From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 22 Sep 2015 19:45:51 GMT
Subject: Re: [PATCHv3 02/13] xread: poll on non blocking fds
Message-ID: <xmqqy4fy2q6o.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <CA+P7+xozmsT4mZsBdvSQkGx4Wk-bOE1h-vAbRG_LAL5A-MAwTw@mail.gmail.com>

Jacob Keller <jacob.keller@gmail.com> writes:

> I don't think this patch actually changes behavior as it stands now. I
> think Junio's suggestion does. Personally, I'd prefer some sort of
> warning when you use xread and get EAGAIN or EWOULDBLOCK. I'd rather
> see it somehow warn so that we can find the bug (since we really
> really shouldn't be calling xread with a blocking socket, especially
> if we have xread_noblock or similar as in this series.

One caveat is that the caller may not know in the first place.

The last time I checked the existing callers of xread(), there were
a few that read from a file descriptor they did not open themselves
(e.g. unpack-objects that read from standard input).  The invoker of
these processes is free to do O_NONBLOCK their input stream for
whatever reason.