* Optimize logging statements using placeholder to avoid unnecessary concatenation (issue #1735)

Signed-off-by: yunfeiyanggzq <yunfeiyang@buaa.edu.cn>

Signed-off-by: yunfeiyanggzq <yunfeiyang@buaa.edu.cn>

Signed-off-by: yunfeiyanggzq <yunfeiyang@buaa.edu.cn>

Signed-off-by: yunfeiyanggzq <yunfeiyang@buaa.edu.cn>

Fix issue #1705.

- Use CAS to make it thread safe and limited in the declared range.

Signed-off-by: cj <power4j@outlook.com>

Use `getRequestURI` instead of `getServletPath` to get URI of current request(Both in prefix and regex matching).

Signed-off-by: yunfeiyanggzq <yunfeiyang@buaa.edu.cn>

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

- Fix NPE bug in consumer filter (when non-biz error occurred)
- Improve default fallback in Dubbo 2.7.x adapter: convert the BlockException to a simple RuntimeException (with necessary message)
- Polish code and comments

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

If entry already exists in request just skip creation.

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

* Support customized origin parser in Apache Dubbo 2.7.x adapter
* Unify Dubbo callback registry (for fallback and origin parser) into DubboAdapterGlobalConfig
* Polish default fallback implementation (wrap exception with RpcResult rather than directly throw it out)

- Unify the extended interface as a few event handlers: onPass, onBlocked, onComplete and onError
- Polish related code

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

* Unify Dubbo callback registry (for fallback and origin parser) into DubboAdapterGlobalConfig
* Polish default fallback implementation (wrap exception with RpcResult rather than directly throw it out)

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

- Add EntryType args to all hook methods

- Rename: whenComplete -> whenTerminate
- Execute the exit handler directly after the onExit hook of all slots

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

- Only carry context in tryPass/onComplete method (this might be generic in upcoming versions)

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

* Refactor the workflow to fix the bug that circuit breaker may remain half-open state forever when the request is blocked by upcoming rules: revert the state change in exit handler (as a temporary workaround)
* Add exit handler in Entry as a per-invocation hook.

Signed-off-by: cj <power4j@outlook.com>

Signed-off-by: yunfeiyanggzq <yunfeiyang@buaa.edu.cn>

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

* Add `CircuitBreaker` abstraction (with half-open state) and add circuit breaker state change event observer support.
* Improve circuit breaking strategy (avg RT → slow request ratio) and make statistics of each rule dependent (to support arbitrary statistic interval).
* Add simple "trial" mechanism (aka. half-open).
* Refactor mechanism of metric recording and state change handling for circuit breakers: record RT and error when requests have completed (i.e. `onExit`, based on #1420).

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Signed-off-by: yunfeiyanggzq <yunfeiyang@buaa.edu.cn>

- One config per interceptor instead of the global config
- Polish document and demo

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Signed-off-by: yunfeiyanggzq <yunfeiyang@buaa.edu.cn>

Introduce support through a customized client builder `SentinelApacheHttpClientBuilder`.

Signed-off-by: yunfeiyanggzq <yunfeiyang@buaa.edu.cn>

Signed-off-by: Eric Zhao <sczyh16@gmail.com>