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

    ID:         $Id$

    Author:     Makarius

Multithreading in Poly/ML 5.1 (cf. polyml/basis/Thread.sml).

*)

open Thread;

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

  else ();

val available = true;

val max_threads = ref 1;

fun max_threads_value () =

  let val m = ! max_threads

  in if m <= 0 then Thread.numProcessors () else m end;

(* misc utils *)

fun cons x xs = x :: xs;

fun change r f = r := f (! r);

fun inc i = (i := ! i + 1; ! i);

fun dec i = (i := ! i - 1; ! i);

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

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

fun read_file name =

  let val is = TextIO.openIn name

  in TextIO.inputAll is before TextIO.closeIn is end;

fun write_file name txt =

  let val os = TextIO.openOut name

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

(* thread attributes *)

fun with_attributes new_atts f x =

  let

    val orig_atts = Thread.getAttributes ();

    fun restore () = Thread.setAttributes orig_atts;

  in

    Exn.release

    (*RACE for fully asynchronous interrupts!*)

    (let

        val _ = Thread.setAttributes new_atts;

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

        val _ = restore ();

      in result end

      handle Interrupt => (restore (); Exn.Exn Interrupt))

  end;

fun interruptible f =

  with_attributes

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

    (fn _ => f);

fun uninterruptible f =

  with_attributes

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

    (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), []);

    (*RACE! timeout signal vs. external Interrupt*)

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

    val was_timeout = (case result of 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_threaded 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 _ => 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 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 Interrupt | Result rc => rc);

  in (output, rc) end) ();

val system_out =

  if ml_system = "polyml-5.1" then system_out  (*signals not propagated from root thread!*)

  else system_out_threaded;

(* 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 id => Thread.equal (id, 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 _ = tracing (if Time.> (time, Time.fromMilliseconds 10) then 3 else 4) (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;

(* scheduling -- multiple threads working on a queue of tasks *)

datatype 'a task =

  Task of {body: unit -> unit, cont: 'a -> 'a, fail: 'a -> 'a} | Wait | Terminate;

fun schedule n next_task = uninterruptible (fn restore_attributes => fn tasks =>

  let

    (*protected execution*)

    val lock = Mutex.mutex ();

    val protected_name = ref "";

    fun PROTECTED name e =

      let

        val name' = ! protected_name;

        val _ =

          if Mutex.trylock lock then ()

          else

            let

              val _ = tracing 2 (fn () => "PROTECTED" ^ show name ^ show' name' ^ ": waiting");

              val _ = Mutex.lock lock;

              val _ = tracing 2 (fn () => "PROTECTED" ^ show name ^ show' name' ^ ": passed");

            in () end;

        val _ = protected_name := name;

        val res = Exn.capture e ();

        val _ = protected_name := "";

        val _ = Mutex.unlock lock;

      in Exn.release res end;

    (*wakeup condition*)

    val wakeup = ConditionVar.conditionVar ();

    fun wakeup_all () = ConditionVar.broadcast wakeup;

    fun wait () = ConditionVar.wait (wakeup, lock);

    fun wait_timeout () = ConditionVar.waitUntil (wakeup, lock, Time.now () + Time.fromSeconds 1);

    (*queue of tasks*)

    val queue = ref tasks;

    val active = ref 0;

    fun trace_active () = tracing 1 (fn () => "SCHEDULE: " ^ Int.toString (! active) ^ " active");

    fun dequeue () =

      let

        val (next, tasks') = next_task (! queue);

        val _ = queue := tasks';

      in

        (case next of Wait =>

          (dec active; trace_active ();

            wait ();

            inc active; trace_active ();

            dequeue ())

        | _ => next)

      end;

    (*pool of running threads*)

    val status = ref ([]: exn list);

    val running = ref ([]: Thread.thread list);

    fun start f =

      (inc active;

       change running (cons (Thread.fork (f, [Thread.InterruptState Thread.InterruptDefer]))));

    fun stop () =

      (dec active;

       change running (List.filter (fn t => not (Thread.equal (t, Thread.self ())))));

   (*worker thread*)

    fun worker () =

      (case PROTECTED "dequeue" dequeue of

        Task {body, cont, fail} =>

          (case Exn.capture (restore_attributes body) () of

            Exn.Result () =>

              (PROTECTED "cont" (fn () => (change queue cont; wakeup_all ())); worker ())

          | Exn.Exn exn =>

              PROTECTED "fail" (fn () =>

                (change status (cons exn); change queue fail; stop (); wakeup_all ())))

      | Terminate => PROTECTED "terminate" (fn () => (stop (); wakeup_all ())));

    (*main control: fork and wait*)

    fun fork 0 = ()

      | fork k = (start worker; fork (k - 1));

    val _ = PROTECTED "main" (fn () =>

     (fork (Int.max (n, 1));

      while not (List.null (! running)) do

      (trace_active ();

       if not (List.null (! status))

       then (List.app (fn t => Thread.interrupt t handle Thread _ => ()) (! running))

       else ();

       wait_timeout ())));

  in ! status 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 res = inc serial_count;

    val _ = Mutex.unlock serial_lock;

  in res end);

end;

(* thread data *)

val get_data = Thread.getLocal;

val put_data = Thread.setLocal;

end;

structure BasicMultithreading: BASIC_MULTITHREADING = Multithreading;

open BasicMultithreading;