Method get_or_create

nodedb/src/control/metrics/database.rs:65–78

Get or create the counter handle for `db_name`. The returned `Arc ` is stable for the process lifetime.

(&self, db_name: &str)

    ///
    /// The returned `Arc<DatabaseCounters>` is stable for the process lifetime.
    pub fn get_or_create(&self, db_name: &str) -> Arc<DatabaseCounters> {
        // Fast path: read lock.
        {
            let r = self.counters.read().unwrap_or_else(|p| p.into_inner());
            if let Some(c) = r.get(db_name) {
                return Arc::clone(c);
            }
        }
        // Slow path: write lock.
        let mut w = self.counters.write().unwrap_or_else(|p| p.into_inner());
        w.entry(db_name.to_string())
            .or_insert_with(|| Arc::new(DatabaseCounters::default()))
            .clone()
    }

    /// Increment the QPS counter for `db_name` by 1.
    pub fn record_qps(&self, db_name: &str) {