gcc/ada/5vtaspri.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                GNU ADA 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              --
   6 --                                                                          --
   7 --                                  S p e c                                 --
   8 --                                                                          --
   9 --                                                                          --
  10 --          Copyright (C) 1991-2000 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,  59 Temple Place - Suite 330,  Boston, --
  21 -- MA 02111-1307, 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. It is --
  31 -- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
  32 -- State University (http://www.gnat.com).                                  --
  33 --                                                                          --
  34 ------------------------------------------------------------------------------
  35
  36 --  This is a OpenVMS/Alpha version of this package.
  37
  38 --  This package provides low-level support for most tasking features.
  39
  40 pragma Polling (Off);
  41 --  Turn off polling, we do not want ATC polling to take place during
  42 --  tasking operations. It causes infinite loops and other problems.
  43
  44 with Interfaces.C;
  45 --  used for int
  46 --           size_t
  47
  48 with System.OS_Interface;
  49 --  used for pthread_mutex_t
  50 --           pthread_cond_t
  51 --           pthread_t
  52
  53 package System.Task_Primitives is
  54
  55    type Lock is limited private;
  56    --  Should be used for implementation of protected objects.
  57
  58    type RTS_Lock is limited private;
  59    --  Should be used inside the runtime system.
  60    --  The difference between Lock and the RTS_Lock is that the later
  61    --  one serves only as a semaphore so that do not check for
  62    --  ceiling violations.
  63
  64    type Task_Body_Access is access procedure;
  65    --  Pointer to the task body's entry point (or possibly a wrapper
  66    --  declared local to the GNARL).
  67
  68    type Private_Data is limited private;
  69    --  Any information that the GNULLI needs maintained on a per-task
  70    --  basis.  A component of this type is guaranteed to be included
  71    --  in the Ada_Task_Control_Block.
  72
  73 private
  74
  75    type Exc_Stack_T is array (0 .. 8192) of aliased Character;
  76    for Exc_Stack_T'Alignment use Standard'Maximum_Alignment;
  77    type Exc_Stack_Ptr_T is access all Exc_Stack_T;
  78
  79    type Lock is record
  80       L         : aliased System.OS_Interface.pthread_mutex_t;
  81       Prio      : Interfaces.C.int;
  82       Prio_Save : Interfaces.C.int;
  83    end record;
  84
  85    type RTS_Lock is new System.OS_Interface.pthread_mutex_t;
  86    type Private_Data is record
  87       Thread      : aliased System.OS_Interface.pthread_t;
  88       pragma Atomic (Thread);
  89       --  Thread field may be updated by two different threads of control.
  90       --  (See, Enter_Task and Create_Task in s-taprop.adb).
  91       --  They put the same value (thr_self value). We do not want to
  92       --  use lock on those operations and the only thing we have to
  93       --  make sure is that they are updated in atomic fashion.
  94
  95       CV          : aliased System.OS_Interface.pthread_cond_t;
  96       L           : aliased RTS_Lock;
  97       --  protection for all components is lock L
  98
  99       Exc_Stack_Ptr : Exc_Stack_Ptr_T;
 100       --  ??? This needs comments.
 101
 102       AST_Pending : Boolean;
 103       --  Used to detect delay and sleep timeouts
 104
 105    end record;
 106
 107 end System.Task_Primitives;