flow

type Limiter interface {
	// Acquire tries to acquire a free slot for a flow, if the value of flows is already above
	// the maximum it returns ErrTooManyActiveFlows.
	Acquire(flowType string) error
	// Release releases a slot for a flow.
	Release()
	// SetLimit allows to hot swap the limit value of the limiter.
	SetLimit(uint64)
}