On 15/09/2015 23:06, Phil Clayton wrote:
In MLton, creating a finalizable value from the pointer and size is
simple. Roughly as follows:
fun fromNewPtr p n =
let
val array = Finalizable.new p
in
Finalizable.addFinalizer (t, fn p => free_ (p, n));
array
end
where free_ is the C free function. If Poly/ML can use the same or
similar code, that would be much easier!
This is my quick attempt to create something similar. As long as the
result of the call to makeFinal is reachable the finalisation function
will not be called. Once it becomes unreachable the finalisation
function will be called soon after the GC. I've only tested it with
explicit calls to PolyML.fullGC but it should work equally when the GC
is activated automatically. However it does require a full GC and that
can occur relatively infrequently.
David
local
open Weak
val finals = ref []
fun threadFn () =
let
val () = Thread.Mutex.lock weakLock
fun doFilter (ref (SOME _), _) = true
| doFilter (ref NONE, f) = (f(); false)
in
while true do
(
finals := List.filter doFilter (!finals);
Thread.ConditionVar.wait(weakSignal, weakLock)
)
end
val _ = Thread.Thread.fork(threadFn, [])
in
fun makeFinal (f : unit -> unit) =
let
val r = ref ()
val () =
ThreadLib.protect weakLock
(fn () => finals := (weak(SOME r), f) :: ! finals) ()
in
r
end
end;
_______________________________________________
polyml mailing list
[email protected]
http://lists.inf.ed.ac.uk/mailman/listinfo/polyml
