From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on ip-172-31-74-118.ec2.internal X-Spam-Level: X-Spam-Status: No, score=-1.9 required=3.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.6 Path: eternal-september.org!reader02.eternal-september.org!aioe.org!Hx95GBhnJb0Xc8StPhH8AA.user.46.165.242.91.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Custom Storage Pool questions Date: Mon, 20 Sep 2021 09:35:21 +0200 Organization: Aioe.org NNTP Server Message-ID: References: <9bc55d72-b90e-45c5-bfd8-cbce565d139dn@googlegroups.com> <44be7c73-f69e-45da-9916-b14a43a05ea3n@googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Info: gioia.aioe.org; logging-data="26393"; posting-host="Hx95GBhnJb0Xc8StPhH8AA.user.gioia.aioe.org"; mail-complaints-to="abuse@aioe.org"; User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 Content-Language: en-US X-Notice: Filtered by postfilter v. 0.9.2 Xref: reader02.eternal-september.org comp.lang.ada:62784 List-Id: On 2021-09-20 08:48, Emmanuel Briot wrote: >>> If a compiler is allowed to break up an allocation into multiple >>> calls to Allocate (and of course Deallocate), how does one go about >>> enforcing that the user's header is only created once? >> I think one cannot enforce that, because the calls to Allocate do not >> indicate (with parameters) which set of calls concern the same object >> allocation. > > I think the only solution would be for this compiler to have another attribute similar to 'Storage_Pool, but that would define the pool for the descriptor: > > for X'Storage_Pool use Pool; > for X'Descriptor_Storage_Pool use Other_Pool; > > That way the user can decide when to add (or not) extra headers. This will not work with arenas and stack pools. And it is error-prone because the attribute is associated with the access type. Furthermore, it is the descriptor you wanted to tag with extra data. One could add another primitive operation to Root_Storage_Pool: procedure Allocate_Secondary ( 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; Segment_No : in Positive); -- Re-dispatches to Allocate The object allocation protocol would be: Allocate_Secondary (Pool, ..., 1); Allocate_Secondary (Pool, ..., 2); ... Allocate_Secondary (Pool, ..., N); Allocate (Pool, ...); -- Header goes here -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de