Package: Util.Tasking.Conflict_Resolvers

Dependencies

with Ada.Task_Identification;

with Util.Tasking.Complex_Locks;

Description

Copyright © 2002 by Thomas Wolf.
This piece of software 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, or (at your option) any later version. This software 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 with this distribution, see file "GPL.txt". If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
As a special exception from the GPL, if other files instantiate generics from this unit, or you link this unit with other files to produce an executable, this unit does not by itself cause the resulting executable to be covered by the GPL. This exception does not however invalidate any other reasons why the executable file might be covered by the GPL.

Version: 1.1

Author:
Thomas Wolf (TW) <twolf AT acm DOT org>
Purpose:
Provides a lock promotion conflict resolution policy that aborts the request of the task with the lower priority.

Provided here instead of in Complex_Locks because the implementation depends on package Ada.Dynamic_Priorities, which is defined in the "Real Time Systems" annex, not in the "Systems Programming" annex. (There might be Ada implementations that support annex C, but not annex D. Separating out the stuff that needs annex D facilitates thus porting this library to implementations without annex D support: just remove this package.)

Storage Semantics
No dynamic storage allocation.
Tasking Semantics
Fully task-safe.

Header

package Util.Tasking.Conflict_Resolvers is
 
pragma Elaborate_Body;

Type Summary

Priority_Conflict_Resolver derived from Conflict_Resolver
Overridden Operations:  Decide

Other Items:

type Priority_Conflict_Resolver is
  new Util.Tasking.Complex_Locks.Conflict_Resolver with null record;

function Decide
  (Self        : access Priority_Conflict_Resolver;
   Queued_Task : in     Ada.Task_Identification.Task_Id;
   New_Task    : in     Ada.Task_Identification.Task_Id)
  return Boolean;
Returns True if the priority of the task denoted by New_Task is <= the priority of the task denoted by Queued_Task.
end Util.Tasking.Conflict_Resolvers;