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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Custom Storage Pool questions
Date: Wed, 15 Sep 2021 21:07:22 +0200
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On 2021-09-15 18:43, Simon Wright wrote:

> To save having to recompile the runtime with debug symbols, I wrote a
> tiny pool which delegates to GNAT's
> System.Pool_Global.Global_Pool_Object (the default pool), e.g.
> 
>     overriding procedure Allocate
>       (Pool                     : in out My_Pool.Pool;
>        Storage_Address          :    out Address;
>        Size_In_Storage_Elements : in     Storage_Elements.Storage_Count;
>        Alignment                : in     Storage_Elements.Storage_Count)
>     is
>        pragma Unreferenced (Pool);
>     begin
>        Global_Pool_Object.Allocate
>          (Address      => Storage_Address,
>           Storage_Size => Size_In_Storage_Elements,
>           Alignment    => Alignment);
>     end Allocate;
> 
> and I find with
> 
>        Pool : My_Pool.Pool;
> 
>        type C is new Ada.Finalization.Controlled with null record;
>        type Cs is array (Natural range <>) of C;
>        type Csp is access Cs with Storage_Pool => Pool;

Now define and implement the following function:

    function Get_Allocation_Time (Pointer : Csp) return Time;

The function returns the time when the pointed object was allocated in 
the pool.

[...]

> Mind, I don't quite see how to actually access the header info for a
> particular allocation ...

By subtracting a fixed offset from Pointer.all'Address. The offset is to 
be determined, because X'Address lies.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de