1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
5 -- A D A . F I N A L I Z A T I O N . H E A P _ M A N A G E M E N T --
9 -- Copyright (C) 2008-2011, Free Software Foundation, Inc. --
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. --
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. --
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/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
32 with Ada.Exceptions; use Ada.Exceptions;
33 with Ada.Unchecked_Conversion;
34 with Ada.Unchecked_Deallocation;
36 with System; use System;
37 with System.Address_Image;
38 with System.IO; use System.IO;
39 with System.Soft_Links; use System.Soft_Links;
40 with System.Storage_Elements; use System.Storage_Elements;
41 with System.Storage_Pools; use System.Storage_Pools;
43 package body Ada.Finalization.Heap_Management is
45 Header_Size : constant Storage_Count := Node'Size / Storage_Unit;
46 Header_Offset : constant Storage_Offset := Header_Size;
49 function Address_To_Node_Ptr is
50 new Ada.Unchecked_Conversion (Address, Node_Ptr);
52 procedure Attach (N : Node_Ptr; L : Node_Ptr);
53 -- Prepend a node to a list
55 procedure Detach (N : Node_Ptr);
56 -- Unhook a node from an arbitrary list
58 procedure Free is new Ada.Unchecked_Deallocation (Node, Node_Ptr);
60 ---------------------------
61 -- Add_Offset_To_Address --
62 ---------------------------
64 function Add_Offset_To_Address
65 (Addr : System.Address;
66 Offset : System.Storage_Elements.Storage_Offset) return System.Address
69 return System.Storage_Elements."+" (Addr, Offset);
70 end Add_Offset_To_Address;
77 (Collection : in out Finalization_Collection;
78 Addr : out System.Address;
79 Storage_Size : System.Storage_Elements.Storage_Count;
80 Alignment : System.Storage_Elements.Storage_Count;
81 Needs_Header : Boolean := True)
84 -- Allocation of a controlled object
88 -- Do not allow the allocation of controlled objects while the
89 -- associated collection is being finalized.
91 if Collection.Finalization_Started then
92 raise Program_Error with "allocation after finalization started";
100 -- Use the underlying pool to allocate enough space for the object
101 -- and the list header. The returned address points to the list
105 (Collection.Base_Pool.all,
107 Storage_Size + Header_Size,
110 -- Map the allocated memory into a Node record. This converts the
111 -- top of the allocated bits into a list header.
113 N_Ptr := Address_To_Node_Ptr (N_Addr);
114 Attach (N_Ptr, Collection.Objects);
116 -- Move the address from Prev to the start of the object. This
117 -- operation effectively hides the list header.
119 Addr := N_Addr + Header_Offset;
122 -- Allocation of a non-controlled object
126 (Collection.Base_Pool.all,
137 procedure Attach (N : Node_Ptr; L : Node_Ptr) is
159 (Collection : Finalization_Collection) return Any_Storage_Pool_Ptr
162 return Collection.Base_Pool;
170 (Collection : in out Finalization_Collection;
171 Addr : System.Address;
172 Storage_Size : System.Storage_Elements.Storage_Count;
173 Alignment : System.Storage_Elements.Storage_Count;
174 Has_Header : Boolean := True)
177 -- Deallocation of a controlled object
185 -- Move the address from the object to the beginning of the list
188 N_Addr := Addr - Header_Offset;
190 -- Converts the bits preceding the object into a list header
192 N_Ptr := Address_To_Node_Ptr (N_Addr);
195 -- Use the underlying pool to destroy the object along with the
199 (Collection.Base_Pool.all,
201 Storage_Size + Header_Size,
205 -- Deallocation of a non-controlled object
209 (Collection.Base_Pool.all,
220 procedure Detach (N : Node_Ptr) is
225 and then N.Next /= null
227 N.Prev.Next := N.Next;
228 N.Next.Prev := N.Prev;
245 overriding procedure Finalize
246 (Collection : in out Finalization_Collection)
248 function Head (L : Node_Ptr) return Node_Ptr;
249 -- Return the node which comes after the dummy head
251 function Is_Dummy_Head (N : Node_Ptr) return Boolean;
252 -- Determine whether a node acts as a dummy head. Such nodes do not
253 -- have an actual "object" attached to them and point to themselves.
255 function Is_Empty_List (L : Node_Ptr) return Boolean;
256 -- Determine whether a list is empty
258 function Node_Ptr_To_Address (N : Node_Ptr) return Address;
259 -- Not the reverse of Address_To_Node_Ptr. Return the address of the
260 -- object following the list header.
266 function Head (L : Node_Ptr) return Node_Ptr is
275 function Is_Dummy_Head (N : Node_Ptr) return Boolean is
277 -- To be a dummy head, the node must point to itself in both
283 and then N.Prev /= null
291 function Is_Empty_List (L : Node_Ptr) return Boolean is
293 return L = null or else Is_Dummy_Head (L);
296 -------------------------
297 -- Node_Ptr_To_Address --
298 -------------------------
300 function Node_Ptr_To_Address (N : Node_Ptr) return Address is
302 return N.all'Address + Header_Offset;
303 end Node_Ptr_To_Address;
306 Ex_Occur : Exception_Occurrence;
308 Raised : Boolean := False;
310 -- Start of processing for Finalize
313 -- Lock the collection to prevent any allocations while the objects are
314 -- being finalized. The collection remains locked because the associated
315 -- access type is about to go out of scope.
