------------------------------------------------------------------------------
--                                                                          --
--                           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) 2004-2012, Free Software Foundation, Inc.          --
--                                                                          --
-- This is free software;  you can redistribute it  and/or modify it  under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
-- sion.  This software 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.                                               --
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--                                                                          --
-- You should have received a copy of the GNU General Public License and    --
-- a copy of the GCC Runtime Library Exception along with this program;     --
-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
-- <http://www.gnu.org/licenses/>.                                          --
--                                                                          --
--                  PolyORB is maintained by AdaCore                        --
--                     (email: sales@adacore.com)                           --
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------------------------------------------------------------------------------

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;
