%%% -*- Mode: Prolog; -*- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % Concurrent alarms was developed at Katholieke Universiteit Leuven % % Copyright 2010 % Katholieke Universiteit Leuven % % Contributions to this file: % Author: Theofrastos Mantadelis % $Date: 2011-02-04 16:04:49 +0100 (Fri, 04 Feb 2011) $ % $Revision: 11 $ % Contributions: The timer implementation is inspired by Bernd Gutmann's timers % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % Artistic License 2.0 % % Copyright (c) 2000-2006, The Perl Foundation. % % Everyone is permitted to copy and distribute verbatim copies of this % license document, but changing it is not allowed. Preamble % % This license establishes the terms under which a given free software % Package may be copied, modified, distributed, and/or % redistributed. 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UNLESS REQUIRED BY LAW, NO COPYRIGHT % HOLDER OR CONTRIBUTOR WILL BE LIABLE FOR ANY DIRECT, INDIRECT, % INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING IN ANY WAY OUT OF THE USE % OF THE PACKAGE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% :- module(c_alarms, [set_alarm/3, unset_alarm/1, time_out_call_once/3, timer_start/1, timer_restart/1, timer_stop/2, timer_elapsed/2, timer_pause/2]). % set_alarm(+Seconds, +Execute, -ID) % calls Executes after a time interval of Seconds % ID is returned to be able to unset the alarm (the call will not be executed) % set_alarm/3 supports multiple & nested settings of alarms. % Known Bug: There is the case that an alarm might trigger +-1 second of the set time. % % unset_alarm(+ID) % It will unschedule the alarm. % It will not affect other concurrent alarms. % % time_out_call(+Seconds, +Goal, -Return) % It will will execute the closure Goal and returns its success or failure at Return. % If the goal times out in Seconds then Return = timeout. :- use_module(library(lists), [member/2, memberchk/2, delete/3]). :- use_module(library(ordsets), [ord_add_element/3]). :- use_module(library(maplist), [maplist/3]). :- dynamic('$timer'/3). :- meta_predicate(set_alarm(+, 0, -)). :- meta_predicate(time_out_call_once(+, 0, -)). :- meta_predicate(prove_once(0)). :- initialization(local_init). local_init:- bb_put(alarms, []), bb_put(identity, 0). get_next_identity(ID):- bb_get(identity, ID), NID is ID + 1, bb_put(identity, NID). set_alarm(Seconds, Execute, ID):- bb_get(alarms, []), get_next_identity(ID), !, bb_put(alarms, [alarm(Seconds, ID, Execute)]), alarm(Seconds, alarm_handler, _). set_alarm(Seconds, Execute, ID):- get_next_identity(ID), !, bb_get(alarms, [alarm(CurrentSeconds, CurrentID, CurrentExecute)|Alarms]), alarm(0, true, Remaining), Elapsed is CurrentSeconds - Remaining - 1, maplist(subtract(Elapsed), [alarm(CurrentSeconds, CurrentID, CurrentExecute)|Alarms], RemainingAlarms), ord_add_element(RemainingAlarms, alarm(Seconds, ID, Execute), [alarm(NewSeconds, NewID, NewToExecute)|NewAlarms]), bb_put(alarms, [alarm(NewSeconds, NewID, NewToExecute)|NewAlarms]), alarm(NewSeconds, alarm_handler, _). set_alarm(Seconds, Execute, ID):- throw(error(permission_error(create, alarm, set_alarm(Seconds, Execute, ID)), 'Non permitted alarm identifier.')). subtract(Elapsed, alarm(Seconds, ID, Execute), alarm(NewSeconds, ID, Execute)):- NewSeconds is Seconds - Elapsed. unset_alarm(ID):- \+ ground(ID), throw(error(instantiation_error, 'Alarm ID needs to be instantiated.')). unset_alarm(ID):- bb_get(alarms, Alarms), \+ memberchk(alarm(_Seconds, ID, _Execute), Alarms), throw(error(existence_error(alarm, unset_alarm(ID)), 'Alarm does not