-- --
-- B o d y --
-- --
--- --
--- Copyright (C) 1992-2001 Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2007, 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- --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
+-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
+-- Boston, MA 02110-1301, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- --
------------------------------------------------------------------------------
-with System.Storage_Elements;
-with System.Address_To_Access_Conversions;
+with System.Soft_Links;
+
+with Ada.Unchecked_Conversion;
package body System.Pool_Size is
package SSE renames System.Storage_Elements;
use type SSE.Storage_Offset;
- package SC is new Address_To_Access_Conversions (SSE.Storage_Count);
+ -- Even though these storage pools are typically only used
+ -- by a single task, if multiple tasks are declared at the
+ -- same or a more nested scope as the storage pool, there
+ -- still may be concurrent access. The current implementation
+ -- of Stack_Bounded_Pool always uses a global lock for protecting
+ -- access. This should eventually be replaced by an atomic
+ -- linked list implementation for efficiency reasons.
+
+ package SSL renames System.Soft_Links;
- SC_Size : constant
- := SSE.Storage_Count'Object_Size / System.Storage_Unit;
+ type Storage_Count_Access is access SSE.Storage_Count;
+ function To_Storage_Count_Access is
+ new Ada.Unchecked_Conversion (Address, Storage_Count_Access);
+
+ SC_Size : constant := SSE.Storage_Count'Object_Size / System.Storage_Unit;
package Variable_Size_Management is
Alignment : SSE.Storage_Count)
is
begin
+ SSL.Lock_Task.all;
+
if Pool.Elmt_Size = 0 then
Vsize.Allocate (Pool, Address, Storage_Size, Alignment);
elsif Pool.First_Free /= 0 then
Address := Pool.The_Pool (Pool.First_Free)'Address;
- Pool.First_Free := SC.To_Pointer (Address).all;
+ Pool.First_Free := To_Storage_Count_Access (Address).all;
elsif
Pool.First_Empty <= (Pool.Pool_Size - Pool.Aligned_Elmt_Size + 1)
else
raise Storage_Error;
end if;
+
+ SSL.Unlock_Task.all;
+
+ exception
+ when others =>
+ SSL.Unlock_Task.all;
+ raise;
end Allocate;
----------------
Alignment : SSE.Storage_Count)
is
begin
+ SSL.Lock_Task.all;
+
if Pool.Elmt_Size = 0 then
Vsize.Deallocate (Pool, Address, Storage_Size, Alignment);
else
- SC.To_Pointer (Address).all := Pool.First_Free;
+ To_Storage_Count_Access (Address).all := Pool.First_Free;
Pool.First_Free := Address - Pool.The_Pool'Address + 1;
end if;
+
+ SSL.Unlock_Task.all;
+ exception
+ when others =>
+ SSL.Unlock_Task.all;
+ raise;
end Deallocate;
----------------
----------------
procedure Initialize (Pool : in out Stack_Bounded_Pool) is
+
+ -- Define the appropriate alignment for allocations. This is the
+ -- maximum of the requested alignment, and the alignment required
+ -- for Storage_Count values. The latter test is to ensure that we
+ -- can properly reference the linked list pointers for free lists.
+
Align : constant SSE.Storage_Count :=
- SSE.Storage_Count'Max (SSE.Storage_Count'Alignment, Pool.Alignment);
+ SSE.Storage_Count'Max
+ (SSE.Storage_Count'Alignment, Pool.Alignment);
begin
if Pool.Elmt_Size = 0 then
Pool.First_Empty := 1;
-- Compute the size to allocate given the size of the element and
- -- the possible Alignment clause
+ -- the possible alignment requirement as defined above.
Pool.Aligned_Elmt_Size :=
SSE.Storage_Count'Max (SC_Size,
------------------
function Storage_Size
- (Pool : Stack_Bounded_Pool)
- return SSE.Storage_Count
+ (Pool : Stack_Bounded_Pool) return SSE.Storage_Count
is
begin
return Pool.Pool_Size;
function Size
(Pool : Stack_Bounded_Pool;
- Chunk : SSE.Storage_Count)
- return SSE.Storage_Count;
+ Chunk : SSE.Storage_Count) return SSE.Storage_Count;
-- Fetch the field 'size' of a chunk of available storage
function Next
(Pool : Stack_Bounded_Pool;
- Chunk : SSE.Storage_Count)
- return SSE.Storage_Count;
+ Chunk : SSE.Storage_Count) return SSE.Storage_Count;
-- Fetch the field 'next' of a chunk of available storage
function Chunk_Of
(Pool : Stack_Bounded_Pool;
- Addr : System.Address)
- return SSE.Storage_Count;
+ Addr : System.Address) return SSE.Storage_Count;
-- Give the chunk number in the pool from its Address
--------------
function Chunk_Of
(Pool : Stack_Bounded_Pool;
- Addr : System.Address)
- return SSE.Storage_Count
+ Addr : System.Address) return SSE.Storage_Count
is
begin
return 1 + abs (Addr - Pool.The_Pool (1)'Address);
Align_Size : constant SSE.Storage_Count :=
((Storage_Size + Alignment - 1) / Alignment) *
Alignment;
- Chunk : SSE.Storage_Count := Chunk_Of (Pool, Address);
+ Chunk : constant SSE.Storage_Count := Chunk_Of (Pool, Address);
begin
-- Attach the freed chunk to the chain
function Next
(Pool : Stack_Bounded_Pool;
- Chunk : SSE.Storage_Count)
- return SSE.Storage_Count
+ Chunk : SSE.Storage_Count) return SSE.Storage_Count
is
begin
- return SC.To_Pointer (Pool.The_Pool (Chunk + SC_Size)'Address).all;
+ pragma Warnings (Off);
+ -- Kill alignment warnings, we are careful to make sure
+ -- that the alignment is correct.
+
+ return To_Storage_Count_Access
+ (Pool.The_Pool (Chunk + SC_Size)'Address).all;
+
+ pragma Warnings (On);
end Next;
--------------
Chunk, Next : SSE.Storage_Count)
is
begin
- SC.To_Pointer (Pool.The_Pool (Chunk + SC_Size)'Address).all := Next;
+ pragma Warnings (Off);
+ -- Kill alignment warnings, we are careful to make sure
+ -- that the alignment is correct.
+
+ To_Storage_Count_Access
+ (Pool.The_Pool (Chunk + SC_Size)'Address).all := Next;
+
+ pragma Warnings (On);
end Set_Next;
--------------
Chunk, Size : SSE.Storage_Count)
is
begin
- SC.To_Pointer (Pool.The_Pool (Chunk)'Address).all := Size;
+ pragma Warnings (Off);
+ -- Kill alignment warnings, we are careful to make sure
+ -- that the alignment is correct.
+
+ To_Storage_Count_Access
+ (Pool.The_Pool (Chunk)'Address).all := Size;
+
+ pragma Warnings (On);
end Set_Size;
----------
function Size
(Pool : Stack_Bounded_Pool;
- Chunk : SSE.Storage_Count)
- return SSE.Storage_Count
+ Chunk : SSE.Storage_Count) return SSE.Storage_Count
is
begin
- return SC.To_Pointer (Pool.The_Pool (Chunk)'Address).all;
+ pragma Warnings (Off);
+ -- Kill alignment warnings, we are careful to make sure
+ -- that the alignment is correct.
+
+ return To_Storage_Count_Access (Pool.The_Pool (Chunk)'Address).all;
+
+ pragma Warnings (On);
end Size;
end Variable_Size_Management;
OSDN Git Service
