On Mon, Feb 8, 2021 at 5:27 AM RADERMACHER Ansgar via lttng-dev <lttng-dev@lists.lttng.org> wrote: > > Dear all, > > having thought a bit more about it, I can see now that nested types are > problematic in general: some types in the language need to be mapped to types > that match but are not identical, i.e. have likely a different memory layout. > This would be problematic for nested types.
Exactly: compound types represent a challenge in general because we don't know the memory layout details of the user data, so we can't just copy bytes as is to a CTF data stream. There are strategies to achieve such a feature in barectf and in LTTng-UST (similar problem), but implementing and testing them is not on the roadmap currently. This is why both barectf and LTTng-UST support basic arrays of simple/scalar instances (numbers and strings), but not the rest, even if CTF itself can represent more complex data. barectf supports nested static arrays [1], but not nested dynamic arrays. Hope this helps, Phil [1]: https://barectf.org/docs/barectf/3.0/yaml/static-array-ft-obj.html > Thus, I'm opting for flattening data (with the exception of lists). > > Best regards > > Ansgar > > > ________________________________ > From: lttng-dev [lttng-dev-boun...@lists.lttng.org] on behalf of RADERMACHER > Ansgar via lttng-dev [lttng-dev@lists.lttng.org] > Sent: Friday, February 05, 2021 22:58 > To: lttng-dev@lists.lttng.org > Subject: [lttng-dev] [barectf] no nested types? > > Hello, > > I've generated a config.yaml from type definitions in UML. If the type of a > payload field is a UML DataType, the generator produces an associated type > alias file with "class = structure" and the contained members. > > When I tried to compile the configuration file, I get an error message from > barectf: > `field-type` property: Nested structure field types are not supported > > It this really not supported or are there other mechanisms that enable the > use of nested types? If not supported, it would be an important restriction > which seems to be not prominently documented (in [1], there is a parenthesis > "except a structure field type object" but it's easy to miss) > > Best regards > > Ansgar > > > [1] https://barectf.org/docs/barectf/3.0/yaml/struct-ft-obj.html > > > _______________________________________________ > lttng-dev mailing list > lttng-dev@lists.lttng.org > https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
