On Jul 11, 2006, at 12:11 PM, Michael Smith wrote:
On Jul 11, 2006, at 12:04 PM, email@hidden
wrote:
Read(2) will block if there is no data so there's no need to sleep.
Using select(2) is one way to go about it but with only one file
descriptor/socket, it seems pointless to me.
Select(2) makes timeout handling (mandatory for disconnectable
devices such as those attached by USB or serial interfaces) much
simpler.
Shouldn't that return -1 or 0?
I note in your example that you don't test for ret == 0, which in
the case
of a blocking read means that if the fd is closed for some reason
(e.g. the
device is destroyed due to removal) you will spin forever.
You're right. That's what happens when I write code in mail right
after waking up. =)
IMO, select with a non-blocking fd is a much cleaner way to implement
this; it also has the advantage of making additions to the code over
time much simpler, as it's an architectural stepping stone to a
state-machine.
I agree with the latter statement. For the former, I'm not sure. It
tends to lead to a long while loop consisting of checking if you can
read from each of the fds, reading from them, handling whatever that
was supposed to do, then doing the same for writing. When dealing
with multiple streams, this is the way to go. If there is only one
and will only ever be one, I think it's the wrong way to go unless
it's required for the timeout handling.
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