RecvMulti

RecvMulti abstracts the underlying [io_uring::opcode::RecvMulti](https://docs.rs/io-uring/latest/io_uring/opcode/struct.Recv Multi.html).

Note: This is being migrated to implement the OpCode + OpCompletion traits similar to EpollCtl.

Construct

RecvMulti requires both a registered filehandle and previously registered / kernel-mapped buffer/s with the referred group.

Submission

Use UringBearer::add_recv_multi to submit a RecvMulti to kernel.

Completion

RecvMulti(RecvMultiRec) is provided normally through the handler API via UringBearer.

See Buffers on how to deal with individual "selected buffers" within registered "grouped" Buffers.

Lifetime (Manual handling)

It would be undefined behaviour if the submission record is invalidated before the Multi-shot submission is either confirmed cancelled or timed out.