Attribute Macro timeout 

#[timeout]

Timeout macro

A proc macro attribute that can be put on an async function, running within a tokio runtime, with the feature time enabled, which wraps the function in tokio::time::timeout

#[tokio_timeout::timeout(duration = "1s", on_error = "panic")]
async fn my_fn() {
    println!("hello!");
}

It takes two mandatory arguments ‘duration’ and on_error.

Duration

‘Duration’ can be either a string-literal that specifies a duration, valid values are <n>h for hours, <n>m for minutes, <n>s for seconds, and <n>ms for milliseconds. They can be chained together.

#[tokio_timeout::timeout(duration = "5h4m3s2ms", on_error = "panic")]
async fn my_fn() {
    println!("hello!");
}

Duration can also be specified to be some constant

use std::time::Duration;

const MY_DUR: Duration = Duration::from_millis(55);

#[tokio_timeout::timeout(duration = MY_DUR, on_error = "panic")]
async fn my_fn() {
    println!("hello!");
}

On error

On error can either be the string literal “panic”, as seen in examples above, or something that can be invoked with a &'static str to produce an error.

fn to_error_result(s: &str) -> Result<(), String>{
   Err(s.to_string())
}

#[tokio_timeout::timeout(duration = "5h4m3s2ms", on_error = to_error_result)]
async fn my_fn_string_err() -> Result<(), String>{
    println!("hello!");
    Ok(())
}

pub enum MyErr {
    Timeout(&'static str)
}

const fn to_error_enum(s: &'static str) -> Result<(), MyErr> {
    Err(MyErr::Timeout(s))
}

#[tokio_timeout::timeout(duration = "5h4m3s2ms", on_error = to_error_enum)]
async fn my_fn_enum_err() -> Result<(), MyErr>{
    println!("hello!");
    Ok(())
}

fn print_err(s: &'static str) {
    eprintln!("oh no: {s}")
}

#[tokio_timeout::timeout(duration = "5h4m3s2ms", on_error = print_err)]
async fn my_print_timeout_fn() {
    println!("hello!");
}

#[tokio_timeout::timeout(duration = "5h4m3s2ms", on_error = anyhow::bail!)]
async fn anyhow_err_fn() -> anyhow::Result<()> {
    println!("hello!");
    Ok(())
}

#[tokio_timeout::timeout]
async fn both_attrs_needed() {}

#[tokio_timeout::timeout]
fn only_async_functions() {}

#[tokio_timeout::timeout(duration = "1z", on_error = "panic")]
async fn unrecognized_duration() {}

#[tokio_timeout::timeout(duration = "1s", on_error = "panico")]
async fn unrecognized_on_error() {}