Date: Fri, 08 Aug 2008 16:27:27 -0400 From: Chuck Robey <chuckr@telenix.org> To: Pieter de Goeje <pieter@degoeje.nl> Cc: "Carlos A. M. dos Santos" <unixmania@gmail.com>, freebsd-hackers@freebsd.org, Nate Eldredge <neldredge@math.ucsd.edu> Subject: Re: read with timeout ?? Message-ID: <489CAC2F.1070907@telenix.org> In-Reply-To: <200808081009.56521.pieter@degoeje.nl> References: <489B9D4D.4010009@telenix.org> <Pine.GSO.4.64.0808071813530.11980@zeno.ucsd.edu> <e71790db0808071950j32e196e4o42fab1aeb62ab8a4@mail.gmail.com> <200808081009.56521.pieter@degoeje.nl>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Pieter de Goeje wrote: > On Friday 08 August 2008, Carlos A. M. dos Santos wrote: >> On Thu, Aug 7, 2008 at 10:14 PM, Nate Eldredge <neldredge@math.ucsd.edu> > wrote: >>> On Thu, 7 Aug 2008, Chuck Robey wrote: >>>> -----BEGIN PGP SIGNED MESSAGE----- >>>> Hash: SHA1 >>>> >>>> I have my head lost in a code problem. I just hit a point where I need >>>> to do a >>>> read from an fd, but I need to associate it with a timeout, on the order >>>> of 1 >>>> second, something like that. I had the feeling that there's a function >>>> in FreeBSD's libc that makes that simple, but I forget the function >>>> name. If anyone can remember something like what I'm talking about, I >>>> sure would appreciate a function name. I can figure out how it works, >>>> if I could only >>>> dredge up that name. >>> man 2 select >> If the fd is a socket then you can also use setsockopt(2) to set >> SO_RCVTIMEO and check for EWOULDBLOCK (same as EAGAIN) upon read(2) or >> recv(2) errors. The net effect is the same of using select but the >> syntax is simpler, IMO. > > I think poll(2) is also simpler than select for this purpose. > It does look like that, I need to check the implementation a bit, because the name of this thing makes me really suspicious about how often it checks for an fd for being ready for a read. I know select comes right back, I was under the impression that poll didn't use signals to do this. Anyhow, I sure do appreciate the hint, that's just exactly what I was asking for. Spending the time figuring it all out, that'll actually be fun for me. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkicrC8ACgkQz62J6PPcoOmYjACfWP/IGjSvak1hLYSJwWBKkTjb 8qUAoJfSYOZcPJKMqqUb3Y1mltG51sgI =USHT -----END PGP SIGNATURE-----
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