[lttng-dev] Correct way to use the tpl file

[John O'Sullivan]

Hi,

I am looking for some advice on the best way to manage the tracing of some user space events.


I have a series of events that are fed to queues, they look something like the following sample



EventEnd* event_end_new()
{
    EventEnd* event_end = bb_xnew(EventEnd,__func__);

    if (event_end != NULL)
    {
        event_end->type = EQ_EVENT_END;
    .   .. other event specific fields here

        ..
    }
#ifdef LTTNG_TRACE
    tracepoint(core_event_trace, end_event_tracepoint, EQ_EVENT_END);
#endif
    return event_end;
}




I want to try and trace these so created the following template shown below. My question is, does the class have to have all of the possible members that the different instances will have, as each unique event is likely to have different members will the class have to have all of these members defines, and if this is the case is it okay for an instance to just implement a subset of the members the class defines?





TRACEPOINT_EVENT_CLASS(
    /* Tracepoint provider name */
    core_event_trace,

    /* Tracepoint class name */
    core_event_tracepoint_class,

/* Input arguments */
    TP_ARGS(
      int, event_type

    ),

    /* Output event fields */
    TP_FIELDS(
        ctf_integer(int, event_type, event_type)

    )
)





TRACEPOINT_EVENT_INSTANCE(
    core_event_trace,
    core_event_tracepoint_class,
    end_event_tracepoint,
    TP_ARGS(
      int, event_type

    )
)

TRACEPOINT_EVENT_INSTANCE(
    core_event_trace,
    core_event_tracepoint_class,
    start_event_tracepoint,
    TP_ARGS(
      int, event_type
    )
)



TRACEPOINT_EVENT_INSTANCE(
    core_event_trace,
    core_event_tracepoint_class,
    foo_event_tracepoint,
    TP_ARGS(
      int, event_type
    )
)

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