Struct BackpressureTracker 

pub struct BackpressureTracker { /* private fields */ }

Per-peer receiver-side back-pressure state.

Sibling field on PeerState per bb-runtime/src/framework/peer_state.rs. The tracker is receiver-state-only; sender-side back-off lives in the existing BackoffTable.

Implementations

impl BackpressureTracker

pub fn new() -> Self

Construct a fresh tracker with the spec’s defaults (high-water = 75%, K = 3, min-notice-interval = 1 second).

pub fn with_config( high_water_mark_pct: u8, notice_threshold_k: u32, min_notice_interval_ns: u64, ) -> Self

Construct a tracker with custom config values. high_water_mark_pct is clamped to 1..=100; notice_threshold_k is clamped to at least 1; min_notice_interval_ns is clamped to at least 1.

pub fn high_water_mark_pct(&self) -> u8

High-water mark threshold as a percentage.

pub fn is_over_high_water(&self, len: usize, capacity: usize) -> bool

Whether the supplied queue depth (len) crosses the configured high-water mark for the supplied capacity.

pub fn notice_threshold_k(&self) -> u32

K threshold (notices-without-recovery before silent-drop).

pub fn min_notice_interval_ns(&self) -> u64

Minimum interval enforced between successive notices to the same peer.

pub fn is_silent_drop_active(&self, peer: PeerId) -> bool

Whether the peer is currently in silent-drop mode.

pub fn entry(&self, peer: PeerId) -> Option<BackpressureEntry>

Inspect the recorded entry for peer. Returns None when no overload event has been observed for this peer yet.

pub fn iter(&self) -> impl Iterator<Item = (PeerId, BackpressureEntry)> + '_

Iterate (PeerId, BackpressureEntry) for snapshot capture.

pub fn len(&self) -> usize

Number of peers currently tracked.

pub fn is_empty(&self) -> bool

Whether any peer has been tracked.

pub fn observe_overload( &mut self, peer: PeerId, cause: BackoffCause, min_backoff_ns: u64, now_ns: u64, ) -> Decision

Observe an overload condition for peer at now_ns.

Returns:

• Decision::SilentDrop if the peer is already in silent-drop mode. The caller drops the envelope; no notice is emitted.
• Decision::Suppress if a recent notice’s quoted back-off window has not yet elapsed (duplicate suppression).
• Decision::EmitNotice if the caller should emit a notice. The tracker increments notices_sent + records the emission timestamp + back-off. If this push crosses the K threshold, the entry transitions to silent_drop_active in the next observation - the current decision still emits the K-th notice so the sender gets the final warning before silent drop kicks in.

min_backoff_ns is the back-off duration the caller intends to quote on the notice. The tracker uses it for the duplicate-suppression window. A 0 value collapses to the configured min_notice_interval_ns floor.

pub fn record_recovery(&mut self, peer: PeerId)

Record that the sender has recovered (e.g., φ-accrual transitioned back to Live). Resets the per-peer counter and clears silent_drop_active. The next observe_overload for the peer starts fresh.

pub fn in_suppression_window(&self, peer: PeerId, now_ns: u64) -> bool

Whether peer is currently inside its duplicate-suppression window. Used by tests + introspection.

Trait Implementations

impl Default for BackpressureTracker

fn default() -> Self

Returns the “default value” for a type.