----- On Nov 30, 2018, at 12:30 PM, John OSullivan <john.osulli...@blackbox.com> wrote:
> Hi Mathieu, > Thank you for the reply and my apologies for the confusion. Let me try and > clarify. > I understood that the use of the class and instance concepts in the tpl file > was > to be able to declare a class with as you say a number of fields and then > create instances of that class that provided a way of defining specific > variants of that class. > For example > TRACEPOINT_EVENT_CLASS( > /* Tracepoint provider name */ > core_event_trace, > /* Tracepoint class name */ > core_event_tracepoint_class, > /* Input arguments */ > TP_ARGS( > int, event_type > int, second_field > int, third_field > int, fourth_field > ), > /* Output event fields */ > TP_FIELDS( > ctf_integer(int, event_type, event_type) > ctf_integer(int, second_field, second_field) > ctf_integer(int, third_field, third_field) > ) > ) > Then we declare an instance > TRACEPOINT_EVENT_INSTANCE( > core_event_trace, > core_event_tracepoint_class, > first_event_tracepoint, > TP_ARGS( > int, event_type > Int, first_field > ) > ) > And a second one > TRACEPOINT_EVENT_INSTANCE( > core_event_trace, > core_event_tracepoint_class, > second_event_tracepoint, > TP_ARGS( > int, event_type > Int, second_field > ) > ) > So the two instances do not define all of the fields in the class definition, > the first only defines first_field and the second only defines second_field, > will this work or do the field in the instance always have to match the fields > in the class? I see from the examples above that when you say "field" in your question here, you actually mean "arguments to TP_ARGS". So the answer is that the arguments need to match exactly between the instances and the class they refer to. Thanks, Mathieu > From: Mathieu Desnoyers [mailto:mathieu.desnoy...@efficios.com] > Sent: 30 November 2018 17:13 > To: John O'Sullivan > Cc: lttng-dev > Subject: [EXTERNAL] Re: [lttng-dev] Correct way to use the tpl file > ----- On Nov 30, 2018, at 11:09 AM, John OSullivan > <john.osulli...@blackbox.com> > wrote: >> 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? > I am a bit confused by your use of the word "members" here. A tracepoint class > has a provider name, > a class name, input argument, and output fields. > The event instance refers to the class by provider and class name, defines its > own name, and needs to > have a compatible input argument prototype (same number of arguments, same > types). It will serialize > the output fields in the exact layout described by the event class. > I know it does not directly answer your question, but I'm really unsure about > what you mean > by "members". > Thanks, > Mathieu >> 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 >> ) >> ) >> This email and any files transmitted with it are confidential and are >> intended >> for the sole use of the individual to whom they are addressed. Black Box >> Corporation reserves the right to scan all e-mail traffic for restricted >> content and to monitor all e-mail in general. If you are not the intended >> recipient or you have received this email in error, any use, dissemination or >> forwarding of this email is strictly prohibited. If you have received this >> email in error, please notify the sender by replying to this email. >> _______________________________________________ >> lttng-dev mailing list >> lttng-dev@lists.lttng.org >> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
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