Re: [PATCH 2/2] trace2: randomize/timestamp trace2 targets

Jeff King [off-list ref] writes:

This definitely seems useful. Could we drop the final "%" and make it
either a single-character "%t" or "%(iso8601)" to match our other
formatting strings? There's no _technical_ reason to do that, but it
just seems like there's not much point in being unnecessarily
inconsistent.

I do agree that %TOKEN% is not among the patterns we've used before,
and I fully anticipated that it would attract paintbrushes when the
proposal hits the public list ;-)

A big question is what we want to be consisten with, though.  From
the readability point-of-view, for-each-ref language %(token) is
easier to read and extend.  A secondary question is that there
likely are things other than the timestamp of the time process
started that may want to be interpolated, so we may want to pick
some useful vocabulary upfront.  If we can declare interpolation
will be done ONLY for timestamps, as Ævar suggests, taking strftime
pattern directly from the caller may be sufficiently simple to
explain and useful, but I am not sure "only for timestamps" is a
limitation we would want to adopt this early in the design process.

Doing this automatically for directories feels kind of magical. I'd have
expected it to be just another placeholder. And in fact, I'd think using
the process id as a placeholder would be pretty common. Between
timestamp and pid, that's generally unique (though I'm not opposed to
the random placeholder if somebody really wants to be thorough).

That leaves the door open for being able to append to or overwrite
existing trace files later, if we want to make that a possibility.

Thanks.