PACKET offline manager                        (* Autor: Thomas Berlage *)
                                              (* Stand: 20.01.88       *)
  DEFINES

  begin,
  deferred end,
  own task password,
  continued from,
  continue,
  partner task :


LET
  ack               = 0,
  nak               = 1,
  error nak         = 2,
  second phase ack  = 5,
  password ack      = 6,

  begin code        = 4,
  password code     = 9,

  continue code         = 100,
  ask for password code = 199;

LET
  taskname invalid =
    "Taskname ungültig",
  task not ready =
    "Vater antwortet nicht",
  direct continue impossible =
    "Zieltask kann nicht direkt angekoppelt werden",
  t password =
    "Passwort:",
  t wrong password =
    "Falsches Passwort",
  order task no partner =
    "Ankoppeln nur für Partnertasks",
  continue not partner =
    "Nur Partner können angekoppelt werden";


BOOL VAR
  controlled mode := FALSE,
  end myself := FALSE;

TEXT VAR
  own password := "";

DATASPACE VAR ds := nilspace;

INT VAR
  reply,
  order,
  control channel,
  last order,
  phase number;

BOUND TEXT VAR reply message;

BOUND STRUCT (TEXT tname, tpass, TASK task, PROCA start proc) VAR sv msg;

TASK VAR
  order task,
  last order task := niltask;

ROW 4 TASK VAR pt;

INITFLAG VAR pt init;



PROC begin (TEXT CONST task name, father name) :

  enable stop;
  init partner;
  IF task name = "-" THEN
    errorstop (taskname invalid)
  END IF;
  call begin code;
  IF reply = password code THEN
    sv msg := ds;
    get password;
    call (task (father name), begin code, ds, reply)
  END IF;
  IF reply = ack THEN
    TASK CONST new task := task (task name);
    forget (ds);
    wait for init
  ELIF reply = error nak THEN
    reply message := ds;
    disable stop;
    errorstop (CONCR (reply message));
    forget (ds)
  ELSE
    forget (ds)
  END IF .

call begin code :
  INT VAR i;
  forget (ds); ds := nilspace;
  sv msg := ds;
  CONCR (sv msg). tname := task name;
  CONCR (sv msg). tpass := "";
  FOR i FROM 1 UPTO 5 REP
    pingpong (task (father name), begin code, ds, reply);
    IF reply = -2 THEN pause (5) END IF
  UNTIL reply <> -2 END REP;
  IF reply = -2 THEN
    errorstop (task not ready)
  END IF .

get password :
  dialog (t password);
  get secret line (CONCR (sv msg). tpass);
  cover tracks .

wait for init :
  WHILE status (new task) <> 2 REP pause (10) END REP .

END PROC begin;

PROC deferred end :

  end myself := TRUE

END PROC deferred end;

PROC own task password (TEXT CONST word) :

  own password := length (own password) * " ";
  own password := word;
  cover tracks

END PROC own task password;

TASK PROC continued from :

  last order task

END PROC continued from;

PROC i continue (TASK CONST t,
     PROC (DATASPACE VAR, INT CONST, INT CONST, TASK CONST) manager) :

  enable stop;
  IF is niltask (t) THEN
    break;
    disable stop
  ELSE
    ask for continue
  END IF;
  end if required;
  WHILE NOT online REP
    remember error message;
    prepare manager;
    wait for order
  END REP;
  repeat error message .

ask for continue :
  INT CONST my channel := channel;
  ask if password required;
  break (quiet);
  send continue request .

ask if password required :
  INT VAR i;
  forget (ds); ds := nilspace;
  FOR i FROM 1 UPTO 5 REP
    pingpong (t, ask for password code, ds, reply);
    IF reply = -2 THEN pause (5) END IF
  UNTIL reply <> -2 END REP;
  init password ds;
  IF reply = password ack THEN
    get password from user
  ELIF reply = ack THEN
    set password empty
  ELSE
    errorstop (direct continue impossible)
  END IF .

init password ds :
  forget (ds);
  ds := nilspace;
  reply message := ds .

get password from user :
  dialog (t password);
  get secret line (CONCR (reply message));
  cover tracks .

set password empty :
  CONCR (reply message) := "" .

