Re: [linuxtools-dev] TMF

[Francois Chouinard <fchouinard@xxxxxxxxx>]

Hi,

I had a look on the model and the code.
It seems excellent. I easily created a dummy trace viewer (with both a TmfEventsEditor and a TimeChartView).

Good.

 

I just have one question, about ITmfEvent.getReference(). The javadoc is not very explicit.

Looking a Lttng code, it seems this fields contains the trace name.
So, if I understood well, this field is used when a ITmfTrace is composed of many "streams". In this case, reference is used to identify the original "stream" of the event.

Am I right ?

Xavier

The reference field is a free form field where you can store whatever data you wish. At one point I had in mind to store something like "filename:linenumber" so an app could open an editor and display, say, the source code line where the trace event was generated. But this is really an application-specific free-form field.

About LTTng: the soon-to-be-revised experiment is used to correlate multiple traces and present them to the application as a single, time-ordered stream of events.  However, the LTTng State System and viewers (e.g. Statistics) need to know the original trace name to correctly populate their structures. Since there was no handle to the event's parent trace, the reference field was used to keep track of this information. I haven't updated the LTTng part yet but the ITmfEvent.getTrace() fixes this shortcoming in the revised Event Model.

Thanks for the comments.

-- 

Francois