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Groups > comp.lang.ada > #49499
| From | "Randy Brukardt" <randy@rrsoftware.com> |
|---|---|
| Newsgroups | comp.lang.ada |
| Subject | Re: Custom Storage Pool questions |
| Date | 2021-09-13 00:29 -0500 |
| Organization | JSA Research & Innovation |
| Message-ID | <shmnk1$lgf$1@franka.jacob-sparre.dk> (permalink) |
| References | <e3c5c553-4a7f-408a-aaa7-60ec0b70202dn@googlegroups.com> |
Not sure what you are expecting. There is no requirement that objects are
allocated contigiously. Indeed, Janus/Ada will call Allocate as many times
as needed for each object; for instance, unconstrained arrays are in two
parts (descriptor and data area).
The only thing that you can assume in a portable library is that you get
called the same number of times and sizes/alignment for Allocate and
Deallocate; there's no assumptions about size or alignment that you can
make.
If you want to build a pool around some specific allocated size, then if it
needs to be portable, (A) you have to calculate the allocated size, and (B)
you have to have a mechanism for what to do if some other size is requested.
(Allocate a whole block for smaller sizes, fall back to built-in heap for
too large is what I usually do).
More likely, you'll build a pool for a particular implementation. Pools are
very low level by their nature, and useful ones are even more so (because
they are using target facilities to allocate memory, or need to assume
something about the allocations, or because they are doing icky things like
address math, or ...).
Randy.
Randy.
"Jere" <jhb.chat@gmail.com> wrote in message
news:e3c5c553-4a7f-408a-aaa7-60ec0b70202dn@googlegroups.com...
>I was learning about making user defined storage pools when
> I came across an article that made me pause and wonder how
> portable storage pools actually can be. In particular, I assumed
> that the Size_In_Storage_Elements parameter in the Allocate
> operation actually indicated the total number of storage elements
> needed.
>
> procedure Allocate(
> Pool : in out Root_Storage_Pool;
> Storage_Address : out Address;
> Size_In_Storage_Elements : in Storage_Elements.Storage_Count;
> Alignment : in Storage_Elements.Storage_Count) is abstract;
>
> But after reading the following AdaCore article, my assumption is now
> called into question:
> https://blog.adacore.com/header-storage-pools
>
> In particular, the blog there advocates for separately counting for
> things like unconstrained array First/Last indices or the Prev/Next
> pointers used for Controlled objects. Normally I would have assumed
> that the Size_In_Storage_Elements parameter in Allocate would account
> for that, but the blog clearly shows that it doesn't
>
> So that seems to mean to make a storage pool, I have to make it
> compiler specific or else risk someone creating a type like an
> array and my allocation size and address values will be off.
>
> Is it intended not to be able to do portable Storage Pools or am
> I missing some Ada functionality that helps me out here. I
> scanned through the list of attributes but none seem to give
> any info about where the object's returned address is relative
> to the top of the memory actually allocated for the object. I saw
> the attribute Max_Size_In_Storage_Elements, but it doesn't seem
> to guarantee to include things like the array indices and it still
> doesn't solve the issue of knowing where the returned address
> needs to be relative to the top of allocated memory.
>
> I can easily use a generic to ensure that the types I care about
> are portably made by the pool, but I can't prevent someone from
> using my pool to create other objects that I hadn't accounted for.
> Unless there is a way to restrict a pool from allocating objects
> of other types?
Back to comp.lang.ada | Previous | Next — Previous in thread | Next in thread | Find similar
Custom Storage Pool questions Jere <jhb.chat@gmail.com> - 2021-09-12 17:53 -0700
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-13 00:29 -0500
Re: Custom Storage Pool questions Jere <jhb.chat@gmail.com> - 2021-09-13 18:04 -0700
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-20 19:06 -0500
Re: Custom Storage Pool questions Simon Wright <simon@pushface.org> - 2021-09-18 12:32 +0100
Re: Custom Storage Pool questions Jere <jhb.chat@gmail.com> - 2021-09-19 17:31 -0700
Re: Custom Storage Pool questions Niklas Holsti <niklas.holsti@tidorum.invalid> - 2021-09-20 09:34 +0300
Re: Custom Storage Pool questions Emmanuel Briot <briot.emmanuel@gmail.com> - 2021-09-19 23:48 -0700
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-20 09:35 +0200
Re: Custom Storage Pool questions Shark8 <onewingedshark@gmail.com> - 2021-09-20 09:59 -0700
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-20 19:50 -0500
Re: Custom Storage Pool questions Jere <jhb.chat@gmail.com> - 2021-09-21 16:08 -0700
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-27 23:42 -0500
Re: Custom Storage Pool questions Jere <jhb.chat@gmail.com> - 2021-10-02 16:19 -0700
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-10-03 10:52 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-10-13 20:26 -0500
Re: Custom Storage Pool questions "J-P. Rosen" <rosen@adalog.fr> - 2021-09-13 13:12 +0200
Re: Custom Storage Pool questions Jere <jhb.chat@gmail.com> - 2021-09-13 17:48 -0700
Re: Custom Storage Pool questions "J-P. Rosen" <rosen@adalog.fr> - 2021-09-14 08:08 +0200
Re: Custom Storage Pool questions Jere <jhb.chat@gmail.com> - 2021-09-14 17:39 -0700
Re: Custom Storage Pool questions Simon Wright <simon@pushface.org> - 2021-09-15 08:01 +0100
Re: Custom Storage Pool questions Jere <jhb.chat@gmail.com> - 2021-09-16 16:32 -0700
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-20 18:51 -0500
