gcc/ada/5itaspri.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 --           Copyright (C) 1991-2001 Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNARL 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 2,  or (at your option) any later ver- --
  14 -- sion. GNARL 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.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNARL was developed by the GNARL team at Florida State University.       --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This is the GNU/Linux (GNU/LinuxThreads) version of this package.
  35
  36 --  This package provides low-level support for most tasking features.
  37
  38 pragma Polling (Off);
  39 --  Turn off polling, we do not want ATC polling to take place during
  40 --  tasking operations. It causes infinite loops and other problems.
  41
  42 with System.OS_Interface;
  43 --  used for pthread_mutex_t
  44 --           pthread_cond_t
  45 --           pthread_t
  46
  47 package System.Task_Primitives is
  48
  49    type Lock is limited private;
  50    --  Should be used for implementation of protected objects.
  51
  52    type RTS_Lock is limited private;
  53    --  Should be used inside the runtime system.
  54    --  The difference between Lock and the RTS_Lock is that the later
  55    --  one serves only as a semaphore so that do not check for
  56    --  ceiling violations.
  57
  58    type Task_Body_Access is access procedure;
  59    --  Pointer to the task body's entry point (or possibly a wrapper
  60    --  declared local to the GNARL).
  61
  62    type Private_Data is limited private;
  63    --  Any information that the GNULLI needs maintained on a per-task
  64    --  basis.  A component of this type is guaranteed to be included
  65    --  in the Ada_Task_Control_Block.
  66
  67 private
  68
  69    type Prio_Array_Type is array (System.Any_Priority) of Integer;
  70
  71    type Lock is record
  72       L          : aliased System.OS_Interface.pthread_mutex_t;
  73       Ceiling    : System.Any_Priority := System.Any_Priority'First;
  74       Saved_Priority : System.Any_Priority := System.Any_Priority'First;
  75    end record;
  76
  77    type RTS_Lock is new System.OS_Interface.pthread_mutex_t;
  78    type Private_Data is record
  79       Thread      : aliased System.OS_Interface.pthread_t;
  80       pragma Atomic (Thread);
  81       --  Thread field may be updated by two different threads of control.
  82       --  (See, Enter_Task and Create_Task in s-taprop.adb).
  83       --  They put the same value (thr_self value). We do not want to
  84       --  use lock on those operations and the only thing we have to
  85       --  make sure is that they are updated in atomic fashion.
  86
  87       CV          : aliased System.OS_Interface.pthread_cond_t;
  88       L           : aliased RTS_Lock;
  89       --  protection for all components is lock L
  90
  91       Active_Priority : System.Any_Priority := System.Any_Priority'First;
  92       --  Simulated active priority,
  93       --  used only if Priority_Ceiling_Support is True.
  94    end record;
  95
  96 end System.Task_Primitives;