IllegalArgumentException when using with Brave Tracer about java-api-extensions

[objectiser]

Unfortunately this is not possible, as the library needs to register the APIExtensionsSpan instance with the ScopeManager, rather than the BraveSpan, as the wrapper intercepts various method calls on the span to then invoke the SpanObserver.

For example, instrumentation may later retrieve the active span from the ScopeManager to add tags, logs or finish the span. These must be performed on the APIExtensionsSpan instance, otherwise the observer would not be called.

[objectiser]

I'm going to close the issue, but feel free to re-open if you would like to discuss further. Other option would be to raise an issue against the OT spec to start a discussion about supporting the observer as part of the core API.

[michbeck100]

Another option to implement the extensions would be to use a proxy using java.lang.reflect.Proxy. This would solve the problem with class casts.
Did you think about this option when implementing?

[sjoerdtalsma]

@michbeck100 Using proxies could actually be a really good idea.
One possibly complicating factor that must be considered is the new module system introduced by Java 9. Switching to proxies may make modularizing the api-extensions in the future more difficult.

[objectiser]

@michbeck100 no didn't consider this option at the time, but as @sjoerdtalsma says, could be a good idea.

Would you be interested in contributing a PR, and also possibly looking into the java9 issue mentioned by @sjoerdtalsma ?

[whiskeysierra]

Another option to implement the extensions would be to use a proxy using java.lang.reflect.Proxy. This would solve the problem with class casts.

Java Proxies only support interfaces, not classes and BraveSpan is a class. I don't believe this would work.

What might work is to keep references to spans in weak-reference, identity hashmap which maps real span to instrumented span. Before passing something to the underlying implementation you unwrap it and when we get an uninstrumented span back that we need to expose we look it up in that map.

[whiskeysierra]

On a second thought, why not have a proxy for ScopeManager which automatically decorates any span it exposes via activeSpan?

[objectiser]

@whiskeysierra How would the proxied ScopeManager be set on the tracer?

[whiskeysierra]

You just return it upon every call to the scopeManager method.

…

On Tue, Sep 10, 2019, 18:14 Gary Brown ***@***.***> wrote: @whiskeysierra <https://github.com/whiskeysierra> How would the proxied ScopeManager be set on the tracer? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#16?email_source=notifications&email_token=AADI7HOHZ7F6ECJXGWJAX53QI7BVJA5CNFSM4FG6TKDKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD6LVGEI#issuecomment-530010897>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AADI7HICRUCGJMLZEGNT4S3QI7BVJANCNFSM4FG6TKDA> .