------------------------------------------------------------------------------
-- --
-- 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 --
-- --
-- B o d y --
-- --
-- Copyright (C) 2015-2022, 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 --
-- . --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with Ada.Exceptions; use Ada.Exceptions;
with System.Address_Image;
with System.HTable; use System.HTable;
with System.IO; use System.IO;
with System.Soft_Links; use System.Soft_Links;
with System.Storage_Elements; use System.Storage_Elements;
package body System.Finalization_Masters is
-- Finalize_Address hash table types. In general, masters are homogeneous
-- collections of controlled objects. Rare cases such as allocations on a
-- subpool require heterogeneous masters. The following table provides a
-- relation between object address and its Finalize_Address routine.
type Header_Num is range 0 .. 127;
function Hash (Key : System.Address) return Header_Num;
-- Address --> Finalize_Address_Ptr
package Finalize_Address_Table is new Simple_HTable
(Header_Num => Header_Num,
Element => Finalize_Address_Ptr,
No_Element => null,
Key => System.Address,
Hash => Hash,
Equal => "=");
---------------------------
-- Add_Offset_To_Address --
---------------------------
function Add_Offset_To_Address
(Addr : System.Address;
Offset : System.Storage_Elements.Storage_Offset) return System.Address
is
begin
return System.Storage_Elements."+" (Addr, Offset);
end Add_Offset_To_Address;
------------
-- Attach --
------------
procedure Attach (N : not null FM_Node_Ptr; L : not null FM_Node_Ptr) is
begin
Lock_Task.all;
Attach_Unprotected (N, L);
Unlock_Task.all;
-- Note: No need to unlock in case of an exception because the above
-- code can never raise one.
end Attach;
------------------------
-- Attach_Unprotected --
------------------------
procedure Attach_Unprotected
(N : not null FM_Node_Ptr;
L : not null FM_Node_Ptr)
is
begin
L.Next.Prev := N;
N.Next := L.Next;
L.Next := N;
N.Prev := L;
end Attach_Unprotected;
---------------
-- Base_Pool --
---------------
function Base_Pool
(Master : Finalization_Master) return Any_Storage_Pool_Ptr
is
begin
return Master.Base_Pool;
end Base_Pool;
-----------------------------------------
-- Delete_Finalize_Address_Unprotected --
-----------------------------------------
procedure Delete_Finalize_Address_Unprotected (Obj : System.Address) is
begin
Finalize_Address_Table.Remove (Obj);
end Delete_Finalize_Address_Unprotected;
------------------------
-- Detach_Unprotected --
------------------------
procedure Detach_Unprotected (N : not null FM_Node_Ptr) is
begin
if N.Prev /= null and then N.Next /= null then
N.Prev.Next := N.Next;
N.Next.Prev := N.Prev;
N.Prev := null;
N.Next := null;
end if;
end Detach_Unprotected;
--------------
-- Finalize --
--------------
overriding procedure Finalize (Master : in out Finalization_Master) is
Cleanup : Finalize_Address_Ptr;
Curr_Ptr : FM_Node_Ptr;
Ex_Occur : Exception_Occurrence;
Obj_Addr : Address;
Raised : Boolean := False;
function Is_Empty_List (L : not null FM_Node_Ptr) return Boolean;
-- Determine whether a list contains only one element, the dummy head
-------------------
-- Is_Empty_List --
-------------------
function Is_Empty_List (L : not null FM_Node_Ptr) return Boolean is
begin
return L.Next = L and then L.Prev = L;
end Is_Empty_List;
-- Start of processing for Finalize
begin
Lock_Task.all;
-- Synchronization:
-- Read - allocation, finalization
-- Write - finalization
if Master.Finalization_Started then
Unlock_Task.all;
-- Double finalization may occur during the handling of stand alone
-- libraries or the finalization of a pool with subpools. Due to the
-- potential aliasing of masters in these two cases, do not process
-- the same master twice.
return;
end if;
-- Lock the master to prevent any allocations while the objects are
-- being finalized. The master remains locked because either the master
-- is explicitly deallocated or the associated access type is about to
-- go out of scope.
