(*  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.

 *)

 signature ISABELLE_PROCESS =

 sig

   val is_active: unit -> bool

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

   val reset_tracing: Document_ID.exec -> 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 =>

       (Toplevel.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 exec_id =

   Synchronized.change tracing_messages (Inttab.delete_safe exec_id);

 fun update_tracing () =

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

     NONE => ()

   | SOME exec_id =>

       let

         val ok =

           Synchronized.change_result tracing_messages (fn tab =>

             let

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

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

             in (ok, Inttab.update (exec_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 (exec_id, 0) (fn k => k - m))

           end

       end);

 (* output channels *)

 val serial_props = Markup.serial_properties o serial;

 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 msg_channel = Message_Channel.make channel;

     fun message name props body =

       Message_Channel.send msg_channel (Message_Channel.message name props body);

     fun standard_message props name body =

       if body = "" then ()

       else

         message name

           (fold_rev Properties.put props (Position.properties_of (Position.thread_data ()))) body;

   in

     Output.Internal.status_fn := standard_message [] Markup.statusN;

     Output.Internal.report_fn := standard_message [] Markup.reportN;

     Output.Internal.result_fn :=

       (fn props => fn s => standard_message (props @ serial_props ()) Markup.resultN s);

     Output.Internal.writeln_fn := (fn s => standard_message (serial_props ()) Markup.writelnN s);

     Output.Internal.tracing_fn :=

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

     Output.Internal.warning_fn := (fn s => standard_message (serial_props ()) Markup.warningN s);

     Output.Internal.error_fn :=

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

     Output.Internal.protocol_message_fn := message Markup.protocolN;

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

     Output.Internal.prompt_fn := ignore;

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

     msg_channel

   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 header " ^ quote len));

     val chunk = System_Channel.inputN channel n;

     val i = size chunk;

   in

     if i <> n then

       error ("Isabelle process: bad chunk (unexpected EOF after " ^

         string_of_int i ^ " of " ^ string_of_int n ^ " bytes)")

     else chunk

   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 task_context e =

   Future.task_context "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 => (task_context (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 (Future.shutdown (); Execution.reset (); ())

   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 _ = SHA1_Samples.test ()

       handle exn as Fail msg => (Output.physical_stderr (msg ^ "\n"); reraise exn);

     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 msg_channel = init_channels channel;

     val _ = Session.init_protocol_handlers ();

     val _ = loop channel;

   in Message_Channel.shutdown msg_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;