------------------------------------------------------------------------------
--                                                                          --
--                           POLYORB COMPONENTS                             --
--                                                                          --
--  P O L Y O R B . T A S K I N G . I D L E _ T A S K S _ M A N A G E R S   --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--         Copyright (C) 2004-2009, Free Software Foundation, Inc.          --
--                                                                          --
-- PolyORB is free software; you  can  redistribute  it and/or modify it    --
-- under terms of the  GNU General Public License as published by the  Free --
-- Software Foundation;  either version 2,  or (at your option)  any  later --
-- version. PolyORB is distributed  in the hope that it will be  useful,    --
-- but WITHOUT ANY WARRANTY;  without even the implied warranty of MERCHAN- --
-- TABILITY 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 distributed with PolyORB; see file COPYING. If    --
-- not, write to the Free Software Foundation, 51 Franklin Street, Fifth    --
-- Floor, Boston, MA 02111-1301, USA.                                       --
--                                                                          --
--                                                                          --
--                  PolyORB is maintained by AdaCore                        --
--                     (email: sales@adacore.com)                           --
--                                                                          --
------------------------------------------------------------------------------

with PolyORB.Task_Info;
with PolyORB.Tasking.Condition_Variables;
with PolyORB.Utils.Chained_Lists;

package PolyORB.Tasking.Idle_Tasks_Managers is

   pragma Preelaborate;

   package PTI renames PolyORB.Task_Info;
   package PTCV renames PolyORB.Tasking.Condition_Variables;

   type Idle_Tasks_Manager is limited private;

   type Idle_Tasks_Manager_Access is access all Idle_Tasks_Manager;

   procedure Awake_Idle_Task
     (ITM : access Idle_Tasks_Manager;
      TI  : PTI.Task_Info_Access);
   --  Awake one specific idle task

   function Awake_One_Idle_Task
     (ITM             : access Idle_Tasks_Manager;
      Allow_Transient : Boolean) return Boolean;
   --  Awake one idle task, if any, else do nothing. If Allow_Transient is
   --  True, we can awaken any Kind of task; otherwise, we must awaken a
   --  Permanent task (or do nothing). Returns True when an idle task has been
   --  awakened.

   procedure Awake_All_Idle_Tasks (ITM : access Idle_Tasks_Manager);
   --  Awake all idle tasks

   procedure Remove_Idle_Task
     (ITM : access Idle_Tasks_Manager;
      TI  : PTI.Task_Info_Access);
   --  Called after task TI has exited Idle to return its CV to the free list

   function Insert_Idle_Task
     (ITM : access Idle_Tasks_Manager;
      TI  :  PTI.Task_Info_Access) return PTCV.Condition_Access;
   --  Add TI to the pool of tasks managed by ITM. The returned CV
   --  will be used by a task to put itself in an idle (waiting) state.

private

   pragma Inline (Remove_Idle_Task);
   pragma Inline (Insert_Idle_Task);

   package CV_Lists is
     new PolyORB.Utils.Chained_Lists (PTCV.Condition_Access, PTCV."=");

   type Task_List_Array is array (PTI.Task_Kind) of PTI.Task_List;

   type Idle_Tasks_Manager is limited record
      Idle_Task_Lists : Task_List_Array;
      --  Lists of idle tasks, segregated by Kind

      Free_CV : CV_Lists.List;
      --  Free_CV is the list of pre-allocated CV. When scheduling a task
      --  to idle state, the ORB controller first looks for an availble
      --  CV in this list; or else allocates one new CV. When a task
      --  leaves idle state, the ORB controller puts its CV in Free_CV.
   end record;

end PolyORB.Tasking.Idle_Tasks_Managers;
