table of contents
XS_POLL(3) | Crossroads I/O Manual | XS_POLL(3) |
NAME¶
xs_poll - input/output multiplexingSYNOPSIS¶
int xs_poll (xs_pollitem_t *items, int nitems , int timeout);DESCRIPTION¶
The xs_poll() function provides a mechanism for applications to multiplex input/output events in a level-triggered fashion over a set of sockets. Each member of the array pointed to by the items argument is a xs_pollitem_t structure. The nitems argument specifies the number of items in the items array. The xs_pollitem_t structure is defined as follows:typedef struct { void *socket; int fd; short events; short revents; } xs_pollitem_t;
For Crossroads sockets, at least one message may be
received from the socket without blocking. For standard sockets this is
equivalent to the POLLIN flag of the poll() system call and
generally means that at least one byte of data may be read from fd
without blocking.
XS_POLLOUT
For Crossroads sockets, at least one message may be sent
to the socket without blocking. For standard sockets this is equivalent
to the POLLOUT flag of the poll() system call and generally
means that at least one byte of data may be written to fd without
blocking.
XS_POLLERR
For standard sockets, this flag is passed through
xs_poll() to the underlying poll() system call and generally
means that some sort of error condition is present on the socket specified by
fd. For Crossroads sockets this flag has no effect if set in
events, and shall never be returned in revents by
xs_poll().
RETURN VALUE¶
Upon successful completion, the xs_poll() function shall return the number of xs_pollitem_t structures with events signaled in revents or 0 if no events have been signaled. Upon failure, xs_poll() shall return -1 and set errno to one of the values defined below.ERRORS¶
ETERMAt least one of the members of the items array
refers to a socket whose associated context was
terminated.
EFAULT
The provided items was not valid (NULL).
EINTR
The operation was interrupted by delivery of a signal
before any events were available.
EXAMPLE¶
Polling indefinitely for input events on both a Crossroads socket and a standard socket..xs_pollitem_t items [2]; /* First item refers to Crossroads socket 'socket' */ items[0].socket = socket; items[0].events = XS_POLLIN; /* Second item refers to standard socket 'fd' */ items[1].socket = NULL; items[1].fd = fd; items[1].events = XS_POLLIN; /* Poll for events indefinitely */ int rc = xs_poll (items, 2, -1); assert (rc >= 0); /* Returned events will be stored in items[].revents */
SEE ALSO¶
xs_socket(3) xs_send(3) xs_recv(3) xs(7) Your operating system documentation for the poll() system call.AUTHORS¶
The Crossroads documentation was written by Martin Sustrik < sustrik@250bpm.com[1]> and Martin Lucina < martin@lucina.net[2]>.NOTES¶
- 1.
- sustrik@250bpm.com
mailto:sustrik@250bpm.com
- 2.
- martin@lucina.net
mailto:martin@lucina.net
06/13/2012 | Crossroads I/O 1.2.0 |