317 Collection.Finalization_Started := True;
319 while not Is_Empty_List (Collection.Objects) loop
321 -- Find the real head of the collection, skipping the dummy head
323 Curr_Ptr := Head (Collection.Objects);
325 -- If the dummy head is the only remaining node, all real objects
326 -- have already been detached and finalized.
328 if Is_Dummy_Head (Curr_Ptr) then
332 -- Store the next node now since the detachment will destroy the
335 Next_Ptr := Curr_Ptr.Next;
337 -- Remove the current node from the list
341 -- ??? Kludge: Don't do anything until the proper place to set
342 -- primitive Finalize_Address has been determined.
344 if Collection.Finalize_Address /= null then
346 Collection.Finalize_Address (Node_Ptr_To_Address (Curr_Ptr));
349 when Fin_Except : others =>
352 Save_Occurrence (Ex_Occur, Fin_Except);
357 Curr_Ptr := Next_Ptr;
360 -- Deallocate the dummy head
362 Free (Collection.Objects);
364 -- If the finalization of a particular node raised an exception, reraise
365 -- it after the remainder of the list has been finalized.
368 Reraise_Occurrence (Ex_Occur);
376 overriding procedure Initialize
377 (Collection : in out Finalization_Collection)
380 Collection.Objects := new Node;
382 -- The dummy head must point to itself in both directions
384 Collection.Objects.Next := Collection.Objects;
385 Collection.Objects.Prev := Collection.Objects;
392 procedure pcol (Collection : Finalization_Collection) is
393 Head_Seen : Boolean := False;
397 -- Output the basic contents of the collection
399 -- Collection: 0x123456789
400 -- Base_Pool : null <or> 0x123456789
401 -- Fin_Addr : null <or> 0x123456789
402 -- Fin_Start : TRUE <or> FALSE
404 Put ("Collection: ");
405 Put_Line (Address_Image (Collection'Address));
407 Put ("Base_Pool : ");
408 if Collection.Base_Pool = null then
411 Put_Line (Address_Image (Collection.Base_Pool'Address));
415 if Collection.Finalize_Address = null then
418 Put_Line (Address_Image (Collection.Finalize_Address'Address));
421 Put ("Fin_Start : ");
422 Put_Line (Collection.Finalization_Started'Img);
424 -- Output all chained elements. The format is the following:
426 -- ^ <or> ? <or> null
427 -- |Header: 0x123456789 (dummy head)
428 -- | Prev: 0x123456789
429 -- | Next: 0x123456789
432 -- ^ - the current element points back to the correct element
433 -- ? - the current element points back to an erroneous element
434 -- n - the current element points back to null
436 -- Header - the address of the list header
437 -- Prev - the address of the list header which the current element
439 -- Next - the address of the list header which the current element
441 -- (dummy head) - present if dummy head
443 N_Ptr := Collection.Objects;
445 while N_Ptr /= null loop
448 -- The current node is the head. If we have already traversed the
449 -- chain, the head will be encountered again since the chain is
452 if N_Ptr = Collection.Objects then
460 -- The current element points back to null. This should never happen
461 -- since the list is circular.
463 if N_Ptr.Prev = null then
464 Put_Line ("null (ERROR)");
466 -- The current element points back to the correct element
468 elsif N_Ptr.Prev.Next = N_Ptr then
471 -- The current element points back to an erroneous element
474 Put_Line ("? (ERROR)");
477 -- Output the header and fields
480 Put (Address_Image (N_Ptr.all'Address));
482 -- Detect the dummy head
484 if N_Ptr = Collection.Objects then
485 Put_Line (" (dummy head)");
491 if N_Ptr.Prev = null then
494 Put_Line (Address_Image (N_Ptr.Prev.all'Address));
498 if N_Ptr.Next = null then
501 Put_Line (Address_Image (N_Ptr.Next.all'Address));
508 ------------------------------
509 -- Set_Finalize_Address_Ptr --
510 ------------------------------
512 procedure Set_Finalize_Address_Ptr
513 (Collection : in out Finalization_Collection;
514 Proc_Ptr : Finalize_Address_Ptr)
517 Collection.Finalize_Address := Proc_Ptr;
518 end Set_Finalize_Address_Ptr;
520 --------------------------
521 -- Set_Storage_Pool_Ptr --
522 --------------------------
524 procedure Set_Storage_Pool_Ptr
525 (Collection : in out Finalization_Collection;
526 Pool_Ptr : Any_Storage_Pool_Ptr)
529 Collection.Base_Pool := Pool_Ptr;
530 end Set_Storage_Pool_Ptr;
532 end Ada.Finalization.Heap_Management;