RE: [lwip-users] tcp_poll(), event handlers and possible misinformation

[Bill Auerbach]

>When a connection is idle (i.e., no data is either transmitted or
>received), lwIP will repeatedly poll the application by calling a
>specified callback function. This can be used either as a watchdog
>timer for killing connections that have stayed idle for too long, or
>as a method of waiting for memory to become available. For instance,
>if a call to tcp_write() has failed because memory wasn't available,
>the application may use the polling functionality to call tcp_write()
>again when the connection has been idle for a while.

Maybe this is legacy now.  If tcp_write cannot send data, it will be called
by the stack when data can be sent.

Or empirically, I don't use tcp_poll (it gave me problems) and I don't have
memory to send 500k at once. tcp_sent is simply called until I am able to
send all of my data.

Bill