HDDS-3130. Add jaeger trace span in s3gateway

[runzhiwang]

What changes were proposed in this pull request?

Add jaeger trace span in s3gateway.

What is the link to the Apache JIRA

https://jira.apache.org/jira/browse/HDDS-3130

How was this patch tested?

The jaeger UI shows the right trace information.

[runzhiwang]

@elek Could you help review this patch ? Thank you very much.

[elek]

Thank you very much the idea and the patch @runzhiwang I 100% support to introduce tracing for s3g. It's a very good idea.

About the implementation: It's definitely a step forward but I started to think how is it possible to do in a transparent way without duplication. I check if the resource name is available from some generic filter and it seems to be possible.

My proposal is to do it from a central place, something like this:

@Provider
public class TracingFilter implements ContainerRequestFilter,
    ContainerResponseFilter {

  public static final String TRACING_SCOPE = "TRACING_SCOPE";

  @Context
  private ResourceInfo resourceInfo;

  @Override
  public void filter(ContainerRequestContext requestContext)
      throws IOException {
    Scope scope = GlobalTracer.get().buildSpan(
        resourceInfo.getResourceClass().getSimpleName() + "." + resourceInfo
            .getResourceMethod().getName()).startActive(true);

    requestContext.setProperty(TRACING_SCOPE, scope);
  }

  @Override
  public void filter(ContainerRequestContext requestContext,
      ContainerResponseContext responseContext) throws IOException {

    Object scope = requestContext.getProperty(TRACING_SCOPE);
    if (scope != null) {
      ((Scope) scope).span().finish();
    }
  }
}

What do you think? I think it would simplify this patch (you don't need to modify all the methods...)

[runzhiwang]

@elek Very reasonable suggestion. I will try it, thank you very much.

[runzhiwang]

@elek Hi, I have updated PR according to you suggestion, thank you very much. Additionally, if throw exception when execute request, the method public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext) will not be executed, and span can not be finished, then the following jaeger span will have a error parent, just as the image shows. So I finish the old span before build a new span in closeActiveScope. Besides, scope.close also can not be ignored.

[runzhiwang]

The CI failure has nothing to do with this PR.

[runzhiwang]

@elek CI passed.

[elek]

+1 Thanks the update @runzhiwang

Tested and worked well. Will merge it soon.