prometheus/promql/value.go
2016-12-29 17:31:14 +01:00

204 lines
4.6 KiB
Go

package promql
import (
"encoding/json"
"fmt"
"strconv"
"strings"
"github.com/prometheus/prometheus/pkg/labels"
)
// Value is a generic interface for values resulting from a query evaluation.
type Value interface {
Type() ValueType
String() string
}
func (Matrix) Type() ValueType { return ValueTypeMatrix }
func (Vector) Type() ValueType { return ValueTypeVector }
func (Scalar) Type() ValueType { return ValueTypeScalar }
func (String) Type() ValueType { return ValueTypeString }
// ValueType describes a type of a value.
type ValueType string
// The valid value types.
const (
ValueTypeNone = "none"
ValueTypeVector = "vector"
ValueTypeScalar = "scalar"
ValueTypeMatrix = "matrix"
ValueTypeString = "string"
)
// String represents a string value.
type String struct {
V string
T int64
}
func (s String) String() string {
return s.V
}
func (s String) MarshalJSON() ([]byte, error) {
return json.Marshal([...]interface{}{float64(s.T) / 1000, s.V})
}
// Scalar is a data point that's explicitly not associated with a metric.
type Scalar struct {
T int64
V float64
}
func (s Scalar) String() string {
v := strconv.FormatFloat(s.V, 'f', -1, 64)
return fmt.Sprintf("scalar: %v @[%v]", v, s.T)
}
func (s Scalar) MarshalJSON() ([]byte, error) {
v := strconv.FormatFloat(s.V, 'f', -1, 64)
return json.Marshal([...]interface{}{float64(s.T) / 1000, v})
}
// Series is a stream of data points belonging to a metric.
type Series struct {
Metric labels.Labels `json:"metric"`
Points []Point `json:"values"`
}
func (s Series) String() string {
vals := make([]string, len(s.Points))
for i, v := range s.Points {
vals[i] = v.String()
}
return fmt.Sprintf("%s =>\n%s", s.Metric, strings.Join(vals, "\n"))
}
// Point represents a single data point for a given timestamp.
type Point struct {
T int64
V float64
}
func (p Point) String() string {
v := strconv.FormatFloat(p.V, 'f', -1, 64)
return fmt.Sprintf("%v @[%v]", v, p.T)
}
// MarshalJSON implements json.Marshaler.
func (p Point) MarshalJSON() ([]byte, error) {
v := strconv.FormatFloat(p.V, 'f', -1, 64)
return json.Marshal([...]interface{}{float64(p.T) / 1000, v})
}
// Sample is a single sample belonging to a metric.
type Sample struct {
Point
Metric labels.Labels
}
func (s Sample) String() string {
return fmt.Sprintf("%s => %s", s.Metric, s.Point)
}
func (s Sample) MarshalJSON() ([]byte, error) {
v := struct {
M labels.Labels `json:"metric"`
V Point `json:"value"`
}{
M: s.Metric,
V: s.Point,
}
return json.Marshal(v)
}
// Vector is basically only an alias for model.Samples, but the
// contract is that in a Vector, all Samples have the same timestamp.
type Vector []Sample
func (vec Vector) String() string {
entries := make([]string, len(vec))
for i, s := range vec {
entries[i] = s.String()
}
return strings.Join(entries, "\n")
}
// Matrix is a slice of Seriess that implements sort.Interface and
// has a String method.
type Matrix []Series
func (m Matrix) String() string {
// TODO(fabxc): sort, or can we rely on order from the querier?
strs := make([]string, len(m))
for i, ss := range m {
strs[i] = ss.String()
}
return strings.Join(strs, "\n")
}
func (m Matrix) Len() int { return len(m) }
func (m Matrix) Less(i, j int) bool { return labels.Compare(m[i].Metric, m[j].Metric) < 0 }
func (m Matrix) Swap(i, j int) { m[i], m[j] = m[j], m[i] }
// Result holds the resulting value of an execution or an error
// if any occurred.
type Result struct {
Err error
Value Value
}
// Vector returns a Vector if the result value is one. An error is returned if
// the result was an error or the result value is not a Vector.
func (r *Result) Vector() (Vector, error) {
if r.Err != nil {
return nil, r.Err
}
v, ok := r.Value.(Vector)
if !ok {
return nil, fmt.Errorf("query result is not a Vector")
}
return v, nil
}
// Matrix returns a Matrix. An error is returned if
// the result was an error or the result value is not a Matrix.
func (r *Result) Matrix() (Matrix, error) {
if r.Err != nil {
return nil, r.Err
}
v, ok := r.Value.(Matrix)
if !ok {
return nil, fmt.Errorf("query result is not a range Vector")
}
return v, nil
}
// Scalar returns a Scalar value. An error is returned if
// the result was an error or the result value is not a Scalar.
func (r *Result) Scalar() (Scalar, error) {
if r.Err != nil {
return Scalar{}, r.Err
}
v, ok := r.Value.(Scalar)
if !ok {
return Scalar{}, fmt.Errorf("query result is not a Scalar")
}
return v, nil
}
func (r *Result) String() string {
if r.Err != nil {
return r.Err.Error()
}
if r.Value == nil {
return ""
}
return r.Value.String()
}