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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S Y S T E M . T A S K _ I N F O --
-- --
-- S p e c --
-- --
-- $Revision$
-- --
-- Copyright (C) 1992-2001 Free Software Foundation, Inc. --
-- --
-- GNAT 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. GNAT 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 GNAT; see file COPYING. If not, write --
-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, 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. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
-- --
------------------------------------------------------------------------------
-- This package contains the definitions and routines associated with the
-- implementation of the Task_Info pragma.
-- This is the SGI (libathread) specific version of this module.
with System.OS_Interface;
with Unchecked_Deallocation;
package System.Task_Info is
pragma Elaborate_Body;
-- To ensure that a body is allowed
---------------------------------------------------------
-- Binding of Tasks to sprocs and sprocs to processors --
---------------------------------------------------------
-- The SGI implementation of the GNU Low-Level Interface (GNULLI)
-- implements each Ada task as a Posix thread (Pthread). The SGI
-- Pthread library distributes threads across one or more processes
-- that are members of a common share group. Irix distributes
-- processes across the available CPUs on a given machine. The
-- pragma Task_Info provides the mechanism to control the distribution
-- of tasks to sprocs, and sprocs to processors.
-- Each thread has a number of attributes that dictate it's scheduling.
-- These attributes are:
--
-- Bound_To_Sproc: whether the thread is bound to a specific sproc
-- for its entire lifetime.
--
-- Timeslice: Amount of time that a thread is allowed to execute
-- before the system yeilds control to another thread
-- of equal priority.
--
-- Resource_Vector: A bitmask used to control the binding of threads
-- to sprocs.
--
-- Each share group process (sproc)
-- The Task_Info pragma:
-- pragma Task_Info (EXPRESSION);
-- allows the specification on a task by task basis of a value of type
-- System.Task_Info.Task_Info_Type to be passed to a task when it is
-- created. The specification of this type, and the effect on the task
-- that is created is target dependent.
-- The Task_Info pragma appears within a task definition (compare the
-- definition and implementation of pragma Priority). If no such pragma
-- appears, then the value Task_Info_Unspecified is passed. If a pragma
-- is present, then it supplies an alternative value. If the argument of
-- the pragma is a discriminant reference, then the value can be set on
-- a task by task basis by supplying the appropriate discriminant value.
-- Note that this means that the type used for Task_Info_Type must be
-- suitable for use as a discriminant (i.e. a scalar or access type).
----------------------
-- Resource Vectors --
----------------------
-- <discussion>
type Resource_Vector_T is array (0 .. 31) of Boolean;
pragma Pack (Resource_Vector_T);
NO_RESOURCES : constant Resource_Vector_T := (others => False);
generic
type Resource_T is (<>);
-- Discrete type up to 32 entries
package Resource_Vector_Functions is
function "+"
(R : Resource_T)
return Resource_Vector_T;
function "+"
(R1 : Resource_T;
R2 : Resource_T)
return Resource_Vector_T;
function "+"
(R : Resource_T;
S : Resource_Vector_T)
return Resource_Vector_T;
function "+"
(S : Resource_Vector_T;
R : Resource_T)
return Resource_Vector_T;
function "+"
(S1 : Resource_Vector_T;
S2 : Resource_Vector_T)
return Resource_Vector_T;
function "-"
(S : Resource_Vector_T;
R : Resource_T)
return Resource_Vector_T;
end Resource_Vector_Functions;
----------------------
-- Sproc Attributes --
----------------------
subtype sproc_t is System.OS_Interface.sproc_t;
subtype CPU_Number is Integer range -1 .. Integer'Last;
ANY_CPU : constant CPU_Number := CPU_Number'First;
type Non_Degrading_Priority is range 0 .. 255;
-- Specification of IRIX Non Degrading Priorities.
--
-- WARNING: IRIX priorities have the reverse meaning of Ada priorities.
-- The lower the priority value, the greater the greater the
-- scheduling preference.
--
-- See the schedctl(2) man page for a complete discussion of non-degrading
-- priorities.
