microservices 0.9.0

// LNP/BP Core Library implementing LNPBP specifications & standards
// Written in 2020 by
//     Dr. Maxim Orlovsky <orlovsky@pandoracore.com>
//
// To the extent possible under law, the author(s) have dedicated all
// copyright and related and neighboring rights to this software to
// the public domain worldwide. This software is distributed without
// any warranty.
//
// You should have received a copy of the MIT License
// along with this software.
// If not, see <https://opensource.org/licenses/MIT>.

use std::error::Error;

/// Trait for simpler service implementation with run loops
pub trait Service {
    /// Run loop for the service, which must never return. If you have a run
    /// loop that may fail, use [`TryService`] trait instead
    fn run_loop(self);
}

/// Trait for simpler service implementation with run loops which may fail with
/// `TryService::ErrorType` errors; otherwise they should never return
pub trait TryService: Sized {
    /// Type of the error which is produced in case of service failure and
    /// is returned from the internal [`Self::try_run_loop`] method
    type ErrorType: Error;

    /// NB: Do not reimplement this one: the function keeps in check that if the
    /// failure happens during run loop, the program will panic reporting the
    /// failure. To implement the actual run loop please provide implementation
    /// for [`Self::try_run_loop`]
    fn run_or_panic(self, service_name: &str) {
        match self.try_run_loop() {
            Err(err) => {
                panic!("{} run loop has failed with {}", service_name, err)
            }
            Ok(_) => {
                panic!("{} has failed without reporting a error", service_name)
            }
        }
    }

    /// Main failable run loop implementation. Must produce an error of type
    /// [`TryService::ErrorType`] or never return.
    fn try_run_loop(self) -> Result<(), Self::ErrorType>;
}