-- Synchronization:
-- Read - allocation, finalization
-- Write - finalization
Master.Finalization_Started := True;
while not Is_Empty_List (Master.Objects'Unchecked_Access) loop
Curr_Ptr := Master.Objects.Next;
-- Synchronization:
-- Write - allocation, deallocation, finalization
Detach_Unprotected (Curr_Ptr);
-- Skip the list header in order to offer proper object layout for
-- finalization.
Obj_Addr := Curr_Ptr.all'Address + Header_Size;
-- Retrieve TSS primitive Finalize_Address depending on the master's
-- mode of operation.
-- Synchronization:
-- Read - allocation, finalization
-- Write - outside
if Master.Is_Homogeneous then
-- Synchronization:
-- Read - finalization
-- Write - allocation, outside
Cleanup := Master.Finalize_Address;
else
-- Synchronization:
-- Read - finalization
-- Write - allocation, deallocation
Cleanup := Finalize_Address_Unprotected (Obj_Addr);
end if;
begin
Cleanup (Obj_Addr);
exception
when Fin_Occur : others =>
if not Raised then
Raised := True;
Save_Occurrence (Ex_Occur, Fin_Occur);
end if;
end;
-- When the master is a heterogeneous collection, destroy the object
-- - Finalize_Address pair since it is no longer needed.
-- Synchronization:
-- Read - finalization
-- Write - outside
if not Master.Is_Homogeneous then
-- Synchronization:
-- Read - finalization
-- Write - allocation, deallocation, finalization
Delete_Finalize_Address_Unprotected (Obj_Addr);
end if;
end loop;
Unlock_Task.all;
-- If the finalization of a particular object failed or Finalize_Address
-- was not set, reraise the exception now.
if Raised then
Reraise_Occurrence (Ex_Occur);
end if;
end Finalize;
----------------------
-- Finalize_Address --
----------------------
function Finalize_Address
(Master : Finalization_Master) return Finalize_Address_Ptr
is
begin
return Master.Finalize_Address;
end Finalize_Address;
----------------------------------
-- Finalize_Address_Unprotected --
----------------------------------
function Finalize_Address_Unprotected
(Obj : System.Address) return Finalize_Address_Ptr
is
begin
return Finalize_Address_Table.Get (Obj);
end Finalize_Address_Unprotected;
--------------------------
-- Finalization_Started --
--------------------------
function Finalization_Started
(Master : Finalization_Master) return Boolean
is
begin
return Master.Finalization_Started;
end Finalization_Started;
----------
-- Hash --
----------
function Hash (Key : System.Address) return Header_Num is
begin
return
Header_Num
(To_Integer (Key) mod Integer_Address (Header_Num'Range_Length));
end Hash;
-----------------
-- Header_Size --
-----------------
function Header_Size return System.Storage_Elements.Storage_Count is
begin
return FM_Node'Size / Storage_Unit;
end Header_Size;
----------------
-- Initialize --
----------------
overriding procedure Initialize (Master : in out Finalization_Master) is
begin
-- The dummy head must point to itself in both directions
Master.Objects.Next := Master.Objects'Unchecked_Access;
Master.Objects.Prev := Master.Objects'Unchecked_Access;
end Initialize;
--------------------
-- Is_Homogeneous --
--------------------
function Is_Homogeneous (Master : Finalization_Master) return Boolean is
begin
return Master.Is_Homogeneous;
end Is_Homogeneous;
-------------
-- Objects --
-------------
function Objects (Master : Finalization_Master) return FM_Node_Ptr is
begin
return Master.Objects'Unrestricted_Access;
end Objects;
------------------
-- Print_Master --
------------------
procedure Print_Master (Master : Finalization_Master) is
Head : constant FM_Node_Ptr := Master.Objects'Unrestricted_Access;
Head_Seen : Boolean := False;
N_Ptr : FM_Node_Ptr;
begin
-- Output the basic contents of a master
-- Master : 0x123456789
-- Is_Hmgen : TURE FALSE
-- Base_Pool: null 0x123456789
-- Fin_Addr : null 0x123456789
-- Fin_Start: TRUE FALSE
Put ("Master : ");
Put_Line (Address_Image (Master'Address));
Put ("Is_Hmgen : ");
Put_Line (Master.Is_Homogeneous'Img);
Put ("Base_Pool: ");
if Master.Base_Pool = null then
Put_Line ("null");
else
Put_Line (Address_Image (Master.Base_Pool'Address));
end if;
Put ("Fin_Addr : ");
if Master.Finalize_Address = null then
Put_Line ("null");
else
Put_Line (Address_Image (Master.Finalize_Address'Address));
end if;
Put ("Fin_Start: ");
Put_Line (Master.Finalization_Started'Img);
-- Output all chained elements. The format is the following:
-- ^ ? null
-- |Header: 0x123456789 (dummy head)
-- | Prev: 0x123456789
-- | Next: 0x123456789
-- V
-- ^ - the current element points back to the correct element
-- ? - the current element points back to an erroneous element
-- n - the current element points back to null
-- Header - the address of the list header
-- Prev - the address of the list header which the current element
-- points back to
-- Next - the address of the list header which the current element
-- points to
-- (dummy head) - present if dummy head
N_Ptr := Head;
while N_Ptr /= null loop -- Should never be null
Put_Line ("V");
-- We see the head initially; we want to exit when we see the head a
-- second time.
