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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
-- --
-- S Y S T E M . T A S K _ P R I M I T I V E S --
-- --
-- S p e c --
-- --
-- Copyright (C) 1991-1994, Florida State University --
-- Copyright (C) 1995-2005, AdaCore --
-- --
-- GNARL 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 2, or (at your option) any later ver- --
-- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
-- OUT 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 distributed with GNARL; see file COPYING. If not, write --
-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
-- Boston, MA 02110-1301, USA. --
-- --
-- As a special exception, 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 GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- GNARL was developed by the GNARL team at Florida State University. --
-- Extensive contributions were provided by Ada Core Technologies, Inc. --
-- --
------------------------------------------------------------------------------
-- This is an OS/2 version of this package
-- This package provides low-level support for most tasking features
pragma Polling (Off);
-- Turn off polling, we do not want ATC polling to take place during
-- tasking operations. It causes infinite loops and other problems.
with Interfaces.OS2Lib.Threads;
with Interfaces.OS2Lib.Synchronization;
package System.Task_Primitives is
pragma Preelaborate;
type Lock is limited private;
-- Should be used for implementation of protected objects.
type RTS_Lock is limited private;
-- Should be used inside the runtime system.
-- The difference between Lock and the RTS_Lock is that the later
-- one serves only as a semaphore so that do not check for
-- ceiling violations.
type Task_Body_Access is access procedure;
-- Pointer to the task body's entry point (or possibly a wrapper
-- declared local to the GNARL).
type Private_Data is limited private;
-- Any information that the GNULLI needs maintained on a per-task
-- basis. A component of this type is guaranteed to be included
-- in the Ada_Task_Control_Block.
private
type Lock is record
Mutex : aliased Interfaces.OS2Lib.Synchronization.HMTX;
Priority : Integer;
Owner_Priority : Integer;
Owner_ID : Address;
end record;
type RTS_Lock is new Lock;
type Suspension_Object is record
State : Boolean;
pragma Atomic (State);
-- Boolean that indicates whether the object is open. This field is
-- marked Atomic to ensure that we can read its value without locking
-- the access to the Suspension_Object.
Waiting : Boolean;
-- Flag showing if there is a task already suspended on this object
L : aliased Interfaces.OS2Lib.Synchronization.HMTX;
-- Protection for ensuring mutual exclusion on the Suspension_Object
CV : aliased Interfaces.OS2Lib.Synchronization.HEV;
-- Condition variable used to queue threads until condition is signaled
end record;
type Private_Data is record
Thread : aliased Interfaces.OS2Lib.Threads.TID;
pragma Atomic (Thread);
-- Thread field may be updated by two different threads of control.
-- (See, Enter_Task and Create_Task in s-taprop.adb). They put the same
-- value (thr_self value). We do not want to use lock on those
-- operations and the only thing we have to make sure is that they are
-- updated in atomic fashion.
CV : aliased Interfaces.OS2Lib.Synchronization.HEV;
L : aliased RTS_Lock;
-- Protection for all components is lock L
Current_Priority : Integer := -1;
-- The Current_Priority is the actual priority of a thread. This field
-- is needed because it is only possible to set delta priority in OS/2.
-- The only places where this field should be set are Set_Priority,
-- Create_Task and Initialize (Environment).
Wrapper : Interfaces.OS2Lib.Threads.PFNTHREAD;
-- This is the original wrapper passed by Operations.Create_Task. When
-- installing an exception handler in a thread, the thread starts
-- executing the Exception_Wrapper which calls Wrapper when the handler
-- has been installed. The handler is removed when wrapper returns.
end record;
end System.Task_Primitives;
|
