Rust Snippet: Exec with Update Intervals

Recently, I needed to kick off a long running process for encoding videos using ffmpeg in the middle of handling an SQS message. In order to keep the message from showing back up in the queue before the video processing is finished.

So that means, I need to be able to send the change message visibility timeout periodically during the process. so, I came up with this little function to help. It calls a “progress” function every 10 seconds while the command is executing, and then ends once it’s done.

Using tokio as the Async Runtime

pub async fn exec<F, Fut>(mut cmd: Command, progress: F) -> Result<Output, ProgressingExecError>
where
    F: Fn() -> Fut,
    Fut: Future<Output = ()>,
{
    let (tx, mut rx) = oneshot::channel();
    let mut interval = interval(Duration::from_millis(10000));

    tokio::spawn(async move {
        let output = cmd.output().await;
        let _ = tx.send(output);
    });

    loop {
        tokio::select! {
            _ = interval.tick() => progress().await,
            msg = &mut rx => return Ok(msg??)
        }
    }
}