File : generic_atomic_action.ads

--                              -*- Mode: Ada -*-
-- Filename        : generic_atomic_action.ads
-- Description     : automatically executes parts of an atomic action
--                    and stopps them all, if at least one of them fails
--                    (by means of an exception)
-- Author          : Uwe Zimmer
-- Created On      : Wed Aug 28 17:06:35 2002
-- Last Modified By: .
-- Last Modified On: .
-- Update Count    : 0
-- Status          : Unknown, Use with caution!

------------------------------------------------------------------
--
-- Atomic actions are indivisible and and instantaneous. In case of
-- an atomic action, which consists itself of multiple concurrent parts,
-- some support for these conditions are provided here:
-- Either
--     - the full set of concurrent parts is completing their
--       action-part fully and without timing violations or other exceptions
--    or
--     - all parts of the action are executing a cleanup procedure to
--       restore the initial state (in case that any part of the action
--       was not able to complete fully) - regardless whether they completed
--       their action-part fully or to some extend, or whether they have
--       not even started executing it.
--
-- Each concurrent part of the atomic action is defined by:
--
--  (see also the definitions in atomic_action_types.ads)
--
--   1. A minimal and maximal delay after which this part
--      of the atomic action is started. First this part is delayed
--      by the minimal delay time. Then, if the action-part is not active
--      after the maximal delay time, the whole action is stopped.
--
--   2. This local action-part is started.
--
--   3. If this action-part is not completed before the maximal elapse time
--      (starting with the actual activation of the task, after the delay)
--      and before the absolute deadline, the whole action is stopped.
--
--   4. If this action-part is exiting with any exception, the whole
--      action is stopped.
--
--   5. If the whole action is stopped, each part excecutes its 'cleanup'
--      procedure, in order to fully restore the initial state.
--
-- All parts are blocked until either every part has completed its
-- action-part or every part (in case of a stopped action) has completed
-- its 'cleanup' procedure. Therefore the atomic action can only be completed
-- with all part successfully completed, or reset to the initial state.
--
-- The final state of the atomic action is determined and exceptions are
-- propagated in case the atomic action was not successfully completed.
-- Timing violations are indicated with specific exceptions. All other
-- exceptions are propagated as the 'Failure_State' exception.
--
------------------------------------------------------------------

with Atomic_Action_Types; use Atomic_Action_Types;

generic
   Actions : in Action_Parts;

package Generic_Atomic_Action is

   procedure Perform;

   Failure_State,
   Time_Out_State,
   Late_Activation_State : exception;

end Generic_Atomic_Action;