1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
5 -- S Y S T E M . T A S K _ I N F O --
8 -- (Compiler Interface) --
10 -- Copyright (C) 1992-2001 Free Software Foundation, Inc. --
12 -- GNAT is free software; you can redistribute it and/or modify it under --
13 -- terms of the GNU General Public License as published by the Free Soft- --
14 -- ware Foundation; either version 2, or (at your option) any later ver- --
15 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
16 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
17 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
18 -- for more details. You should have received a copy of the GNU General --
19 -- Public License distributed with GNAT; see file COPYING. If not, write --
20 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
21 -- MA 02111-1307, USA. --
23 -- As a special exception, if other files instantiate generics from this --
24 -- unit, or you link this unit with other files to produce an executable, --
25 -- this unit does not by itself cause the resulting executable to be --
26 -- covered by the GNU General Public License. This exception does not --
27 -- however invalidate any other reasons why the executable file might be --
28 -- covered by the GNU Public License. --
30 -- GNAT was originally developed by the GNAT team at New York University. --
31 -- Extensive contributions were provided by Ada Core Technologies Inc. --
33 ------------------------------------------------------------------------------
35 -- This package contains the definitions and routines associated with the
36 -- implementation of the Task_Info pragma. It is specialized appropriately
37 -- for targets that make use of this pragma.
39 -- Note: the compiler generates direct calls to this interface, via Rtsfind.
40 -- Any changes to this interface may require corresponding compiler changes.
42 with Unchecked_Deallocation;
43 package System.Task_Info is
44 pragma Elaborate_Body;
45 -- To ensure that a body is allowed
47 -----------------------------------------
48 -- Implementation of Task_Info Feature --
49 -----------------------------------------
51 -- The Task_Info pragma:
53 -- pragma Task_Info (EXPRESSION);
55 -- allows the specification on a task by task basis of a value of type
56 -- System.Task_Info.Task_Info_Type to be passed to a task when it is
57 -- created. The specification of this type, and the effect on the task
58 -- that is created is target dependent.
60 -- The Task_Info pragma appears within a task definition (compare the
61 -- definition and implementation of pragma Priority). If no such pragma
62 -- appears, then the value Task_Info_Unspecified is passed. If a pragma
63 -- is present, then it supplies an alternative value. If the argument of
64 -- the pragma is a discriminant reference, then the value can be set on
65 -- a task by task basis by supplying the appropriate discriminant value.
67 -- Note that this means that the type used for Task_Info_Type must be
68 -- suitable for use as a discriminant (i.e. a scalar or access type).
76 -- Contend only with threads in same process
79 -- Contend with all threads on same CPU
83 type Task_Info_Type is new Scope_Type;
84 -- Type used for passing information to task create call, using the
85 -- Task_Info pragma. This type may be specialized for individual
86 -- implementations, but it must be a type that can be used as a
87 -- discriminant (i.e. a scalar or access type).
89 type Task_Image_Type is access String;
90 -- Used to generate a meaningful identifier for tasks that are variables
91 -- and components of variables.
93 procedure Free_Task_Image is new
94 Unchecked_Deallocation (String, Task_Image_Type);
96 Unspecified_Task_Info : constant Task_Info_Type := Default_Scope;
97 -- Value passed to task in the absence of a Task_Info pragma