gcc/ada/s-taspri-posix-noaltstack.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) 1991-1994, Florida State University            --
  10 --                     Copyright (C) 1995-2011, AdaCore                     --
  11 --                                                                          --
  12 -- GNAT 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 3,  or (at your option) any later ver- --
  15 -- sion.  GNAT 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.                                     --
  18 --                                                                          --
  19 -- As a special exception under Section 7 of GPL version 3, you are granted --
  20 -- additional permissions described in the GCC Runtime Library Exception,   --
  21 -- version 3.1, as published by the Free Software Foundation.               --
  22 --                                                                          --
  23 -- You should have received a copy of the GNU General Public License and    --
  24 -- a copy of the GCC Runtime Library Exception along with this program;     --
  25 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  26 -- <http://www.gnu.org/licenses/>.                                          --
  27 --                                                                          --
  28 -- GNARL was developed by the GNARL team at Florida State University.       --
  29 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  30 --                                                                          --
  31 ------------------------------------------------------------------------------
  32
  33 --  This is a POSIX-like version of this package where no alternate stack
  34 --  is needed for stack checking.
  35
  36 --  Note: this file can only be used for POSIX compliant systems
  37
  38 pragma Polling (Off);
  39 --  Turn off polling, we do not want ATC polling to take place during tasking
  40 --  operations. It causes infinite loops and other problems.
  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 declared
  60    --  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 in the
  65    --  Ada_Task_Control_Block.
  66
  67    subtype Task_Address is System.Address;
  68    --  In some versions of Task_Primitives, notably for VMS, Task_Address is
  69    --  the short version of address defined in System.Aux_DEC. To avoid
  70    --  dragging Aux_DEC into tasking packages a tasking specific subtype is
  71    --  defined here.
  72
  73    Task_Address_Size : constant := Standard'Address_Size;
  74    --  The size of Task_Address
  75
  76    Alternate_Stack_Size : constant := 0;
  77    --  No alternate signal stack is used on this platform
  78
  79 private
  80
  81    type Lock is record
  82       WO : aliased System.OS_Interface.pthread_mutex_t;
  83       RW : aliased System.OS_Interface.pthread_rwlock_t;
  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 condition 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 same
 110       --  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 are
 112       --  updated in atomic fashion.
 113
 114       LWP : aliased System.Address;
 115       --  The purpose of this field is to provide a better tasking support on
 116       --  gdb. The order of the two first fields (Thread and LWP) is important.
 117       --  On targets where lwp is not relevant, this is equivalent to Thread.
 118
 119       CV : aliased System.OS_Interface.pthread_cond_t;
 120       --  Should be commented ??? (in all versions of taspri)
 121
 122       L : aliased RTS_Lock;
 123       --  Protection for all components is lock L
 124    end record;
 125
 126 end System.Task_Primitives;