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