gcc/ada/s-taspri-vms.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNAT 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) 1991-2005 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,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, 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 a OpenVMS/Alpha 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 Interfaces.C;
  43 --  used for int
  44 --           size_t
  45
  46 with System.OS_Interface;
  47 --  used for pthread_mutex_t
  48 --           pthread_cond_t
  49 --           pthread_t
  50
  51 package System.Task_Primitives is
  52    pragma Preelaborate;
  53
  54    type Lock is limited private;
  55    --  Should be used for implementation of protected objects
  56
  57    type RTS_Lock is limited private;
  58    --  Should be used inside the runtime system. The difference between Lock
  59    --  and the RTS_Lock is that the later one serves only as a semaphore so
  60    --  that do not check for ceiling violations.
  61
  62    type Suspension_Object is limited private;
  63    --  Should be used for the implementation of Ada.Synchronous_Task_Control
  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 basis.
  71    --  A component of this type is guaranteed to be included in the
  72    --  Ada_Task_Control_Block.
  73
  74 private
  75
  76    type Exc_Stack_T is array (0 .. 8192) of aliased Character;
  77    for Exc_Stack_T'Alignment use Standard'Maximum_Alignment;
  78    type Exc_Stack_Ptr_T is access all Exc_Stack_T;
  79
  80    type Lock is record
  81       L         : aliased System.OS_Interface.pthread_mutex_t;
  82       Prio      : Interfaces.C.int;
  83       Prio_Save : Interfaces.C.int;
  84    end record;
  85
  86    type RTS_Lock is new System.OS_Interface.pthread_mutex_t;
  87
  88    type Suspension_Object is record
  89       State   : Boolean;
  90       pragma Atomic (State);
  91       --  Boolean that indicates whether the object is open. This field is
  92       --  marked Atomic to ensure that we can read its value without locking
  93       --  the access to the Suspension_Object.
  94
  95       Waiting : Boolean;
  96       --  Flag showing if there is a task already suspended on this object
  97
  98       L : aliased System.OS_Interface.pthread_mutex_t;
  99       --  Protection for ensuring mutual exclusion on the Suspension_Object
 100
 101       CV : aliased System.OS_Interface.pthread_cond_t;
 102       --  Condition variable used to queue threads until ondition is signaled
 103    end record;
 104
 105    type Private_Data is record
 106       Thread : aliased System.OS_Interface.pthread_t;
 107       pragma Atomic (Thread);
 108       --  Thread field may be updated by two different threads of control.
 109       --  (See, Enter_Task and Create_Task in s-taprop.adb). They put the
 110       --  same value (thr_self value). We do not want to use lock on those
 111       --  operations and the only thing we have to make sure is that they
 112       --  are updated in atomic fashion.
 113
 114       CV : aliased System.OS_Interface.pthread_cond_t;
 115
 116       L : aliased RTS_Lock;
 117       --  Protection for all components is lock L
 118
 119       Exc_Stack_Ptr : Exc_Stack_Ptr_T;
 120       --  ??? This needs comments
 121
 122       AST_Pending : Boolean;
 123       --  Used to detect delay and sleep timeouts
 124
 125    end record;
 126
 127 end System.Task_Primitives;