From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 18 Jul 2022 16:50:45 GMT
Subject: Re: [PATCH v3] trace2: only include "fsync" events if we git_fsync()
Message-ID: <xmqq5yjus6u2.fsf@gitster.g>
In-Reply-To: <patch-v3-1.1-979dea5956a-20220718T102747Z-avarab@gmail.com>

Ævar Arnfjörð Bjarmason  <avarab@gmail.com> writes:

> As we're needing to indent the trace2_data_intmax() lines let's
> introduce helper variables to ensure that our resulting lines (which
> were already too) don't exceed the recommendations of the
> CodingGuidelines. Doing that requires either wrapping them twice, or
> introducing short throwaway variable names, let's do the latter.

Or a macro that can be used like

	log_trace_fsync_nonzero(writeout_only);
	log_trace_fsync_nonzero(hardware_flush);

something along the lines of

#define log_trace_fsync_nonzero(var) \
	if (count_fsync_ #var) \
		trace2_data_intmax("fsync", the_repository, \
			"fsync/" ##var, count_fsync_ #var)

using token pasting and token stringification ;-)

The macro itself I am not serious at all.  s/_if/_nonzero/ may be
worth pondering, though.

>    We now test how many "writeout" and "flush" sync events we emit,
>    rather than the (meaningless) previous behavior (see above)>

Makes sense.

Neeraj, Ack, as the author of 9a498767 (trace2: add stats for fsync
operations, 2022-03-30)?

Thanks all.