gcc/ada/libgnarl/s-taspri__posix.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) 1991-2017, Florida State University             --
  10 --                     Copyright (C) 1995-2024, 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
  34
  35 --  Note: this file can only be used for POSIX compliant systems
  36
  37 with System.OS_Interface;
  38 with System.OS_Locks;
  39
  40 package System.Task_Primitives is
  41    pragma Preelaborate;
  42
  43    type Lock is limited private;
  44    --  Should be used for implementation of protected objects
  45
  46    type Suspension_Object is limited private;
  47    --  Should be used for the implementation of Ada.Synchronous_Task_Control
  48
  49    type Task_Body_Access is access procedure;
  50    --  Pointer to the task body's entry point (or possibly a wrapper declared
  51    --  local to the GNARL).
  52
  53    type Private_Data is limited private;
  54    --  Any information that the GNULLI needs maintained on a per-task basis.
  55    --  A component of this type is guaranteed to be included in the
  56    --  Ada_Task_Control_Block.
  57
  58    subtype Task_Address is System.Address;
  59    Task_Address_Size : constant := Standard'Address_Size;
  60    --  Type used for task addresses and its size
  61
  62    Alternate_Stack_Size : constant := System.OS_Interface.Alternate_Stack_Size;
  63    --  Import value from System.OS_Interface
  64
  65 private
  66
  67    type Lock is record
  68       RW : aliased System.OS_Interface.pthread_rwlock_t;
  69       WO : aliased System.OS_Locks.RTS_Lock;
  70    end record;
  71
  72    type Suspension_Object is record
  73       State : Boolean;
  74       pragma Atomic (State);
  75       --  Boolean that indicates whether the object is open. This field is
  76       --  marked Atomic to ensure that we can read its value without locking
  77       --  the access to the Suspension_Object.
  78
  79       Waiting : Boolean;
  80       --  Flag showing if there is a task already suspended on this object
  81
  82       L : aliased System.OS_Locks.RTS_Lock;
  83       --  Protection for ensuring mutual exclusion on the Suspension_Object
  84
  85       CV : aliased System.OS_Interface.pthread_cond_t;
  86       --  Condition variable used to queue threads until condition is signaled
  87    end record;
  88
  89    type Private_Data is limited record
  90       Thread : aliased System.OS_Interface.pthread_t;
  91       --  This component is written to once before concurrent access to it is
  92       --  possible, and then remains constant. The place where it is written to
  93       --  depends on how the enclosing ATCB comes into existence:
  94       --
  95       --  1. For the environment task, the component is set in
  96       --     System.Task_Primitive.Operations.Initialize.
  97       --  2. For foreign threads, it happens in
  98       --     System.Task_Primitives.Operations.Register_Foreign_Thread.
  99       --  3. For others tasks, it's in
 100       --     System.Task_Primitives.Operations.Create_Task.
 101
 102       LWP : aliased System.Address;
 103       --  The purpose of this field is to provide a better tasking support on
 104       --  gdb. The order of the two first fields (Thread and LWP) is important.
 105       --  On targets where lwp is not relevant, this is equivalent to Thread.
 106
 107       CV : aliased System.OS_Interface.pthread_cond_t;
 108       --  Condition variable used to queue threads until condition is signaled
 109
 110       L : aliased System.OS_Locks.RTS_Lock;
 111       --  Protection for all components is lock L
 112    end record;
 113
 114 end System.Task_Primitives;