vrtd::QdmaQpair

class QdmaQpair

RAII wrapper for a QDMA queue pair (qpair).

A QdmaQpair owns a qpair created through a Session. It provides convenience methods to start/stop the qpair and to obtain a read/write file descriptor. On destruction, it requests deletion of the qpair.

Warning

A QdmaQpair becomes invalid if its originating Session is closed or moved; methods will throw in that case. The destructor never throws and will silently ignore errors when attempting to delete the qpair.

Public Functions

inline uint32_t getDeviceNum() const noexcept

Device index owning this qpair.

inline uint32_t getQid() const noexcept

Qpair identifier as assigned by the kernel.

void start()

Start the qpair.

Throws:

vrtd::Error – on error.

void stop()

Stop the qpair.

Throws:

vrtd::Error – on error.

int fd(uint32_t flags = O_CLOEXEC)

Obtain a read/write file descriptor for this qpair.

Parameters:

flags – OR of O_CLOEXEC and 0 (other flags may be rejected).

Throws:

vrtd::Error – on error.

Returns:

New file descriptor owned by the caller.

std::fstream fstream(uint32_t flags = O_CLOEXEC, std::ios_base::openmode mode = std::ios_base::in | std::ios_base::out | std::ios_base::binary)

Obtain a std::fstream bound to this qpair.

Note

Implementation is Linux-specific and relies on /proc/self/fd.

Parameters:

• flags – OR of O_CLOEXEC and 0 (other flags may be rejected).

• mode – Standard iostream open mode (defaults to in|out|binary).

Throws:

vrtd::Error – or std::runtime_error on error.

Returns:

A std::fstream owning a new file descriptor for this qpair.