gcc/ada/5staspri.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) 1992-2000, 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 Solaris version of this package.
  37 --  It was created by hand for use with new "checked"
  38 --  GNULLI primitives.
  39
  40 --  This package provides low-level support for most tasking features.
  41
  42 pragma Polling (Off);
  43 --  Turn off polling, we do not want ATC polling to take place during
  44 --  tasking operations. It causes infinite loops and other problems.
  45
  46 with System.OS_Interface;
  47 --  used for mutex_t
  48 --           cond_t
  49 --           thread_t
  50
  51 package System.Task_Primitives is
  52    pragma Preelaborate;
  53
  54    type Lock is limited private;
  55    type Lock_Ptr is access all Lock;
  56    --  Should be used for implementation of protected objects.
  57
  58    type RTS_Lock is limited private;
  59    type RTS_Lock_Ptr is access all RTS_Lock;
  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 Private_Task_Serial_Number is mod 2 ** 64;
  77    --  Used to give each task a unique serial number.
  78
  79    type Base_Lock is new System.OS_Interface.mutex_t;
  80
  81    type Owner_Int is new Integer;
  82    for Owner_Int'Alignment use Standard'Maximum_Alignment;
  83
  84    type Owner_ID is access all Owner_Int;
  85
  86    type Lock is record
  87       L : aliased Base_Lock;
  88       Ceiling : System.Any_Priority := System.Any_Priority'First;
  89       Saved_Priority : System.Any_Priority :=  System.Any_Priority'First;
  90       Owner : Owner_ID;
  91       Next  : Lock_Ptr;
  92       Level : Private_Task_Serial_Number := 0;
  93       Buddy : Owner_ID;
  94       Frozen : Boolean := False;
  95    end record;
  96
  97    type RTS_Lock is new Lock;
  98
  99    --  Note that task support on gdb relies on the fact that the first
 100    --  2 fields of Private_Data are Thread and LWP.
 101
 102    type Private_Data is record
 103       Thread      : aliased System.OS_Interface.thread_t;
 104       pragma Atomic (Thread);
 105       --  Thread field may be updated by two different threads of control.
 106       --  (See, Enter_Task and Create_Task in s-taprop.adb).
 107       --  They put the same value (thr_self value). We do not want to
 108       --  use lock on those operations and the only thing we have to
 109       --  make sure is that they are updated in atomic fashion.
 110
 111       LWP : System.OS_Interface.lwpid_t;
 112       --  The LWP id of the thread. Set by self in Enter_Task.
 113
 114       CV          : aliased System.OS_Interface.cond_t;
 115       L           : aliased RTS_Lock;
 116       --  protection for all components is lock L
 117
 118       Active_Priority : System.Any_Priority := System.Any_Priority'First;
 119       --  Simulated active priority,
 120       --  used only if Priority_Ceiling_Support is True.
 121
 122       Locking : Lock_Ptr;
 123       Locks : Lock_Ptr;
 124       Wakeups : Natural := 0;
 125    end record;
 126
 127 end System.Task_Primitives;