How to force returning a response in a hook and stop further execution?

[larryro]

I have a feature requirement to detect the hash value of a file when a user uploads it. If the file already exists, I want to stop further execution and directly return the existing document.

Currently, I am trying to achieve this requirement by adding custom handlers. However, I have encountered a strange issue where even if I use res.end to forcefully end the request in the handler, it doesn't work.