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rpma_cq_get_fd(3) RPMA Programmer's Manual rpma_cq_get_fd(3)


rpma_cq_get_fd - get the completion queue's file descriptor


#include <librpma.h>
struct rpma_cq;
int rpma_cq_get_fd(const struct rpma_cq *cq, int *fd);


rpma_cq_get_fd() gets the file descriptor of the completion queue (CQ in short). When a next completion in the CQ is ready to be consumed by rpma_cq_get_wc(3), the notification is delivered via the file descriptor. The default mode of the file descriptor is blocking but it can be changed to non-blocking mode using fcntl(2). The CQ is either the connection's main CQ or the receive CQ or CQ of shared RQ, please see rpma_conn_get_cq(3), rpma_conn_get_rcq(3) or rpma_srq_get_rcq() for details.

Note after spotting the notification using the provided file descriptor you do not have to call rpma_cq_wait(3) before consuming the completion but it may cause that the next call to rpma_cq_wait(3) will notify you of already consumed completion.


The rpma_cq_get_fd() function returns 0 on success or a negative error code on failure. rpma_cq_get_fd() does not set *fd value on failure.


rpma_cq_get_fd() can fail with the following error:

RPMA_E_INVAL - cq or fd is NULL


fcntl(2), rpma_conn_get_cq(3), rpma_conn_get_rcq(3), rpma_srq_get_rcq(3), rpma_cq_wait(3), rpma_cq_get_wc(3), librpma(7) and

29 May 2023 RPMA