File : s-tpopsp-posix-foreign.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 POSIX version of this package where foreign threads are
33 -- recognized.
34
35 separate (System.Task_Primitives.Operations)
36 package body Specific is
37
38 ATCB_Key : aliased pthread_key_t;
39 -- Key used to find the Ada Task_Id associated with a thread
40
41 ----------------
42 -- Initialize --
43 ----------------
44
45 procedure Initialize (Environment_Task : Task_Id) is
46 pragma Warnings (Off, Environment_Task);
47 Result : Interfaces.C.int;
48
49 begin
50 Result := pthread_key_create (ATCB_Key'Access, null);
51 pragma Assert (Result = 0);
52 end Initialize;
53
54 -------------------
55 -- Is_Valid_Task --
56 -------------------
57
58 function Is_Valid_Task return Boolean is
59 begin
60 return pthread_getspecific (ATCB_Key) /= System.Null_Address;
61 end Is_Valid_Task;
62
63 ---------
64 -- Set --
65 ---------
66
67 procedure Set (Self_Id : Task_Id) is
68 Result : Interfaces.C.int;
69 begin
70 Result := pthread_setspecific (ATCB_Key, To_Address (Self_Id));
71 pragma Assert (Result = 0);
72 end Set;
73
74 ----------
75 -- Self --
76 ----------
77
78 -- To make Ada tasks and C threads interoperate better, we have added some
79 -- functionality to Self. Suppose a C main program (with threads) calls an
80 -- Ada procedure and the Ada procedure calls the tasking runtime system.
81 -- Eventually, a call will be made to self. Since the call is not coming
82 -- from an Ada task, there will be no corresponding ATCB.
83
84 -- What we do in Self is to catch references that do not come from
85 -- recognized Ada tasks, and create an ATCB for the calling thread.
86
87 -- The new ATCB will be "detached" from the normal Ada task master
88 -- hierarchy, much like the existing implicitly created signal-server
89 -- tasks.
90
91 function Self return Task_Id is
92 Result : System.Address;
93
94 begin
95 Result := pthread_getspecific (ATCB_Key);
96
97 -- If the key value is Null then it is a non-Ada task
98
99 if Result /= System.Null_Address then
100 return To_Task_Id (Result);
101 else
102 return Register_Foreign_Thread;
103 end if;
104 end Self;
105
106 end Specific;