Re: tasksing and TCP sockets

[Simon Wright <simon@pushface.org>]

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> On 30 Jan 2006 14:12:51 -0800, Rolf wrote:

>>  - I don't know much about sockets (or better I don't remember much).
>> Does a waiting read (in the second task) block a write in the first
>> task?
>
> Usually not. Note that you must wait not for a socket read, but for a
> "variable-update" event from the middleware layer.

_Something_ has to wait for a socket read! If you're writing your own
'middleware' (lower layers, anyway) that will be you.

Windows is not wonderful for this sort of thing but I have not seen
problems of the sort you describe with a task blocked on the read
(input_t'Input) and other code (either another single task, or some
sort of mutex) for output_t'Output.

>>  - what other hints can you give me?
>
> Never ever use UPD, avoid TCP_NO_DELAY with TCP/IP. The first is
> unreliable for your purpose, the second quickly brings the network
> down.

Probably best to avoid these (I guess that UPD was a typo for UDP) at
the start, but sometimes they are the appropriate solution. Not often,
maybe.