exist.')). unset_alarm(ID):- alarm(0, true, Remaining), bb_get(alarms, Alarms), [alarm(Seconds, _, _)|_] = Alarms, Elapsed is Seconds - Remaining - 1, delete_alarm(Alarms, ID, NewAlarms), bb_put(alarms, NewAlarms), (NewAlarms = [alarm(NewSeconds, _, _)|_] -> RemainingSeconds is NewSeconds - Elapsed, alarm(RemainingSeconds, alarm_handler, _) ; true ). delete_alarm(Alarms, ID, NewAlarms):- memberchk(alarm(Seconds, ID, Execute), Alarms), delete(Alarms, alarm(Seconds, ID, Execute), NewAlarms). alarm_handler:- bb_get(alarms, [alarm(_, _, CurrentExecute)|[]]), bb_put(alarms, []), call(CurrentExecute). alarm_handler:- bb_get(alarms, [alarm(Elapsed, CurrentID, CurrentExecute)|Alarms]), maplist(subtract(Elapsed), Alarms, NewAlarms), find_zeros(NewAlarms, ZeroAlarms), findall(alarm(S, ID, E), (member(alarm(S, ID, E), NewAlarms), S > 0), NonZeroAlarms), bb_put(alarms, NonZeroAlarms), (NonZeroAlarms = [alarm(NewSeconds, _, _)|_] -> alarm(NewSeconds, alarm_handler, _) ; true ), execute([alarm(0, CurrentID, CurrentExecute)|ZeroAlarms]). find_zeros([], []). find_zeros([alarm(0, ID, E)|T], [alarm(0, ID, E)|R]):- find_zeros(T, R). find_zeros([alarm(S, _, _)|T], R):- S > 0, find_zeros(T, R). execute([]). execute([alarm(_, _, Execute)|R]):- call(Execute), execute(R). time_out_call_once(Seconds, Goal, Return):- bb_get(identity, ID), set_alarm(Seconds, throw(timeout(ID)), ID), catch(( prove_once(Goal, Return), unset_alarm(ID)) , Exception, ( (Exception == timeout(ID) -> Return = timeout ; unset_alarm(ID), throw(Exception) ))). prove_once(Goal, success):- once(Goal), !. prove_once(_Goal, failure). timer_start(Name):- \+ ground(Name), throw(error(instantiation_error, 'Timer name needs to be instantiated.')). timer_start(Name):- '$timer'(Name, _, _), throw(error(permission_error(create, timer, timer_start(Name)), 'Timer already exists.')). timer_start(Name):- statistics(walltime, [StartTime, _]), assertz('$timer'(Name, running, StartTime)). timer_restart(Name):- \+ ground(Name), throw(error(instantiation_error, 'Timer name needs to be instantiated.')). timer_restart(Name):- \+ '$timer'(Name, _, _), !, statistics(walltime, [StartTime, _]), assertz('$timer'(Name, running, StartTime)). timer_restart(Name):- retract('$timer'(Name, running, _)), !, statistics(walltime, [StartTime, _]), assertz('$timer'(Name, running, StartTime)). timer_restart(Name):- retract('$timer'(Name, paused, Duration)), statistics(walltime, [StartTime, _]), Elapsed is StartTime - Duration, assertz('$timer'(Name, running, Elapsed)). timer_stop(Name, Elapsed):- \+ '$timer'(Name, _, _), throw(error(existence_error(timer, timer_stop(Name, Elapsed)), 'Timer does not exist.')). timer_stop(Name, Elapsed):- retract('$timer'(Name, running, StartTime)), !, statistics(walltime, [EndTime, _]), Elapsed is EndTime - StartTime. timer_stop(Name, Elapsed):- retract('$timer'(Name, paused, Elapsed)). timer_elapsed(Name, Elapsed):- \+ '$timer'(Name, _, _), throw(error(existence_error(timer, timer_elapsed(Name, Elapsed)), 'Timer does not exist.')). timer_elapsed(Name, Elapsed):- '$timer'(Name, running, StartTime), !, statistics(walltime, [EndTime, _]), Elapsed is EndTime - StartTime. timer_elapsed(Name, Elapsed):- '$timer'(Name, paused, Elapsed). timer_pause(Name, Elapsed):- \+ '$timer'(Name, _, _), throw(error(existence_error(timer, timer_pause(Name, Elapsed)), 'Timer does not exist.')). timer_pause(Name, Elapsed):- '$timer'(Name, paused, _), throw(error(permission_error(timer, timer_pause(Name, Elapsed)), 'Timer already paused.')). timer_pause(Name, Elapsed):- retract('$timer'(Name, _, StartTime)), statistics(walltime, [EndTime, _]), Elapsed is EndTime - StartTime, assertz('$timer'(Name, paused, Elapsed)).