Duplicate calls of a custom HandlerInterceptor's methods after updating to Spring Data REST 3.4

[lwitzani]

Hi,
Background:
We have a Spring Boot project and recently updated our dependencies from Spring Boot 2.3.7.RELEASE to 2.4.0!
Spring Framework therefore changed from 5.2.12.RELEASE to 5.3.1

Use case:
We have a custom interceptor (let's call it ActivityLoggerInterceptor) that implements org.springframework.web.servlet.HandlerInterceptor
We are registering the interceptor similar to the following:

@Configuration
public class WebMvcConfig {

    @Bean
    public MappedInterceptor mappedInterceptor() {
        return new MappedInterceptor(
                new String[]{"/api/**"},
                new ActivityLoggerInterceptor()
        );
    }
}

This worked perfectly on Spring Boot 2.3.7.RELEASE / Spring 5.2.12.RELEASE meaning the handler methods preHandle and afterCompletion were called once per request.

The issue:
After updating to Spring Boot 2.4.0 / Spring 5.3.1 the methods preHandle and afterCompletion in our interceptor are each called twice

Observations:
After some debugging i found that our Interceptor is somehow now found twice (see the picture below).

From there it goes deep into Spring ...
Because of this and because i did not find anything that our registration of the Interceptor could be wrong now, i am writing this issue.
Looking through the closed and open issues i did not find anything that would match this problem. But it seems that something around MappedInterceptors has changed in Spring.

Can you help me somehow :)? Thanks so much!

Best regards,
Lukas

[rstoyanchev]

It looks like it's not as simple as adding such a bean to a Boot 2.4.1 application. Any more details on how to reproduce or if you can provide a sample? You can also try debugging in AbstractHandlerMapping#initApplicationContext to see how the interceptor chain gets initialized.

[lwitzani]

Hi,
thanks for answering!

I made a sample project that reproduces the issue. You can find it here https://github.com/lwitzani/springIssue26378
The project has two branches where the only difference is the used Spring Boot version.
I did not debug into AbstractHandlerMapping yet but will do now.

Best regards,
Lukas

[lwitzani]

It seems that on application start in class RepositoryRestMvcConfiguration in method restHandlerMapping() in both branches the result is equal (repositoryMapping has my interceptor in adaptedInterceptors as well as basePathMapping has my my interceptor in adaptedInterceptors).

So when doing the post request i noticed that on the branch with the old version
Class: AbstractHandlerMapping
Method: public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
Line: HandlerExecutionChain executionChain = this.getHandlerExecutionChain(handler, request); is called once and afterwards the interceptors are added to the list in Class: HandlerExecutionChain in the method
public void addInterceptor(HandlerInterceptor interceptor) { this.interceptorList.add(interceptor); }

This is only done once in the old version.

When switching to the new version, this process is done twice for (i think) both of the delegates in the class DelegatingHandlerMapping. The delegates are from my understanding the former mentioned repositoryMapping and basePathMapping (which as mentioned above both have my custom interceptor in their adaptedInterceptors). So this results in adding the custom interceptor twice to the same list.

Whole thing is unfortunately more like searching in the dark for me.

[rstoyanchev]

Thanks for the sample. This looks like a possible bug in Spring Data REST. Its DelegatingHandlerMapping delegates to another HandlerMapping which returns the HandlerExecutionResult with interceptors, but then the base AbstractHandlerMapping still adds (the same) interceptors again. I'll reach out to the Spring Data team to confirm.

[odrotbohm]

Just a quick heads up: the issue stems from Spring Data REST's move to let DelegatingHandlerMapping extend AbstractHandlerMapping instead of only implementing HandlerMapping directly. This causes DHM to also trigger the interceptor discovery and those then invoked in addition to the ones discovered for the handler mapping ultimately invoked.

I'll move the ticket to Spring Data REST for a fix.

[odrotbohm]

This in place. Feel free to give the snapshots a try.

[lwitzani]

I just tried it with 3.4.4-SNAPSHOT of branch "3.4.x" and 3.5.0-SNAPSHOT of branch "master" and can confirm that it works in both cases.

Thanks for fixing this so quickly. Issue should be resolved with the 3.4.4 release! Nice job!