[lttng-dev] Test if tracepoint is enabled

[David Bryant]

Hi all,

Is it feasible to have an officially supported way of determining if a 
tracepoint is currently enabled?

In my code I would like to test if the tracepoint is enabled, and if it 
isn't, avoid doing expensive setup work.

I've been doing the following:

   if 
(__builtin_expect(!!(__tracepoint_sample_component___message.state), 0)) {
       /* setup work */
       tracepoint(sample_component, message);
       /* cleanup work */
   }

But it's weak for two reasons:

  * The 'state' attribute goes true when the tracepoint is enabled, but
    stays true after the tracepoint is disabled. It only goes false when
    the session is destroyed.
  * It uses a private / unofficial API

What I'd like is an official API that correctly evaluates whether a 
tracepoint is enabled or not?

Is this possible?

Thanks,
Dave

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