(*  Title:      Pure/System/isabelle_process.ML

     Author:     Makarius

 Isabelle process wrapper, based on private fifos for maximum

 robustness and performance, or local socket for maximum portability.

 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: channels ready

 *)

 signature ISABELLE_PROCESS =

 sig

   val is_active: unit -> bool

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

   val reset_tracing: 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 protocol 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 protocol command " ^ quote name)

   | SOME cmd =>

       (Runtime.debugging cmd args handle exn =>

         error ("Isabelle protocol command failure: " ^ quote name ^ "\n" ^

           ML_Compiler.exn_message exn)));

 end;

 (* restricted tracing messages *)

 val tracing_messages =

   Synchronized.var "tracing_messages" (Inttab.empty: int Inttab.table);

 fun reset_tracing () =

   Synchronized.change tracing_messages (K Inttab.empty);

 fun update_tracing () =

   (case Position.parse_id (Position.thread_data ()) of

     NONE => ()

   | SOME id =>

       let

         val ok =

           Synchronized.change_result tracing_messages (fn tab =>

             let

               val n = the_default 0 (Inttab.lookup tab id) + 1;

               val ok = n <= Options.default_int "editor_tracing_messages";

             in (ok, Inttab.update (id, n) tab) end);

       in

         if ok then ()

         else

           let

             val (text, promise) = Active.dialog_text ();

             val _ =

               writeln ("Tracing paused.  " ^ text "Stop" ^ ", or continue with next " ^

                 text "100" ^ ", " ^ text "1000" ^ ", " ^ text "10000" ^ " messages?")

             val m = Markup.parse_int (Future.join promise)

               handle Fail _ => error "Stopped";

           in

             Synchronized.change tracing_messages

               (Inttab.map_default (id, 0) (fn k => k - m))

           end

       end);

 (* message channels *)

 local

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

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

 datatype target =

   Sync of {send: string list -> unit} |

   Async of {send: string list -> bool -> unit, shutdown: unit -> unit};

 fun message do_flush target name raw_props body =

   let

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

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

     val msg = chunk header @ chunk body;

   in (case target of Sync {send} => send msg | Async {send, ...} => send msg do_flush) end;

 fun message_output mbox channel =

   let

     fun loop receive =

       (case receive mbox of

         SOME NONE => flush channel

       | SOME (SOME (msg, do_flush)) =>

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

           if do_flush then flush channel else ();

           loop (Mailbox.receive_timeout (seconds 0.02)))

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

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

 fun make_target channel =

   if Multithreading.available then

     let

       val mbox = Mailbox.create ();

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

     in

       Async {

         send = fn msg => fn do_flush => Mailbox.send mbox (SOME (msg, do_flush)),

         shutdown = fn () =>

           (Mailbox.send mbox NONE; Mailbox.await_empty mbox; Simple_Thread.join thread)

       }

     end

   else

     Sync {send = fn msg => (List.app (fn s => System_Channel.output channel s) msg; flush channel)};

 in

 fun init_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 target = make_target channel;

     fun standard_message opt_serial name body =

       if body = "" then ()

       else

         message false target name

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

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

   in

     Output.Private_Hooks.status_fn := standard_message NONE Markup.statusN;

     Output.Private_Hooks.report_fn := standard_message NONE Markup.reportN;

     Output.Private_Hooks.result_fn := (fn (i, s) => standard_message (SOME i) Markup.resultN s);

     Output.Private_Hooks.writeln_fn :=

       (fn s => standard_message (SOME (serial ())) Markup.writelnN s);

     Output.Private_Hooks.tracing_fn :=

       (fn s => (update_tracing (); standard_message (SOME (serial ())) Markup.tracingN s));

     Output.Private_Hooks.warning_fn :=

       (fn s => standard_message (SOME (serial ())) Markup.warningN s);

     Output.Private_Hooks.error_fn :=

       (fn (i, s) => standard_message (SOME i) Markup.errorN s);

     Output.Private_Hooks.protocol_message_fn := message true target Markup.protocolN;

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

     Output.Private_Hooks.prompt_fn := ignore;

     message true target Markup.initN [] (Session.welcome ());

     (case target of Async {shutdown, ...} => shutdown | _ => fn () => ())

   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));

 fun worker_guest e =

   Future.worker_guest "Isabelle_Process.loop" (Future.new_group NONE) e ();

 in

 fun loop channel =

   let val continue =

     (case read_command channel of

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

     | name :: args => (worker_guest (fn () => 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 *)

 val default_modes1 =

   [Syntax_Trans.no_bracketsN, Syntax_Trans.no_type_bracketsN, Graph_Display.active_graphN];

 val default_modes2 = [Symbol.xsymbolsN, isabelle_processN, Pretty.symbolicN];

 val init = uninterruptible (fn _ => fn rendezvous =>

   let

     val _ = Output.physical_stderr Symbol.STX;

     val _ = Printer.show_markup_default := true;

     val _ = Context.set_thread_data NONE;

     val _ =

       Unsynchronized.change print_mode

         (fn mode => (mode @ default_modes1) |> fold (update op =) default_modes2);

     val channel = rendezvous ();

     val shutdown_channels = init_channels channel;

     val _ = Session.init_protocol_handlers ();

     val _ = loop channel;

   in shutdown_channels () 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);

 (* options *)

 val _ =

   protocol_command "Isabelle_Process.options"

     (fn [options_yxml] =>

       let val options = Options.decode (YXML.parse_body options_yxml) in

         Options.set_default options;

         Future.ML_statistics := true;

         Multithreading.trace := Options.int options "threads_trace";

         Multithreading.max_threads := Options.int options "threads";

         Goal.skip_proofs := Options.bool options "editor_skip_proofs";

         Goal.parallel_proofs := (if Options.int options "parallel_proofs" > 0 then 3 else 0)

       end);

 end;