From: Bill Fischofer [mailto:[email protected]] Sent: Friday, May 20, 2016 2:58 AM To: Savolainen, Petri (Nokia - FI/Espoo) <[email protected]> Cc: Christophe Milard <[email protected]>; LNG ODP Mailman List <[email protected]> Subject: Re: [lng-odp] [PATCH 1/2] doc: userguide: add section describing helpers
On Thu, May 19, 2016 at 3:09 AM, Savolainen, Petri (Nokia - FI/Espoo) <[email protected]<mailto:[email protected]>> wrote: > -----Original Message----- > From: lng-odp > [mailto:[email protected]<mailto:[email protected]>] > On Behalf Of > Christophe Milard > Sent: Thursday, May 19, 2016 10:43 AM > To: Bill Fischofer > <[email protected]<mailto:[email protected]>> > Cc: LNG ODP Mailman List > <[email protected]<mailto:[email protected]>> > Subject: Re: [lng-odp] [PATCH 1/2] doc: userguide: add section describing > helpers > > On 19 May 2016 at 06:05, Bill Fischofer > <[email protected]<mailto:[email protected]>> wrote: > > > Signed-off-by: Bill Fischofer > > <[email protected]<mailto:[email protected]>> > > > > +=== ODP Helpers > > +ODP also provides a set of _helper_ functions that are > > +distinguished by the `odph_` prefix. These are not part of the ODP API > > +specification, but may be useful to both applications and > implementations. > > > > This statement allows for circular dependancy: > Using helpers from the application means that helpers will use ODP, as > helpers will perform usual stuff that application needs to do: for > instance > helpers uses the ODP cpu_mask for creating threads, and helpers may do > other common application things toward ODP according to this definition. > Having things such as IP header description in helpers means that helpers > are needed by ODP: > In other words: helper is needed by ODP and needs ODP! > I know this is the situation today, but I am not sure we should write this > in stone. Maybe the helpers should be splitted as ODP_helpers and > APP_helpers? I don't see the need to make this distinction. While it is true that some helpers use ODP APIs that's perfectly fine since ODP implementations are free to use ODP APIs themselves, and we do that a lot to simplify the code in many places. To have a true circular reference would be to have an unresolvable recursive reference, which is not the case here. > Helpers are for applications (reuse code and definitions in examples and tests). Implementations should contain their own (protocol header) definitions, so no dependency to the helper lib. The reason we put the header mappings in the helpers in the first place is to avoid this sort of unnecessary duplication, so this statement seems odd. There is, of course, no requirement that implementations use these or any other helper functions. They are simply there as a matter of application and/or implementation convenience. Since this is user documentation, it does not need to speculate how implementation might have been constructed. From user point of view all odph_ definitions are there for test/example/other app convenience. Each implementation decides independently how and where it defines e.g. protocol headers (include those from SDK or some other library, define from scratch, include odp helpers, …). -Petri _______________________________________________ lng-odp mailing list [email protected] https://lists.linaro.org/mailman/listinfo/lng-odp
