[lttng-dev] LTTng UST structure support

[Jérémie Galarneau]

Hi Charles,

I'm not sure why you can't embed a graph in your application. The idea is to make new events visible to your source component (or the iterator it provides) by exposing some form of "user data" as a shared context [1][2]. When the event is made available to the source through that context, your "write" function can then pass it down the graph by invoking the graph's "run" method.

I'll see if I can find time to produce an exemple if you think it would be helpful.

Regards,
Jérémie

[1] https://babeltrace.org/docs/v2.0/libbabeltrace2/group__api-self-msg-iter.html#gaa0795c9c18725a844df5b5c705255977
[2] https://babeltrace.org/docs/v2.0/libbabeltrace2/group__api-self-comp.html#gae01283b1ee0c3945c4f54205a1528169
[3] https://babeltrace.org/docs/v2.0/libbabeltrace2/group__api-graph.html#gad2e1c1ab20d1400af1b552e70b3d567c

--
Jérémie Galarneau
EfficiOS Inc.
https://www.efficios.com
________________________________
From: lttng-dev <lttng-dev-bounces at lists.lttng.org> on behalf of chafraysse--- via lttng-dev <lttng-dev at lists.lttng.org>
Sent: February 9, 2023 04:15
To: lttng-dev at lists.lttng.org <lttng-dev at lists.lttng.org>
Subject: Re: [lttng-dev] LTTng UST structure support

Hi Jérémie,

Thx for your reply,
I'm doing a mockup on an Ubuntu host for now
Ok for the graph, I cannot embed it in my application though
I wanted that application to directly output CTF (with compound types,
excluding LTTng) but I guess I'll output it in my format and then
post-process it in a bt2 graph with a custom source and the ctf sink

Best regards,

Charles

> Hi Charles,
>
> I can't really comment on what the packages do, but babeltrace2
> provides those headers under "include/babeltrace2-ctf-writer" since
> that library is somewhat "grafted" to the project. Which distro are you
> using?
>
> As for where to "plug" your bindings, that library is there to maintain
> compatibility with the ctf-writer library that was provided by
> Babeltrace 1.x as it had a number of external users. I don't expect it
> to keep up with new CTF versions.
>
> A more "future proof" integration point is to write a source component,
> and instanciate it in a graph configured with the CTF filesystem sink,
> and feed your events through the graph.
>
> Let me know if you want more information,
> Jérémie
>
> --
> Jérémie Galarneau
> EfficiOS Inc.
> https://www.efficios.com
>
> Le 2023-02-02 17:06, chafraysse at free.fr a écrit :
> Hi,
>
> So I wrote a draft of Rust lib above ctf-writer, using the apis as
> demonstrated in the ctf-writer test
> For deployment I wanted to use "libbabeltrace2-ctf-writer.so" in the
> "libbabeltrace2-dev" package but I could not locate the matching
> includes in there or in the other babeltrace 2 packages
> Did I miss them somewhere ? Should I have plugged in at another level
> in babeltrace2 ?
>
> Best regards,
>
> Charles
>
> ----- Mail original -----
> De: chafraysse at free.fr
> À: "Mathieu Desnoyers" <mathieu.desnoyers at efficios.com>
> Cc: lttng-dev at lists.lttng.org
> Envoyé: Lundi 16 Janvier 2023 10:38:28
> Objet: Re: [lttng-dev] LTTng UST structure support
>
> Hi Mathieu,
>
> Thanks for your reply :)
> I'll stick to bt2 modules in the meantime then
> I'll already be saving a ton of time with those and the CTF spec which
> is great !
>
> Best regards,
>
> Charles
>
> ----- Mail original -----
> De: "Mathieu Desnoyers" <mathieu.desnoyers at efficios.com>
> À: chafraysse at free.fr, lttng-dev at lists.lttng.org
> Envoyé: Jeudi 12 Janvier 2023 21:10:57
> Objet: Re: [lttng-dev] LTTng UST structure support
>
> On 2023-01-09 09:02, chafraysse--- via lttng-dev wrote:
>> Hi,
>>
>> I'm looking for a CTF writer to serialize instrumentations in an
>> embedded Linux/Rust framework
>> LTTng UST looked like a very strong option, but I want to serialize
>> structures as CTF compound type structures and I did not see those
>> supported in the doc or api
>
> This is correct. I am currently working on a new project called
> "libside" (see https://git.efficios.com/?p=libside.git;a=summary) which
> features support for compound types.
>
> However, we still need to do the heavy-lifting implementation work of
> integrating this with LTTng-UST. This is the plan towards supporting
> compound types in LTTng-UST.
>
>> I'd love to have confirmation that I did not just miss something :)
>> If LTTng UST is out for me I will probably try to use the ctf-writer
>> module of babeltrace 2 instead
>
> For now the ctf-writer modules of bt2 would be an alternative to
> consider, but remember that it is not designed for low-impact tracing
> such as lttng-ust. So it depends on how much tracer overhead/runtime
> impact you can afford in your use-case.
>
> Thanks,
>
> Mathieu
>
>>
>> Best regards,
>>
>> Charles
>> _______________________________________________
>> lttng-dev mailing list
>> lttng-dev at lists.lttng.org
>> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> https://www.efficios.com
_______________________________________________
lttng-dev mailing list
lttng-dev at lists.lttng.org
https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.lttng.org/pipermail/lttng-dev/attachments/20230209/0642a790/attachment.htm>