gcc/ada/a-taster.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --                 A D A . T A S K _ T E R M I N A T I O N                  --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 2005-2006, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- This specification is derived from the Ada Reference Manual for use with --
  12 -- GNAT. The copyright notice above, and the license provisions that follow --
  13 -- apply solely to the  contents of the part following the private keyword. --
  14 --                                                                          --
  15 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  16 -- terms of the  GNU General Public License as published  by the Free Soft- --
  17 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  18 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  19 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  20 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  21 -- for  more details.  You should have  received  a copy of the GNU General --
  22 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  23 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  24 -- Boston, MA 02110-1301, USA.                                              --
  25 --                                                                          --
  26 -- As a special exception,  if other files  instantiate  generics from this --
  27 -- unit, or you link  this unit with other files  to produce an executable, --
  28 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  29 -- covered  by the  GNU  General  Public  License.  This exception does not --
  30 -- however invalidate  any other reasons why  the executable file  might be --
  31 -- covered by the  GNU Public License.                                      --
  32 --                                                                          --
  33 -- GNAT was originally developed  by the GNAT team at  New York University. --
  34 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  35 --                                                                          --
  36 ------------------------------------------------------------------------------
  37
  38 with System.Tasking;
  39 --  used for Task_Id
  40
  41 with System.Task_Primitives.Operations;
  42 --  used for Self
  43 --           Write_Lock
  44 --           Unlock
  45 --           Lock_RTS
  46 --           Unlock_RTS
  47
  48 with System.Parameters;
  49 --  used for Single_Lock
  50
  51 with System.Soft_Links;
  52 --  use for Abort_Defer
  53 --          Abort_Undefer
  54
  55 with Unchecked_Conversion;
  56
  57 package body Ada.Task_Termination is
  58
  59    use type Ada.Task_Identification.Task_Id;
  60
  61    package STPO renames System.Task_Primitives.Operations;
  62    package SSL  renames System.Soft_Links;
  63
  64    use System.Parameters;
  65
  66    -----------------------
  67    -- Local subprograms --
  68    -----------------------
  69
  70    function To_TT is new Unchecked_Conversion
  71      (System.Tasking.Termination_Handler, Termination_Handler);
  72
  73    function To_ST is new Unchecked_Conversion
  74      (Termination_Handler, System.Tasking.Termination_Handler);
  75
  76    function To_Task_Id is new Unchecked_Conversion
  77      (Ada.Task_Identification.Task_Id, System.Tasking.Task_Id);
  78
  79    -----------------------------------
  80    -- Current_Task_Fallback_Handler --
  81    -----------------------------------
  82
  83    function Current_Task_Fallback_Handler return Termination_Handler is
  84    begin
  85       --  There is no need for explicit protection against race conditions
  86       --  for this function because this function can only be executed by
  87       --  Self, and the Fall_Back_Handler can only be modified by Self.
  88
  89       return To_TT (STPO.Self.Common.Fall_Back_Handler);
  90    end Current_Task_Fallback_Handler;
  91
  92    -------------------------------------
  93    -- Set_Dependents_Fallback_Handler --
  94    -------------------------------------
  95
  96    procedure Set_Dependents_Fallback_Handler
  97      (Handler : Termination_Handler)
  98    is
  99       Self : constant System.Tasking.Task_Id := STPO.Self;
 100
 101    begin
 102       SSL.Abort_Defer.all;
 103
 104       if Single_Lock then
 105          STPO.Lock_RTS;
 106       end if;
 107
 108       STPO.Write_Lock (Self);
 109
 110       Self.Common.Fall_Back_Handler := To_ST (Handler);
 111
 112       STPO.Unlock (Self);
 113
 114       if Single_Lock then
 115          STPO.Unlock_RTS;
 116       end if;
 117
 118       SSL.Abort_Undefer.all;
 119    end Set_Dependents_Fallback_Handler;
 120
 121    --------------------------
 122    -- Set_Specific_Handler --
 123    --------------------------
 124
 125    procedure Set_Specific_Handler
 126      (T       : Ada.Task_Identification.Task_Id;
 127       Handler : Termination_Handler)
 128    is
 129    begin
 130       --  Tasking_Error is raised if the task identified by T has already
 131       --  terminated. Program_Error is raised if the value of T is
 132       --  Null_Task_Id.
 133
 134       if T = Ada.Task_Identification.Null_Task_Id then
 135          raise Program_Error;
 136       elsif Ada.Task_Identification.Is_Terminated (T) then
 137          raise Tasking_Error;
 138       else
 139          declare
 140             Target : constant System.Tasking.Task_Id := To_Task_Id (T);
 141
 142          begin
 143             SSL.Abort_Defer.all;
 144
 145             if Single_Lock then
 146                STPO.Lock_RTS;
 147             end if;
 148
 149             STPO.Write_Lock (Target);
 150
 151             Target.Common.Specific_Handler := To_ST (Handler);
 152
 153             STPO.Unlock (Target);
 154
 155             if Single_Lock then
 156                STPO.Unlock_RTS;
 157             end if;
 158
 159             SSL.Abort_Undefer.all;
 160          end;
 161       end if;
 162    end Set_Specific_Handler;
 163
 164    ----------------------
 165    -- Specific_Handler --
 166    ----------------------
 167
 168    function Specific_Handler
 169      (T : Ada.Task_Identification.Task_Id) return Termination_Handler
 170    is
 171    begin
 172       --  Tasking_Error is raised if the task identified by T has already
 173       --  terminated. Program_Error is raised if the value of T is
 174       --  Null_Task_Id.
 175
 176       if T = Ada.Task_Identification.Null_Task_Id then
 177          raise Program_Error;
 178       elsif Ada.Task_Identification.Is_Terminated (T) then
 179          raise Tasking_Error;
 180       else
 181          declare
 182             Target : constant System.Tasking.Task_Id := To_Task_Id (T);
 183             TH     : Termination_Handler;
 184
 185          begin
 186             SSL.Abort_Defer.all;
 187
 188             if Single_Lock then
 189                STPO.Lock_RTS;
 190             end if;
 191
 192             STPO.Write_Lock (Target);
 193
 194             TH := To_TT (Target.Common.Specific_Handler);
 195
 196             STPO.Unlock (Target);
 197
 198             if Single_Lock then
 199                STPO.Unlock_RTS;
 200             end if;
 201
 202             SSL.Abort_Undefer.all;
 203
 204             return TH;
 205          end;
 206       end if;
 207    end Specific_Handler;
 208
 209 end Ada.Task_Termination;