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yap-6.3/pl/signals.yap

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Prolog
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/*************************************************************************
* *
* YAP Prolog *
* *
* Yap Prolog was developed at NCCUP - Universidade do Porto *
* *
* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 *
* *
**************************************************************************
* *
* File: signals.pl *
* Last rev: *
* mods: *
* comments: signal handling in YAP *
* *
*************************************************************************/
:- meta_predicate on_signal(+,?,:), alarm(+,:,-).
'$creep'(G) :-
% get the first signal from the mask
'$first_signal'(Sig), !,
% process it
'$do_signal'(Sig, G).
'$creep'([M|G]) :-
% noise, just go on with our life.
'$execute'(M:G).
'$do_signal'(sig_wake_up, G) :-
'$awoken_goals'(LG),
% if more signals alive, set creep flag
'$continue_signals',
'$wake_up_goal'(G, LG).
% never creep on entering system mode!!!
% don't creep on meta-call.
'$do_signal'(sig_creep, [M|G]) :-
'$creep_allowed', !,
(
( G = '$notrace'(G0) ; G = '$oncenotrace'(G0) ; G = '$execute0'(G0,M) ; '$system_module'(M), G = G0 )
->
(
'$execute_nonstop'(G0,M),
'$signal_creep'
;
'$signal_creep',
fail
)
;
'$start_creep'([M|G])
).
%
'$do_signal'(sig_creep, [M|G]) :-
( G = '$notrace'(G0) ; G = '$oncenotrace'(G0) ; G = '$execute0'(G0,M) ; '$system_module'(M), G = G0 ),
!,
(
'$execute_nonstop'(G0,M),
'$signal_creep'
;
'$signal_creep',
fail
).
%
'$do_signal'(sig_creep, [M|G]) :-
'$signal_creep',
'$execute_nonstop'(G,M).
'$do_signal'(sig_delay_creep, [M|G]) :-
'$execute'(M:G),
'$creep'.
'$do_signal'(sig_iti, [M|G]) :-
'$thread_gfetch'(Goal),
% if more signals alive, set creep flag
'$continue_signals',
'$current_module'(M0),
'$execute0'(Goal,M0),
'$execute'(M:G).
'$do_signal'(sig_trace, [M|G]) :-
'$continue_signals',
trace,
'$execute'(M:G).
'$do_signal'(sig_debug, [M|G]) :-
'$continue_signals',
debug,
'$execute'(M:G).
'$do_signal'(sig_break, [M|G]) :-
'$continue_signals',
break,
'$execute0'(G,M).
'$do_signal'(sig_statistics, [M|G]) :-
'$continue_signals',
statistics,
'$execute0'(G,M).
% the next one should never be called...
'$do_signal'(fail, [_|_]) :-
fail.
'$do_signal'(sig_stack_dump, [M|G]) :-
'$continue_signals',
'$stack_dump',
'$execute0'(G,M).
% Unix signals
'$do_signal'(sig_alarm, G) :-
'$signal_handler'(sig_alarm, G).
'$do_signal'(sig_vtalarm, G) :-
'$signal_handler'(sig_vtalarm, G).
'$do_signal'(sig_hup, G) :-
'$signal_handler'(sig_hup, G).
'$do_signal'(sig_usr1, G) :-
'$signal_handler'(sig_usr1, G).
'$do_signal'(sig_usr2, G) :-
'$signal_handler'(sig_usr2, G).
'$do_signal'(sig_pipe, G) :-
'$signal_handler'(sig_pipe, G).
'$signal_handler'(Sig, [M|G]) :-
'$signal_do'(Sig, Goal),
% if more signals alive, set creep flag
'$continue_signals',
'$current_module'(M0),
'$execute0'((Goal,M:G),M0).
% '$execute0' should be ignored.
'$start_creep'([_|'$execute0'(G,M)]) :-
!,
'$start_creep'([M|G]).
% '$call'() is a complicated thing
'$start_creep'([M0|'$call'(G, CP, G0, M)]) :-
!,
'$creep',
'$execute_nonstop'('$call'(G, CP, G0, M),M0).
% donotrace: means do not trace! So,
% ignore and then put creep back for the continuation.
'$start_creep'([M0|'$notrace'(G)]) :-
!,
(
CP0 is '$last_choice_pt',
'$execute_nonstop'(G,M0),
CP1 is '$last_choice_pt',
% exit port: creep
'$creep',
(
% if deterministic just creep all you want.
CP0 = CP1 ->
!
;
% extra disjunction protects reentry into usergoal
(
% cannot cut here
true
;
% be sure to disable creep on redo port
'$disable_creep',
fail
)
)
;
% put it back again on fail
'$creep',
fail
).
'$start_creep'([M0|'$oncenotrace'(G)]) :-
!,
('$execute_nonstop'(G,M0),
CP1 is '$last_choice_pt',
% exit port: creep
'$creep',
!
;
% put it back again on fail
'$creep',
fail
).
% do not debug if we are not in debug mode.
