/*************************************************************************
*									 *
*	 YAP Prolog 							 *
*									 *
*	Yap Prolog was developed at NCCUP - Universidade do Porto	 *
*									 *
* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997	 *
*									 *
**************************************************************************
*									 *
* File:		threads.yap						 *
* Last rev:	8/2/88							 *
* mods:									 *
* comments:	support threads						 *
*									 *
*************************************************************************/

:- meta_predicate thread_create(:,-,+), thread_at_exit(:).

'$top_thread_goal'(G) :-
	'$current_module'(Module),
	'$system_catch'((G,'$close_thread'),Module,Exception,'$thread_exception'(Exception)).

'$top_thread_goal'(_) :-
	'$thread_self'(Id0),
	recorda('$thread_exit_status', [Id0|false], _),
	'$run_at_thread_exit'(Id0).

'$close_thread' :-
	'$thread_self'(Id0),
	recorda('$thread_exit_status', [Id0|true], _),
	'$run_at_thread_exit'(Id0).

'$thread_exception'(Exception) :-
	'$thread_self'(Id0),
	recorda('$thread_exit_status', [Id0|exception(Exception)], _),
	'$run_at_thread_exit'(Id0).

thread_create(Goal, Id, Options) :-
	G0 = thread_create(Goal, Id, Options),
	'$check_callable'(Goal,G0),
	'$thread_options'(Options, Aliases, Stack, Trail, System, Detached, G0),
	'$create_thread'(Goal, Stack, Trail, System, Id),
	'$clean_db_on_id'(Id),
	(Detached == true -> '$detach_thread'(Id) ; true),
	'$create_mq'(Id),
	'$add_thread_aliases'(Aliases, Id).

'$clean_db_on_id'(Id) :-
	recorda('$thread_exit_status', [Id|_], R),
	erase(R),
	fail.
'$clean_db_on_id'(Id) :-
	recorded('$thread_alias',[Id|_],R),
	erase(R),
	fail.
'$clean_db_on_id'(Id) :-
	recorded('$thread_exit_hook',[Id|_],R),
	erase(R),
	fail.
'$clean_db_on_id'(_).
	

'$thread_options'(V, _, _, _, _, _, G) :- var(V), !,
	'$do_error'(instantiation_error,G).
'$thread_options'([], [], Stack, Trail, System, _, _) :-
	'$thread_ground_stacks'(Stack),
	'$thread_ground_stacks'(Trail),
	'$thread_ground_stacks'(System).	
'$thread_options'([Opt|OPts], Aliases, Stack, Trail, System, Detached, G0) :-
	'$thread_option'(OPt, Aliases, Stack, Trail, System, Detached, G0, Aliases0),
	'$thread_options'(Opts, Aliases0, Stack, Trail, System, Detached, G0).

'$thread_option'(stacks(Stack), Aliases, Stack, _, _, _, G0, Aliases) :- !,
	( \+ integer(Stack) -> '$do_error'(type_error(integer,Stack),G0) ; true ).
'$thread_option'(trail(Trail), Aliases, _, Trail, _, _, G0, Aliases) :- !,
	( \+ integer(Trail) -> '$do_error'(type_error(integer,Trail),G0) ; true ).
'$thread_option'(system(Trail), Aliases, _, _, System, _, G0, Aliases) :- !,
	( \+ integer(System) -> '$do_error'(type_error(integer,System),G0) ; true ).
'$thread_option'(alias(Alias), [Alias|Aliases], _, _, _, _, G0, Aliases) :- !,
	( \+ atom(Alias) -> '$do_error'(type_error(atom,Alias),G0) ; true ).
'$thread_option'(detached(B), Aliases, _, _, _, B, G0, Aliases) :- !,
	( B \== true, B \== false  -> '$do_error'(domain_error(flag_value,B+[true,false]),G0) ; true ).
'$thread_option'(Option, Aliases, _, _, _, _, G0, Aliases) :-
	'$do_error'(domain_error(thread_option,Option+[stacks(_),trail(_),system(_),alias(_),detached(_)]),G0).

'$thread_ground_stacks'(0) :- !.
'$thread_ground_stacks'(_).

'$add_thread_aliases'([Alias|Aliases], Id) :-
	recorda('$thread_alias',[Id0|Alias],_),
	'$add_thread_aliases'(Aliases, Id).
'$add_thread_aliases'([], _).

thread_self(Id) :-
	'$thread_self'(Id0),
	'$check_thread_alias'(Id0,Id).

'$check_thread_alias'(Id0,Id) :-
	recorded('$thread_alias',[Id0|Id],_), !.
'$check_thread_alias'(Id,Id).

