kubernetes/vendor/github.com/prometheus/client_golang/prometheus/collector.go

type Collector …

// DescribeByCollect is a helper to implement the Describe method of a custom
// Collector. It collects the metrics from the provided Collector and sends
// their descriptors to the provided channel.
//
// If a Collector collects the same metrics throughout its lifetime, its
// Describe method can simply be implemented as:
//
//	func (c customCollector) Describe(ch chan<- *Desc) {
//		DescribeByCollect(c, ch)
//	}
//
// However, this will not work if the metrics collected change dynamically over
// the lifetime of the Collector in a way that their combined set of descriptors
// changes as well. The shortcut implementation will then violate the contract
// of the Describe method. If a Collector sometimes collects no metrics at all
// (for example vectors like CounterVec, GaugeVec, etc., which only collect
// metrics after a metric with a fully specified label set has been accessed),
// it might even get registered as an unchecked Collector (cf. the Register
// method of the Registerer interface). Hence, only use this shortcut
// implementation of Describe if you are certain to fulfill the contract.
//
// The Collector example demonstrates a use of DescribeByCollect.
func DescribeByCollect(c Collector, descs chan<- *Desc) { … }

type selfCollector …

// init provides the selfCollector with a reference to the metric it is supposed
// to collect. It is usually called within the factory function to create a
// metric. See example.
func (c *selfCollector) init(self Metric) { … }

// Describe implements Collector.
func (c *selfCollector) Describe(ch chan<- *Desc) { … }

// Collect implements Collector.
func (c *selfCollector) Collect(ch chan<- Metric) { … }

type collectorMetric …