On Donnerstag, 19. Oktober 2017 12:00:01 CEST Arnaud Clère wrote: > Hi all, > I am evaluating the feasibility of using LTTng as a backend for existing Qt > tracepoints following the discussions at Qt Contributors Summit : > https://wiki.qt.io/QtCS2017_Discuss_Qt_Logging_enhancements . The idea > would be to get less performance impact when tracing and more structured > data to analyse without changing Qt users' code. > > I see that instead of describing all tracepoints, we could use a generic LTT > tracepoint like in Python: > http://git.lttng.org/?p=lttng-ust.git;a=blob;f=liblttng-ust-python-agent/lt > tng_ust_python.h > > Except, I would like to structure the tracepoint data at run-time following > a JSON-based data model. I think I could encode that part of CTF > dynamically by appending binary user data, CTF variants, dynamically-sized > CTF structures and sequences in a local buffer. > > But I am wondering how to pass this buffer along with its size to LTTng. > I am afraid a TP_ARGS(void*, buffer) and TP_FIELDS(buffer) would not work > since it would require LTTng to read the CTF in "buffer" to discover where > it stops... > > Or should I use some other API?
Hey Arnaud, Why do we want to use the generic LTTng tracepoint instead of the concrete ones? See also the existing work that went into https://codereview.qt-project.org/#/c/185287/ and the dependent changesets. We hope to be able to revive this patchset soon. Cheers -- Milian Wolff | [email protected] | Senior Software Engineer KDAB (Deutschland) GmbH&Co KG, a KDAB Group company Tel: +49-30-521325470 KDAB - The Qt Experts _______________________________________________ lttng-dev mailing list [email protected] https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
