log-once

Collection of helper macros for logging some events only once.

This crate provide macro in the log_once family (warn_once!, trace_once!, ...); that only send a logging event once for every message. It rely and uses the logging infrastructure in the log crate; and is fully compatible with any logger implementation.

These macro will store the already seen messages in a BTreeSet, and check if a message is in the set before sending the log event.

Usage

1. Add it to your Cargo.toml file:

[dependencies]
log-once = "0.3"

2. import the macros:

use log_once::{warn_once, log_once};

3. Enjoy!

Examples

use log::info;
use log_once::{info_once, warn_once};

pub fn shave_the_yak(yaks: &[Yak]) {
    for yak in yaks {
        info!(target: "yak_events", "Commencing yak shaving for {:?}", yak);

        loop {
            match find_a_razor() {
                Ok(razor) => {
                    // This will only appear once in the logger output for each razor
                    info_once!("Razor located: {}", razor);
                    yak.shave(razor);
                    break;
                }
                Err(err) => {
                    // This will only appear once in the logger output for each error
                    warn_once!("Unable to locate a razor: {}, retrying", err);
                }
            }
        }
    }
}

License

log-once is distributed under the terms of both the MIT license and the Apache License (Version 2.0).

See LICENSE-APACHE and LICENSE-MIT for details.