Struct RingReader 

pub struct RingReader<R> { /* private fields */ }

The reading end of a CDBG ring: takes frames, never waits, never allocates.

Implementations

impl<R: Region> RingReader<R>

pub unsafe fn new(region: R) -> Result<Self, RingError>

Read the ring in region, after validating its descriptor.

Safety

This must be the ring’s only reader for as long as it lives: two readers would race on read_ptr.

pub fn into_region(self) -> R

The region back.

pub fn region(&self) -> &R

The region this reader reads.

pub fn snapshot(&self) -> Descriptor

A point-in-time copy of the descriptor.

pub fn drain(&mut self, on_frame: impl FnMut(&[u8])) -> Result<usize, RingError>

Take every frame that was in the ring when the call began, handing each to on_frame, and return how many there were.

The batch is bounded by one snapshot of write_ptr: frames the writer appends while the drain runs wait for the next call. A drain that chased the live cursor could run for as long as the writer kept up, starving whatever the caller does between drains (decoding, emitting, checking for shutdown). Allocation-free; a frame is never longer than MAX_FRAME_LEN.

Trait Implementations

impl<R: Region> TransportError for RingReader<R>

type Error = RingError

impl<R: Region> TryRecvTransport for RingReader<R>

Copies the next frame into buf and consumes it.

TryError::WouldBlock means the ring is empty. A frame longer than buf is RingError::BufferTooSmall and stays unread, so the caller can retry with a buffer of max_recv_size bytes, which always fits.

fn try_recv(&mut self, buf: &mut [u8]) -> Result<usize, TryError<RingError>>

Copy the next frame into buf if one is readable now.

fn max_recv_size(&self) -> usize

Maximum bytes transferable in a single try_recv.