gcc/ada/s-finmas.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --           S Y S T E M . F I N A L I Z A T I O N _ M A S T E R S          --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --             Copyright (C) 2011, Free Software Foundation, Inc.           --
  10 --                                                                          --
  11 -- GNAT 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 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 with Ada.Finalization;
  33 with System.Storage_Elements;
  34 with System.Storage_Pools;
  35
  36 pragma Compiler_Unit;
  37
  38 package System.Finalization_Masters is
  39    pragma Preelaborate;
  40
  41    --  A reference to primitive Finalize_Address. The expander generates an
  42    --  implementation of this procedure for each controlled and class-wide
  43    --  type. Since controlled objects are simply viewed as addresses once
  44    --  allocated through a master, Finalize_Address provides a backward
  45    --  indirection from an address to a type-specific context.
  46
  47    type Finalize_Address_Ptr is access procedure (Obj : System.Address);
  48
  49    --  Heterogeneous collection type structure
  50
  51    type FM_Node is private;
  52    type FM_Node_Ptr is access all FM_Node;
  53    pragma No_Strict_Aliasing (FM_Node_Ptr);
  54
  55    --  A reference to any derivation from Root_Storage_Pool. Since this type
  56    --  may not be used to allocate objects, its storage size is zero.
  57
  58    type Any_Storage_Pool_Ptr is
  59      access System.Storage_Pools.Root_Storage_Pool'Class;
  60    for Any_Storage_Pool_Ptr'Storage_Size use 0;
  61
  62    --  Finalization master type structure. A unique master is associated with
  63    --  each access-to-controlled or access-to-class-wide type. Masters also act
  64    --  as components of subpools. By default, a master contains objects of the
  65    --  same designated type but it may also accomodate heterogeneous objects.
  66
  67    type Finalization_Master is
  68      new Ada.Finalization.Limited_Controlled with private;
  69
  70    --  A reference to a finalization master. Since this type may not be used
  71    --  to allocate objects, its storage size is zero.
  72
  73    type Finalization_Master_Ptr is access all Finalization_Master;
  74    for Finalization_Master_Ptr'Storage_Size use 0;
  75
  76    procedure Attach (N : not null FM_Node_Ptr; L : not null FM_Node_Ptr);
  77    --  Compiler interface, do not call from withing the run-time. Prepend a
  78    --  node to a specific finalization master.
  79
  80    procedure Attach_Unprotected
  81      (N : not null FM_Node_Ptr;
  82       L : not null FM_Node_Ptr);
  83    --  Prepend a node to a specific finalization master
  84
  85    procedure Delete_Finalize_Address_Unprotected (Obj : System.Address);
  86    --  Destroy the relation pair object - Finalize_Address from the internal
  87    --  hash table.
  88
  89    procedure Detach (N : not null FM_Node_Ptr);
  90    --  Compiler interface, do not call from within the run-time. Remove a node
  91    --  from an arbitrary finalization master.
  92
  93    procedure Detach_Unprotected (N : not null FM_Node_Ptr);
  94    --  Remove a node from an arbitrary finalization master
  95
  96    overriding procedure Finalize (Master : in out Finalization_Master);
  97    --  Lock the master to prevent allocations during finalization. Iterate over
  98    --  the list of allocated controlled objects, finalizing each one by calling
  99    --  its specific Finalize_Address. In the end, deallocate the dummy head.
 100
 101    function Finalize_Address
 102      (Master : Finalization_Master) return Finalize_Address_Ptr;
 103    --  Return a reference to the TSS primitive Finalize_Address associated with
 104    --  a master.
 105
 106    function Finalize_Address_Unprotected
 107      (Obj : System.Address) return Finalize_Address_Ptr;
 108    --  Retrieve the Finalize_Address primitive associated with a particular
 109    --  object.
