gcc/ada/s-taspri-tru64.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) 1991-2009, 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 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT 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.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNARL was developed by the GNARL team at Florida State University.       --
  28 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This is the DEC Unix 4.0 version of this package
  33
  34 --  This package provides low-level support for most tasking features
  35
  36 pragma Polling (Off);
  37 --  Turn off polling, we do not want ATC polling to take place during tasking
  38 --  operations. It causes infinite loops and other problems.
  39
  40 with Interfaces.C;
  41
  42 with System.OS_Interface;
  43
  44 package System.Task_Primitives is
  45    pragma Preelaborate;
  46
  47    type Lock is limited private;
  48    --  Should be used for implementation of protected objects
  49
  50    type RTS_Lock is limited private;
  51    --  Should be used inside the runtime system. The difference between Lock
  52    --  and the RTS_Lock is that the later one serves only as a semaphore so
  53    --  that do not check for ceiling violations.
  54
  55    type Suspension_Object is limited private;
  56    --  Should be used for the implementation of Ada.Synchronous_Task_Control
  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 basis.
  64    --  A component of this type is guaranteed to be included
  65
  66    subtype Task_Address is System.Address;
  67    --  In some versions of Task_Primitives, notably for VMS, Task_Address is
  68    --  the short version of address defined in System.Aux_DEC. To avoid
  69    --  dragging Aux_DEC into tasking packages a tasking specific subtype is
  70    --  defined here.
  71
  72    Task_Address_Size : constant := Standard'Address_Size;
  73    --  The size of Task_Address
  74
  75    Alternate_Stack_Size : constant := 0;
  76    --  No alternate signal stack is used on this platform
  77
  78 private
  79
  80    type Lock is record
  81       L       : aliased System.OS_Interface.pthread_mutex_t;
  82       Ceiling : Interfaces.C.int;
  83    end record;
  84
  85    type RTS_Lock is new System.OS_Interface.pthread_mutex_t;
  86
  87    type Suspension_Object is record
  88       State : Boolean;
  89       pragma Atomic (State);
  90       --  Boolean that indicates whether the object is open. This field is
  91       --  marked Atomic to ensure that we can read its value without locking
  92       --  the access to the Suspension_Object.
  93
  94       Waiting : Boolean;
  95       --  Flag showing if there is a task already suspended on this object
  96
  97       L : aliased System.OS_Interface.pthread_mutex_t;
  98       --  Protection for ensuring mutual exclusion on the Suspension_Object
  99
 100       CV : aliased System.OS_Interface.pthread_cond_t;
 101       --  Condition variable used to queue threads until the is signaled
 102    end record;
 103
 104    type Private_Data is record
 105       Thread : aliased System.OS_Interface.pthread_t;
 106       pragma Atomic (Thread);
 107       --  Thread field may be updated by two different threads of control.
 108       --  (See, Enter_Task and Create_Task in s-taprop.adb). They put the same
 109       --  value (thr_self value). We do not want to use lock on those
 110       --  operations and the only thing we have to make sure is that they are
 111       --  updated in atomic fashion.
 112
 113       CV : aliased System.OS_Interface.pthread_cond_t;
 114
 115       L : aliased RTS_Lock;
 116       --  Protection for all components is lock L
 117    end record;
 118
 119 end System.Task_Primitives;