gcc/ada/libgnarl/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) 2005-2018, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT 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 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  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 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 with System.Tasking;
  33 with System.Task_Primitives.Operations;
  34 with System.Parameters;
  35 with System.Soft_Links;
  36
  37 with Ada.Unchecked_Conversion;
  38
  39 package body Ada.Task_Termination is
  40
  41    use type Ada.Task_Identification.Task_Id;
  42
  43    package STPO renames System.Task_Primitives.Operations;
  44    package SSL  renames System.Soft_Links;
  45
  46    use System.Parameters;
  47
  48    -----------------------
  49    -- Local subprograms --
  50    -----------------------
  51
  52    function To_TT is new Ada.Unchecked_Conversion
  53      (System.Tasking.Termination_Handler, Termination_Handler);
  54
  55    function To_ST is new Ada.Unchecked_Conversion
  56      (Termination_Handler, System.Tasking.Termination_Handler);
  57
  58    function To_Task_Id is new Ada.Unchecked_Conversion
  59      (Ada.Task_Identification.Task_Id, System.Tasking.Task_Id);
  60
  61    -----------------------------------
  62    -- Current_Task_Fallback_Handler --
  63    -----------------------------------
  64
  65    function Current_Task_Fallback_Handler return Termination_Handler is
  66    begin
  67       --  There is no need for explicit protection against race conditions
  68       --  for this function because this function can only be executed by
  69       --  Self, and the Fall_Back_Handler can only be modified by Self.
  70
  71       return To_TT (STPO.Self.Common.Fall_Back_Handler);
  72    end Current_Task_Fallback_Handler;
  73
  74    -------------------------------------
  75    -- Set_Dependents_Fallback_Handler --
  76    -------------------------------------
  77
  78    procedure Set_Dependents_Fallback_Handler
  79      (Handler : Termination_Handler)
  80    is
  81       Self : constant System.Tasking.Task_Id := STPO.Self;
  82
  83    begin
  84       SSL.Abort_Defer.all;
  85
  86       if Single_Lock then
  87          STPO.Lock_RTS;
  88       end if;
  89
  90       STPO.Write_Lock (Self);
  91
  92       Self.Common.Fall_Back_Handler := To_ST (Handler);
  93
  94       STPO.Unlock (Self);
  95
  96       if Single_Lock then
  97          STPO.Unlock_RTS;
  98       end if;
  99
 100       SSL.Abort_Undefer.all;
 101    end Set_Dependents_Fallback_Handler;
 102
 103    --------------------------
 104    -- Set_Specific_Handler --
 105    --------------------------
 106
 107    procedure Set_Specific_Handler
 108      (T       : Ada.Task_Identification.Task_Id;
 109       Handler : Termination_Handler)
 110    is
 111    begin
 112       --  Tasking_Error is raised if the task identified by T has already
 113       --  terminated. Program_Error is raised if the value of T is
 114       --  Null_Task_Id.
 115
 116       if T = Ada.Task_Identification.Null_Task_Id then
 117          raise Program_Error;
 118       elsif Ada.Task_Identification.Is_Terminated (T) then
 119          raise Tasking_Error;
 120       else
 121          declare
 122             Target : constant System.Tasking.Task_Id := To_Task_Id (T);
 123
 124          begin
 125             SSL.Abort_Defer.all;
 126
 127             if Single_Lock then
 128                STPO.Lock_RTS;
 129             end if;
 130
 131             STPO.Write_Lock (Target);
 132
 133             Target.Common.Specific_Handler := To_ST (Handler);
 134
 135             STPO.Unlock (Target);
 136
 137             if Single_Lock then
 138                STPO.Unlock_RTS;
 139             end if;
 140
 141             SSL.Abort_Undefer.all;
 142          end;
 143       end if;
 144    end Set_Specific_Handler;
 145
 146    ----------------------
 147    -- Specific_Handler --
 148    ----------------------
 149
 150    function Specific_Handler
 151      (T : Ada.Task_Identification.Task_Id) return Termination_Handler
 152    is
 153    begin
 154       --  Tasking_Error is raised if the task identified by T has already
 155       --  terminated. Program_Error is raised if the value of T is
 156       --  Null_Task_Id.
 157
 158       if T = Ada.Task_Identification.Null_Task_Id then
 159          raise Program_Error;
 160       elsif Ada.Task_Identification.Is_Terminated (T) then
 161          raise Tasking_Error;
 162       else
 163          declare
 164             Target : constant System.Tasking.Task_Id := To_Task_Id (T);
 165             TH     : Termination_Handler;
 166
 167          begin
 168             SSL.Abort_Defer.all;
 169
 170             if Single_Lock then
 171                STPO.Lock_RTS;
 172             end if;
 173
 174             STPO.Write_Lock (Target);
 175
 176             TH := To_TT (Target.Common.Specific_Handler);
 177
 178             STPO.Unlock (Target);
 179
 180             if Single_Lock then
 181                STPO.Unlock_RTS;
 182             end if;
 183
 184             SSL.Abort_Undefer.all;
 185
 186             return TH;
 187          end;
 188       end if;
 189    end Specific_Handler;
 190
 191 end Ada.Task_Termination;