kubernetes/vendor/golang.org/x/time/rate/sometimes.go

type Sometimes …

// Do runs the function f as allowed by First, Every, and Interval.
//
// The model is a union (not intersection) of filters.  The first call to Do
// always runs f.  Subsequent calls to Do run f if allowed by First or Every or
// Interval.
//
// A non-zero First:N causes the first N Do(f) calls to run f.
//
// A non-zero Every:M causes every Mth Do(f) call, starting with the first, to
// run f.
//
// A non-zero Interval causes Do(f) to run f if Interval has elapsed since
// Do last ran f.
//
// Specifying multiple filters produces the union of these execution streams.
// For example, specifying both First:N and Every:M causes the first N Do(f)
// calls and every Mth Do(f) call, starting with the first, to run f.  See
// Examples for more.
//
// If Do is called multiple times simultaneously, the calls will block and run
// serially.  Therefore, Do is intended for lightweight operations.
//
// Because a call to Do may block until f returns, if f causes Do to be called,
// it will deadlock.
func (s *Sometimes) Do(f func()) { … }