prometheus/labels/labels.go
2016-12-21 15:12:26 +01:00

90 lines
1.9 KiB
Go

package labels
import (
"sort"
"github.com/cespare/xxhash"
)
const sep = '\xff'
// Label is a key/value pair of strings.
type Label struct {
Name, Value string
}
// Labels is a sorted set of labels. Order has to be guaranteed upon
// instantiation.
type Labels []Label
func (ls Labels) Len() int { return len(ls) }
func (ls Labels) Swap(i, j int) { ls[i], ls[j] = ls[j], ls[i] }
func (ls Labels) Less(i, j int) bool { return ls[i].Name < ls[j].Name }
// Hash returns a hash value for the label set.
func (ls Labels) Hash() uint64 {
b := make([]byte, 0, 1024)
for _, v := range ls {
b = append(b, v.Name...)
b = append(b, sep)
b = append(b, v.Value...)
b = append(b, sep)
}
return xxhash.Sum64(b)
}
// Get returns the value for the label with the given name.
// Returns an empty string if the label doesn't exist.
func (ls Labels) Get(name string) string {
for _, l := range ls {
if l.Name == name {
return l.Value
}
}
return ""
}
// Equals returns whether the two label sets are equal.
func (ls Labels) Equals(o Labels) bool {
if len(ls) != len(o) {
return false
}
for i, l := range ls {
if l.Name != o[i].Name || l.Value != o[i].Value {
return false
}
}
return true
}
// Map returns a string map of the labels.
func (ls Labels) Map() map[string]string {
m := make(map[string]string, len(ls))
for _, l := range ls {
m[l.Name] = l.Value
}
return m
}
// New returns a sorted Labels from the given labels.
// The caller has to guarantee that all label names are unique.
func New(ls ...Label) Labels {
set := make(Labels, 0, len(ls))
for _, l := range ls {
set = append(set, l)
}
sort.Sort(set)
return set
}
// FromMap returns new sorted Labels from the given map.
func FromMap(m map[string]string) Labels {
l := make([]Label, 0, len(m))
for k, v := range m {
l = append(l, Label{Name: k, Value: v})
}
return New(l...)
}