Method render_prometheus

nodedb/src/control/metrics/database.rs:155–243

Render all registered databases as Prometheus text format 0.0.4. Labels: `database=" "`.

(&self, out: &mut String)

    ///
    /// Labels: `database="<name>"`.
    pub fn render_prometheus(&self, out: &mut String) {
        use std::fmt::Write as _;

        let r = self.counters.read().unwrap_or_else(|p| p.into_inner());
        if r.is_empty() {
            return;
        }

        let mut pairs: Vec<_> = r.iter().collect();
        pairs.sort_by(|a, b| a.0.cmp(b.0));

        macro_rules! emit_counter {
            ($name:literal, $help:literal, $field:ident) => {
                let _ = write!(
                    out,
                    "# HELP {} {}\n# TYPE {} counter\n",
                    $name, $help, $name
                );
                for (db, c) in &pairs {
                    let _ = writeln!(
                        out,
                        r#"{}{{database="{}"}} {}"#,
                        $name,
                        db,
                        c.$field.load(Ordering::Relaxed)
                    );
                }
                out.push('\n');
            };
        }

        macro_rules! emit_gauge {
            ($name:literal, $help:literal, $field:ident) => {
                let _ = write!(out, "# HELP {} {}\n# TYPE {} gauge\n", $name, $help, $name);
                for (db, c) in &pairs {
                    let _ = writeln!(
                        out,
                        r#"{}{{database="{}"}} {}"#,
                        $name,
                        db,
                        c.$field.load(Ordering::Relaxed)
                    );
                }
                out.push('\n');
            };
        }

        emit_counter!(
            "nodedb_database_qps_total",
            "Cumulative requests admitted per database",
            qps_total
        );
        emit_gauge!(
            "nodedb_database_memory_used_bytes",
            "Current memory usage per database in bytes",
            memory_bytes
        );
        emit_gauge!(