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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--           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          --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--             Copyright (C) 2011, Free Software Foundation, Inc.           --

--                                                                          --

-- GNAT is free software;  you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --

--                                                                          --

-- As a special exception under Section 7 of GPL version 3, you are granted --

-- additional permissions described in the GCC Runtime Library Exception,   --

-- version 3.1, as published by the Free Software Foundation.               --

--                                                                          --

-- You should have received a copy of the GNU General Public License and    --

-- a copy of the GCC Runtime Library Exception along with this program;     --

-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --

-- <http://www.gnu.org/licenses/>.                                          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

------------------------------------------------------------------------------

with Ada.Finalization;

with System.Storage_Elements;

with System.Storage_Pools;

pragma Compiler_Unit;

package System.Finalization_Masters is

   pragma Preelaborate;

   --  A reference to primitive Finalize_Address. The expander generates an

   --  implementation of this procedure for each controlled and class-wide

   --  type. Since controlled objects are simply viewed as addresses once

   --  allocated through a master, Finalize_Address provides a backward

   --  indirection from an address to a type-specific context.

   type Finalize_Address_Ptr is access procedure (Obj : System.Address);

   --  Heterogeneous collection type structure

   type FM_Node is private;

   type FM_Node_Ptr is access all FM_Node;

   pragma No_Strict_Aliasing (FM_Node_Ptr);

   --  A reference to any derivation from Root_Storage_Pool. Since this type

   --  may not be used to allocate objects, its storage size is zero.

   type Any_Storage_Pool_Ptr is

     access System.Storage_Pools.Root_Storage_Pool'Class;

   for Any_Storage_Pool_Ptr'Storage_Size use 0;

   --  Finalization master type structure. A unique master is associated with

   --  each access-to-controlled or access-to-class-wide type. Masters also act

   --  as components of subpools. By default, a master contains objects of the

   --  same designated type but it may also accomodate heterogeneous objects.

   type Finalization_Master is

     new Ada.Finalization.Limited_Controlled with private;

   --  A reference to a finalization master. Since this type may not be used

   --  to allocate objects, its storage size is zero.

   type Finalization_Master_Ptr is access all Finalization_Master;

   for Finalization_Master_Ptr'Storage_Size use 0;

   procedure Attach (N : not null FM_Node_Ptr; L : not null FM_Node_Ptr);

   --  Compiler interface, do not call from withing the run-time. Prepend a

   --  node to a specific finalization master.

   procedure Attach_Unprotected

     (N : not null FM_Node_Ptr;

      L : not null FM_Node_Ptr);

   --  Prepend a node to a specific finalization master

   procedure Delete_Finalize_Address_Unprotected (Obj : System.Address);

   --  Destroy the relation pair object - Finalize_Address from the internal

   --  hash table.

   procedure Detach (N : not null FM_Node_Ptr);

   --  Compiler interface, do not call from within the run-time. Remove a node

   --  from an arbitrary finalization master.

   procedure Detach_Unprotected (N : not null FM_Node_Ptr);

   --  Remove a node from an arbitrary finalization master

   overriding procedure Finalize (Master : in out Finalization_Master);

   --  Lock the master to prevent allocations during finalization. Iterate over

   --  the list of allocated controlled objects, finalizing each one by calling

   --  its specific Finalize_Address. In the end, deallocate the dummy head.

   function Finalize_Address

     (Master : Finalization_Master) return Finalize_Address_Ptr;

   --  Return a reference to the TSS primitive Finalize_Address associated with

   --  a master.

   function Finalize_Address_Unprotected

     (Obj : System.Address) return Finalize_Address_Ptr;

   --  Retrieve the Finalize_Address primitive associated with a particular

   --  object.

   function Finalization_Started (Master : Finalization_Master) return Boolean;

   --  Return the finalization status of a master

   function Header_Offset return System.Storage_Elements.Storage_Offset;

   --  Return the size of type FM_Node as Storage_Offset

   function Header_Size return System.Storage_Elements.Storage_Count;

   --  Return the size of type FM_Node as Storage_Count

   function Is_Homogeneous (Master : Finalization_Master) return Boolean;

   --  Return the behavior flag of a master

   function Objects (Master : Finalization_Master) return FM_Node_Ptr;

   --  Return the header of the doubly-linked list of controlled objects

   procedure Print_Master (Master : Finalization_Master);

   --  Debug routine, outputs the contents of a master

   procedure Set_Finalize_Address

     (Master       : in out Finalization_Master;

      Fin_Addr_Ptr : Finalize_Address_Ptr);

   --  Compiler interface, do not call from within the run-time. Set the clean

   --  up routine of a finalization master

   procedure Set_Finalize_Address_Unprotected

     (Master       : in out Finalization_Master;

      Fin_Addr_Ptr : Finalize_Address_Ptr);

   --  Set the clean up routine of a finalization master

   procedure Set_Heterogeneous_Finalize_Address_Unprotected

     (Obj          : System.Address;

      Fin_Addr_Ptr : Finalize_Address_Ptr);

   --  Add a relation pair object - Finalize_Address to the internal hash

   --  table. This is done in the context of allocation on a heterogeneous

   --  finalization master where a single master services multiple anonymous

   --  access-to-controlled types.

   procedure Set_Is_Heterogeneous (Master : in out Finalization_Master);

   --  Mark the master as being a heterogeneous collection of objects

private

   --  Heterogeneous collection type structure

   type FM_Node is record

      Prev : FM_Node_Ptr := null;

      Next : FM_Node_Ptr := null;

   end record;

   --  Finalization master type structure. A unique master is associated with

   --  each access-to-controlled or access-to-class-wide type. Masters also act

   --  as components of subpools. By default, a master contains objects of the

   --  same designated type but it may also accomodate heterogeneous objects.

   type Finalization_Master is

     new Ada.Finalization.Limited_Controlled with

   record

      Is_Homogeneous : Boolean := True;

      --  A flag which controls the behavior of the master. A value of False

      --  denotes a heterogeneous collection.

      Base_Pool : Any_Storage_Pool_Ptr := null;

      --  A reference to the pool which this finalization master services. This

      --  field is used in conjunction with the build-in-place machinery.

      Objects : aliased FM_Node;

      --  A doubly linked list which contains the headers of all controlled

      --  objects allocated in a [sub]pool.

      Finalize_Address : Finalize_Address_Ptr := null;

      --  A reference to the routine reponsible for object finalization. This

      --  is used only when the master is in homogeneous mode.

      Finalization_Started : Boolean := False;

      --  A flag used to detect allocations which occur during the finalization

      --  of a master. The allocations must raise Program_Error. This scenario

      --  may arise in a multitask environment.

   end record;

   --  Since RTSfind cannot contain names of the form RE_"+", the following

   --  routine serves as a wrapper around System.Storage_Elements."+".

   function Add_Offset_To_Address

     (Addr   : System.Address;

      Offset : System.Storage_Elements.Storage_Offset) return System.Address;

   function Base_Pool

     (Master : Finalization_Master) return Any_Storage_Pool_Ptr;

   --  Return a reference to the underlying storage pool on which the master

   --  operates.

   overriding procedure Initialize (Master : in out Finalization_Master);

   --  Initialize the dummy head of a finalization master

   procedure Set_Base_Pool

     (Master   : in out Finalization_Master;

      Pool_Ptr : Any_Storage_Pool_Ptr);

   --  Set the underlying pool of a finalization master

end System.Finalization_Masters;