Re: [tip:perf/core] tracing: Add DEFINE_EVENT(),DEFINE_SINGLE_EVENT() support to docbook

[Mathieu Desnoyers]

* Steven Rostedt (rostedt@xxxxxxxxxxx) wrote:
> On Wed, 2009-12-02 at 15:43 +0100, Ingo Molnar wrote:
> > * Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> > 
> > > On Wed, 2009-12-02 at 15:01 +0100, Ingo Molnar wrote:
> > > 
> > > > >  DECLARE_CLASS_AND_DEFINE_EVENT()
> > > > 
> > > > Hm, that's a bit too long. How about 'DEFINE_CLASS_EVENT()' as a 
> > > > compromise? It's similarly short-ish to TRACE_EVENT(), and it also 
> > > > conveys the fact that we create both a class and an event there.
> > > > 
> > > > The full series would thus be:
> > > > 
> > > > 	DECLARE_EVENT_CLASS
> > > > 	DEFINE_EVENT
> > > > 	DEFINE_CLASS_EVENT
> > > > 
> > > > hm?
> > > 
> > > I thought about that too, but it actually makes it more confusing. 
> > > Because, looking at this with a fresh POV, I would think that after I 
> > > declare a class, I would use DEFINE_CLASS_EVENT with that class.
> > 
> > yeah. Hence was my second-best choice 'DEFINE_STANDALONE_EVENT' or 
> > 'DEFINE_SINGLE_EVENT' - to stress the special nature it, and to actually 
> > nudge people towards creating classes of events instead of doing 
> > separate, standalone points. (which are a waste in the majority of 
> > cases)
> 
> But the current TRACE_EVENT is still defining a class. Thus, you could
> create a TRACE_EVENT (or whatever it is called) and then create
> DEFINE_EVENTs based on the TRACE_EVENT.
> 
> That's why I want a name that describes this.
> 
> DEFINE_EVENT_CLASS?
> 
> Perhaps that's the best.
> 
> DECLARE_EVENT_CLASS - only creates a class
> DEFINE_EVENT - defines an event based off of a class
> DEFINE_EVENT_CLASS - creates a class and defines an event by the same name
> 
> Perhaps this is best in keeping with linux kernel naming conventions?

Hi Steve,

A few questions about the semantic:

Is "declare" here always only used as a declaration ? (e.g. only in
headers, never impacted by CREATE_TRACE_POINT ?)

Is "define" here always mapping to a definition ? (e.g. to be used in a
C file to define the class or event handling stub)

I feel that your DEFINE_EVENT_CLASS might actually be doing a bit more
than just "defining", it would actually also perform the declaration.
Same goes for "DEFINE_EVENT". So can you tell us a bit more about that
is the context of templates ?

Thanks,

Mathieu

> 
> -- Steve
> 
> 

-- 
Mathieu Desnoyers
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