//! Core implementations of Sentinel.
/// Basic definitions, traits, and implementations for Sentinel slot chain, entry, context and so on.
/// Circuit breaker rules and slots.
/// Configuration utilities.
/// Flow control rules and slots.
/// Hot key rules and slots.
/// Resource isolation rules and slots. Currently, only concurrency is supported.
/// Metric logging slots.
/// Statistic slots and basic data structures,
/// such as the slding window and its underlying LeapArray
/// System status rules and slots.
/// System status collector.