'$start_creep'([Mod|G]) :-
'$debug_on'(DBON), DBON = false, !,
'$execute_nonstop'(G,Mod).
'$start_creep'([Mod|G]) :-
nb_getval('$system_mode',on), !,
'$execute_nonstop'(G,Mod).
% notice that the last signal to be processed must always be creep
'$start_creep'([_|'$cut_by'(CP)]) :- !,
'$$cut_by'(CP),
'$creep'.
'$start_creep'([_|true]) :- !,
'$creep'.
'$start_creep'([Mod|G]) :-
'$hidden_predicate'(G,Mod), !,
'$execute_nonstop'(G,Mod),
'$creep'.
% do not debug if we are zipping through.
'$start_creep'([Mod|G]) :-
nb_getval('$debug_run',Run),
Run \= off,
'$zip'(-1, G, Mod), !,
'$signal_creep',
'$execute_goal'(G, Mod).
'$start_creep'([Mod|G]) :-
CP is '$last_choice_pt',
'$do_spy'(G, Mod, CP, no).
'$execute_goal'(G, Mod) :-
(
'$is_metapredicate'(G, Mod)
->
'$meta_call'(G,Mod)
;
'$execute_nonstop'(G,Mod)
).
'$signal_do'(Sig, Goal) :-
recorded('$signal_handler', action(Sig,Goal), _), !.
'$signal_do'(Sig, Goal) :-
'$signal_def'(Sig, Goal).
% reconsult init files.
'$signal_def'(sig_hup, (( exists('~/.yaprc') -> [-'~/.yaprc'] ; true ),
( exists('~/.prologrc') -> [-'~/.prologrc'] ; true ),
( exists('~/prolog.ini') -> [-'~/prolog.ini'] ; true ))).
% die on signal default.
'$signal_def'(sig_usr1, throw(error(signal(usr1,[]),true))).
'$signal_def'(sig_usr2, throw(error(signal(usr2,[]),true))).
'$signal_def'(sig_pipe, throw(error(signal(pipe,[]),true))).
% ignore sig_alarm by default
'$signal_def'(sig_alarm, true).
'$signal'(sig_hup).
'$signal'(sig_usr1).
'$signal'(sig_usr2).
'$signal'(sig_pipe).
'$signal'(sig_alarm).
'$signal'(sig_vtalarm).
on_signal(Signal,OldAction,NewAction) :-
var(Signal), !,
(nonvar(OldAction) -> throw(error(instantiation_error,on_signal/3)) ; true),
'$signal'(Signal),
on_signal(Signal, OldAction, NewAction).
on_signal(Signal,OldAction,default) :-
'$reset_signal'(Signal, OldAction).
on_signal(Signal,OldAction,Action) :-
var(Action), !,
throw(error(system_error,'Somehow the meta_predicate declarations of on_signal are subverted!')).
on_signal(Signal,OldAction,Action) :-
Action = (_:Goal),
var(Goal), !,
'$check_signal'(Signal, OldAction),
Goal = OldAction.
on_signal(Signal,OldAction,Action) :-
'$reset_signal'(Signal, OldAction),
% 13211-2 speaks only about callable
( Action = M:Goal -> true ; throw(error(type_error(callable,Action),on_signal/3)) ),
% the following disagrees with 13211-2:6.7.1.4 which disagrees with 13211-1:7.12.2a
% but the following agrees with 13211-1:7.12.2a
( nonvar(M) -> true ; throw(error(instantiation_error,on_signal/3)) ),
( atom(M) -> true ; throw(error(type_error(callable,Action),on_signal/3)) ),
( nonvar(Goal) -> true ; throw(error(instantiation_error,on_signal/3)) ),
recordz('$signal_handler', action(Signal,Action), _).
'$reset_signal'(Signal, OldAction) :-
recorded('$signal_handler', action(Signal,OldAction), Ref), !,
erase(Ref).
'$reset_signal'(_, default).
'$check_signal'(Signal, OldAction) :-
recorded('$signal_handler', action(Signal,OldAction), _), !.
'$check_signal'(_, default).
alarm(Interval, Goal, Left) :-
Interval == 0, !,
'$alarm'(0, 0, Left0, _),
on_signal(sig_alarm, _, Goal),
Left = Left0.
alarm(Interval, Goal, Left) :-
integer(Interval), !,
on_signal(sig_alarm, _, Goal),
'$alarm'(Interval, 0, Left, _).
alarm(Number, Goal, Left) :-
float(Number), !,
Secs is integer(Number),
USecs is integer((Number-Secs)*1000000) mod 1000000,
on_signal(sig_alarm, _, Goal),
'$alarm'(Interval, 0, Left, _).
alarm(Interval.USecs, Goal, Left.LUSecs) :-
on_signal(sig_alarm, _, Goal),
'$alarm'(Interval, USecs, Left, LUSecs).
raise_exception(Ball) :- throw(Ball).
on_exception(Pat, G, H) :- catch(G, Pat, H).
read_sig :-
recorded('$signal_handler',X,_),
writeq(X),nl,
fail.
read_sig.
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