File : s-tpopsp-tls.adb
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
4 -- --
5 -- SYSTEM.TASK_PRIMITIVES.OPERATIONS.SPECIFIC --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2011, Free Software Foundation, Inc. --
10 -- --
11 -- GNARL 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 -- --
19 -- --
20 -- --
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 -- GNARL was developed by the GNARL team at Florida State University. --
28 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
29 -- --
30 ------------------------------------------------------------------------------
31
32 -- This is a version of this package using TLS and where foreign threads are
33 -- recognized.
34
35 separate (System.Task_Primitives.Operations)
36 package body Specific is
37
38 ATCB : aliased Task_Id := null;
39 pragma Thread_Local_Storage (ATCB);
40
41 ----------------
42 -- Initialize --
43 ----------------
44
45 procedure Initialize (Environment_Task : Task_Id) is
46 begin
47 ATCB := Environment_Task;
48 end Initialize;
49
50 -------------------
51 -- Is_Valid_Task --
52 -------------------
53
54 function Is_Valid_Task return Boolean is
55 begin
56 return ATCB /= null;
57 end Is_Valid_Task;
58
59 ---------
60 -- Set --
61 ---------
62
63 procedure Set (Self_Id : Task_Id) is
64 begin
65 ATCB := Self_Id;
66 end Set;
67
68 ----------
69 -- Self --
70 ----------
71
72 -- To make Ada tasks and C threads interoperate better, we have added some
73 -- functionality to Self. Suppose a C main program (with threads) calls an
74 -- Ada procedure and the Ada procedure calls the tasking runtime system.
75 -- Eventually, a call will be made to self. Since the call is not coming
76 -- from an Ada task, there will be no corresponding ATCB.
77
78 -- What we do in Self is to catch references that do not come from
79 -- recognized Ada tasks, and create an ATCB for the calling thread.
80
81 -- The new ATCB will be "detached" from the normal Ada task master
82 -- hierarchy, much like the existing implicitly created signal-server
83 -- tasks.
84
85 function Self return Task_Id is
86 Result : constant Task_Id := ATCB;
87 begin
88 if Result /= null then
89 return Result;
90 else
91 -- If the value is Null then it is a non-Ada task
92
93 return Register_Foreign_Thread;
94 end if;
95 end Self;
96
97 end Specific;