if N_Ptr = Head then
exit when Head_Seen;
Head_Seen := True;
end if;
-- The current element is null. This should never happen since the
-- list is circular.
if N_Ptr.Prev = null then
Put_Line ("null (ERROR)");
-- The current element points back to the correct element
elsif N_Ptr.Prev.Next = N_Ptr then
Put_Line ("^");
-- The current element points to an erroneous element
else
Put_Line ("? (ERROR)");
end if;
-- Output the header and fields
Put ("|Header: ");
Put (Address_Image (N_Ptr.all'Address));
-- Detect the dummy head
if N_Ptr = Head then
Put_Line (" (dummy head)");
else
Put_Line ("");
end if;
Put ("| Prev: ");
if N_Ptr.Prev = null then
Put_Line ("null");
else
Put_Line (Address_Image (N_Ptr.Prev.all'Address));
end if;
Put ("| Next: ");
if N_Ptr.Next = null then
Put_Line ("null");
else
Put_Line (Address_Image (N_Ptr.Next.all'Address));
end if;
N_Ptr := N_Ptr.Next;
end loop;
end Print_Master;
-------------------
-- Set_Base_Pool --
-------------------
procedure Set_Base_Pool
(Master : in out Finalization_Master;
Pool_Ptr : Any_Storage_Pool_Ptr)
is
begin
Master.Base_Pool := Pool_Ptr;
end Set_Base_Pool;
--------------------------
-- Set_Finalize_Address --
--------------------------
procedure Set_Finalize_Address
(Master : in out Finalization_Master;
Fin_Addr_Ptr : Finalize_Address_Ptr)
is
begin
-- Synchronization:
-- Read - finalization
-- Write - allocation, outside
Lock_Task.all;
Set_Finalize_Address_Unprotected (Master, Fin_Addr_Ptr);
Unlock_Task.all;
end Set_Finalize_Address;
--------------------------------------
-- Set_Finalize_Address_Unprotected --
--------------------------------------
procedure Set_Finalize_Address_Unprotected
(Master : in out Finalization_Master;
Fin_Addr_Ptr : Finalize_Address_Ptr)
is
begin
if Master.Finalize_Address = null then
Master.Finalize_Address := Fin_Addr_Ptr;
end if;
end Set_Finalize_Address_Unprotected;
----------------------------------------------------
-- Set_Heterogeneous_Finalize_Address_Unprotected --
----------------------------------------------------
procedure Set_Heterogeneous_Finalize_Address_Unprotected
(Obj : System.Address;
Fin_Addr_Ptr : Finalize_Address_Ptr)
is
begin
Finalize_Address_Table.Set (Obj, Fin_Addr_Ptr);
end Set_Heterogeneous_Finalize_Address_Unprotected;
--------------------------
-- Set_Is_Heterogeneous --
--------------------------
procedure Set_Is_Heterogeneous (Master : in out Finalization_Master) is
begin
-- Synchronization:
-- Read - finalization
-- Write - outside
Lock_Task.all;
Master.Is_Homogeneous := False;
Unlock_Task.all;
end Set_Is_Heterogeneous;
end System.Finalization_Masters;