Re: [PATCHv3 02/13] xread: poll on non blocking fds

> On Tue, Sep 22, 2015 at 12:45:51PM -0700, Junio C Hamano wrote:
>
>> 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.
>
> Yeah. I do not think this is a bug at all; the user might have their
> reasons for handing off an O_NONBLOCK pipe. If we take xread() to mean
> "try to read from fd until we get a real error, some data, or an EOF",
> then it is perfectly reasonable to replace spinning on read() (which we
> do now) with a poll() for efficiency. The caller (and the user) does not
> have to care, and should not notice; the outcome will be the same.