Module rate 

Rate primitives: express “N units per period” and enforce it.

The core of this module is sans-IO and no_std: TokenBucket never reads a clock, the caller provides time as monotonic nanoseconds. This keeps it trivially testable and embeddable in other sans-IO state machines (e.g. a send scheduler pacing datagrams).

On top (behind the std feature) RateLimiter wraps a TokenBucket in a cheap-to-clone shared handle that can wait (pace) or reject (rate limit) using tokio timers.

Units are whatever you want them to be: requests, connections, messages, bytes.

Structs

Rate

A rate: units per per period.

RateLimiter

A cheap-to-clone async handle around a shared TokenBucket: clones share the same budget.

TokenBucket

A sans-IO token bucket: spend units at a bounded Rate with a configurable burst capacity.

Enums

Acquire

The result of TokenBucket::try_acquire (and RateLimiter::try_acquire).