Date: Mon, 18 Oct 2004 23:30:28 -0700 From: "Ronald F. Guilmette" <rfg@monkeys.com> To: Garrett Wollman <wollman@khavrinen.lcs.mit.edu> Cc: freebsd-net@FreeBSD.ORG Subject: Re: aio_connect ? Message-ID: <67378.1098167428@monkeys.com> In-Reply-To: Your message of Mon, 18 Oct 2004 17:38:57 -0400. <200410182138.i9ILcvmG095282@khavrinen.lcs.mit.edu>
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In message <200410182138.i9ILcvmG095282@khavrinen.lcs.mit.edu>, you wrote: ><<On Sun, 17 Oct 2004 13:19:45 -0700, "Ronald F. Guilmette" <rfg@monkeys.com> said: > >> I'm sitting here looking at that man pages for aio_read and aio_write, >> and the question occurs to me: ``Home come there is no such thing as >> an aio_connect function?'' > >Mostly because there is no need, since connect() doesn't transfer any >data; it just establishes a connection. If the socket is put in >non-blocking mode, connect() will take place in the background. That is a very interesting point, and one which I am now pondering. I myself _have_ in fact done what you are talking about before, i.e. starting up a non-blocking connect and then coming back later on with, say, either select() or poll() to see if it has finished. So I _do_ know how to do what you are describing. But thinking about it now, I'd just like to say that it seems to me that that approach may have some significantly different semantics than the hypothetical aio_connect() function that I had suggested. (But then again, maybe not. I'll have to give it some more thought.) Anyway, upon further reflection (and further RTFM'ing) I am now inclined towards a distinct dislike for the entire aio_*() family of functions because, as I just now realized, they provide the programmer with a synchronous way (i.e. the aio_error function) of checking for inherently _asynchronous_ events, i.e. I/O completions. All things considered, I think that I personally would prefer to receive such notifications (of asynchronous I/O completions) via interrupts... er... I mean via signals. (I suppose that there is some way of doing that, but I confess that I per- sonally have never come across it, so if anybody wants to educate me, then by all means please do so.) P.S. And before anybody lambasts me about the head and neck for even suggesting the use of signals to indicate I/O completions, allow me to just say that yes, I _do_ undertstand that this would be quite costly, but for some applications, the cost would be acceptable.
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