syncthing/vendor/github.com/prometheus/common/model/value.go

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cmd/stdiscosrv: New discovery server (fixes #4618) This is a new revision of the discovery server. Relevant changes and non-changes: - Protocol towards clients is unchanged. - Recommended large scale design is still to be deployed nehind nginx (I tested, and it's still a lot faster at terminating TLS). - Database backend is leveldb again, only. It scales enough, is easy to setup, and we don't need any backend to take care of. - Server supports replication. This is a simple TCP channel - protect it with a firewall when deploying over the internet. (We deploy this within the same datacenter, and with firewall.) Any incoming client announces are sent over the replication channel(s) to other peer discosrvs. Incoming replication changes are applied to the database as if they came from clients, but without the TLS/certificate overhead. - Metrics are exposed using the prometheus library, when enabled. - The database values and replication protocol is protobuf, because JSON was quite CPU intensive when I tried that and benchmarked it. - The "Retry-After" value for failed lookups gets slowly increased from a default of 120 seconds, by 5 seconds for each failed lookup, independently by each discosrv. This lowers the query load over time for clients that are never seen. The Retry-After maxes out at 3600 after a couple of weeks of this increase. The number of failed lookups is stored in the database, now and then (avoiding making each lookup a database put). All in all this means clients can be pointed towards a cluster using just multiple A / AAAA records to gain both load sharing and redundancy (if one is down, clients will talk to the remaining ones). GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4648
2018-01-14 08:52:31 +00:00
// Copyright 2013 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package model
import (
"encoding/json"
"fmt"
"math"
"sort"
"strconv"
"strings"
)
var (
// ZeroSamplePair is the pseudo zero-value of SamplePair used to signal a
// non-existing sample pair. It is a SamplePair with timestamp Earliest and
// value 0.0. Note that the natural zero value of SamplePair has a timestamp
// of 0, which is possible to appear in a real SamplePair and thus not
// suitable to signal a non-existing SamplePair.
ZeroSamplePair = SamplePair{Timestamp: Earliest}
// ZeroSample is the pseudo zero-value of Sample used to signal a
// non-existing sample. It is a Sample with timestamp Earliest, value 0.0,
// and metric nil. Note that the natural zero value of Sample has a timestamp
// of 0, which is possible to appear in a real Sample and thus not suitable
// to signal a non-existing Sample.
ZeroSample = Sample{Timestamp: Earliest}
)
// A SampleValue is a representation of a value for a given sample at a given
// time.
type SampleValue float64
// MarshalJSON implements json.Marshaler.
func (v SampleValue) MarshalJSON() ([]byte, error) {
return json.Marshal(v.String())
}
// UnmarshalJSON implements json.Unmarshaler.
func (v *SampleValue) UnmarshalJSON(b []byte) error {
if len(b) < 2 || b[0] != '"' || b[len(b)-1] != '"' {
return fmt.Errorf("sample value must be a quoted string")
}
f, err := strconv.ParseFloat(string(b[1:len(b)-1]), 64)
if err != nil {
return err
}
*v = SampleValue(f)
return nil
}
// Equal returns true if the value of v and o is equal or if both are NaN. Note
// that v==o is false if both are NaN. If you want the conventional float
// behavior, use == to compare two SampleValues.
func (v SampleValue) Equal(o SampleValue) bool {
if v == o {
return true
}
return math.IsNaN(float64(v)) && math.IsNaN(float64(o))
}
func (v SampleValue) String() string {
return strconv.FormatFloat(float64(v), 'f', -1, 64)
}
// SamplePair pairs a SampleValue with a Timestamp.
type SamplePair struct {
Timestamp Time
Value SampleValue
}
// MarshalJSON implements json.Marshaler.
func (s SamplePair) MarshalJSON() ([]byte, error) {
t, err := json.Marshal(s.Timestamp)
if err != nil {
return nil, err
}
v, err := json.Marshal(s.Value)
if err != nil {
return nil, err
}
return []byte(fmt.Sprintf("[%s,%s]", t, v)), nil
}
// UnmarshalJSON implements json.Unmarshaler.
