metrics

type MemoryConfig struct {
	Retention time.Duration
	MaxPoints int
}

type Point struct {
	At    time.Time `json:"at"`
	Value float64   `json:"value"`
}

type QueryRequest struct {
	ID    string
	Since time.Time
	Until time.Time
}

type RecordRequest struct {
	ID    string
	At    time.Time
	Value float64
}

type Series struct {
	// ID is unique within a response: the requested id itself, or the
	// requested id plus "#" and the canonical label set when one requested id
	// expands to several series (a query profile grouped by pod, say).
	ID string `json:"id"`
	// Source is the id the panel asked for, so a panel can find every series a
	// request of its expanded into.
	Source string            `json:"source"`
	Label  string            `json:"label,omitempty"`
	Labels map[string]string `json:"labels,omitempty"`
	// Unit is a clicky-ui formatUnit key (percent, bytes, ms, …).
	Unit   string  `json:"unit,omitempty"`
	Points []Point `json:"points"`
}

type SeriesRequest struct {
	IDs   []string
	Since time.Time
	Until time.Time
	Step  time.Duration
}

type SeriesSource interface {
	QuerySeries(ctx context.Context, req SeriesRequest) ([]Series, error)
}

type Sources map[string]SeriesSource

type StoreConfig struct {
	// KeyPrefix is prepended to every key so metrics share the caller's
	// namespace. The full key is KeyPrefix + "metric:" + id.
	KeyPrefix string
	// Retention drops points older than this on each Record. Zero -> 7d.
	Retention time.Duration
	// MaxPoints caps the points kept per metric ID, dropping the oldest on
	// overflow. Zero leaves the series uncapped (time-based retention only).
	MaxPoints int
}

type StreamFrame struct {
	Series  []Series `json:"series"`
	Removed []string `json:"removed,omitempty"`
}

type Timeseries interface {
	// Record appends a point. Recording is best-effort instrumentation: an
	// implementation backed by an unavailable store may return an error, but
	// callers are expected to log-and-continue rather than fail the producer.
	Record(req RecordRequest) error

	// Query returns the points in the requested range, ascending by time.
	Query(req QueryRequest) ([]Point, error)
}

type UnknownSeriesError struct{ ID string }