invoking a function while dropping a TCP connection of a client

[agent-batman]

Summary

I am trying to implement a service which will hold some value of an user and on dropping the TCP connection the data will be removed from the database.
I thought about using TTL on values, but it doesn't work because if the user tries to log in before the value is dropped then it causes a problem. And if the user stays idle for a long time while keeping the TCP connection the value will get automatically dropped due to TTL which will also cause a problem.

axum version

0.8.7

[mladedav]

You could create a custom Listener that returns the underlying stream wrapped in some kind of a guard that does your cleanup on drop, assuming that you don't need asynchronous operations or that you don't mind spawning the cleanup to the background.

[agent-batman]

Hey! Can you give me an example?

[mladedav]

Not a full example, but something like this should work, I hope it's clear enough for you to iterate on it.

struct MyIo(TcpStream);

impl AsyncRead for MyIo {..}
impl AsyncWrite for MyIo {..}
...
impl Drop for MyIo {
  fn drop(&mut self) {
    // cleanup
  }
}

struct MyListener(TcpListener);

impl Listener for MyListener {
  type Io = MyIo;
  type Addr = SocketAddr;

  async fn accept(&mut self) -> (Self::Io, Self::Addr) {
    let (io, addr) = self.0.accept(&mut self.0).await;
    (MyIo(io), addr)
  }
}

[agent-batman]

thanks! I finally made it. #3583