* Add reactive adapter implementation for Project Reactor (Mono/Flux) including a reactor transformer and an experimental `ReactorSphU`
* Add an `InheritableBaseSubscriber` that derives from the original BaseSubscriber of reactor-core
* Add basic test cases for reactor adapter
* Add Sentinel context enter support for EntryConfig in reactor transformer
Signed-off-by: Eric Zhao <sczyh16@gmail.com>
- Add callback registry for statistic slot for extensions.
- Add a new module `sentinel-parameter-flow-control` under `sentinel-extension`.
- Add a `CacheMap` interface to provide abstraction for cache. We use ConcurrentLinkedHashMap as the default implementation (LRU strategy)..
- Add a `ParameterMetric` class as frequent parameter metrics for a specific resource. The metric map is located in `ParamFlowSlot` rather than `ClusterNode`.
- Implement `ParameterLeapArray` as statistic data structure for frequent parameters in a period of time window.
- Add `ParamFlowSlot` as the checker slot; Add `ParamFlowChecker` to do rule checking; Add `ParamFlowRuleManager` to do rule managing.
- The statistic metrics for frequent parameters is enabled only if the related resource has configured parameter flow rule; Parameter metrics for removed rules will be cleared automatically.
- Leverage extensible `SlotChainBuilder` to provide a `HotParamSlotChainBuilder`.
- Add command handlers for hot param rules.
- Add test cases and demo.