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Newsgroups: comp.lang.ada
Date: Wed, 30 May 2018 01:14:42 -0700 (PDT)
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Subject: Re: Memory pools
From: joakimds@kth.se
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Xref: reader02.eternal-september.org comp.lang.ada:52780
Date: 2018-05-30T01:14:42-07:00
List-Id: <comp.lang.ada>

> I apologize if this is a dumb question, but:
>=20
> I've read that Ada uses memory pools for each type. When I read this, I t=
hink it means, for instance, Ada sets up something like an array of 10000 e=
lements for each type, and when the user asks to allocate a new object of s=
uch-and-such type, the run-time system hands that to you.
>=20
> Is that the idea, or do they mean something else?

I agree the descriptions can be fuzzy. The way I understand it is that when=
ever one defines an access type a memory pool is associated with it. If one=
 doesn't specify a memory pool, the default is to use the Global memory poo=
l which on ordinary desktop computers means the heap.

When it comes to memory pools I've used Deepend. Maybe I can find the time =
to write more about this tonight when I come home from work but Brad Moore =
wrote the following in February 2017:

Its been a while since a new release of Deepend has been announced, the las=
t announced version being version 3.4, though there have been updates since=
 then.=20

Now that 3.9 has been posted, seems like a good time to mention the availab=
ility of new features and fixes.=20

Deepend is a set of storage pools for Ada 95, Ada 2005, and Ada 2012 that=
=20
includes subpool capabilities. Groups of memory allocations from a storage=
=20
pool can be assigned to specific subpools where groups of objects can be  d=
eallocated as a group by deallocating the subpool, rather than by individua=
l deallocations of objects.=20

Each subpool is "owned" by a specific task in Ada, allowing allocations and=
=20
deallocations to be efficient, as well as being safer and less error prone.=
=20

Since version 3.4, the most notable changes are;=20

- Ada 2012 subpools were not working in version 3.4, but now work properly=
=20
  with the Ada 2012 subpool syntax.=20
- It is now possible to set task ownership of the storage pool itself, as=
=20
  well as subpools.=20
- Portability changes made to integrate with PTC's ObjectAda 64bit compiler=
=20
  for Ada 2005 and Ada 95=20
- Portability changes made to integrate with RR Software's Janus Ada=20
  compiler for Ada 95=20
- Memory allocations returned by the generic allocators were not=20
  initializing memory. This is important for types that have discriminants=
=20
  or tags. Now memory is initialised which is consistent with behaviour whe=
n=20
  one uses Ada's "new" keyword syntax to provide the allocations.=20
- The generic allocator routines now support allocating unconstrained types=
,=20
  such as strings.=20

There are 4 different storage pools to choose from;=20
   - Unbounded storage pool with subpool support=20
   - Bounded storage pool with subpool support=20
   - Unbounded storage pool without subpool support=20
   - Bounded storage pool without subpool support=20

Deepend source code can be found at;=20

https://sourceforge.net/projects/deepend/files/=20

Regards,=20

Brad Moore