1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                     S Y S T E M . T A S K _ I N F O                      --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--            Copyright (C) 2007-2012, Free Software Foundation, Inc.       --
10--                                                                          --
11-- GNAT is free software;  you can  redistribute it  and/or modify it under --
12-- terms of the  GNU General Public License as published  by the Free Soft- --
13-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
14-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
15-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
16-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
17--                                                                          --
18-- As a special exception under Section 7 of GPL version 3, you are granted --
19-- additional permissions described in the GCC Runtime Library Exception,   --
20-- version 3.1, as published by the Free Software Foundation.               --
21--                                                                          --
22-- You should have received a copy of the GNU General Public License and    --
23-- a copy of the GCC Runtime Library Exception along with this program;     --
24-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
25-- <http://www.gnu.org/licenses/>.                                          --
26--                                                                          --
27-- GNAT was originally developed  by the GNAT team at  New York University. --
28-- Extensive contributions were provided by Ada Core Technologies Inc.      --
29--                                                                          --
30------------------------------------------------------------------------------
31
32--  This package contains the definitions and routines associated with the
33--  implementation and use of the Task_Info pragma. It is specialized
34--  appropriately for targets that make use of this pragma.
35
36--  Note: the compiler generates direct calls to this interface, via Rtsfind.
37--  Any changes to this interface may require corresponding compiler changes.
38
39--  This unit may be used directly from an application program by providing
40--  an appropriate WITH, and the interface can be expected to remain stable.
41
42--  This is the GNU/Linux version of this module
43
44with System.OS_Interface;
45
46package System.Task_Info is
47   pragma Preelaborate;
48   pragma Elaborate_Body;
49   --  To ensure that a body is allowed
50
51   --  The Linux kernel provides a way to define the ideal processor to use for
52   --  a given thread. The ideal processor is not necessarily the one that will
53   --  be used by the OS but the OS will always try to schedule this thread to
54   --  the specified processor if it is available.
55
56   --  The Task_Info pragma:
57
58   --    pragma Task_Info (EXPRESSION);
59
60   --  allows the specification on a task by task basis of a value of type
61   --  System.Task_Info.Task_Info_Type to be passed to a task when it is
62   --  created. The specification of this type, and the effect on the task
63   --  that is created is target dependent.
64
65   --  The Task_Info pragma appears within a task definition (compare the
66   --  definition and implementation of pragma Priority). If no such pragma
67   --  appears, then the value Unspecified_Task_Info is passed. If a pragma
68   --  is present, then it supplies an alternative value. If the argument of
69   --  the pragma is a discriminant reference, then the value can be set on
70   --  a task by task basis by supplying the appropriate discriminant value.
71
72   --  Note that this means that the type used for Task_Info_Type must be
73   --  suitable for use as a discriminant (i.e. a scalar or access type).
74
75   -----------------------
76   -- Thread Attributes --
77   -----------------------
78
79   subtype CPU_Set is System.OS_Interface.cpu_set_t;
80
81   Any_CPU : constant CPU_Set := (bits => (others => True));
82   No_CPU  : constant CPU_Set := (bits => (others => False));
83
84   Invalid_CPU_Number : exception;
85   --  Raised when an invalid CPU mask has been specified
86   --  i.e. An empty CPU set
87
88   type Thread_Attributes is record
89      CPU_Affinity : aliased CPU_Set := Any_CPU;
90   end record;
91
92   Default_Thread_Attributes : constant Thread_Attributes := (others => <>);
93
94   type Task_Info_Type is access all Thread_Attributes;
95
96   Unspecified_Task_Info : constant Task_Info_Type := null;
97
98   function Number_Of_Processors return Positive;
99   --  Returns the number of processors on the running host
100
101end System.Task_Info;
102