Table of Contents
stream_poll
Polls the stream to determine whether it is possible to send or receive or accept a connection without blocking.
Description
This function polls the stream to determine whether it is possible to send or receive or accept a connection without blocking. The flags argument determines the conditions for which to check. The return value indicates the conditions which occurred. This function returns after the given timeout with a value of 0 if none of the conditions occurs. If an error occurs, then it returns a negative error code. The function will return before the timeout if at least one of the conditions occurs prior to the timeout.
Prototype
t_int stream_poll(t_stream stream, const t_timeout * timeout, t_uint flags);
Parameters
t_stream stream
A stream established using stream_listen, stream_connect or stream_accept.
const t_timeout * timeout
A relative or absolute timeout which determines the maximum time that this function will wait for one of the conditions to occur before returning. A value of NULL indicates an infinite timeout.
t_uint flags
A bit mask indicating the conditions for which to check. Valid flags are:
STREAM_POLL_RECEIVE | - | on a listening stream, check for connections pending from clients. On a client stream, check whether there is any data available to receive. |
STREAM_POLL_SEND | - | not valid on a listening stream. On a client stream, check whether there is space in the stream buffer to store any data. |
STREAM_POLL_FLUSH | - | not valid on a listening stream. On a client stream, check whether it is possible to flush any more data without blocking. |
STREAM_POLL_ACCEPT | - | not valid on a client stream. On a listening stream, check whether there is a pending client connection. |
STREAM_POLL_CONNECT | - | not valid on a listening stream. On a client stream, check whether the connection has completed. |
Return value
A bit mask containing the conditions which were satisfied. It has the same definition as the flags argument. If none of the specified conditions occurs before the timeout, then 0 is returned. If an error occurs then a negative error code is returned.
Error codes
QERR_CANNOT_CONNECT
It was not possible to connect to the specified URI.
Requirements
Include Files |
Libraries |
---|---|
quanser_stream.h |
quanser_communications.lib;quanser_runtime.lib;quanser_common.lib |
Examples
const char uri[] = "shmem://foobar:1"; const t_boolean nonblocking = true; t_stream server; result = stream_listen(uri, nonblocking, &server); if (result == 0) { t_timeout timeout = { 1, 0, false }; ... while (!stop) { ... result = stream_poll(server, &timeout, STREAM_POLL_ACCEPT); if (result < 0) break; ... } }
See Also
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