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/* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (C): 1985-2014, University of Amsterdam
VU University Amsterdam
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
As a special exception, if you link this library with other files,
compiled with a Free Software compiler, to produce an executable, this
library does not by itself cause the resulting executable to be covered
by the GNU General Public License. This exception does not however
invalidate any other reasons why the executable file might be covered by
the GNU General Public License.
*/
:- module(time,
[ alarm/3, % +Time, :Callable, -Id
alarm/4, % +Time, :Callable, -Id, +Options
alarm_at/3, % +Time, :Callable, -Id
alarm_at/4, % +Time, :Callable, -Id, +Options
remove_alarm/1, % +Id
install_alarm/1, % +Id
install_alarm/2, % +Id, +Time
uninstall_alarm/1, % +Id
current_alarm/4, % ?At, ?:Goal, ?Id, ?Status
call_with_time_limit/2 % +Time, :Callable
]).
:- use_module(library(lists)).
:- set_prolog_flag(generate_debug_info, false).
:- meta_predicate
call_with_time_limit(+, 0),
alarm(+, 0, -),
alarm(+, 0, -, +),
alarm_at(+, 0, -, +),
current_alarm(?, :, ?, ?).
:- predicate_options(alarm/4, 4,
[ remove(boolean),
install(boolean)
]).
/** <module> Time and alarm library
*/
%% alarm(+Time, :Callable, -Id) is det.
%% alarm(+Time, :Callable, -Id, +Options) is det.
%
% Set up an alarm to be signaled Time seconds from now. If the
% alarm expires, Callable is called asynchronously. Callable can
% be used to raise an exception using throw/1 to abort some
% execution.
%
% Options is a list of Name(Value) options. Currently defined
% options are:
%
% * remove(Bool)
% If =true= (default =false=), remove the alarm-event (as
% remove_alarm/1) after it has been fired.
% * install(Bool)
% If =false= (default =true=) do not install the alarm.
% It must be installed separately using install_alarm/1.
%% alarm_at(+Time, :Callable, -Id) is det.
%% alarm_at(+Time, :Callable, -Id, +Options) is det.
%
% As alarm/3 and alarm/4, but schedule the alarm at an absolute
% point in time.
%
% @see date_time_stamp/2.
%% install_alarm(+Id) is det.
%% install_alarm(+Id, +RelTime) is det.
%
% Install an alarm allocated using alarm/4 with the install(false)
% option or de-activated using uninstall_alarm/1. With a given
% RelTime, the alarm is scheduled at the RelTime from now.
% Otherwise it is scheduled on the same (absolute) time on which
% is was created.
%% uninstall_alarm(+Id) is det.
%
% De-activate an alarm. This does _not_ invalidate Id, but ensures
% that the alarm will not fire. The alarm can be rescheduled to
% the original time using install_alarm/1 or to a new time using
% install_alarm/2.
%% remove_alarm(+Id) is det.
%
% Remove an alarm. If it has not yet been fired, it never will.
%% current_alarm(?Time, :Goal, ?Id, ?Status) is nondet.
%
% Enumerate the alarms in the schedule. Time is the absolute time
% the event is scheduled for (see also get_time/1). Goal is the
% goal to execute, Id is the identifier and Status is the
% scheduling status. It takes the value =done= if the alarm has
% been fired, =next= if the event is the next to be executed and
% =scheduled= otherwise.
:- use_foreign_library(foreign(time)).
:- public time_debug/1. % set debugging
%% call_with_time_limit(+Time, :Goal) is semidet.
%
% Call Goal, while watching out for a (wall-time) limit. If this
% limit is exceeded, the exception =time_limit_exceeded= is
% raised. Goal is called as in once/1.
%
% @throws =time_limit_exceeded=
call_with_time_limit(Time, Goal) :-
Time > 0, !,
setup_call_cleanup(alarm(Time, time_limit_exceeded(Time),
Id, [install(false)]),
run_alarm_goal(Id, Goal),
remove_alarm_notrace(Id)).
call_with_time_limit(_Time, _Goal) :-
throw(time_limit_exceeded).
run_alarm_goal(AlarmID, Goal) :-
install_alarm(AlarmID),
Goal, !.
time_limit_exceeded(_Time) :-
throw(time_limit_exceeded).
current_alarm(Time, Goal, Id, Status) :-
current_alarms(Time, Goal, Id, Status, List),
member(alarm(Time, Goal, Id, Status), List).
/*******************************
* HANDLE MESSAGES *
*******************************/
:- multifile
prolog:message/3.
prolog:message(time_limit_exceeded) -->
[ 'Time limit exceeded' ].
|