/* Exit status may be true, false, exception(Term), exited(Term) */
thread_join(Id, Status) :-
	'$check_thread_alias'(Id0,Id),
	'$thread_join'(Id0),
	'$erase_thread_aliases'(Id0),
	recorded('$thread_exit_status',[Id0|Status],R),
	erase(R).

'$erase_thread_aliases'(Id0) :-
	recorded('$thread_alias',[Id0|_],R),
	erase(R),
	fail.
'$erase_thread_aliases'(_).

thread_detach(Id) :-
	'$check_thread_alias'(Id0,Id),
	'$detach_thread'(Id0).

thread_exit(Term) :-
	'$thread_self'(Id0),
	'$run_at_thread_exit'(Id0),
	recorda('$thread_exit_status', [Id0|Term], _),
	'$thread_exit'.

'$run_at_thread_exit'(Id0) :-
	findall(Hook, (recorded('$thread_exit_hook',[Id0|Hook],R), erase(R)), Hooks),
	'$run_thread_hooks'(Hooks),
	message_queue_destroy(Id0).

'$run_thread_hooks'([]).
'$run_thread_hooks'([Hook|Hooks]) :-
	'$thread_top_goal'(Hook),
	'$run_thread_hooks'(Hooks).

thread_at_exit(Goal) :-
	'$check_callable'(Goal,thread_at_exit(Goal)),
	'$thread_self'(Id0),
	recordz('$thread_exit_hook',[Id0|Goal],_).

current_thread(Tid, Status) :-
	var(Tid), !,
	'$cur_threads'(0, Tid, Status).
current_thread(Tid, Status) :-
	'$check_thread_alias'(Id0,Tid), !,
	'$valid_thread'(Id0),
	'$thr_status'(Id0, Status).
current_thread(Tid, Status) :- integer(Tid), !,
	'$valid_thread'(Tid),
	'$thr_status'(Tid, Status).
current_thread(Tid, Status) :-
	'$do_error'(type_error(integer,Tid),current_thread(Tid, Status)).

'$cur_threads'(Tid, Tid, Status) :-
	'$valid_thread'(Tid),
	'$thr_status'(Tid, Status).
'$cur_threads'(Tid, TidF, Status) :-
	'$valid_thread'(Tid),
	Tid1 is Tid+1,
	'$cur_threads'(Tid1, TidF, Status).
	
'$thr_status'(Tid, Status) :-
	recorded('$thread_exit_status', [Tid|Status], _), !.
'$thr_status'(Tid, running).


mutex_create(V) :-
	var(V), !,
	'$new_mutex'(Id),
	recorda('$mutex'(Id,Id),_).
mutex_create(A) :-
	atom(A),
	recorded('$mutex',[A|_],_), !,
	'$do_error'(permission_error(create,mutex,A),mutex_create(A)).
mutex_create(A) :-
	atom(A), !,
	'$new_mutex'(Id),
	recorda('$mutex'(A,Id),_).
mutex_create(V) :-
	'$do_error'(type_error(atom,V),mutex_create(V)).
	
mutex_destroy(V) :-
	var(V), !,
	'$do_error'(instantiation_error,mutex_destroy(A)).
mutex_destroy(A) :-
	recorded('$mutex',[A|Id],R),
	'$kill_mutex'(Id),
	erase(R).
mutex_destroy(A) :-
	atom(A), !,
	'$do_error'(existence_error(mutex,A),mutex_destroy(A)).
mutex_destroy(V) :-
	'$do_error'(type_error(atom,V),mutex_destroy(V)).
	
mutex_lock(V) :-
	var(V), !,
	'$do_error'(instantiation_error,mutex_lock(A)).
mutex_lock(A) :-
	recorded('$mutex',[A|Id],_),
	'$lock_mutex'(Id).
mutex_lock(A) :-
	atom(A), !,
	mutex_create(A),
	mutex_lock(A).
mutex_lock(V) :-
	'$do_error'(type_error(atom,V),mutex_lock(V)).
	
mutex_trylock(V) :-
	var(V), !,
	'$do_error'(instantiation_error,mutex_trylock(A)).
mutex_trylock(A) :-
	recorded('$mutex',[A|Id],_),
	'$trylock_mutex'(Id).
mutex_trylock(A) :-
	atom(A), !,
	mutex_create(A),
	mutex_trylock(A).
mutex_trylock(V) :-
	'$do_error'(type_error(atom,V),mutex_trylock(V)).
	
