Implement scope.close method

[pavolloffay]

Related to: opentracing/opentracing-java#267 #82 and #74 (comment)

Signed-off-by: Pavol Loffay ploffay@redhat.com

[codefromthecrypt]

this programming pattern can cause misalignment bugs as it encourages people to close a scope they didn't open. I left a comment here opentracing/opentracing-java#267 (comment)

you can refer to serious users of tracing like @anuraaga and folks at LINE who spend hours trying to debug misalignment problems. please don't make apis that encourage bugs

[pavolloffay]

this programming pattern can cause misalignment bugs as it encourages people to close a scope they didn't open. I left a comment here opentracing/opentracing-java#267 (comment)

I agree, however this should be changed in the OT API and not by not implementing the method correctly. The issues is that the current implementation does not work with many OT instrumentations:

• IllegalArgumentException on BraveScopeManager.active().close() #73
• BraveScopeManager.active() and opentracing-jaxrs #82 (comment)
• Fix for issue #73: Allow ScopeManager.active().close() and let it be a no-op #74

[codefromthecrypt]

sorry, the javadoc says this is only used to get the active span.

https://github.com/opentracing/opentracing-java/blob/master/opentracing-api/src/main/java/io/opentracing/ScopeManager.java#L39

that part is implemented and you guys have no tests. This issue will be left open to encourage you to fix the api.

[codefromthecrypt]

by the way. you personally wrote or copied most of the instrumentations that don't work. You can fix those.