flexi_logger 0.10.4

An easy-to-configure and flexible logger that writes logs to stderr and/or to files. It allows custom logline formats, and it allows changing the log specification at runtime. It also allows defining additional log streams, e.g. for alert or security messages.
Documentation 
use chrono::Local;
use log::Record;
use std::{io, thread};

/// A logline-formatter that produces log lines like <br>
/// ```INFO [my_prog::some_submodule] Task successfully read from conf.json```
pub fn default_format(w: &mut io::Write, record: &Record) -> Result<(), io::Error> {
    write!(
        w,
        "{} [{}] {}",
        record.level(),
        record.module_path().unwrap_or("<unnamed>"),
        record.args()
    )
}

/// A logline-formatter that produces log lines like
/// <br>
/// ```[2016-01-13 15:25:01.640870 +01:00] INFO [src/foo/bar:26] Task successfully read from conf.json```
/// <br>
/// i.e. with timestamp and file location.
pub fn opt_format(w: &mut io::Write, record: &Record) -> Result<(), io::Error> {
    write!(
        w,
        "[{}] {} [{}:{}] {}",
        Local::now().format("%Y-%m-%d %H:%M:%S%.6f %:z"),
        record.level(),
        record.file().unwrap_or("<unnamed>"),
        record.line().unwrap_or(0),
        &record.args()
    )
}

/// A logline-formatter that produces log lines like
/// <br>
/// ```[2016-01-13 15:25:01.640870 +01:00] INFO [foo::bar] src/foo/bar.rs:26: Task successfully read from conf.json```
/// <br>
/// i.e. with timestamp, module path and file location.
pub fn detailed_format(w: &mut io::Write, record: &Record) -> Result<(), io::Error> {
    write!(
        w,
        "[{}] {} [{}] {}:{}: {}",
        Local::now().format("%Y-%m-%d %H:%M:%S%.6f %:z"),
        record.level(),
        record.module_path().unwrap_or("<unnamed>"),
        record.file().unwrap_or("<unnamed>"),
        record.line().unwrap_or(0),
        &record.args()
    )
}

/// A logline-formatter that produces log lines like
/// <br>
/// ```[2016-01-13 15:25:01.640870 +01:00] T[taskreader] INFO [src/foo/bar:26] Task successfully read from conf.json```
/// <br>
/// i.e. with timestamp, thread name and file location.
pub fn with_thread(w: &mut io::Write, record: &Record) -> Result<(), io::Error> {
    write!(
        w,
        "[{}] T[{:?}] {} [{}:{}] {}",
        Local::now().format("%Y-%m-%d %H:%M:%S%.6f %:z"),
        thread::current().name().unwrap_or("<unnamed>"),
        record.level(),
        record.file().unwrap_or("<unnamed>"),
        record.line().unwrap_or(0),
        &record.args()
    )
}