[GitHub] [incubator-nuttx] v01d opened a new issue #3370: POLL/SELECT ON TCP/UDP SOCKETS NEEDS READ-AHEAD

[GitBox <gi...@apache.org>]

v01d opened a new issue #3370:
URL: https://github.com/apache/incubator-nuttx/issues/3370


   ```
     Description: poll()/select() only works for availability of buffered TCP/UDP
                  read data (when read-ahead is enabled).  The way writing is
                  handled in the network layer, either (1) If CONFIG_UDP/TCP_WRITE_BUFFERS=y
                  then we never have to wait to send; otherwise, we always have
                  to wait to send.  So it is impossible to notify the caller
                  when it can send without waiting.
   
                  An exception "never having to wait" is the case where we are
                  out of memory for use in write buffering.  In that case, the
                  blocking send()/sendto() would have to wait for the memory
                  to become available.
     Status:      Open, probably will not be fixed.
     Priority:    Medium... this does effect porting of applications that expect
                  different behavior from poll()/select()
   ```


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