How to know the response had sent finished ?

[ideadawn]

Summary

I want to release some resource when the response finished.
The TraceLayer's latency time is shorter than actual, because it's not include the response time.

axum version

0.8.3

[jplatte]

Can you please be a bit more specific? The solution probably involves writing a custom implementation of http_body::Body, but it's hard to say more without a better understanding of the problem.

[ideadawn]

async fn handler(req: Request) -> Response {
    let permit = STATE.limit_pool.lock().await.apply_permit();
    // do something, mey be need some time
    /// let resp = some_fn_returned();
    STATE.limit_pool.lock().await.back_permit(permit);
    // In fact, I want to free the permit after all data had sent, but now, it was freed earlier.
    resp
}

[jplatte]

Okay, so you want to limit the number of concurrent requests to a specific route that your service allows? Where are these apply_permit() / back_permit() methods coming from? The fact that the former is not async suggest that this limit_pool is not something you should be using in an async context.

This is application code, right? You could probably implement http_body::Body for a wrapper type that delegates all the methods to the inner type (using pin projection), and use Pinned Drop to give back the permit. Would have to spawn a tokio task for that last bit, if it can't be made non-async.

If that's all still too abstract, I can try to find some time to write up a code snippet.

[ideadawn]

Finally, I defined a new Mutex, implement Future without .await, and then, it could be used in http_body::Body wrapper.

Thank you so much.