(* Title: Pure/ML-Systems/multithreading_polyml.ML
Author: Makarius
Multithreading in Poly/ML (cf. polyml/basis/Thread.sml).
*)
signature MULTITHREADING =
sig
include MULTITHREADING
val interruptible: ('a -> 'b) -> 'a -> 'b
val uninterruptible: ((('c -> 'd) -> 'c -> 'd) -> 'a -> 'b) -> 'a -> 'b
end;
structure Multithreading: MULTITHREADING =
struct
(* thread attributes *)
val no_interrupts =
[Thread.EnableBroadcastInterrupt false, Thread.InterruptState Thread.InterruptDefer];
val test_interrupts =
[Thread.EnableBroadcastInterrupt false, Thread.InterruptState Thread.InterruptSynch];
val public_interrupts =
[Thread.EnableBroadcastInterrupt true, Thread.InterruptState Thread.InterruptAsynchOnce];
val private_interrupts =
[Thread.EnableBroadcastInterrupt false, Thread.InterruptState Thread.InterruptAsynchOnce];
val sync_interrupts = map
(fn x as Thread.InterruptState Thread.InterruptDefer => x
| Thread.InterruptState _ => Thread.InterruptState Thread.InterruptSynch
| x => x);
val safe_interrupts = map
(fn Thread.InterruptState Thread.InterruptAsynch =>
Thread.InterruptState Thread.InterruptAsynchOnce
| x => x);
fun interrupted () =
let
val orig_atts = safe_interrupts (Thread.getAttributes ());
val _ = Thread.setAttributes test_interrupts;
val test = Exn.capture Thread.testInterrupt ();
val _ = Thread.setAttributes orig_atts;
in Exn.release test end;
fun with_attributes new_atts e =
let
val orig_atts = safe_interrupts (Thread.getAttributes ());
val result = Exn.capture (fn () =>
(Thread.setAttributes (safe_interrupts new_atts); e orig_atts)) ();
val _ = Thread.setAttributes orig_atts;
in Exn.release result end;
(* portable wrappers *)
fun interruptible f x = with_attributes public_interrupts (fn _ => f x);
fun uninterruptible f x =
with_attributes no_interrupts (fn atts =>
f (fn g => fn y => with_attributes atts (fn _ => g y)) x);
(* options *)
val available = true;
fun max_threads_result m =
if m > 0 then m else Int.min (Int.max (Thread.numProcessors (), 1), 8);
val max_threads = ref 1;
fun max_threads_value () = ! max_threads;
fun max_threads_update m = max_threads := max_threads_result m;
fun max_threads_setmp m f x =
uninterruptible (fn restore_attributes => fn () =>
let
val max_threads_orig = ! max_threads;
val _ = max_threads_update m;
val result = Exn.capture (restore_attributes f) x;
val _ = max_threads := max_threads_orig;
in Exn.release result end) ();
fun enabled () = max_threads_value () > 1;
(* synchronous wait *)
fun sync_wait opt_atts time cond lock =
with_attributes
(sync_interrupts (case opt_atts of SOME atts => atts | NONE => Thread.getAttributes ()))
(fn _ =>
(case time of
SOME t => Exn.Res (ConditionVar.waitUntil (cond, lock, t))
| NONE => (ConditionVar.wait (cond, lock); Exn.Res true))
handle exn => Exn.Exn exn);
(* tracing *)
val trace = ref 0;
fun tracing level msg =
if level > ! trace then ()
else uninterruptible (fn _ => fn () =>
(TextIO.output (TextIO.stdErr, (">>> " ^ msg () ^ "\n")); TextIO.flushOut TextIO.stdErr)
handle _ (*sic*) => ()) ();
fun tracing_time detailed time =
tracing
(if not detailed then 5
else if Time.>= (time, seconds 1.0) then 1
else if Time.>= (time, seconds 0.1) then 2
else if Time.>= (time, seconds 0.01) then 3
else if Time.>= (time, seconds 0.001) then 4 else 5);
fun real_time f x =
let
val timer = Timer.startRealTimer ();
val () = f x;
val time = Timer.checkRealTimer timer;
in time end;
(* synchronized evaluation *)
fun synchronized name lock e =
Exn.release (uninterruptible (fn restore_attributes => fn () =>
let
val immediate =
if Mutex.trylock lock then true
else
let
val _ = tracing 5 (fn () => name ^ ": locking ...");
val time = real_time Mutex.lock lock;
val _ = tracing_time true time (fn () => name ^ ": locked after " ^ Time.toString time);
in false end;
val result = Exn.capture (restore_attributes e) ();
val _ = if immediate then () else tracing 5 (fn () => name ^ ": unlocking ...");
val _ = Mutex.unlock lock;
in result end) ());
(* serial numbers *)
local
val serial_lock = Mutex.mutex ();
val serial_count = ref 0;
in
val serial = uninterruptible (fn _ => fn () =>
let
val _ = Mutex.lock serial_lock;
val _ = serial_count := ! serial_count + 1;
val res = ! serial_count;
val _ = Mutex.unlock serial_lock;
in res end);
end;
end;
val interruptible = Multithreading.interruptible;
val uninterruptible = Multithreading.uninterruptible;