gcc/ada/s-tpopsp-posix-foreign.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS               --
   4 --                                                                          --
   5 --                SYSTEM.TASK_PRIMITIVES.OPERATIONS.SPECIFIC                --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --         Copyright (C) 1992-2004, 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 2,  or (at your option) any later ver- --
  14 -- sion. GNARL 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.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNARL was developed by the GNARL team at Florida State University.       --
  30 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This is a POSIX version of this package where foreign threads are
  35 --  recognized.
  36
  37 --  Currently, DEC Unix, SCO UnixWare, Solaris pthread, HPUX pthread and
  38 --  GNU/Linux threads use this version.
  39
  40 separate (System.Task_Primitives.Operations)
  41 package body Specific is
  42
  43    ----------------
  44    -- Initialize --
  45    ----------------
  46
  47    procedure Initialize (Environment_Task : Task_Id) is
  48       pragma Warnings (Off, Environment_Task);
  49       Result : Interfaces.C.int;
  50
  51    begin
  52       Result := pthread_key_create (ATCB_Key'Access, null);
  53       pragma Assert (Result = 0);
  54    end Initialize;
  55
  56    -------------------
  57    -- Is_Valid_Task --
  58    -------------------
  59
  60    function Is_Valid_Task return Boolean is
  61    begin
  62       return pthread_getspecific (ATCB_Key) /= System.Null_Address;
  63    end Is_Valid_Task;
  64
  65    ---------
  66    -- Set --
  67    ---------
  68
  69    procedure Set (Self_Id : Task_Id) is
  70       Result : Interfaces.C.int;
  71    begin
  72       Result := pthread_setspecific (ATCB_Key, To_Address (Self_Id));
  73       pragma Assert (Result = 0);
  74    end Set;
  75
  76    ----------
  77    -- Self --
  78    ----------
  79
  80    --  To make Ada tasks and C threads interoperate better, we have added some
  81    --  functionality to Self. Suppose a C main program (with threads) calls an
  82    --  Ada procedure and the Ada procedure calls the tasking runtime system.
  83    --  Eventually, a call will be made to self. Since the call is not coming
  84    --  from an Ada task, there will be no corresponding ATCB.
  85
  86    --  What we do in Self is to catch references that do not come from
  87    --  recognized Ada tasks, and create an ATCB for the calling thread.
  88
  89    --  The new ATCB will be "detached" from the normal Ada task master
  90    --  hierarchy, much like the existing implicitly created signal-server
  91    --  tasks.
  92
  93    function Self return Task_Id is
  94       Result : System.Address;
  95
  96    begin
  97       Result := pthread_getspecific (ATCB_Key);
  98
  99       --  If the key value is Null, then it is a non-Ada task.
 100
 101       if Result /= System.Null_Address then
 102          return To_Task_Id (Result);
 103       else
 104          return Register_Foreign_Thread;
 105       end if;
 106    end Self;
 107
 108 end Specific;