feat: add try_wait_n for atomic multi-token acquisition#8
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Consumes n tokens in a single CAS or fails without partial consumption. Introduces TryWaitError with two variants: Insufficient(Duration) for transient shortage (same retry semantics as try_wait's Err) and ExceedsCapacity when n > max_tokens. The capacity check runs before refill so callers get a clear signal instead of spinning against a bucket that can never fill. try_wait() is unchanged. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
Ratelimiter::try_wait_n(n)— atomically consumesntokens in a single CAS, or fails without partial consumption.TryWaitErrorwithInsufficient(Duration)(transient; retry after duration) andExceedsCapacity(n > max_tokens; waiting will never satisfy).try_wait()signature unchanged — stillResult<(), Duration>.Changes
Test plan
cargo test— 23 tests pass (4 new covering try_wait_n basic, zero-noop, unlimited, no-partial-consumption, and exceeds-capacity)cargo test --releasecargo clippy --all-targets -- -D warningscargo fmt --all -- --checkRUSTDOCFLAGS="-D warnings" cargo doc --no-depsmax_tokens >= batch_sizeat construction, or handleTryWaitError::ExceedsCapacityexplicitly🤖 Generated with Claude Code