Interface Collector

prometheus/collector.go:27–63

Collector is the interface implemented by anything that can be used by Prometheus to collect metrics. A Collector has to be registered for collection. See Registerer.Register. The stock metrics provided by this package (Gauge, Counter, Summary, Histogram, Untyped) are also Collectors (which only ev

// (i.e. collection of multiple instances of the same Metric but with different
// label values) like GaugeVec or SummaryVec, and the ExpvarCollector.
type Collector interface {
	// Describe sends the super-set of all possible descriptors of metrics
	// collected by this Collector to the provided channel and returns once
	// the last descriptor has been sent. The sent descriptors fulfill the
	// consistency and uniqueness requirements described in the Desc
	// documentation.
	//
	// It is valid if one and the same Collector sends duplicate
	// descriptors. Those duplicates are simply ignored. However, two
	// different Collectors must not send duplicate descriptors.
	//
	// Sending no descriptor at all marks the Collector as “unchecked”,
	// i.e. no checks will be performed at registration time, and the
	// Collector may yield any Metric it sees fit in its Collect method.
	//
	// This method idempotently sends the same descriptors throughout the
	// lifetime of the Collector. It may be called concurrently and
	// therefore must be implemented in a concurrency safe way.
	//
	// If a Collector encounters an error while executing this method, it
	// must send an invalid descriptor (created with NewInvalidDesc) to
	// signal the error to the registry.
	Describe(chan<- *Desc)
	// Collect is called by the Prometheus registry when collecting
	// metrics. The implementation sends each collected metric via the
	// provided channel and returns once the last metric has been sent. The
	// descriptor of each sent metric is one of those returned by Describe
	// (unless the Collector is unchecked, see above). Returned metrics that
	// share the same descriptor must differ in their variable label
	// values.
	//
	// This method may be called concurrently and must therefore be
	// implemented in a concurrency safe way. Blocking occurs at the expense
	// of total performance of rendering all registered metrics. Ideally,
	// Collector implementations support concurrent readers.
	Collect(chan<- Metric)
}

// DescribeByCollect is a helper to implement the Describe method of a custom
// Collector. It collects the metrics from the provided Collector and sends