gcc/ada/5ataspri.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 --                             $Revision: 1.8 $
  10 --                                                                          --
  11 --          Copyright (C) 1991-2000 Free Software Foundation, Inc.          --
  12 --                                                                          --
  13 -- GNARL is free software; you can  redistribute it  and/or modify it under --
  14 -- terms of the  GNU General Public License as published  by the Free Soft- --
  15 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  16 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
  17 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  18 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  19 -- for  more details.  You should have  received  a copy of the GNU General --
  20 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  21 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  22 -- MA 02111-1307, USA.                                                      --
  23 --                                                                          --
  24 -- As a special exception,  if other files  instantiate  generics from this --
  25 -- unit, or you link  this unit with other files  to produce an executable, --
  26 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  27 -- covered  by the  GNU  General  Public  License.  This exception does not --
  28 -- however invalidate  any other reasons why  the executable file  might be --
  29 -- covered by the  GNU Public License.                                      --
  30 --                                                                          --
  31 -- GNARL was developed by the GNARL team at Florida State University. It is --
  32 -- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
  33 -- State University (http://www.gnat.com).                                  --
  34 --                                                                          --
  35 ------------------------------------------------------------------------------
  36
  37 --  This is the DEC Unix 4.0 version of this package.
  38
  39 --  This package provides low-level support for most tasking features.
  40
  41 pragma Polling (Off);
  42 --  Turn off polling, we do not want ATC polling to take place during
  43 --  tasking operations. It causes infinite loops and other problems.
  44
  45 with Interfaces.C;
  46 --  used for int
  47 --           size_t
  48
  49 with System.OS_Interface;
  50 --  used for pthread_mutex_t
  51 --           pthread_cond_t
  52 --           pthread_t
  53
  54 package System.Task_Primitives is
  55
  56    type Lock is limited private;
  57    --  Should be used for implementation of protected objects.
  58
  59    type RTS_Lock is limited private;
  60    --  Should be used inside the runtime system.
  61    --  The difference between Lock and the RTS_Lock is that the later
  62    --  one serves only as a semaphore so that do not check for
  63    --  ceiling violations.
  64
  65    type Task_Body_Access is access procedure;
  66    --  Pointer to the task body's entry point (or possibly a wrapper
  67    --  declared local to the GNARL).
  68
  69    type Private_Data is limited private;
  70    --  Any information that the GNULLI needs maintained on a per-task
  71    --  basis.  A component of this type is guaranteed to be included
  72    --  in the Ada_Task_Control_Block.
  73
  74 private
  75
  76    type Lock is record
  77       L          : aliased System.OS_Interface.pthread_mutex_t;
  78       Ceiling    : Interfaces.C.int;
  79    end record;
  80
  81    type RTS_Lock is new System.OS_Interface.pthread_mutex_t;
  82    type Private_Data is record
  83       Thread      : aliased System.OS_Interface.pthread_t;
  84       pragma Atomic (Thread);
  85       --  Thread field may be updated by two different threads of control.
  86       --  (See, Enter_Task and Create_Task in s-taprop.adb).
  87       --  They put the same value (thr_self value). We do not want to
  88       --  use lock on those operations and the only thing we have to
  89       --  make sure is that they are updated in atomic fashion.
  90
  91       CV          : aliased System.OS_Interface.pthread_cond_t;
  92       L           : aliased RTS_Lock;
  93       --  protection for all components is lock L
  94    end record;
  95
  96 end System.Task_Primitives;