How to handle canceled request in vapor?

I am using Vapor on a mac server. The server makes lengthy computation so I need to allow the client to be able to cancel the computation.

On the client side, I have the following Javascript code to send a POST request and wait for the result:

async function doSomething(text) {
    controller = new AbortController()
    const response = await fetch("http://" + website + "/api/dosomething",
        {
            method: 'POST',
            signal: controller.signal,
            headers: {
                'Accept': 'application/json',
                'Content-Type': 'application/json'
        },
        body: JSON.stringify({ text: text })
        })
    const results = await response.json()
    return results
}

as well as a button to cancel the process:

async function cancelquery() {
    controller.abort()
}

This works fine on the client side, i.e., the client does no longer wait for the result when I click the Cancel button. However, I don't know how to catch the "abort" signal on the server side to stop the computation. Is there any external variable, method or event in Vapor that I could use to know that the client sent an Abort signal?

It is absolutely not related to server-side since server doesn't know if client still waiting for the response or not.

https://stackoverflow.com/questions/7506413/aborting-an-http-request-server-side-advantage

Here's similar question but not related to exactly Vapor.

I would investigate submitting your 'fetch' to an eventLoop or promise, but keeping track of it by storing a pointer to it in a dictionary on an App Config Key and passing a key back to your client. You can then create a 'cancel' route that uses the key to retrieve this event loop and invokes close() on it.

I haven't played with doing this, but it seems a reasonable place to start. See here. You can allow for normal termination by adding a whenComplete handler to remove the entry in your dictionary.