[ltt-dev] LTTng-UST tracepoint API updates

[Matthew Khouzam]

To clarify:
A tracepoint event now takes
provider name /*a string no spaces, starts with a letter, alpha numeric
+ _. */
the event name /* same as above */
TP_ARGS( type , arg , ... ) /* every odd element is the type of the
argument in the next place, must be a c type, not void... that's looking
for trouble */
                                         /* every even element is the
name of the argument */
                                         /* theres always an even number
of args */
TP_FIELDS( ctf_type( type, fieldname, arg) ... ));

I like the improvements... I don't know if it's just me, but this makes
TP_ARGS and ctf_type much more harmonized, IMO.
Why is ctf_type not CTF_TYPE, it is a macro and can be clearer to the
user that the args need not be declared, they can be strings without
quotes or types? I'm sure you have a well thought out answer. :)

I really like that TP_ARGS() works.





On 11-11-13 02:12 PM, Mathieu Desnoyers wrote:
> * Mathieu Desnoyers (mathieu.desnoyers at efficios.com) wrote:
>> Hi,
>>
>> I introduced the following API changes for LTTng-UST, after receiving
>> very appropriate feedback:
>>
>>     Tracepoint API change: rename TRACEPOINT_SYSTEM to TRACEPOINT_PROVIDER
>>     
>>     Eliminates the confusion between the first TRACEPOINT_EVENT "provider"
>>     argument and the "TRACEPOINT_SYSTEM", which need to be the same thing.
>>     
>> and made sure TRACEPOINT_PROVIDER always match TRACEPOINT_SYSTEM by
>> adding a compiler warning:
>>
>>     Tracepoints: add provider mismatch check
>>     
>> Finally, rename TP_ARGS to TP_VARS, in preparation for combining
>> TP_PROTO and TP_ARGS:
>>
>>     tracepoint API change: rename TP_ARGS to TP_VARS
>>     
>>     In preparation of folding of both TP_PROTO and TP_ARGS into TP_ARGS.
>>
>> Hopefully I'll succeed to getting both TP_PROTO and TP_VARS combined
>> into TP_ARGS, but even if this does not work out, TP_VARS seems much
>> more appropriate than TP_ARGS here.
> The API change is completed by the following commit:
>
> commit 63ef26930fe613a266cc69f5089cf643dd59b012
> Author: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> Date:   Sun Nov 13 14:07:57 2011 -0500
>
>     Tracepoint API change: combine TP_PROTO and TP_VARS into TP_ARGS, remove _NOARGS macros
>     
>     New API for tracepoints, combining the TP_PROTO and TP_VARS arguments
>     into a single "TP_ARGS" macro. It takes up to 10 parameters (from 0 to
>     10). The "_NOARGS" special-case is not needed anymore: it can be
>     achieved simply by passing an empty TP_ARGS:
>     
>       TP_ARGS(),
>     
>     to the standard tracepoint event declarations.
>     
>     Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
>
> Best regards,
>
> Mathieu
>
>> Thanks,
>>
>> Mathieu
>>
>> -- 
>> Mathieu Desnoyers
>> Operating System Efficiency R&D Consultant
>> EfficiOS Inc.
>> http://www.efficios.com