NDPHIMAX : constant Non_Degrading_Priority := 30;
NDPHIMIN : constant Non_Degrading_Priority := 39;
-- These priorities are higher than ALL normal user process priorities
subtype NDP_High is Non_Degrading_Priority range NDPHIMAX .. NDPHIMIN;
NDPNORMMAX : constant Non_Degrading_Priority := 40;
NDPNORMMIN : constant Non_Degrading_Priority := 127;
-- These priorities overlap normal user process priorities
subtype NDP_Norm is Non_Degrading_Priority range NDPNORMMAX .. NDPNORMMIN;
NDPLOMAX : constant Non_Degrading_Priority := 128;
NDPLOMIN : constant Non_Degrading_Priority := 254;
-- These priorities are below ALL normal user process priorities
NDP_NONE : constant Non_Degrading_Priority := 255;
subtype NDP_LOW is Non_Degrading_Priority range NDPLOMAX .. NDPLOMIN;
type Page_Locking is
(NOLOCK, -- Do not lock pages in memory
PROCLOCK, -- Lock text and data segments into memory (process lock)
TXTLOCK, -- Lock text segment into memory (text lock)
DATLOCK -- Lock data segment into memory (data lock)
);
type Sproc_Attributes is record
Sproc_Resources : Resource_Vector_T := NO_RESOURCES;
CPU : CPU_Number := ANY_CPU;
Resident : Page_Locking := NOLOCK;
NDPRI : Non_Degrading_Priority := NDP_NONE;
-- ??? why is that commented out, should it be removed ?
-- Sproc_Slice : Duration := 0.0;
-- Deadline_Period : Duration := 0.0;
-- Deadline_Alloc : Duration := 0.0;
end record;
Default_Sproc_Attributes : constant Sproc_Attributes :=
(NO_RESOURCES, ANY_CPU, NOLOCK, NDP_NONE);
function New_Sproc (Attr : Sproc_Attributes) return sproc_t;
function New_Sproc
(Sproc_Resources : Resource_Vector_T := NO_RESOURCES;
CPU : CPU_Number := ANY_CPU;
Resident : Page_Locking := NOLOCK;
NDPRI : Non_Degrading_Priority := NDP_NONE)
return sproc_t;
-- Allocates a sproc_t control structure and creates the
-- corresponding sproc.
Invalid_CPU_Number : exception;
Permission_Error : exception;
Sproc_Create_Error : exception;
-----------------------
-- Thread Attributes --
-----------------------
type Thread_Attributes (Bound_To_Sproc : Boolean) is record
Thread_Resources : Resource_Vector_T := NO_RESOURCES;
Thread_Timeslice : Duration := 0.0;
case Bound_To_Sproc is
when False =>
null;
when True =>
Sproc : sproc_t;
end case;
end record;
Default_Thread_Attributes : constant Thread_Attributes :=
(False, NO_RESOURCES, 0.0);
function Unbound_Thread_Attributes
(Thread_Resources : Resource_Vector_T := NO_RESOURCES;
Thread_Timeslice : Duration := 0.0)
return Thread_Attributes;
function Bound_Thread_Attributes
(Thread_Resources : Resource_Vector_T := NO_RESOURCES;
Thread_Timeslice : Duration := 0.0;
Sproc : sproc_t)
return Thread_Attributes;
function Bound_Thread_Attributes
(Thread_Resources : Resource_Vector_T := NO_RESOURCES;
Thread_Timeslice : Duration := 0.0;
Sproc_Resources : Resource_Vector_T := NO_RESOURCES;
CPU : CPU_Number := ANY_CPU;
Resident : Page_Locking := NOLOCK;
NDPRI : Non_Degrading_Priority := NDP_NONE)
return Thread_Attributes;
type Task_Info_Type is access all Thread_Attributes;
function New_Unbound_Thread_Attributes
(Thread_Resources : Resource_Vector_T := NO_RESOURCES;
Thread_Timeslice : Duration := 0.0)
return Task_Info_Type;
function New_Bound_Thread_Attributes
(Thread_Resources : Resource_Vector_T := NO_RESOURCES;
Thread_Timeslice : Duration := 0.0;
Sproc : sproc_t)
return Task_Info_Type;
function New_Bound_Thread_Attributes
(Thread_Resources : Resource_Vector_T := NO_RESOURCES;
Thread_Timeslice : Duration := 0.0;
Sproc_Resources : Resource_Vector_T := NO_RESOURCES;
CPU : CPU_Number := ANY_CPU;
Resident : Page_Locking := NOLOCK;
NDPRI : Non_Degrading_Priority := NDP_NONE)
return Task_Info_Type;
type Task_Image_Type is access String;
-- Used to generate a meaningful identifier for tasks that are variables
-- and components of variables.
procedure Free_Task_Image is new
Unchecked_Deallocation (String, Task_Image_Type);
Unspecified_Task_Info : constant Task_Info_Type := null;
end System.Task_Info;
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