Re: [MI400] what is a reasonable socket select() wait time?

[Rich Duzenbury <rduz@xxxxxxxxxxxxxxxxxxx>]

>
>Why does the select() periodically fail?  How can my client truly, TRULY
>determine if more data is available from the server?  Do I need a non-zero
>wait time?  What is a reasonable value?

I don't think select is 'failing' per se.  There just isn't any data
-yet-.  Lost & retransmitted packets by the underlying transport mechanism
could cause this, as another poster mentioned.  A busy network might also
cause select give up before any data is available.

Perhaps I read too much into your message, but I wonder how your actual
protocol is setup.  The receive side of the socket knows how much data to
expect, right?

If you send a fixed length message, your read loop should loop until a
complete message is read, or an error occurs.

If you send a delimited message - e.g. a null byte at the end of each
message, your read loop should read until the null is located, or an error
occurs

Otherwise, you could preface a variable length message with the number of
bytes to follow, and then loop until that many bytes are received, or an
error occurs.

The point is, the receive loop has to *know* how much data to look for.
Also, the loop must be prepared to receive a message in 'chunks' or
'pieces' by comparing the received count with the requested count, and
acting accordingly by requesting to read the remaining data.