/**
* Get the amount of buffer space available and enable notifications if needed.
*/
static inline int fast_get_data_ready(struct libxenvchan *ctrl, size_t request)
{
int ready = rd_prod(ctrl) - rd_cons(ctrl);
if (ready >= request)
return ready;
/* We plan to consume all data; please tell us if you send more */
request_notify(ctrl, VCHAN_NOTIFY_WRITE);
/*
* If the writer moved rd_prod after our read but before request, we
* will not get notified even though the actual amount of data ready is
* above request. Reread rd_prod to cover this case.
*/
return rd_prod(ctrl) - rd_cons(ctrl);
}
int libxenvchan_data_ready(struct libxenvchan *ctrl)
{
/* Since this value is being used outside libxenvchan, request notification
* when it changes
*/
request_notify(ctrl, VCHAN_NOTIFY_WRITE);
return rd_prod(ctrl) - rd_cons(ctrl);
}
/*
* Get the amount of buffer space available, and do nothing about
* notifications.
*/
static inline int raw_get_data_ready(struct libxenvchan *ctrl)
{
uint32_t ready = rd_prod(ctrl) - rd_cons(ctrl);
if (ready >= rd_ring_size(ctrl))
/* We have no way to return errors. Locking up the ring is
* better than the alternatives. */
return 0;
return ready;
}
int libvchan_data_ready(struct libvchan *ctrl)
{
return rd_prod(ctrl) - rd_cons(ctrl);
}