mutex_unlock(V) :-
	var(V), !,
	'$do_error'(instantiation_error,mutex_unlock(A)).
mutex_unlock(A) :-
	recorded('$mutex',[A|Id],_),
	( '$unlock_mutex'(Id) ->
	    true
	;
	    '$do_error'(permission_error(unlock,mutex,A),mutex_unlock(A))
	).
mutex_unlock(A) :-
	atom(A), !,
	'$do_error'(existence_error(mutex,A),mutex_unlock(A)).
mutex_unlock(V) :-
	'$do_error'(type_error(atom,V),mutex_unlock(V)).

mutex_unlock_all :-
	'$thread_self'(T),
	recorded('$mutex',[_|Id],_),
	'$mutex_info'(Id, NRefs, T),
	NRefs > 0,
	'$mutex_unlock_all'(Id),
	fail.
mutex_unlock_all.

'$mutex_unlock_all'(Id) :-
	'$mutex_info'(Id, NRefs, _),
	NRefs > 0,
	'$unlock_mutex'(Id),
	'$mutex_unlock_all'(Id).
	
current_mutex(M, T, NRefs) :-
	recorded('$mutex',[M|Id],_),
	'$mutex_info'(Id, NRefs, T).

message_queue_create(Cond) :-
	var(Cond), !,
	mutex_create(Mutex),
	'$cond_create'(Cond),
	recorda('$queue',q(Cond,Mutex,Cond), _).
message_queue_create(Name) :-
	atom(Name), !,
	recorded('$thread_alias',[Name|_],_),
	'$do_error'(permission_error(create,queue,Name),thread_queue_create(Name)).
message_queue_create(Name) :-
	atom(Name), !,
	'$create_mq'(Name).
message_queue_create(Name) :-
	'$do_error'(type_error(atom,Name),thread_queue_create(Name)).

'$create_mq'(Name) :-
	mutex_create(Mutex),
	'$cond_create'(Cond),
	recorda('$queue',q(Name,Mutex,Cond),_).

	
message_queue_destroy(Name) :-
	var(Name), !,
	'$do_error'(instantiation_error,thread_queue_destroy(Name)).
message_queue_destroy(Queue) :-
	recorded('$queue',q(Queue,Mutex,Cond),R), !,
	erase(R),
	mutex_destroy(Mutex),
	'$cond_destroy'(Cond),
	'$clean_mqueue'(Queue).
message_queue_destroy(Queue) :-
	atom(Queue), !,
	'$do_error'(existence_error(queue,Queue),thread_queue_destroy(Name)).
message_queue_destroy(Name) :-
	'$do_error'(type_error(atom,Name),thread_queue_destroy(Name)).

'$clean_mqueue'(Q) :-
	recorded('$msg_queue',q(Queue,_),R),
	erase(R),
	fail.
'$clean_mqueue'(_).
	
thread_send_message(Queue, Term) :-
	recorded('$thread_alias',[Queue|Id],_),
	thread_send_message(Id, Term).
thread_send_message(Queue, Term) :-
	recorded('$queue',q(Queue,Mutex,Cond),_),
	mutex_lock(Mutex),
	recordz('$msg_queue',q(Queue,Term),_),
	'$cond_broadcast'(Cond),
	mutex_unlock(Mutex).

thread_get_message(Term) :-
	'$thread_self'(Id),
	thread_get_message(Id, Term).

thread_get_message(Queue, Term) :-
	recorded('$queue',q(Queue,Mutex,Cond),_),
	mutex_lock(Mutex),
	'$thread_get_message_loop'(Queue, Term, Mutex, Cond).

'$thread_get_message_loop'(Queue, Term, Mutex, Cond) :-
	recorded('$msg_queue',q(Queue,Term),R), !,
	mutex_unlock(Mutex),
	erase(R).
'$thread_get_message_loop'(Queue, Term, Mutex, Cond) :-
	'$cond_wait'(Cond, Mutex),
	'$thread_get_message_loop'(Queue, Term, Mutex, Cond).

thread_peek_message(Term) :-
	'$thread_self'(Id),
	thread_peek_message(Id, Term).

thread_peek_message(Queue, Term) :-
	recorded('$queue',q(Queue,Mutex,Cond),_),
	mutex_lock(Mutex),
	'$thread_peek_message2'(Queue, Term, Mutex).

'$thread_get_message_loop'(Queue, Term, Mutex) :-
	recorded('$msg_queue',q(Queue,Term),_), !,
	mutex_unlock(Mutex).
'$thread_get_message_loop'(Queue, Term, Mutex) :-
	mutex_unlock(Mutex),
	fail.