Re: [PATCH 8/9] trace2: add counter events to perf and event target formats

[Jeff Hostetler <git@jeffhostetler.com>]

On 12/20/21 11:51 AM, Ævar Arnfjörð Bjarmason wrote:
> 
> On Mon, Dec 20 2021, Jeff Hostetler via GitGitGadget wrote:
> 
>> From: Jeff Hostetler <jeffhost@microsoft.com>
>> [...]
> 
>> +static void fn_counter(uint64_t us_elapsed_absolute,
>> +		       const char *thread_name,
>> +		       const char *category,
>> +		       const char *counter_name,
>> +		       uint64_t value)
>> +{
>> +	const char *event_name = "counter";
>> +	struct strbuf buf_payload = STRBUF_INIT;
>> +
>> +	strbuf_addf(&buf_payload, "name:%s", counter_name);
>> +	strbuf_addf(&buf_payload, " value:%"PRIu64, value);
> 
> Odd to have these be two seperate strbuf_addf()...

yeah, i'll combine.  and in the body of fn_timer in 6/9.


> ....but more generally, and I see from e.g. the existing fn_version_fl
> that you're just using existing patterns, but it seems odd not to have a
> trivial varargs fmt helper for perf_io_write_fl that would avoid the
> whole strbuf/addf/release dance.
[...]

yeah, cut-n-paste was used here and i was maintaining
consistency with the other functions -- rather than inventing
something new and refactoring stuff that didn't need be refactored
in the middle of an on-going patch series.


> I did a quick experiment to do that, patch on "master" below. A lot of
> the boilerplate could be simplified by factoring out the
> sq_quote_buf_pretty() case, and even this approach (re)allocs in a way
> that looks avoidable in many cases if perf_fmt_prepare() were improved
> (but it looks like it nedes its if/while loops in some cases still):
> 
[...]
>   
> +__attribute__((format (printf, 8, 9)))
> +static void perf_io_write_fl_fmt(const char *file, int line, const char *event_name,
> +				 const struct repository *repo,
> +				 uint64_t *p_us_elapsed_absolute,
> +				 uint64_t *p_us_elapsed_relative,
> +				 const char *category,
> +				 const char *fmt, ...)
> +{
> +	va_list ap;
> +	struct strbuf sb = STRBUF_INIT;
> +
> +	va_start(ap, fmt);
> +	strbuf_vaddf(&sb, fmt, ap);
> +	va_end(ap);
> +
> +	perf_io_write_fl(file, line, event_name, repo, p_us_elapsed_absolute,
> +			 p_us_elapsed_relative, category, &sb);
> +
> +	strbuf_release(&sb);
> +}
> +
>   static void fn_version_fl(const char *file, int line)
>   {
>   	const char *event_name = "version";
> -	struct strbuf buf_payload = STRBUF_INIT;
> -
> -	strbuf_addstr(&buf_payload, git_version_string);
>   
> -	perf_io_write_fl(file, line, event_name, NULL, NULL, NULL, NULL,
> -			 &buf_payload);
> -	strbuf_release(&buf_payload);
> +	perf_io_write_fl_fmt(file, line, event_name, NULL, NULL, NULL, NULL,
> +			     "%s", git_version_string);
>   }
[...]

Yes, it might be nice to have a _fmt() version as you suggest
and simplify many of the existing fn_*() function bodies.

It seems like I keep saying this today, but can we discuss that
in a new top-level topic and not down inside commit 8/9 of this
series?

Thanks,
Jeff