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|
open Posix.Signal MLton.Signal
fun for (start, stop, f) =
let
fun loop i =
if i >= stop
then ()
else (f i; loop (i + 1))
in
loop start
end
structure Queue:
sig
type 'a t
val new: unit -> 'a t
val enque: 'a t * 'a -> unit
val deque: 'a t -> 'a option
end =
struct
datatype 'a t = T of {front: 'a list ref, back: 'a list ref}
fun new () = T {front = ref [], back = ref []}
fun enque (T {back, ...}, x) = back := x :: !back
fun deque (T {front, back}) =
case !front of
[] => (case !back of
[] => NONE
| l => let val l = rev l
in case l of
[] => raise Fail "deque"
| x :: l => (back := []; front := l; SOME x)
end)
| x :: l => (front := l; SOME x)
end
structure Thread:
sig
val exit: unit -> 'a
val run: unit -> unit
val spawn: (unit -> unit) -> unit
val yield: unit -> unit
structure Mutex:
sig
type t
val new: unit -> t
val lock: t -> unit
val unlock: t -> unit
end
end =
struct
open MLton
open Itimer Signal Thread
val topLevel: Thread.Runnable.t option ref = ref NONE
local
val threads: Thread.Runnable.t Queue.t = Queue.new ()
in
fun ready t = Queue.enque (threads, t)
fun next () : Thread.Runnable.t =
case Queue.deque threads of
NONE => valOf (!topLevel)
| SOME t => t
end
fun 'a exit (): 'a = switch (fn _ =>
(print "exiting\n"
; next ()))
fun new (f: unit -> unit): Thread.Runnable.t =
Thread.prepare
(Thread.new (fn () => ((f () handle _ => exit ())
; exit ())),
())
fun schedule t = (ready t; next ())
fun yield (): unit = switch (fn t => schedule (Thread.prepare (t, ())))
val spawn = ready o new
fun setItimer t =
Itimer.set (Itimer.Real,
{value = t,
interval = t})
fun run (): unit =
(switch (fn t =>
(topLevel := SOME (Thread.prepare (t, ()))
; new (fn () =>
(setHandler (alrm, Handler.handler schedule)
; setItimer (Time.fromMilliseconds 10)))))
; setItimer Time.zeroTime
; setHandler (alrm, Handler.ignore)
; topLevel := NONE)
structure Mutex =
struct
datatype t = T of {locked: bool ref,
waiting: unit Thread.t Queue.t}
fun new () =
T {locked = ref false,
waiting = Queue.new ()}
fun lock (T {locked, waiting, ...}) =
let
fun loop () =
(Thread.atomicBegin ()
; if !locked
then (Thread.atomicEnd ()
; switch (fn t =>
(Queue.enque (waiting, t)
; next ()))
; loop ())
else (locked := true
; Thread.atomicEnd ()))
in loop ()
end
fun safeUnlock (T {locked, waiting, ...}) =
(locked := false
; (case Queue.deque waiting of
NONE => ()
| SOME t => ready (Thread.prepare (t,()))))
fun unlock (m: t) =
(Thread.atomicBegin ()
; safeUnlock m
; Thread.atomicEnd ())
end
end
open Thread
fun main (name, args) =
let
val m = Mutex.new ()
val gotIt = ref false
val _ =
for (0, 10, fn _ =>
Thread.spawn
(fn () =>
let
val _ = print "starting\n"
fun loop i =
if i = 0
then ()
else (Mutex.lock m
; if !gotIt
then raise Fail "bug"
else (gotIt := true
; for (0, 100000, fn _ => ())
; gotIt := false
; Mutex.unlock m
; loop (i - 1)))
in loop 10000
end))
in
run ()
end
val _ = main ( CommandLine.name (), CommandLine.arguments () )
|
