(*  Title:      Pure/ML-Systems/multithreading_polyml.ML

    Author:     Makarius

Multithreading in Poly/ML 5.2.1 or later (cf. polyml/basis/Thread.sml).

*)

signature MULTITHREADING_POLYML =

sig

  val interruptible: ('a -> 'b) -> 'a -> 'b

  val uninterruptible: ((('c -> 'd) -> 'c -> 'd) -> 'a -> 'b) -> 'a -> 'b

  val system_out: string -> string * int

  structure TimeLimit: TIME_LIMIT

end;

signature BASIC_MULTITHREADING =

sig

  include BASIC_MULTITHREADING

  include MULTITHREADING_POLYML

end;

signature MULTITHREADING =

sig

  include MULTITHREADING

  include MULTITHREADING_POLYML

end;

structure Multithreading: MULTITHREADING =

struct

(* options *)

val trace = ref 0;

fun tracing level msg =

  if level > ! trace then ()

  else (TextIO.output (TextIO.stdErr, (">>> " ^ msg () ^ "\n")); TextIO.flushOut TextIO.stdErr)

    handle _ (*sic*) => ();

val available = true;

val max_threads = ref 1;

val tested_platform =

  let val ml_platform = getenv "ML_PLATFORM"

  in String.isSuffix "linux" ml_platform orelse String.isSuffix "darwin" ml_platform end;

fun max_threads_value () =

  let val m = ! max_threads in

    if m > 0 then m

    else if not tested_platform then 1

    else Int.min (Int.max (Thread.numProcessors (), 1), 8)

  end;

fun enabled () = max_threads_value () > 1;

(* misc utils *)

fun show "" = "" | show name = " " ^ name;

fun show' "" = "" | show' name = " [" ^ name ^ "]";

fun read_file name =

  let val is = TextIO.openIn name

  in Exn.release (Exn.capture TextIO.inputAll is before TextIO.closeIn is) end;

fun write_file name txt =

  let val os = TextIO.openOut name

  in Exn.release (Exn.capture TextIO.output (os, txt) before TextIO.closeOut os) end;

(* thread attributes *)

val no_interrupts =

  [Thread.EnableBroadcastInterrupt false, Thread.InterruptState Thread.InterruptDefer];

val regular_interrupts =

  [Thread.EnableBroadcastInterrupt true, Thread.InterruptState Thread.InterruptAsynchOnce];

val restricted_interrupts =

  [Thread.EnableBroadcastInterrupt false, Thread.InterruptState Thread.InterruptAsynchOnce];

val safe_interrupts = map

  (fn Thread.InterruptState Thread.InterruptAsynch =>

      Thread.InterruptState Thread.InterruptAsynchOnce

    | x => x);

fun with_attributes new_atts f x =

  let

    val orig_atts = safe_interrupts (Thread.getAttributes ());

    val result = Exn.capture (fn () =>

      (Thread.setAttributes (safe_interrupts new_atts); f orig_atts x)) ();

    val _ = Thread.setAttributes orig_atts;

  in Exn.release result end;

fun interruptible f = with_attributes regular_interrupts (fn _ => f);

fun uninterruptible f =

  with_attributes no_interrupts (fn atts => f (fn g => with_attributes atts (fn _ => g)));

(* execution with time limit *)

structure TimeLimit =

struct

exception TimeOut;

fun timeLimit time f x = uninterruptible (fn restore_attributes => fn () =>

  let

    val worker = Thread.self ();

    val timeout = ref false;

    val watchdog = Thread.fork (fn () =>

      (OS.Process.sleep time; timeout := true; Thread.interrupt worker), []);

    val result = Exn.capture (restore_attributes f) x;

    val was_timeout = (case result of Exn.Exn Exn.Interrupt => ! timeout | _ => false);

    val _ = Thread.interrupt watchdog handle Thread _ => ();

  in if was_timeout then raise TimeOut else Exn.release result end) ();

end;

(* system shell processes, with propagation of interrupts *)

fun system_out script = uninterruptible (fn restore_attributes => fn () =>

  let

    val script_name = OS.FileSys.tmpName ();

    val _ = write_file script_name script;

    val pid_name = OS.FileSys.tmpName ();

    val output_name = OS.FileSys.tmpName ();

