144 lines
6.4 KiB
Ada
144 lines
6.4 KiB
Ada
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------------------------------------------------------------------------------
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-- --
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-- GNAT COMPILER COMPONENTS --
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-- --
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-- S Y S T E M . T A S K _ I N F O --
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-- --
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-- S p e c --
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-- --
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-- --
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-- Copyright (C) 1992-2000 Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 2, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
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-- for more details. You should have received a copy of the GNU General --
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-- Public License distributed with GNAT; see file COPYING. If not, write --
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-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
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-- MA 02111-1307, USA. --
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-- --
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-- As a special exception, if other files instantiate generics from this --
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-- unit, or you link this unit with other files to produce an executable, --
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-- this unit does not by itself cause the resulting executable to be --
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-- covered by the GNU General Public License. This exception does not --
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-- however invalidate any other reasons why the executable file might be --
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-- covered by the GNU Public License. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- This package contains the definitions and routines associated with the
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-- implementation of the Task_Info pragma.
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-- This is the NetBSD (native) version of this module.
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with System.OS_Interface;
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with Unchecked_Deallocation;
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package System.Task_Info is
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pragma Elaborate_Body;
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-- To ensure that a body is allowed
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-----------------------------------------------------
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-- Binding of Tasks to LWPs and LWPs to processors --
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-----------------------------------------------------
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-- The NetBSD implementation of the GNU Low-Level Interface (GNULLI)
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-- implements each Ada task as a NetBSD thread. The NetBSD thread
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-- library distributes threads across one or more LWPs (Light Weight
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-- Process) that are members of the same process. NetBSD distributes
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-- processes and LWPs across the available CPUs on a given machine. The
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-- pragma Task_Info provides the mechanism to control the distribution
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-- of tasks to LWPs, and LWPs to processors.
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-- Each thread has a number of attributes that dictate it's scheduling.
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-- These attributes are:
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--
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-- New_LWP: whether a new LWP is created for this thread.
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--
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-- Bound_To_LWP: whether the thread is bound to a specific LWP
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-- for its entire lifetime.
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--
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-- CPU: the CPU number associated to the LWP
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--
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-- The Task_Info pragma:
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-- pragma Task_Info (EXPRESSION);
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-- allows the specification on a task by task basis of a value of type
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-- System.Task_Info.Task_Info_Type to be passed to a task when it is
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-- created. The specification of this type, and the effect on the task
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-- that is created is target dependent.
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-- The Task_Info pragma appears within a task definition (compare the
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-- definition and implementation of pragma Priority). If no such pragma
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-- appears, then the value Task_Info_Unspecified is passed. If a pragma
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-- is present, then it supplies an alternative value. If the argument of
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-- the pragma is a discriminant reference, then the value can be set on
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-- a task by task basis by supplying the appropriate discriminant value.
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-- Note that this means that the type used for Task_Info_Type must be
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-- suitable for use as a discriminant (i.e. a scalar or access type).
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-----------------------
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-- Thread Attributes --
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-----------------------
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subtype CPU_Number is System.OS_Interface.processorid_t;
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CPU_UNCHANGED : constant CPU_Number := System.OS_Interface.PBIND_QUERY;
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-- Do not bind the LWP to a specific processor
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ANY_CPU : constant CPU_Number := System.OS_Interface.PBIND_NONE;
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-- Bind the LWP to any processor
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Invalid_CPU_Number : exception;
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type Thread_Attributes (New_LWP : Boolean) is record
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Bound_To_LWP : Boolean := True;
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case New_LWP is
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when False =>
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null;
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when True =>
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CPU : CPU_Number := CPU_UNCHANGED;
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end case;
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end record;
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Default_Thread_Attributes : constant Thread_Attributes := (False, True);
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function Unbound_Thread_Attributes
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return Thread_Attributes;
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function Bound_Thread_Attributes
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return Thread_Attributes;
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function Bound_Thread_Attributes (CPU : CPU_Number)
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return Thread_Attributes;
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type Task_Info_Type is access all Thread_Attributes;
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function New_Unbound_Thread_Attributes
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return Task_Info_Type;
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function New_Bound_Thread_Attributes
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return Task_Info_Type;
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function New_Bound_Thread_Attributes (CPU : CPU_Number)
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return Task_Info_Type;
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type Task_Image_Type is access String;
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-- Used to generate a meaningful identifier for tasks that are variables
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-- and components of variables.
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procedure Free_Task_Image is new
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Unchecked_Deallocation (String, Task_Image_Type);
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Unspecified_Task_Info : constant Task_Info_Type := null;
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end System.Task_Info;
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