func (s *SamplePair) UnmarshalJSON(b []byte) error {
v := [...]json.Unmarshaler{&s.Timestamp, &s.Value}
return json.Unmarshal(b, &v)
}
// Equal returns true if this SamplePair and o have equal Values and equal
// Timestamps. The sematics of Value equality is defined by SampleValue.Equal.
func (s *SamplePair) Equal(o *SamplePair) bool {
return s == o || (s.Value.Equal(o.Value) && s.Timestamp.Equal(o.Timestamp))
}
func (s SamplePair) String() string {
return fmt.Sprintf("%s @[%s]", s.Value, s.Timestamp)
}
// Sample is a sample pair associated with a metric.
type Sample struct {
Metric Metric `json:"metric"`
Value SampleValue `json:"value"`
Timestamp Time `json:"timestamp"`
}
// Equal compares first the metrics, then the timestamp, then the value. The
// sematics of value equality is defined by SampleValue.Equal.
func (s *Sample) Equal(o *Sample) bool {
if s == o {
return true
}
if !s.Metric.Equal(o.Metric) {
return false
}
if !s.Timestamp.Equal(o.Timestamp) {
return false
}
return s.Value.Equal(o.Value)
}
func (s Sample) String() string {
return fmt.Sprintf("%s => %s", s.Metric, SamplePair{
Timestamp: s.Timestamp,
Value: s.Value,
})
}
// MarshalJSON implements json.Marshaler.
func (s Sample) MarshalJSON() ([]byte, error) {
v := struct {
Metric Metric `json:"metric"`
Value SamplePair `json:"value"`
}{
Metric: s.Metric,
Value: SamplePair{
Timestamp: s.Timestamp,
Value: s.Value,
},
}
return json.Marshal(&v)
}
// UnmarshalJSON implements json.Unmarshaler.
func (s *Sample) UnmarshalJSON(b []byte) error {
v := struct {
Metric Metric `json:"metric"`
Value SamplePair `json:"value"`
}{
Metric: s.Metric,
Value: SamplePair{
Timestamp: s.Timestamp,
Value: s.Value,
},
}
if err := json.Unmarshal(b, &v); err != nil {
return err
}
s.Metric = v.Metric
s.Timestamp = v.Value.Timestamp
s.Value = v.Value.Value
return nil
}
// Samples is a sortable Sample slice. It implements sort.Interface.
type Samples []*Sample
func (s Samples) Len() int {
return len(s)
}
// Less compares first the metrics, then the timestamp.
func (s Samples) Less(i, j int) bool {
switch {
case s[i].Metric.Before(s[j].Metric):
return true
case s[j].Metric.Before(s[i].Metric):
return false
case s[i].Timestamp.Before(s[j].Timestamp):
return true
default:
return false
}
}
func (s Samples) Swap(i, j int) {
s[i], s[j] = s[j], s[i]
}
// Equal compares two sets of samples and returns true if they are equal.
func (s Samples) Equal(o Samples) bool {
if len(s) != len(o) {
return false
}
for i, sample := range s {
if !sample.Equal(o[i]) {
return false
}
}
return true
}
// SampleStream is a stream of Values belonging to an attached COWMetric.
type SampleStream struct {
Metric Metric `json:"metric"`
Values []SamplePair `json:"values"`
}
func (ss SampleStream) String() string {
vals := make([]string, len(ss.Values))
for i, v := range ss.Values {
vals[i] = v.String()
}
return fmt.Sprintf("%s =>\n%s", ss.Metric, strings.Join(vals, "\n"))
}
// Value is a generic interface for values resulting from a query evaluation.
type Value interface {
Type() ValueType
String() string
}
func (Matrix) Type() ValueType { return ValMatrix }
func (Vector) Type() ValueType { return ValVector }
func (*Scalar) Type() ValueType { return ValScalar }
func (*String) Type() ValueType { return ValString }
type ValueType int
const (
ValNone ValueType = iota
ValScalar
ValVector
ValMatrix
ValString
)
// MarshalJSON implements json.Marshaler.
