Struct UpstreamInstance 

pub struct UpstreamInstance { /* private fields */ }

One backend instance (host:port) of an upstream, with its health state (ADR 000017).

The hot path (pick → UpstreamInstance::is_healthy) reads a lock-free AtomicBool. State transitions take a small per-instance Mutex so “increment a counter, compare the threshold, flip the bit, reset” is race-free — but the mutex is touched only on a probe (cold, every interval) or a passive connect failure (rare), never on the success hot path.

Implementations

impl UpstreamInstance

pub fn address(&self) -> &str

This instance’s host:port.

pub fn weight(&self) -> u32

This instance’s load-balancing weight (ADR 000035), >= 1.

pub fn in_flight(&self) -> usize

Current active forwarded-request count to this instance (ADR 000035) — the least-request load signal. Lock-free read.

pub fn is_healthy(&self) -> bool

Whether this instance is currently in rotation. Lock-free — the round-robin hot path.

pub fn is_outlier_ejected(&self, now_ms: u64) -> bool

Whether this instance is currently outlier-ejected at now_ms (ADR 000032). Lock-free — the pick hot path. The ejection auto-expires when its window passes (no probe needed); this is a distinct axis from is_healthy (an instance can be probe-healthy yet outlier-ejected).

pub fn record_probe_success(&self)

Record a successful active probe (a 2xx within the timeout). Promotes a pessimistic / ejected instance once it reaches its threshold — one success the first time ever, healthy_threshold after a later eject — and resets the consecutive-failure streak.

pub fn record_probe_failure(&self)

Record a failed active probe (non-2xx, timeout, or connect error).

pub fn record_passive_failure(&self)

Record a passive failure — a real forwarded request that could not even connect to this instance (ADR 000017). It demotes exactly like a probe failure, but can only ever demote: an ejected instance receives no traffic, so only the active prober restores it.

Trait Implementations

impl Debug for UpstreamInstance

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

Formats the value using the given formatter.