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.
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    9    Redistribution and use in source and binary forms, with or without
   10    modification, are permitted provided that the following conditions
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   14       notice, this list of conditions and the following disclaimer.
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   16    2. Redistributions in binary form must reproduce the above copyright
   17       notice, this list of conditions and the following disclaimer in
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   21    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   22    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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   34
   35:- module(timed_call,
   36          [ timed_call/2
   37          ]).   38:- use_module(library(time)).

 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.

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