## io-cleanup-at-shutdown.pkg
# Compiled by:
# src/lib/std/src/standard-core.sublib# This module keeps track of open I/O streams,
# and closes themc cleanly at process exit.
#
# NOTE: there is currently a problem with removing
# the at-functions for streams that get dropped
# by the application, but the system limit on
# open files will limit this. XXX BUGGO FIXME
package io_cleanup_at_shutdown
: Io_Cleanup_At_Shutdown # Io_Cleanup_At_Shutdown is from src/lib/std/src/io/io-cleanup-at-shutdown.api{
Tag = Ref( Void ); # Here we use refcells as ids, taking advantage of the fact that every refcell equals itself but does not equal any other refcell.
# This saves us the usual bother of setting up a counter to issue unique small integers, protecting that counter with a mutex etc etc.
Cleaner = {
tag: Tag, # unique ID for this cleaner
init: Void -> Void, # Called STARTUP and APP_STARTUP
flush: Void -> Void, # Called FORK_TO_DISK
close: Void -> Void # Called SHUTDOWN and SPAWN_TO_DISK
};
os_init_hook = REF (fn () = ());
std_strm_hook = REF (fn () = ());
cleaners = REF ([]: List( Cleaner ));
fun add_cleaner { init, flush, close }
=
{ tag = REF ();
cleaner_rec
=
{ tag, init, flush, close };
cleaners := cleaner_rec ! *cleaners;
tag;
};
fun get_tag ( { tag, ... } : Cleaner)
=
tag;
fun rebind_cleaner (t, { init, flush, close } )
=
cleaners := f *cleaners
where
fun f [] => raise exception FAIL "rebind_cleaner: tag not found";
f (x ! r)
=>
{ t' = get_tag x;
if (t' == t)
{ tag=>t, init, flush, close } ! r;
else x ! f r; fi;
};
end;
end;
fun remove_cleaner t
=
cleaners := f *cleaners
where
fun f [] => []; # should we raise an exception here?
f (x ! r) => if (get_tag x == t) r; else x ! f r;fi;
end;
end;
fun run_selected_functions sel_g
=
loop *cleaners
where
fun loop [] => ();
loop (x ! r)
=>
{ ((sel_g x) ())
except
_ = ();
loop r;
};
end;
end;
# at is from src/lib/std/src/nj/at.pkg fun run (at::FORK_TO_DISK)
=>
run_selected_functions .flush;
run (at::SPAWN_TO_DISK | at::SHUTDOWN)
=>
run_selected_functions .close;
run (at::STARTUP | at::APP_STARTUP)
=>
{ *os_init_hook ();
*std_strm_hook ();
run_selected_functions .init;
};
end;
my _ =
at::schedule ("IO", at::all, run);
}; # package io_cleanup_at_shutdown