Re: [PATCH V2 3/3] strbuf: allow to use preallocated memory

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 8, 2016, 19:48 UTC
Message-ID: <xmqq37onlawb.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <20160608191918.GB19572@sigill.intra.peff.net>

Jeff King <peff@peff.net> writes:

Show 7 quoted lines

> That made me wonder if we could repeatedly reuse a buffer attached to
> the file descriptor. And indeed, isn't that what stdio is? The whole
> reason this buffer exists is because we are using a direct descriptor
> write. If we switched this function to use fprintf(), we'd avoid the
> whole buffer question, have a fixed cap on our memory use (since we just
> flush anytime the buffer is full) _and_ we'd reduce the number of
> write syscalls we're making by almost a factor of 100.

The primary reason why we avoid stdio in the lower level part of I/O is that the error reporting and handling is horrible.

e.g. c.f. http://article.gmane.org/gmane.comp.version-control.git/27019

Otherwise, I'd agree with your "Why aren't we using stdio if counting and avoiding overflow is so hard?".