    debug(timed_call, 'Calling nested ~p', [Goal]),
   86    once(Goal).
   87timed_call(Goal, Options) :-
   88    '$timed_call_nested'(Goal, Options),
   89    no_lco.
   90
   91no_lco.
   92
   93ok_nested(Goal) :-
   94    prolog_current_frame(Fr),
   95    prolog_frame_attribute(Fr, parent, Fr2),
   96    prolog_frame_attribute(Fr2, parent, Parent),
   97    prolog_frame_attribute(Parent, parent_goal,
   98                           timed_call:timed_call(_,_:Options)),
   99    !,
  100    debug(timed_call, 'Nested ~p: found parent timed call with options ~p',
  101          [Goal, Options]),
  102    (   memberchk(nesting, Options)
  103    ->  true
  104    ;   permission_error(nest, timed_goal, Goal)
  105    ).
  106
  107
  108'$timed_call_nested'(Goal, M:Options) :-
  109    memberchk(max(MaxInterval, MaxHandler), Options),
  110    !,
  111    run_max_goal(Goal, MaxInterval, MaxHandler, M:Options).
  112'$timed_call_nested'(Goal, M:Options) :-
  113    memberchk(repeating(RepInterval, RepHandler), Options),
  114    !,
  115    run_repeating_goal(Goal, RepInterval, RepHandler, M:Options).
  116'$timed_call_nested'(_Goal, _M:Options) :-
  117    domain_error(timed_call_options, Options).
  118
  119run_max_goal(Goal, MaxInterval, MaxHandler, M:Options) :-
  120    (   MaxInterval > 0
  121    ->  Time is MaxInterval/1000,
  122        setup_call_cleanup(alarm(Time, ignore(M:MaxHandler),
  123                                 Id, [install(false)]),
  124                           run_opt_releating(Id, Goal, M:Options),
  125                           time:remove_alarm_notrace(Id))
  126    ;   call(M:MaxHandler)
  127    ).
  128
  129run_opt_releating(AlarmID, Goal, M:Options) :-
  130    memberchk(repeating(RepInterval, RepHandler), Options),
  131    !,
  132    install_alarm(AlarmID),
  133    run_repeating_goal(Goal, RepInterval, RepHandler, M:Options).
  134run_opt_releating(AlarmID, Goal, _Options) :-
  135    install_alarm(AlarmID),
  136    call(Goal),
  137    !.
  138
  139run_repeating_goal(Goal, RepInterval, RepHandler, M:_Options) :-
  140    (   RepInterval > 0
  141    ->  Time is RepInterval/1000,
  142        setup_call_cleanup(alarm(Time, repeat_handler(Id, Time, M:RepHandler),
  143                                 Id, [install(false)]),
  144                           run_alarm_goal(Id, Goal),
  145                           time:remove_alarm_notrace(Id))
  146    ;   domain_error(repeating_interval, RepInterval)
  147    ).
  148
  149
  150repeat_handler(Id, Time, M:RepHandler) :-
  151    ignore(M:RepHandler),
  152    uninstall_alarm(Id),
  153    install_alarm(Id, Time).
  154
  155run_alarm_goal(AlarmID, Goal) :-
  156    install_alarm(AlarmID),
  157    call(Goal),
  158    !