1------------------------------------------------------------------------------
2--                                                                          --
3--                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
4--                                                                          --
5--         S Y S T E M . T A S K I N G . T A S K _ A T T R I B U T E S      --
6--                                                                          --
7--                                  S p e c                                 --
8--                                                                          --
9--             Copyright (C) 1991-1994, Florida State University            --
10--                     Copyright (C) 1995-2010, AdaCore                     --
11--                                                                          --
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 3,  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.                                     --
18--                                                                          --
19-- As a special exception under Section 7 of GPL version 3, you are granted --
20-- additional permissions described in the GCC Runtime Library Exception,   --
21-- version 3.1, as published by the Free Software Foundation.               --
22--                                                                          --
23-- You should have received a copy of the GNU General Public License and    --
24-- a copy of the GCC Runtime Library Exception along with this program;     --
25-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
26-- <http://www.gnu.org/licenses/>.                                          --
27--                                                                          --
28-- GNARL was developed by the GNARL team at Florida State University.       --
29-- Extensive contributions were provided by Ada Core Technologies, Inc.     --
30--                                                                          --
31------------------------------------------------------------------------------
32
33--  This package provides support for the body of Ada.Task_Attributes
34
35with Ada.Finalization;
36
37with System.Storage_Elements;
38
39package System.Tasking.Task_Attributes is
40
41   type Attribute is new Integer;
42   --  A stand-in for the generic formal type of Ada.Task_Attributes
43   --  in the following declarations.
44
45   type Node;
46   type Access_Node is access all Node;
47   --  This needs comments ???
48
49   function To_Access_Node is new Ada.Unchecked_Conversion
50     (Access_Address, Access_Node);
51   --  Used to fetch pointer to indirect attribute list. Declaration is in
52   --  spec to avoid any problems with aliasing assumptions.
53
54   type Dummy_Wrapper;
55   type Access_Dummy_Wrapper is access all Dummy_Wrapper;
56   pragma No_Strict_Aliasing (Access_Dummy_Wrapper);
57   --  Needed to avoid possible incorrect aliasing situations from
58   --  instantiation of Unchecked_Conversion in body of Ada.Task_Attributes.
59
60   for Access_Dummy_Wrapper'Storage_Size use 0;
61   --  Access_Dummy_Wrapper is a stand-in for the generic type Wrapper defined
62   --  in Ada.Task_Attributes. The real objects allocated are always
63   --  of type Wrapper, no Dummy_Wrapper objects are ever created.
64
65   type Deallocator is access procedure (P : in out Access_Node);
66   --  Called to deallocate an Wrapper. P is a pointer to a Node within
67
68   type Instance;
69
70   type Access_Instance is access all Instance;
71
72   type Instance is new Ada.Finalization.Limited_Controlled with record
73      Deallocate    : Deallocator;
74      Initial_Value : aliased System.Storage_Elements.Integer_Address;
75
76      Index : Direct_Index;
77      --  The index of the TCB location used by this instantiation, if it is
78      --  stored in the TCB, otherwise zero.
79
80      Next : Access_Instance;
81      --  Next instance in All_Attributes list
82   end record;
83
84   procedure Finalize (X : in out Instance);
85
86   type Node is record
87      Wrapper  : Access_Dummy_Wrapper;
88      Instance : Access_Instance;
89      Next     : Access_Node;
90   end record;
91
92   --  The following type is a stand-in for the actual wrapper type, which is
93   --  different for each instantiation of Ada.Task_Attributes.
94
95   type Dummy_Wrapper is record
96      Dummy_Node : aliased Node;
97
98      Value : aliased Attribute;
99      --  The generic formal type, may be controlled
100   end record;
101
102   for Dummy_Wrapper'Alignment use Standard'Maximum_Alignment;
103   --  A number of unchecked conversions involving Dummy_Wrapper_Access
104   --  sources are performed in other units (e.g. Ada.Task_Attributes).
105   --  Ensure that the designated object is always strictly enough aligned.
106
107   In_Use : Direct_Index_Vector := 0;
108   --  Set True for direct indexes that are already used (True??? type???)
109
110   All_Attributes : Access_Instance;
111   --  A linked list of all indirectly access attributes, which includes all
112   --  those that require finalization.
113
114   procedure Initialize_Attributes (T : Task_Id);
115   --  Initialize all attributes created via Ada.Task_Attributes for T. This
116   --  must be called by the creator of the task, inside Create_Task, via
117   --  soft-link Initialize_Attributes_Link. On entry, abort must be deferred
118   --  and the caller must hold no locks
119
120   procedure Finalize_Attributes (T : Task_Id);
121   --  Finalize all attributes created via Ada.Task_Attributes for T.
122   --  This is to be called by the task after it is marked as terminated
123   --  (and before it actually dies), inside Vulnerable_Free_Task, via the
124   --  soft-link Finalize_Attributes_Link. On entry, abort must be deferred
125   --  and T.L must be write-locked.
126
127end System.Tasking.Task_Attributes;
128