ptth/crates/ptth_server/src/file_server/metrics.rs

use chrono::{DateTime, Utc};
use ulid::Ulid;

fn serialize_ulid <S: serde::Serializer> (t: &Ulid, s: S) 
-> Result <S::Ok, S::Error> 
{
	let t = t.to_string ();
	s.serialize_str (&t)
}

// Instance metrics are captured when the ptth_server process starts.
// They don't change after that.

#[derive (Debug, serde::Serialize)]
pub struct PerInstance {
	// D-Bus machine ID, if we're on Linux
	pub machine_id: Option <String>,
	
	// Git version that ptth_server was built from (unimplemented)
	pub git_version: Option <String>,
	
	// User-assigned and human-readable name for this server.
	// Must be unique within a relay.
	pub server_name: String,
	
	// Random base64 instance ID. ptth_server generates this at process start.
	// It's a fallback for detecting outages without relying on any clocks.
	#[serde (serialize_with = "serialize_ulid")]
	pub instance_id: Ulid,
	
	pub startup_utc: DateTime <Utc>,
}

#[derive (Debug, serde::Serialize)]
pub struct Gauges {
	pub rss_mib: u64,
}

fn get_machine_id () -> Option <String> {
	use std::{
		fs::File,
		io::Read,
	};
	
	let mut buf = vec! [0; 1024];
	let mut f = File::open ("/etc/machine-id").ok ()?;
	let bytes_read = f.read (&mut buf).ok ()?;
	
	buf.truncate (bytes_read);
	
	let s = std::str::from_utf8 (&buf).ok ()?;
	let s = s.trim_end ().to_string ();
	
	Some (s)
}

impl PerInstance {
	#[must_use]
	pub fn new (server_name: String) -> Self
	{
		Self {
			machine_id: get_machine_id (),
			git_version: None,
			server_name,
			instance_id: ulid::Ulid::new (),
			startup_utc: Utc::now (),
		}
	}
}

#[cfg (test)]
mod tests {
	use super::*;
	
	#[test]
	fn ulid_null () {
		let a = PerInstance::new ("bogus".to_string ());
		let b = PerInstance::new ("bogus".to_string ());
		
		assert_ne! (a.instance_id, b.instance_id);
	}
}