Turnstiles

A WIP library which wraps the io::Write trait to enable file rotation i.e. for logs. The goal is to enable file rotation at the file handle level and do so with as few dependencies as possible.

Implemented/planned rotation conditions:

• None (never rotate)
• SizeMB (file size)
• Duration (time since last modified)
• SizeLines (number of lines in file)

Note:

Currently this library only supports rotation by creating new files when a rotation is required, rather than renaming existing files. For example if my_file.log is given then when the first rotation occurs a file with the name my_file.log.1 will be created and written to. This means the latest file has the highest index, not the original filename. This is done to minimize surface area with the filesystem, but it is part of future work to potentially include the case where my_file.log is always the latest.

Examples

Rotate when a log file exceeds a certain filesize

let some_bytes: Vec<u8> = vec![0; 1_000_000];
let mut log_file =
    RotatingFile::new("logs/super_important_service.log", RotationOption::SizeMB(500))
    .expect("failed to create RotatingFile");
file.write(&some_bytes).expect("Failed to write bytes to file");

Rotate when a log file is too old (based on filesystem metadata timestamps)

let max_log_age = Duration::from_secs(3600);
let some_bytes: Vec<u8> = vec![0; 10_000_000];
let mut log_file =
    RotatingFile::new("logs/super_important_service.log", RotationOption::Duration(max_log_age))
    .expect("failed to create RotatingFile");
file.write(&some_bytes).expect("Failed to write bytes to file");

Future work

More direct integration with dedicated logging libraries, i.e. impl log::Log.

Why turnstiles?

It's a metal thing that rotates, and also the name of the Billy Joel album which has Summer, Highland Falls on it, one of my favourite songs.