func (et ValueType) MarshalJSON() ([]byte, error) {
return json.Marshal(et.String())
}
func (et *ValueType) UnmarshalJSON(b []byte) error {
var s string
if err := json.Unmarshal(b, &s); err != nil {
return err
}
switch s {
case "<ValNone>":
*et = ValNone
case "scalar":
*et = ValScalar
case "vector":
*et = ValVector
case "matrix":
*et = ValMatrix
case "string":
*et = ValString
default:
return fmt.Errorf("unknown value type %q", s)
}
return nil
}
func (e ValueType) String() string {
switch e {
case ValNone:
return "<ValNone>"
case ValScalar:
return "scalar"
case ValVector:
return "vector"
case ValMatrix:
return "matrix"
case ValString:
return "string"
}
panic("ValueType.String: unhandled value type")
}
// Scalar is a scalar value evaluated at the set timestamp.
type Scalar struct {
Value SampleValue `json:"value"`
Timestamp Time `json:"timestamp"`
}
func (s Scalar) String() string {
return fmt.Sprintf("scalar: %v @[%v]", s.Value, s.Timestamp)
}
// MarshalJSON implements json.Marshaler.
func (s Scalar) MarshalJSON() ([]byte, error) {
v := strconv.FormatFloat(float64(s.Value), 'f', -1, 64)
return json.Marshal([...]interface{}{s.Timestamp, string(v)})
}
// UnmarshalJSON implements json.Unmarshaler.
func (s *Scalar) UnmarshalJSON(b []byte) error {
var f string
v := [...]interface{}{&s.Timestamp, &f}
if err := json.Unmarshal(b, &v); err != nil {
return err
}
value, err := strconv.ParseFloat(f, 64)
if err != nil {
return fmt.Errorf("error parsing sample value: %s", err)
}
s.Value = SampleValue(value)
return nil
}
// String is a string value evaluated at the set timestamp.
type String struct {
Value string `json:"value"`
Timestamp Time `json:"timestamp"`
}
func (s *String) String() string {
return s.Value
}
// MarshalJSON implements json.Marshaler.
func (s String) MarshalJSON() ([]byte, error) {
return json.Marshal([]interface{}{s.Timestamp, s.Value})
}
// UnmarshalJSON implements json.Unmarshaler.
func (s *String) UnmarshalJSON(b []byte) error {
v := [...]interface{}{&s.Timestamp, &s.Value}
return json.Unmarshal(b, &v)
}
// Vector is basically only an alias for 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")
}
func (vec Vector) Len() int { return len(vec) }
func (vec Vector) Swap(i, j int) { vec[i], vec[j] = vec[j], vec[i] }
// Less compares first the metrics, then the timestamp.
func (vec Vector) Less(i, j int) bool {
switch {
case vec[i].Metric.Before(vec[j].Metric):
return true
case vec[j].Metric.Before(vec[i].Metric):
return false
case vec[i].Timestamp.Before(vec[j].Timestamp):
return true
default:
return false
}
}
// Equal compares two sets of samples and returns true if they are equal.
func (vec Vector) Equal(o Vector) bool {
if len(vec) != len(o) {
return false
}
for i, sample := range vec {
if !sample.Equal(o[i]) {
return false
}
}
return true
}
// Matrix is a list of time series.
type Matrix []*SampleStream
func (m Matrix) Len() int { return len(m) }
func (m Matrix) Less(i, j int) bool { return m[i].Metric.Before(m[j].Metric) }
func (m Matrix) Swap(i, j int) { m[i], m[j] = m[j], m[i] }
func (mat Matrix) String() string {
matCp := make(Matrix, len(mat))
copy(matCp, mat)
sort.Sort(matCp)
strs := make([]string, len(matCp))
for i, ss := range matCp {
strs[i] = ss.String()
}
return strings.Join(strs, "\n")
}