type Collector interface {
	// Collect metrics from this collector.
	// Returns the next time this collector should be collected from.
	// Next collection time is always returned, even when an error occurs.
	// A collection time of zero means no more collection.
	Collect() (time.Time, []v2.Metric, error)

	// Name of this collector.
	Name() string
}

type CollectorManager interface {
	// Register a collector.
	RegisterCollector(collector Collector) error

	// Collect from collectors that are ready and return the next time
	// at which a collector will be ready to collect from.
	// Next collection time is always returned, even when an error occurs.
	// A collection time of zero means no more collection.
	Collect() (time.Time, []v2.Metric, error)
}

type FakeCollectorManager struct {
}