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

     ID:         $Id$

     Author:     Makarius

 Dummy implementation of multithreading setup.

 *)

 signature BASIC_MULTITHREADING =

 sig

   val NAMED_CRITICAL: string -> (unit -> 'a) -> 'a

   val CRITICAL: (unit -> 'a) -> 'a

 end;

 signature MULTITHREADING =

 sig

   include BASIC_MULTITHREADING

   val trace: int ref

   val tracing: int -> (unit -> string) -> unit

   val available: bool

   val max_threads: int ref

   val max_threads_value: unit -> int

   val no_interrupts: Thread.threadAttribute list

   val regular_interrupts: Thread.threadAttribute list

   val with_attributes: Thread.threadAttribute list ->

     (Thread.threadAttribute list -> 'a -> 'b) -> 'a -> 'b

   val self_critical: unit -> bool

   val serial: unit -> int

 end;

 structure Multithreading: MULTITHREADING =

 struct

 (* options *)

 val trace = ref (0: int);

 fun tracing _ _ = ();

 val available = false;

 val max_threads = ref (1: int);

 fun max_threads_value () = 1: int;

 val no_interrupts =

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

 val regular_interrupts =

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

 fun with_attributes _ f x = f [] x;

 (* critical section *)

 fun self_critical () = false;

 fun NAMED_CRITICAL _ e = e ();

 fun CRITICAL e = e ();

 (* serial numbers *)

 local val count = ref (0: int)

 in fun serial () = (count := ! count + 1; ! count) end;

 end;

 structure BasicMultithreading: BASIC_MULTITHREADING = Multithreading;

 open BasicMultithreading;