Method timer

datafusion/physical-expr-common/src/metrics/value.rs:214–219

return a scoped guard that adds the amount of time elapsed between its creation and its drop or call to `stop` to the underlying metric.

(&self)

    /// between its creation and its drop or call to `stop` to the
    /// underlying metric.
    pub fn timer(&self) -> ScopedTimerGuard<'_> {
        ScopedTimerGuard {
            inner: self,
            start: Some(Instant::now()),
        }
    }

    /// Get the number of nanoseconds record by this Time metric
    pub fn value(&self) -> usize {