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

     Author:     Makarius

 Multithreading in Poly/ML 5.2 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;

 fun max_threads_value () =

   let val m = ! max_threads

   in if m <= 0 then Int.max (Thread.numProcessors (), 1) else m 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 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;