Storing Rust crius circuit breakers in structs

crius-struct.rs

extern crate crius;
use crius::command::{RunnableCommand, Command, CommandError};

/// Convenience type alias for breaker function pointers.
pub type BreakerFn<I, O> = fn(I) -> Result<O, Box<CommandError>>;

/// Convenience type alias for working with crius commands:
pub type Breaker<I, O> =
    RunnableCommand<I, O,
                    BreakerFn<I,O>,
                    fn(Box<CommandError>) -> O>;

/// Helper function for creating a breaker and preventing rustc from
/// inferring a closure type instead of a function pointer without
/// extra type annotations.
pub fn create_breaker<I, O>(f: BreakerFn<I, O>) -> Breaker<I, O> where
    I: Send,
    O: Send {
    Command::define(f).create()
}

/// Test struct capable that stores an example circuit breaker.
pub struct BreakerOwner {
    pub breaker: Breaker<u8, String>,
}

pub fn make_breaker_owner() -> BreakerOwner {
    BreakerOwner {
        breaker: create_breaker(|num| Ok(format!("Number is {}", num)))
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_breaker_struct() {
        let mut b = make_breaker_owner();
        let res = b.breaker.run(10).recv()
            .expect("Channel failed")
            .expect("Breaker command failed");
        assert_eq!(res, "Number is 10")
    }
}