(*  Title:      Pure/System/isabelle_process.ML

    Author:     Makarius

Isabelle process wrapper, based on private fifos for maximum

robustness and performance.

Startup phases:

  . raw Posix process startup with uncontrolled output on stdout/stderr

  . stderr \002: ML running

  .. stdin/stdout/stderr freely available (raw ML loop)

  .. protocol thread initialization

  ... rendezvous on system channel

  ... message INIT(pid): channels ready

  ... message RAW(keywords)

  ... message RAW(ready): main loop ready

*)

signature ISABELLE_PROCESS =

sig

  val is_active: unit -> bool

  val protocol_command: string -> (string list -> unit) -> unit

  val crashes: exn list Synchronized.var

  val init_fifos: string -> string -> unit

  val init_socket: string -> unit

end;

structure Isabelle_Process: ISABELLE_PROCESS =

struct

(* print mode *)

val isabelle_processN = "isabelle_process";

fun is_active () = Print_Mode.print_mode_active isabelle_processN;

val _ = Output.add_mode isabelle_processN Output.default_output Output.default_escape;

val _ = Markup.add_mode isabelle_processN YXML.output_markup;

(* protocol commands *)

local

val commands =

  Synchronized.var "Isabelle_Process.commands" (Symtab.empty: (string list -> unit) Symtab.table);

in

fun protocol_command name cmd =

  Synchronized.change commands (fn cmds =>

   (if not (Symtab.defined cmds name) then ()

    else warning ("Redefining Isabelle process command " ^ quote name);

    Symtab.update (name, cmd) cmds));

fun run_command name args =

  (case Symtab.lookup (Synchronized.value commands) name of

    NONE => error ("Undefined Isabelle process command " ^ quote name)

  | SOME cmd =>

      (Runtime.debugging cmd args handle exn =>

        error ("Isabelle process protocol failure: " ^ name ^ "\n" ^ ML_Compiler.exn_message exn)));

end;

(* message channels *)

local

fun chunk s = [string_of_int (size s), "\n", s];

fun message do_flush mbox ch raw_props body =

  let

    val robust_props = map (pairself YXML.embed_controls) raw_props;

    val header = YXML.string_of (XML.Elem ((ch, robust_props), []));

  in Mailbox.send mbox (chunk header @ chunk body, do_flush) end;

fun standard_message mbox opt_serial ch body =

  if body = "" then ()

  else

    message false mbox ch

      ((case opt_serial of SOME i => cons (Isabelle_Markup.serialN, string_of_int i) | _ => I)

        (Position.properties_of (Position.thread_data ()))) body;

fun message_output mbox channel =

  let

    fun flush () = ignore (try System_Channel.flush channel);

    fun loop receive =

      (case receive mbox of

        SOME (msg, do_flush) =>

         (List.app (fn s => System_Channel.output channel s) msg;

          if do_flush then flush () else ();

          loop (Mailbox.receive_timeout (seconds 0.02)))

      | NONE => (flush (); loop (SOME o Mailbox.receive)));

  in fn () => loop (SOME o Mailbox.receive) end;

in

fun setup_channels channel =

  let

    val _ = TextIO.StreamIO.setBufferMode (TextIO.getOutstream TextIO.stdOut, IO.LINE_BUF);

    val _ = TextIO.StreamIO.setBufferMode (TextIO.getOutstream TextIO.stdErr, IO.LINE_BUF);

    val mbox = Mailbox.create () : (string list * bool) Mailbox.T;

    val _ = Simple_Thread.fork false (message_output mbox channel);

  in

    Output.Private_Hooks.status_fn := standard_message mbox NONE "B";

    Output.Private_Hooks.report_fn := standard_message mbox NONE "C";

    Output.Private_Hooks.writeln_fn := (fn s => standard_message mbox (SOME (serial ())) "D" s);

    Output.Private_Hooks.tracing_fn := (fn s => standard_message mbox (SOME (serial ())) "E" s);

    Output.Private_Hooks.warning_fn := (fn s => standard_message mbox (SOME (serial ())) "F" s);

    Output.Private_Hooks.error_fn := (fn (i, s) => standard_message mbox (SOME i) "G" s);

    Output.Private_Hooks.protocol_message_fn := message true mbox "H";

    Output.Private_Hooks.urgent_message_fn := ! Output.Private_Hooks.writeln_fn;

    Output.Private_Hooks.prompt_fn := ignore;

    message true mbox "A" [] (Session.welcome ())

  end;

end;

(* protocol loop -- uninterruptible *)

val crashes = Synchronized.var "Isabelle_Process.crashes" ([]: exn list);

local

fun recover crash =

  (Synchronized.change crashes (cons crash);

    warning "Recovering from Isabelle process crash -- see also Isabelle_Process.crashes");

fun read_chunk channel len =

  let

    val n =

      (case Int.fromString len of

        SOME n => n

      | NONE => error ("Isabelle process: malformed chunk header " ^ quote len));

    val chunk = System_Channel.inputN channel n;

    val m = size chunk;

  in

    if m = n then chunk

    else error ("Isabelle process: bad chunk (" ^ string_of_int m ^ " vs. " ^ string_of_int n ^ ")")

  end;

fun read_command channel =

  (case System_Channel.input_line channel of

    NONE => raise Runtime.TERMINATE

  | SOME line => map (read_chunk channel) (space_explode "," line));

in

fun loop channel =

  let val continue =

    (case read_command channel of

      [] => (Output.error_msg "Isabelle process: no input"; true)

    | name :: args => (run_command name args; true))

    handle Runtime.TERMINATE => false

      | exn => (Output.error_msg (ML_Compiler.exn_message exn) handle crash => recover crash; true);

  in if continue then loop channel else () end;

end;

(* init *)

fun init rendezvous = ignore (Simple_Thread.fork false (fn () =>

  let

    val _ = OS.Process.sleep (seconds 0.5);  (*yield to raw ML toplevel*)

    val _ = Output.physical_stderr Symbol.STX;

    val _ = quick_and_dirty := false;

    val _ = Goal.parallel_proofs := 1;

    val _ =

      if Multithreading.max_threads_value () < 2

      then Multithreading.max_threads := 2 else ();

    val _ = Context.set_thread_data NONE;

    val _ =

      Unsynchronized.change print_mode

        (fn mode =>

          (mode @ [Syntax_Trans.no_bracketsN, Syntax_Trans.no_type_bracketsN])

          |> fold (update op =)

            [Symbol.xsymbolsN, isabelle_processN, Keyword.keyword_statusN, Pretty.symbolicN]);

    val channel = rendezvous ();

    val _ = setup_channels channel;

    val _ = Keyword.status ();

    val _ = Thy_Info.status ();

    val _ = Output.protocol_message Isabelle_Markup.ready "";

  in loop channel end));

fun init_fifos fifo1 fifo2 = init (fn () => System_Channel.fifo_rendezvous fifo1 fifo2);

fun init_socket name = init (fn () => System_Channel.socket_rendezvous name);

end;