Initial tracing

[pankajagrawal16]

This is initial suggestion on implementing tracing like power tool.

This PR is meant to start discussion on different aspect of tracing support that we want to have.

PS: test cases are deferred until we decide on approach

[pankajagrawal16]

Helper utils for setting annotation and metadata on current segment

[stevehouel]

Can we directly do a good Javadoc documentation?
for info, we will extract all javadoc in order to generate our own documentation website and make it publicly available

[pankajagrawal16]

I belive its too early to spend effort on writing java docs. IMO we can delay it a bit until we have a but more structure

[pankajagrawal16]

We can enrich this further like its done in logging part, but we can do that once we agree on approach here.

[pankajagrawal16]

These follow the feature from python powertools

[pankajagrawal16]

Few more things that we should discuss:

• How to support tracing of segment for worker threads ? One options is:

   Entity traceEntity = AWSXRay.getTraceEntity();
            Thread comm = new Thread(() -> {
                AWSXRay.setTraceEntity(traceEntity);
                log();
            });

    @PowerToolTracing
    private void log() {
       log.info("inside threaded logging");
    }

Following what we have here https://docs.aws.amazon.com/xray/latest/devguide/scorekeep-workerthreads.html, I cant see how we can improve this experience any further if we have to keep traces under same parent segment.

• Should annotation give flexibility of creating new Trace entity ?
• How can we autopatch or instrument client which is done as part of python power tool ? For java it has to be client specific and has to be left upto users ? Like this https://docs.aws.amazon.com/xray/latest/devguide/xray-sdk-java-awssdkclients.html ?. Should we provide util methods that can give user XRay instrumented clients with some default configs ?

[pankajagrawal16]

Sample example from XRay

[msailes]

In the python impl this is "service_undefined" by default. Might be worth matching their project for consistency.

[pankajagrawal16]

Xray recorder lib by default uses:

private static final String DEFAULT_METADATA_NAMESPACE = "default";

But i can update it to match with that of powertools.

[msailes]

Can this be renamed to LambdaLoggingAspect

[msailes]

Can we have the cold start logic in a single place?

[stevehouel]

Good to me, only need more Javadoc things in order to meet high standard on our code.

[pankajagrawal16]

I do agree we need to have java doc, but at the same time i feel we should delay it a bit to avoid rework coz of some of the refactoring etc that we might end up doing.