Re: Custom Storage Pool questions Jere <jhb.chat@gmail.com> - 2021-09-21 15:40 -0700
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-14 08:23 +0200
Re: Custom Storage Pool questions "J-P. Rosen" <rosen@adalog.fr> - 2021-09-14 08:42 +0200
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-14 09:00 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-20 18:58 -0500
Re: Custom Storage Pool questions Jere <jhb.chat@gmail.com> - 2021-09-14 17:21 -0700
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-15 08:54 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-20 18:48 -0500
Re: Custom Storage Pool questions Egil H H <ehh.public@gmail.com> - 2021-09-14 03:54 -0700
Re: Custom Storage Pool questions Jere <jhb.chat@gmail.com> - 2021-09-14 17:11 -0700
Re: Custom Storage Pool questions Simon Wright <simon@pushface.org> - 2021-09-15 17:43 +0100
Re: Custom Storage Pool questions Simon Wright <simon@pushface.org> - 2021-09-15 18:03 +0100
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-15 21:07 +0200
Re: Custom Storage Pool questions Simon Wright <simon@pushface.org> - 2021-09-15 21:40 +0100
Re: Custom Storage Pool questions Emmanuel Briot <briot.emmanuel@gmail.com> - 2021-09-16 00:12 -0700
Re: Custom Storage Pool questions Jere <jhb.chat@gmail.com> - 2021-09-16 16:21 -0700
Re: Custom Storage Pool questions Emmanuel Briot <briot.emmanuel@gmail.com> - 2021-09-17 00:08 -0700
Re: Custom Storage Pool questions Simon Wright <simon@pushface.org> - 2021-09-17 08:18 +0100
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-17 15:56 +0200
Re: Custom Storage Pool questions Simon Wright <simon@pushface.org> - 2021-09-17 20:46 +0100
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-17 22:39 +0200
Re: Custom Storage Pool questions Niklas Holsti <niklas.holsti@tidorum.invalid> - 2021-09-18 00:17 +0300
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-18 09:49 +0200
Re: Custom Storage Pool questions Niklas Holsti <niklas.holsti@tidorum.invalid> - 2021-09-18 12:03 +0300
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-18 12:22 +0200
Re: Custom Storage Pool questions Niklas Holsti <niklas.holsti@tidorum.invalid> - 2021-09-18 18:59 +0300
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-18 18:19 +0200
Re: Custom Storage Pool questions Niklas Holsti <niklas.holsti@tidorum.invalid> - 2021-09-19 13:36 +0300
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-19 13:41 +0200
Re: Custom Storage Pool questions Niklas Holsti <niklas.holsti@tidorum.invalid> - 2021-09-20 10:05 +0300
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-20 09:35 +0200
Re: Custom Storage Pool questions Niklas Holsti <niklas.holsti@tidorum.invalid> - 2021-09-20 11:08 +0300
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-20 10:28 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-20 19:45 -0500
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-20 19:40 -0500
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-20 19:30 -0500
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-20 19:37 -0500
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-21 08:28 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-27 23:38 -0500
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-28 09:00 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-20 19:26 -0500
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-21 08:51 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-27 23:31 -0500
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-28 08:56 +0200
Re: Custom Storage Pool questions Simon Wright <simon@pushface.org> - 2021-09-28 08:52 +0100
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-28 10:07 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-28 17:04 -0500
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-29 09:57 +0200
Re: Custom Storage Pool questions Shark8 <onewingedshark@gmail.com> - 2021-09-29 07:41 -0700
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-29 17:16 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-29 19:16 -0500
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-30 10:08 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-30 19:04 -0500
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-10-01 10:25 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-10-02 04:06 -0500
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-10-02 12:18 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-10-02 23:33 -0500
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-10-03 10:40 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-10-13 20:21 -0500
Re: Custom Storage Pool questions "philip...@gmail.com" <philip.munts@gmail.com> - 2021-10-13 20:12 -0700
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-10-14 09:31 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-10-14 19:36 -0500
Re: Custom Storage Pool questions Stephen Leake <stephen_leake@stephe-leake.org> - 2021-10-15 01:08 -0700
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-10-15 10:18 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-10-15 17:22 -0500
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-10-15 10:15 +0200
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-10-15 17:44 -0500
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-10-16 11:00 +0200
Re: Custom Storage Pool questions Simon Wright <simon@pushface.org> - 2021-10-16 15:32 +0100
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-10-16 17:06 +0200
Re: Custom Storage Pool questions Shark8 <onewingedshark@gmail.com> - 2021-10-18 07:23 -0700
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-20 19:19 -0500
Re: Custom Storage Pool questions "Randy Brukardt" <randy@rrsoftware.com> - 2021-09-20 19:18 -0500
Re: Custom Storage Pool questions "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2021-09-16 10:41 +0200
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