File : adagio-monitor.adb


------------------------------------------------------------------------------

--                         ADAGIO - ADALID - AENEA.                         --

--                                                                          --

--                            Copyright (C) 2003                            --

--                                 A. Mosteo.                               --

--                                                                          --

--  Authors: A. Mosteo. (adagio@mosteo.com)                                 --

--                                                                          --

--  If you have any questions in regard to this software, please address    --

--  them to the above email.                                                --

--                                                                          --

--  This program is free software; you can redistribute it and/or modify    --

--  it under the terms of the GNU General Public License as published by    --

--  the Free Software Foundation; either version 2 of the License, or (at   --

--  your option) any later version.                                         --

--                                                                          --

--  This program is distributed in the hope that it will be useful, but     --

--  WITHOUT ANY WARRANTY; without even the implied warranty of              --

--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU       --

--  General Public License for more details.                                --

--                                                                          --

--  You should have received a copy of the GNU General Public License       --

--  along with this library; if not, write to the Free Software Foundation, --

--  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.          --

--                                                                          --

--  You are not allowed to use any part of this code to develop a program   --

--  whose output would be used to harass or prosecute other users of the    --

--  networks Adagio connects with. All data collected with Adagio or a tool --

--  containing Adagio code about other network users must remain            --

--  confidential and cannot be made public by any mean, nor be used to      --

--  harass or legally prosecute these users.                                --

------------------------------------------------------------------------------

--  $Id: adagio-monitor.adb,v 1.3 2004/01/21 21:05:48 Jano Exp $


package body Adagio.Monitor is

   protected body Semaphore is

      entry P when true is
      begin
         if Caller = P'Caller then
            In_use := In_use + 1;
         elsif In_use = 0 then
            Caller := P'Caller;
            In_use := 1;
         else
            requeue Safe_P with abort;
         end if;
      end P;

      entry Safe_P when In_use = 0 is
      begin
         Caller := Safe_P'Caller;
         In_use := 1;
      end Safe_P;

      entry V when true is
      begin
         if V'Caller /= Caller then
            raise Use_error;
         else
            In_use := In_use - 1;
            if In_use = 0 then
               Caller := Null_task_id;
            end if;
         end if;
      end V;

   end Semaphore;

   -- Get

   procedure Initialize(this: in out Object) is
   begin
      this.S.P;
   end Initialize;

   -- Release

   procedure Finalize(this: in out Object) is
   begin
      this.S.V;
   end Finalize;

end Adagio.Monitor;