send continue request :
  FOR i FROM 1 UPTO 5 REP
    pingpong (t, continue code + my channel, ds, reply);
    IF reply = -2 THEN pause (5) END IF
  UNTIL reply <> -2 END REP;
  disable stop;
  forget (ds);
  IF reply <> ack THEN
    continue (my channel)
  END IF .

end if required :
  IF end myself OR (controlled mode CAND NOT exists (pt (1))) THEN
    end (myself)
  END IF .

remember error message :
  TEXT VAR stored error;
  IF is error THEN
    stored error := error message;
    clear error
  ELSE
    stored error := ""
  END IF .

prepare manager :
  set autonom;
  command dialogue (FALSE);
  INT VAR old heap size := heap size;
  last order task := niltask .

wait for order :
  DATASPACE VAR local ds := nilspace;
  REP
    wait (local ds, order, order task);
    IF order <> second phase ack THEN
      prepare first phase;
      manager with end check
    ELIF order task = last order task THEN
      prepare second phase;
      manager (local ds, order, phase number, order task)
    ELSE
      send nak
    END IF;
    send error if necessary;
    collect heap garbage if necessary
  END REP .

prepare first phase :
  phase number := 1;
  last order := order;
  last order task := order task .

prepare second phase :
  phase number INCR 1;
  order := last order .

send nak :
  forget (local ds);
  local ds := nilspace;
  send (order task, nak, local ds) .

send error if necessary :
  IF is error THEN
    forget (local ds);
    local ds := nilspace;
    reply message := local ds;
    CONCR (reply message) := error message;
    clear error;
    send (order task, error nak, local ds)
  END IF .

collect heap garbage if necessary :
  IF heap size > old heap size + 8 THEN
    collect heap garbage;
    old heap size := heap size
  END IF .

manager with end check :
  IF order = ask for password code THEN
    answer if password required
  ELIF order > continue code AND order < continue code + 16 THEN
    try continue channel
  ELSE
    manager (local ds, order, phase number, order task)
  END IF .

answer if password required :
  IF password required THEN
    send (order task, password ack, local ds)
  ELSE
    send (order task, ack, local ds)
  END IF .

password required :
  own password <> "" .

try continue channel :
  check control;
  check password;
  call (supervisor, order, local ds, reply);
  IF NOT (order task = supervisor) THEN
    send (order task, reply, local ds)
  END IF;
  IF reply = ack THEN
    forget (local ds);
    LEAVE wait for order
  END IF .

check control :
  IF controlled mode CAND NOT is partner (order task) OR
       control channel > 0 CAND order - continue code <> control channel THEN
    errorstop (order task no partner);
    LEAVE try continue channel
  END IF .

check password :
  IF NOT (order task = supervisor) THEN
    reply message := local ds;
    IF CONCR (reply message) <> own password THEN
      errorstop (t wrong password);
      LEAVE try continue channel
    END IF
  END IF .

repeat error message :
  IF stored error <> "" THEN errorstop (stored error) END IF;
  command dialogue (TRUE) .

END PROC i continue;

PROC continue (TASK CONST t,
     PROC (DATASPACE VAR, INT CONST, INT CONST, TASK CONST) manager) :

  enable stop;
  init partner;
  control channel := 0;
  IF t = myself THEN
    (* do nothing *)
  ELIF controlled mode THEN
    IF NOT is partner (t) THEN errorstop (continue not partner) END IF
  ELIF is partner (t) THEN
    control channel := channel
  END IF;
  i continue (t,
      PROC (DATASPACE VAR, INT CONST, INT CONST, TASK CONST) manager)

END PROC continue;

BOOL PROC is partner (TASK CONST t) :

  NOT is niltask (t) CAND
    (t = pt (1) OR t = pt (2) OR t = pt (3) OR t = pt (4))

END PROC is partner;

TASK PROC partner task (INT CONST index) :

  init partner;
  pt (index)

END PROC partner task;

PROC partner task (INT CONST index, TASK CONST t) :

  init partner;
  pt (index) := t;
  IF index = 1 CAND NOT (t = myself) THEN
    controlled mode := TRUE
  END IF

END PROC partner task;

PROC init partner :

  IF NOT initialized (pt init) THEN
    do init
  END IF .

do init :
  pt (1) := niltask; pt (2) := niltask;
  pt (3) := niltask; pt (4) := niltask .

END PROC init partner;


END PACKET offline manager;