Re: [lwip-users] TCP Flush

[Kieran Mansley]

On Thu, 2010-08-05 at 15:20 +0200, address@hidden wrote:
> Hello,
> 
> With tcp you never know when exactly the data will be sent.
> With flush (tcp_output) you force the stack to really send the data, but 
> that doesn't work that good.

You sum it up in the first sentence: with TCP you never know when the
data will be sent.  tcp_output() is not a means to know that the data
are sent - it's just a way of asking the stack to send now if it can.
There are lots of reasons why a call to tcp_output() would do nothing
and this is by design - if it was otherwise it would break the TCP
specification.

To discover when data have been successfully sent use the tcp_sent()
callback.

Kieran