On 8/20/22 12:14, Maksim Khmelevskiy via lttng-dev wrote: > Hi Simon, > thanks for the reply!
> What I came up with for now is this example > <https://github.com/ImMax/babeltrace/commit/2082a0f4d77d2edeec6fb95c308a79fb313f7a02>. > It's probably has a lot of design mistakes but it's at least runnable. Looks like a good prototype, it seems right. Some hopefully constructive comments: - You can probably use bt_plugin_find to find a plugin by name instead of your code that does it by hand - When you instantiate a src.ctf.fs component, it may have more than one port (there is one port per data stream), in which case you want to connect them all to a flt.utils.muxer component (which is what the CLI and the Python TraceCollectionMessageIterator class do) to funnel all the messages to a single output port. Of course, if you know the CTF traces you deal with have a single data stream, that is not necessary. > I also see that examples for C API aren't build, but maybe I'm wrong. C API examples in the documentation indeed aren't built. > Another thing, if you have lack of resources I would be happy to help, I > could make a PR with your guidance and review. > > Answers to the questions: > 1) Not sure that I completely understand the question, I wanted to parse > events(name, fields), not the metadata file aligned with the CTF trace file. > 2) Because I wanted to get C-structs directly from the CTF traces. I'm sure > that it's very niche requirement, sane people would not need it. > 3) I would do something like that, but I have a requirement of providing C > structs. I guess to apply filters or do something else with traces (I'm not > sure, not my idea, but I also find it weird) Ok, I understand. When you said you need to write "C structs", I thought you meant that you needed to output some generated C code, for instance convert event types to structures, for use in a program later. But that's not the case, you want to take event payload and fill out some structures at runtime, from what I can see. That explains why you want to use the C API and why you want to create and run a graph in your own application. Following your questions, I have written an example of creating and running a graph, which I just submitted for review here: https://review.lttng.org/c/babeltrace/+/8741 It is roughly equivalent to this Python example: https://babeltrace.org/docs/v2.0/python/bt2/examples.html#build-and-run-a-trace-processing-graph Simon _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
