(*  Title:      HOL/Tools/async_manager.ML

    Author:     Fabian Immler, TU Muenchen

    Author:     Makarius

    Author:     Jasmin Blanchette, TU Muenchen

Central manager for asynchronous diagnosis tool threads.

*)

signature ASYNC_MANAGER =

sig

  val break_into_chunks : string list -> string list

  val launch :

    string -> Time.time -> Time.time -> string -> (unit -> string) -> unit

  val kill_threads : string -> string -> unit

  val running_threads : string -> string -> unit

  val thread_messages : string -> string -> int option -> unit

end;

structure Async_Manager : ASYNC_MANAGER =

struct

(** preferences **)

val message_store_limit = 20;

val message_display_limit = 5;

(** thread management **)

(* data structures over threads *)

structure Thread_Heap = Heap

(

  type elem = Time.time * Thread.thread;

  fun ord ((a, _), (b, _)) = Time.compare (a, b);

);

fun lookup_thread xs = AList.lookup Thread.equal xs;

fun delete_thread xs = AList.delete Thread.equal xs;

fun update_thread xs = AList.update Thread.equal xs;

(* state of thread manager *)

type state =

  {manager: Thread.thread option,

   timeout_heap: Thread_Heap.T,

   active: (Thread.thread * (string * Time.time * Time.time * string)) list,

   canceling: (Thread.thread * (string * Time.time * string)) list,

   messages: (string * string) list,

   store: (string * string) list}

fun make_state manager timeout_heap active canceling messages store : state =

  {manager = manager, timeout_heap = timeout_heap, active = active,

   canceling = canceling, messages = messages, store = store}

val global_state = Synchronized.var "async_manager"

  (make_state NONE Thread_Heap.empty [] [] [] []);

(* unregister thread *)

fun unregister message thread =

  Synchronized.change global_state

  (fn state as {manager, timeout_heap, active, canceling, messages, store} =>

    (case lookup_thread active thread of

      SOME (tool, _, _, desc) =>

        let

          val active' = delete_thread thread active;

          val now = Time.now ()

          val canceling' = (thread, (tool, now, desc)) :: canceling

          val message' = desc ^ "\n" ^ message

          val messages' = (tool, message') :: messages;

          val store' = (tool, message') ::

            (if length store <= message_store_limit then store

             else #1 (chop message_store_limit store));

        in make_state manager timeout_heap active' canceling' messages' store' end

    | NONE => state));

(* main manager thread -- only one may exist *)

val min_wait_time = seconds 0.3;

val max_wait_time = seconds 10.0;

fun replace_all bef aft =

  let

    fun aux seen "" = String.implode (rev seen)

      | aux seen s =

        if String.isPrefix bef s then

          aux seen "" ^ aft ^ aux [] (unprefix bef s)

        else

          aux (String.sub (s, 0) :: seen) (String.extract (s, 1, NONE))

  in aux [] end

(* This is a workaround for Proof General's off-by-a-few sendback display bug,

   whereby "pr" in "proof" is not highlighted. *)

val break_into_chunks = maps (space_explode "\000" o replace_all "\n\n" "\000")

fun print_new_messages () =

  case Synchronized.change_result global_state

         (fn {manager, timeout_heap, active, canceling, messages, store} =>

             (messages, make_state manager timeout_heap active canceling []

                                   store)) of

    [] => ()

  | msgs as (tool, _) :: _ =>

    let val ss = break_into_chunks (map snd msgs) in

      List.app Output.urgent_message (tool ^ ": " ^ hd ss :: tl ss)

    end

fun check_thread_manager () = Synchronized.change global_state

  (fn state as {manager, timeout_heap, active, canceling, messages, store} =>

    if (case manager of SOME thread => Thread.isActive thread | NONE => false) then state

    else let val manager = SOME (Toplevel.thread false (fn () =>

      let

        fun time_limit timeout_heap =

          (case try Thread_Heap.min timeout_heap of

            NONE => Time.+ (Time.now (), max_wait_time)

          | SOME (time, _) => time);

