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Releases

v2.0.0

The 2.0.x release should be considered somewhat unstable.

  • Breaking: Complete API redesign. The v1.x classes (Async::Limiter::Concurrent, Async::Limiter::Unlimited, etc.) have been replaced with a new inheritance-based architecture.
  • Breaking: Removed blocking? method due to inherent race conditions. Use acquire(timeout: 0) for non-blocking checks.
  • Breaking: Timing strategies now use consumption-only model (no explicit release methods).
  • Breaking: Window classes moved from limiter/window/ to limiter/timing/ with renamed classes.

New Architecture (replaces v1.x classes)

  • New: Async::Limiter::Generic - Unlimited concurrency with timing coordination (replaces Async::Limiter::Unlimited).
  • New: Async::Limiter::Limited - Counting semaphore with configurable limits (replaces Async::Limiter::Concurrent).
  • New: Async::Limiter::Queued - Queue-based resource distribution with priority/timeout support (completely new functionality).

Advanced Timeout Features

  • New: Unified timeout API - acquire(timeout: 0/nil/seconds) provides non-blocking and timed acquisition.
  • New: Precise deadline tracking using Async::Deadline (requires async v2.31.0+).
  • New: Convoy effect prevention - quick timeout operations not blocked by slow operations.
  • New: Accurate timeout propagation - remaining time correctly passed through timing and concurrency layers.

Cost-Based Acquisition

  • New: Cost-based acquisition - acquire(cost: 1.5) for proportional resource consumption.
  • New: Starvation prevention - validates cost against timing strategy maximum_cost capacity.
  • New: Flexible operation weighting - light operations consume fewer resources than heavy ones.

Enhanced Timing Strategies

  • Add Async::Limiter::Timing::LeakyBucket for token bucket rate limiting with automatic leaking.
  • Add Async::Limiter::Timing::FixedWindow for discrete time boundary enforcement.
  • Rename Async::Limiter::Timing::Window to Async::Limiter::Timing::SlidingWindow for clarity.
  • Breaking: Remove release methods from timing strategies (consumption-only model).
  • Breaking: Remove try_acquire methods from timing strategies (unified timeout API).

Token-Based Resource Management

  • New: acquire_token method returns Token objects for advanced resource management.
  • New: Token re-acquisition with different options - token.acquire(priority: 5).
  • New: Automatic token cleanup with block usage.

Thread Safety and Performance

  • New: Race condition elimination by moving timing coordination inside mutex.
  • New: Fast path optimizations using deadline.expired? checks.
  • New: Atomic timing coordination prevents race conditions in concurrent access.
  • Improved: Test performance using time simulation instead of actual sleep calls.