Struct AckTracker 

pub struct AckTracker { /* private fields */ }

Thread-safe cumulative ACK tracker with waker notifications.

In Go-Back-N (and ResendSP), ACKs are cumulative. When receiving multiple in-order frames in rapid succession, AckTracker maintains the latest session ID and highest acknowledged sequence number. This prevents reverse-path flooding (e.g. queueing hundreds of redundant individual ACK frames) and ensures the writer task is immediately woken up to emit the cumulative ACK.

Both session_id and seq (along with the pending ACK flag) are packed into a single atomic u64 to prevent mixed-state torn reads between concurrent set_ack and take_ack calls.

Implementations

impl AckTracker

pub fn new() -> Self

Creates a new, empty ACK tracker.

pub fn set_ack(&self, session_id: u32, seq: u8)

Records a new cumulative ACK for session_id up to seq and notifies any waiting writer.

pub fn take_ack(&self) -> Option<(u32, u8)>

Retrieves and clears the latest cumulative ACK if one is pending.

pub fn register_waker(&self, cx: &mut Context<'_>)

Registers the current task waker to be notified when a new ACK is recorded.

pub async fn wait_ack(&self) -> (u32, u8)

Asynchronously waits until a cumulative ACK is recorded and returns (session_id, seq).

Note: Designed for a single waiting task. If multiple tasks await wait_ack(), only the most recently registered waker is notified when an ACK arrives.

Trait Implementations

impl Clone for AckTracker

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for AckTracker

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for AckTracker

fn default() -> Self

Returns the “default value” for a type.