(*  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

   val profile: int -> ('a -> 'b) -> 'a -> 'b

 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 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;

 (* 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);

 (* profiling *)

 local val profile_orig = profile in

 fun profile 0 f x = f x

   | profile n f x = NAMED_CRITICAL "profile" (fn () => profile_orig n f x);

 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;