    (*result state*)

    datatype result = Wait | Signal | Result of int;

    val result = ref Wait;

    val result_mutex = Mutex.mutex ();

    val result_cond = ConditionVar.conditionVar ();

    fun set_result res =

      (Mutex.lock result_mutex; result := res; Mutex.unlock result_mutex;

        ConditionVar.signal result_cond);

    val _ = Mutex.lock result_mutex;

    (*system thread*)

    val system_thread = Thread.fork (fn () =>

      let

        val status =

          OS.Process.system ("perl -w \"$ISABELLE_HOME/lib/scripts/system.pl\" group " ^

            script_name ^ " " ^ pid_name ^ " " ^ output_name);

        val res =

          (case Posix.Process.fromStatus status of

            Posix.Process.W_EXITED => Result 0

          | Posix.Process.W_EXITSTATUS 0wx82 => Signal

          | Posix.Process.W_EXITSTATUS w => Result (Word8.toInt w)

          | Posix.Process.W_SIGNALED s =>

              if s = Posix.Signal.int then Signal

              else Result (256 + LargeWord.toInt (Posix.Signal.toWord s))

          | Posix.Process.W_STOPPED s => Result (512 + LargeWord.toInt (Posix.Signal.toWord s)));

      in set_result res end handle _ (*sic*) => set_result (Result 2), []);

    (*main thread -- proxy for interrupts*)

    fun kill n =

      (case Int.fromString (read_file pid_name) of

        SOME pid =>

          Posix.Process.kill

            (Posix.Process.K_GROUP (Posix.Process.wordToPid (LargeWord.fromInt pid)),

              Posix.Signal.int)

      | NONE => ())

      handle OS.SysErr _ => () | IO.Io _ =>

        (OS.Process.sleep (Time.fromMilliseconds 100); if n > 0 then kill (n - 1) else ());

    val _ = while ! result = Wait do

      restore_attributes (fn () =>

        (ConditionVar.waitUntil (result_cond, result_mutex, Time.now () + Time.fromMilliseconds 100); ())

          handle Exn.Interrupt => kill 10) ();

    (*cleanup*)

    val output = read_file output_name handle IO.Io _ => "";

    val _ = OS.FileSys.remove script_name handle OS.SysErr _ => ();

    val _ = OS.FileSys.remove pid_name handle OS.SysErr _ => ();

    val _ = OS.FileSys.remove output_name handle OS.SysErr _ => ();

    val _ = Thread.interrupt system_thread handle Thread _ => ();

    val rc = (case ! result of Signal => raise Exn.Interrupt | Result rc => rc);

  in (output, rc) end) ();

(* critical section -- may be nested within the same thread *)

local

val critical_lock = Mutex.mutex ();

val critical_thread = ref (NONE: Thread.thread option);

val critical_name = ref "";

in

fun self_critical () =

  (case ! critical_thread of

    NONE => false

  | SOME t => Thread.equal (t, Thread.self ()));

fun NAMED_CRITICAL name e =

  if self_critical () then e ()

  else

    uninterruptible (fn restore_attributes => fn () =>

      let

        val name' = ! critical_name;

        val _ =

          if Mutex.trylock critical_lock then ()

          else

            let

              val timer = Timer.startRealTimer ();

              val _ = tracing 4 (fn () => "CRITICAL" ^ show name ^ show' name' ^ ": waiting");

              val _ = Mutex.lock critical_lock;

              val time = Timer.checkRealTimer timer;

              val trace_time =

                if Time.>= (time, Time.fromMilliseconds 1000) then 1

                else if Time.>= (time, Time.fromMilliseconds 100) then 2

                else if Time.>= (time, Time.fromMilliseconds 10) then 3 else 4;

              val _ = tracing trace_time (fn () =>

                "CRITICAL" ^ show name ^ show' name' ^ ": passed after " ^ Time.toString time);

            in () end;

        val _ = critical_thread := SOME (Thread.self ());

        val _ = critical_name := name;

        val result = Exn.capture (restore_attributes e) ();

        val _ = critical_name := "";

        val _ = critical_thread := NONE;

        val _ = Mutex.unlock critical_lock;

      in Exn.release result end) ();

fun CRITICAL e = NAMED_CRITICAL "" e;

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;

structure BasicMultithreading: BASIC_MULTITHREADING = Multithreading;

open BasicMultithreading;