Fix nested http.route

[heyams]

this will replace #8112

I will try my best to explain the fix:

CONTROLLER(3),
  // Some frameworks, e.g. JaxRS, allow for nested controller/paths and we want to select the
  // longest one
NESTED_CONTROLLER(4, false);

HttpRouteHolder.updateHttpRoute will get called twice.
1st is triggered by the RateOnSuccess with route /{id:[A-Z0-9\-]+}
2nd time is triggered by the HandlerAdapterInstrumentation.onMethodEnter with the full route including the nested paths.

When using HttpRouteSource.CONTROLLER, it has useFirst set to true.
2nd time didn't do anything.

When using 'HttpRouteSource.NESTED_CONTROLLER, it has useFirst set to false.
2nd time it will update the route to /api/accounts/{id:[A-Z|0-9|\-]+}.

I will try to come up with a test for it if it's feasible.

here is the test app https://github.com/heyams/otel-http-route-sample

[heyams]

WebfluxSingletons.httpRoutGetter

the newly added test will fail because ServerWebExchange.getAttribute(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE) returns null, however ServerWebExchange.getAttribute("org.springframework.web.reactive.function.server.RouterFunctions.request has the full nested route.

BEST_MATCHING_PATTERN_ATTRIBUTE is automatically ingested by webflux. I wonder if someone can help me take a look at why BEST_MATCHING_PATTERN_ATTRIBUTE is always null in this case. Http.route will get updated correctly if this attribute is not null using NESTED_CONTROLLER.

self-resolved :)

[trask]

thx for figuring out how to add a test for this!

[trask]

cc @siyuniu-ms

[trask]

can you add a brief comment here about why NESTED_CONTROLLER is needed?

[breedx-splk]

I haven't looked into the test code, but there was a single test failure which suggests an edge case maybe:

> Task :instrumentation:spring:spring-webflux:spring-webflux-5.0:javaagent:test
DelayedControllerSpringWebFluxServerTest > nestedPath() FAILED
    org.opentest4j.AssertionFailedError: 
    expected: 200
     but was: 404

[heyams]

I haven't looked into the test code, but there was a single test failure which suggests an edge case maybe:

> Task :instrumentation:spring:spring-webflux:spring-webflux-5.0:javaagent:test
DelayedControllerSpringWebFluxServerTest > nestedPath() FAILED
    org.opentest4j.AssertionFailedError: 
    expected: 200
     but was: 404

Thanks! It should be fixed now.

[mateuszrzeszutek]

Thanks @heyams !