Re: [DEMO][PATCH v2 6/5] compat: add a qsort_s() implementation based on GNU's qsort_r(1)

From: Jeff King <peff@peff.net>
Date: Jan 25, 2017, 18:51 UTC
Message-ID: <20170125185153.obqwxiniyz2omxsi@sigill.intra.peff.net>
In-Reply-To: <f41e5053-ee24-060f-0fb9-b257b3ba35a0@web.de>

On Wed, Jan 25, 2017 at 07:43:01PM +0100, René Scharfe wrote:

Show 5 quoted lines

> We could track processor time spent and memory allocated in QSORT_S and the
> whole program and show a warning at the end if one of the two exceeded, say,
> 5% of the total, asking nicely to send it to our mailing list.  Would
> something like this be useful for other functions or metrics as well?  Would
> it be too impolite to use users as telemetry transports?

Frankly, that sounds a bit overboard to me. If people want to profile there are profiling tools. If we want users to profile on their systems and send results to us, I think I'd rather give them instructions or a wrapper script for doing so.

> If we find such cases then we'd better fix them for all platforms, e.g. by
> importing timsort, no?

Yes, as long as they are strict improvements. I can't think of a case where some sorting behavior is a matter of opinion, and they'd prefer Git behave like the rest of their system rather than like Git on other systems[1].

-Peff

[1] I wonder the same about regex implementations. I generally consider
    our GNU regex fallback to be a strict improvement over system
    versions, at least in terms of features. But I was interested to see
    recently that musl implements pcre-style "\x" as an extension, but
    it _doesn't_ do REG_STARTEND. So it's at tradeoff. They have to use
    the fallback on newer versions of git (to get REG_STARTEND), but
    that means the rest of their system understands "\x" but Git does
    not.