From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 19 Jul 2016 21:33:09 GMT
Subject: Re: Looking for help to understand external filter driver code
Message-ID: <xmqqr3ape2ju.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <7B44C694-7CB2-411D-9CC6-7334CCBAD20B@gmail.com>

Lars Schneider <larsxschneider@gmail.com> writes:

> Git writes --> 4 byte filename length
> Git writes --> filename string

Why limit to 32GB?  Perhaps NUL termination is more appropriate
here?

> Git writes --> 4 byte content length
> Git writes --> content string
> Git reads <-- 4 byte filtered content length
> Git reads <-- filtered content

Do you really need to force the sender to know the length in
advance?  Together with the sequential nature of the above exchange,
i.e. the filter is forbidden from producing even a single byte of
its output before reading everything Git feeds it, you are making it
impossible to use filters that perform streaming conversion.

Of course, with the "sequential" thing, you do not have to worry
about deadlocking hence no need for poll/select, but I am not sure
that is a good thing.