Struct GcraRateLimiter 

pub struct GcraRateLimiter { /* private fields */ }

Sharded GCRA limiter over one or more stacked windows (DW-017).

Implements the RateLimiter trait: check(key, cost) reserves cost units in every stacked window for key (see the module docs for the stop-at-first-denial consumption semantics). Keys are opaque strings; the caller composes them (see RateLimitEngine).

Clocks: the GCRA math runs on governor’s own quanta monotonic clock; there is deliberately no clock injection for it. The EVICTION bookkeeping (per-key last-touch stamps) has a separate, injectable millisecond clock: new uses elapsed monotonic time, tests use GcraRateLimiter::with_clock to advance deterministically. The two clocks only meet in the idle-eviction threshold (one full refill of the window’s bucket), where both advance with wall time.

Implementations

impl GcraRateLimiter

pub fn new(specs: Vec<GcraWindowSpec>) -> Option<Self>

New limiter over the given window specs (any order; internally sorted shortest window first). Returns None for an empty spec list — a limiter with no windows cannot make decisions.

pub fn with_clock( specs: Vec<GcraWindowSpec>, now_ms: fn() -> u64, ) -> Option<Self>

New limiter using a caller-supplied millisecond clock for the per-key eviction bookkeeping (NOT the GCRA decisions — see the clocks note in the type docs).

Intended for tests and other time-controlled setups; production code should prefer GcraRateLimiter::new. now_ms must return non-decreasing milliseconds and is called once per window per check (cheap).

pub fn live_keys(&self) -> usize

Live per-key cell count across all stacked windows (sum of the shard maps; approximate under concurrent checks). Bounded by GCRA_STORE_SHARDS * crate::config::limits::MAX_RATE_LIMITER_KEYS_PER_SHARD per window — the bound the spray tests assert.

pub fn evictions(&self) -> u64

Cells dropped by eviction sweeps across all stacked windows (monotonic for the limiter’s lifetime; a reload builds a fresh limiter, so the counter resets with the generation).

pub fn check(&self, key: &str, cost: u32) -> GcraOutcome

Check-and-reserve cost units for key across all stacked windows (see module docs). cost 0 is treated as 1 (a request always costs at least one unit); a cost larger than any window’s bucket is always denied.

Trait Implementations

impl Debug for GcraRateLimiter

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

Formats the value using the given formatter.

impl RateLimiter for GcraRateLimiter

fn check<'life0, 'life1, 'async_trait>( &'life0 self, key: &'life1 str, cost: u32, ) -> Pin<Box<dyn Future<Output = Result<RateDecision, ExtensionsError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Atomically decide-and-reserve cost units for key.