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

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
   4 --                                                                          --
   5 --    S Y S T E M . T A S K _ P R I M I T I V E S . O P E R A T I O N S .   --
   6 --                             S P E C I F I C                              --
   7 --                                                                          --
   8 --                                B o d y                                   --
   9 --                                                                          --
  10 --         Copyright (C) 1992-2005, Free Software Foundation, Inc.          --
  11 --                                                                          --
  12 -- GNARL 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. GNARL 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 GNARL; see file COPYING.  If not, write --
  20 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  21 -- Boston, MA 02110-1301, USA.                                              --
  22 --                                                                          --
  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.                                      --
  29 --                                                                          --
  30 -- GNARL was developed by the GNARL team at Florida State University.       --
  31 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 --  This is a POSIX version of this package where foreign threads are
  36 --  recognized.
  37
  38 --  Currently, DEC Unix, SCO UnixWare, Solaris pthread, HPUX pthread and
  39 --  GNU/Linux threads use this version.
  40
  41 separate (System.Task_Primitives.Operations)
  42 package body Specific is
  43
  44    ----------------
  45    -- Initialize --
  46    ----------------
  47
  48    procedure Initialize (Environment_Task : Task_Id) is
  49       pragma Warnings (Off, Environment_Task);
  50       Result : Interfaces.C.int;
  51
  52    begin
  53       Result := pthread_key_create (ATCB_Key'Access, null);
  54       pragma Assert (Result = 0);
  55    end Initialize;
  56
  57    -------------------
  58    -- Is_Valid_Task --
  59    -------------------
  60
  61    function Is_Valid_Task return Boolean is
  62    begin
  63       return pthread_getspecific (ATCB_Key) /= System.Null_Address;
  64    end Is_Valid_Task;
  65
  66    ---------
  67    -- Set --
  68    ---------
  69
  70    procedure Set (Self_Id : Task_Id) is
  71       Result : Interfaces.C.int;
  72    begin
  73       Result := pthread_setspecific (ATCB_Key, To_Address (Self_Id));
  74       pragma Assert (Result = 0);
  75    end Set;
  76
  77    ----------
  78    -- Self --
  79    ----------
  80
  81    --  To make Ada tasks and C threads interoperate better, we have added some
  82    --  functionality to Self. Suppose a C main program (with threads) calls an
  83    --  Ada procedure and the Ada procedure calls the tasking runtime system.
  84    --  Eventually, a call will be made to self. Since the call is not coming
  85    --  from an Ada task, there will be no corresponding ATCB.
  86
  87    --  What we do in Self is to catch references that do not come from
  88    --  recognized Ada tasks, and create an ATCB for the calling thread.
  89
  90    --  The new ATCB will be "detached" from the normal Ada task master
  91    --  hierarchy, much like the existing implicitly created signal-server
  92    --  tasks.
  93
  94    function Self return Task_Id is
  95       Result : System.Address;
  96
  97    begin
  98       Result := pthread_getspecific (ATCB_Key);
  99
 100       --  If the key value is Null, then it is a non-Ada task.
 101
 102       if Result /= System.Null_Address then
 103          return To_Task_Id (Result);
 104       else
 105          return Register_Foreign_Thread;
 106       end if;
 107    end Self;
 108
 109 end Specific;