 110
 111    function Finalization_Started (Master : Finalization_Master) return Boolean;
 112    --  Return the finalization status of a master
 113
 114    function Header_Offset return System.Storage_Elements.Storage_Offset;
 115    --  Return the size of type FM_Node as Storage_Offset
 116
 117    function Header_Size return System.Storage_Elements.Storage_Count;
 118    --  Return the size of type FM_Node as Storage_Count
 119
 120    function Is_Homogeneous (Master : Finalization_Master) return Boolean;
 121    --  Return the behavior flag of a master
 122
 123    function Objects (Master : Finalization_Master) return FM_Node_Ptr;
 124    --  Return the header of the doubly-linked list of controlled objects
 125
 126    procedure Print_Master (Master : Finalization_Master);
 127    --  Debug routine, outputs the contents of a master
 128
 129    procedure Set_Finalize_Address
 130      (Master       : in out Finalization_Master;
 131       Fin_Addr_Ptr : Finalize_Address_Ptr);
 132    --  Compiler interface, do not call from within the run-time. Set the clean
 133    --  up routine of a finalization master
 134
 135    procedure Set_Finalize_Address_Unprotected
 136      (Master       : in out Finalization_Master;
 137       Fin_Addr_Ptr : Finalize_Address_Ptr);
 138    --  Set the clean up routine of a finalization master
 139
 140    procedure Set_Heterogeneous_Finalize_Address_Unprotected
 141      (Obj          : System.Address;
 142       Fin_Addr_Ptr : Finalize_Address_Ptr);
 143    --  Add a relation pair object - Finalize_Address to the internal hash
 144    --  table. This is done in the context of allocation on a heterogeneous
 145    --  finalization master where a single master services multiple anonymous
 146    --  access-to-controlled types.
 147
 148    procedure Set_Is_Heterogeneous (Master : in out Finalization_Master);
 149    --  Mark the master as being a heterogeneous collection of objects
 150
 151 private
 152    --  Heterogeneous collection type structure
 153
 154    type FM_Node is record
 155       Prev : FM_Node_Ptr := null;
 156       Next : FM_Node_Ptr := null;
 157    end record;
 158
 159    --  Finalization master type structure. A unique master is associated with
 160    --  each access-to-controlled or access-to-class-wide type. Masters also act
 161    --  as components of subpools. By default, a master contains objects of the
 162    --  same designated type but it may also accomodate heterogeneous objects.
 163
 164    type Finalization_Master is
 165      new Ada.Finalization.Limited_Controlled with
 166    record
 167       Is_Homogeneous : Boolean := True;
 168       --  A flag which controls the behavior of the master. A value of False
 169       --  denotes a heterogeneous collection.
 170
 171       Base_Pool : Any_Storage_Pool_Ptr := null;
 172       --  A reference to the pool which this finalization master services. This
 173       --  field is used in conjunction with the build-in-place machinery.
 174
 175       Objects : aliased FM_Node;
 176       --  A doubly linked list which contains the headers of all controlled
 177       --  objects allocated in a [sub]pool.
 178
 179       Finalize_Address : Finalize_Address_Ptr := null;
 180       --  A reference to the routine reponsible for object finalization. This
 181       --  is used only when the master is in homogeneous mode.
 182
 183       Finalization_Started : Boolean := False;
 184       --  A flag used to detect allocations which occur during the finalization
 185       --  of a master. The allocations must raise Program_Error. This scenario
 186       --  may arise in a multitask environment.
 187    end record;
 188
 189    --  Since RTSfind cannot contain names of the form RE_"+", the following
 190    --  routine serves as a wrapper around System.Storage_Elements."+".
 191
 192    function Add_Offset_To_Address
 193      (Addr   : System.Address;
 194       Offset : System.Storage_Elements.Storage_Offset) return System.Address;
 195
 196    function Base_Pool
 197      (Master : Finalization_Master) return Any_Storage_Pool_Ptr;
 198    --  Return a reference to the underlying storage pool on which the master
 199    --  operates.
 200
 201    overriding procedure Initialize (Master : in out Finalization_Master);
 202    --  Initialize the dummy head of a finalization master
 203
 204    procedure Set_Base_Pool
 205      (Master   : in out Finalization_Master;
 206       Pool_Ptr : Any_Storage_Pool_Ptr);
 207    --  Set the underlying pool of a finalization master
 208
 209 end System.Finalization_Masters;