This logger implementation has been designed to be fast. It delegates most of the heavy work to a dedicated thread. It offers nice filtering capability that can be combined with an optional and easy to use TOML configuration.
To have a generale view of the capability of this crate, you can run this command:
cargo run --example simple-fastlog-example
cargo run --example from-toml-fastlog-example
Additional examples can be found here as well.
This logging factory handles the environnement variable RUST_LOG as well so it can be used like this (the logger has to be registered):
Building a logger
Here is an example of how to simply build a logger with the
Debug log verbosity level:
FastLoggerBuilder::new() // Optionally you can specify your custom timestamp format .timestamp_format("%Y-%m-%d %H:%M:%S%.6f") .set_level_from_str("Debug") .build() .expect("Fail to init the logging factory."); debug!("What's bugging you today?");
Filtering out every log from dependencies and putting back in everything related to a particular
target is easy:
let toml = r#" [logger] level = "debug" [[logger.rules]] pattern = ".*" exclude = true [[logger.rules]] pattern = "^holochain" exclude = false "#; FastLoggerBuilder::from_toml(toml) .expect("Fail to instantiate the logger from toml.") .build() .expect("Fail to build logger from toml."); // Should NOT be logged debug!(target: "rpc", "This is our dependency log filtering."); // Should be logged each in different color. We avoid filtering by prefixing using the 'target' // argument. info!(target: "holochain", "Log message from Holochain Core."); info!(target: "holochain-app-2", "Log message from Holochain Core with instance ID 2");