        (*action: find threads whose timeout is reached, and interrupt canceling threads*)

        fun action {manager, timeout_heap, active, canceling, messages, store} =

          let val (timeout_threads, timeout_heap') =

            Thread_Heap.upto (Time.now (), Thread.self ()) timeout_heap;

          in

            if null timeout_threads andalso null canceling then

              NONE

            else

              let

                val _ = List.app (Simple_Thread.interrupt o #1) canceling

                val canceling' = filter (Thread.isActive o #1) canceling

                val state' = make_state manager timeout_heap' active canceling' messages store;

              in SOME (map #2 timeout_threads, state') end

          end;

      in

        while Synchronized.change_result global_state

          (fn state as {timeout_heap, active, canceling, messages, store, ...} =>

            if null active andalso null canceling andalso null messages

            then (false, make_state NONE timeout_heap active canceling messages store)

            else (true, state))

        do

          (Synchronized.timed_access global_state (SOME o time_limit o #timeout_heap) action

            |> these

            |> List.app (unregister "Timed out.\n");

            print_new_messages ();

            (*give threads some time to respond to interrupt*)

            OS.Process.sleep min_wait_time)

      end))

    in make_state manager timeout_heap active canceling messages store end)

(* register thread *)

fun register tool birth_time death_time desc thread =

 (Synchronized.change global_state

    (fn {manager, timeout_heap, active, canceling, messages, store} =>

      let

        val timeout_heap' = Thread_Heap.insert (death_time, thread) timeout_heap;

        val active' = update_thread (thread, (tool, birth_time, death_time, desc)) active;

        val state' = make_state manager timeout_heap' active' canceling messages store;

      in state' end);

  check_thread_manager ())

fun launch tool birth_time death_time desc f =

  (Toplevel.thread true

       (fn () =>

           let

             val self = Thread.self ()

             val _ = register tool birth_time death_time desc self

             val message = f ()

           in unregister message self end);

   ())

(** user commands **)

(* kill threads *)

fun kill_threads tool workers = Synchronized.change global_state

  (fn {manager, timeout_heap, active, canceling, messages, store} =>

    let

      val killing =

        map_filter (fn (th, (tool', _, _, desc)) =>

                       if tool' = tool then SOME (th, (tool', Time.now (), desc))

                       else NONE) active

      val state' = make_state manager timeout_heap [] (killing @ canceling) messages store;

      val _ = if null killing then () else Output.urgent_message ("Killed active " ^ workers ^ ".")

    in state' end);

(* running threads *)

fun seconds time = string_of_int (Time.toSeconds time) ^ " s"

fun running_threads tool workers =

  let

    val {active, canceling, ...} = Synchronized.value global_state;

    val now = Time.now ();

    fun running_info (_, (tool', birth_time, death_time, desc)) =

      if tool' = tool then

        SOME ("Running: " ^ seconds (Time.- (now, birth_time)) ^ " -- " ^

              seconds (Time.- (death_time, now)) ^ " to live:\n" ^ desc)

      else

        NONE

    fun canceling_info (_, (tool', death_time, desc)) =

      if tool' = tool then

        SOME ("Trying to interrupt thread since " ^

              seconds (Time.- (now, death_time)) ^ ":\n" ^ desc)

      else

        NONE

    val running =

      case map_filter running_info active of

        [] => ["No " ^ workers ^ " running."]

      | ss => "Running " ^ workers ^ ":" :: ss

    val interrupting =

      case map_filter canceling_info canceling of

        [] => []

      | ss => "Trying to interrupt the following " ^ workers ^ ":" :: ss

  in Output.urgent_message (space_implode "\n\n" (running @ interrupting)) end

fun thread_messages tool worker opt_limit =

  let

    val limit = the_default message_display_limit opt_limit;

    val tool_store = Synchronized.value global_state

                     |> #store |> filter (curry (op =) tool o fst)

    val header =

      "Recent " ^ worker ^ " messages" ^

        (if length tool_store <= limit then ":"

         else " (" ^ string_of_int limit ^ " displayed):");

  in

    List.app Output.urgent_message (header :: break_into_chunks

                                     (map snd (#1 (chop limit tool_store))))

  end

end;