more abstract treatment of interrupts in structure Exn -- hardly ever need to mention Interrupt literally;
(* Title: Pure/ML-Systems/multithreading_polyml.ML
Author: Makarius
Multithreading in Poly/ML 5.2.1 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 bash_output: 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 available = true;
val max_threads = Unsynchronized.ref 0;
fun max_threads_value () =
let val m = ! max_threads in
if m > 0 then m
else Int.min (Int.max (Thread.numProcessors (), 1), 4)
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 public_interrupts =
[Thread.EnableBroadcastInterrupt true, Thread.InterruptState Thread.InterruptAsynchOnce];
val private_interrupts =
[Thread.EnableBroadcastInterrupt false, Thread.InterruptState Thread.InterruptAsynchOnce];
val sync_interrupts = map
(fn x as Thread.InterruptState Thread.InterruptDefer => x
| Thread.InterruptState _ => Thread.InterruptState Thread.InterruptSynch
| x => x);
val safe_interrupts = map
(fn Thread.InterruptState Thread.InterruptAsynch =>
Thread.InterruptState Thread.InterruptAsynchOnce
| x => x);
fun with_attributes new_atts e =
let
val orig_atts = safe_interrupts (Thread.getAttributes ());
val result = Exn.capture (fn () =>
(Thread.setAttributes (safe_interrupts new_atts); e orig_atts)) ();
val _ = Thread.setAttributes orig_atts;
in Exn.release result end;
(* portable wrappers *)
fun interruptible f x = with_attributes public_interrupts (fn _ => f x);
fun uninterruptible f x =
with_attributes no_interrupts (fn atts =>
f (fn g => fn y => with_attributes atts (fn _ => g y)) x);
(* synchronous wait *)
fun sync_wait opt_atts time cond lock =
with_attributes
(sync_interrupts (case opt_atts of SOME atts => atts | NONE => Thread.getAttributes ()))
(fn _ =>
(case time of
SOME t => Exn.Result (ConditionVar.waitUntil (cond, lock, t))
| NONE => (ConditionVar.wait (cond, lock); Exn.Result true))
handle exn => Exn.Exn exn);
(* tracing *)
val trace = Unsynchronized.ref 0;
fun tracing level msg =
if level > ! trace then ()
else uninterruptible (fn _ => fn () =>
(TextIO.output (TextIO.stdErr, (">>> " ^ msg () ^ "\n")); TextIO.flushOut TextIO.stdErr)
handle _ (*sic*) => ()) ();
fun tracing_time detailed time =
tracing
(if not detailed then 5
else 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 if Time.>= (time, Time.fromMilliseconds 1) then 4 else 5);
fun real_time f x =
let
val timer = Timer.startRealTimer ();
val () = f x;
val time = Timer.checkRealTimer timer;
in time end;
(* 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 = Unsynchronized.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 = Exn.is_interrupt_exn result andalso ! timeout;
val _ = Thread.interrupt watchdog handle Thread _ => ();
in if was_timeout then raise TimeOut else Exn.release result end) ();
end;
(* GNU bash processes, with propagation of interrupts *)
fun bash_output script = with_attributes no_interrupts (fn orig_atts =>
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 = Unsynchronized.ref Wait;
val lock = Mutex.mutex ();
val cond = ConditionVar.conditionVar ();
fun set_result res =
(Mutex.lock lock; result := res; ConditionVar.signal cond; Mutex.unlock lock);
val _ = Mutex.lock lock;
(*system thread*)
val system_thread = Thread.fork (fn () =>
let
val status =
OS.Process.system ("exec \"$ISABELLE_HOME/lib/scripts/bash\" 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
let val res =
sync_wait (SOME orig_atts)
(SOME (Time.+ (Time.now (), Time.fromMilliseconds 100))) cond lock
in if Exn.is_interrupt_exn res then kill 10 else () end;
(*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 => 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 = Unsynchronized.ref (NONE: Thread.thread option);
val critical_name = Unsynchronized.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
Exn.release (uninterruptible (fn restore_attributes => fn () =>
let
val name' = ! critical_name;
val _ =
if Mutex.trylock critical_lock then ()
else
let
val _ = tracing 5 (fn () => "CRITICAL" ^ show name ^ show' name' ^ ": waiting");
val time = real_time Mutex.lock critical_lock;
val _ = tracing_time true 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 result end) ());
fun CRITICAL e = NAMED_CRITICAL "" e;
end;
(* serial numbers *)
local
val serial_lock = Mutex.mutex ();
val serial_count = Unsynchronized.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 Basic_Multithreading: BASIC_MULTITHREADING = Multithreading;
open Basic_Multithreading;