1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
|
// Copyright 2014 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 (
"sort"
)
// SeparatorByte is a byte that cannot occur in valid UTF-8 sequences and is
// used to separate label names, label values, and other strings from each other
// when calculating their combined hash value (aka signature aka fingerprint).
const SeparatorByte byte = 255
var (
// cache the signature of an empty label set.
emptyLabelSignature = hashNew()
)
// LabelsToSignature returns a quasi-unique signature (i.e., fingerprint) for a
// given label set. (Collisions are possible but unlikely if the number of label
// sets the function is applied to is small.)
func LabelsToSignature(labels map[string]string) uint64 {
if len(labels) == 0 {
return emptyLabelSignature
}
labelNames := make([]string, 0, len(labels))
for labelName := range labels {
labelNames = append(labelNames, labelName)
}
sort.Strings(labelNames)
sum := hashNew()
for _, labelName := range labelNames {
sum = hashAdd(sum, labelName)
sum = hashAddByte(sum, SeparatorByte)
sum = hashAdd(sum, labels[labelName])
sum = hashAddByte(sum, SeparatorByte)
}
return sum
}
// labelSetToFingerprint works exactly as LabelsToSignature but takes a LabelSet as
// parameter (rather than a label map) and returns a Fingerprint.
func labelSetToFingerprint(ls LabelSet) Fingerprint {
if len(ls) == 0 {
return Fingerprint(emptyLabelSignature)
}
labelNames := make(LabelNames, 0, len(ls))
for labelName := range ls {
labelNames = append(labelNames, labelName)
}
sort.Sort(labelNames)
sum := hashNew()
for _, labelName := range labelNames {
sum = hashAdd(sum, string(labelName))
sum = hashAddByte(sum, SeparatorByte)
sum = hashAdd(sum, string(ls[labelName]))
sum = hashAddByte(sum, SeparatorByte)
}
return Fingerprint(sum)
}
// labelSetToFastFingerprint works similar to labelSetToFingerprint but uses a
// faster and less allocation-heavy hash function, which is more susceptible to
// create hash collisions. Therefore, collision detection should be applied.
func labelSetToFastFingerprint(ls LabelSet) Fingerprint {
if len(ls) == 0 {
return Fingerprint(emptyLabelSignature)
}
var result uint64
for labelName, labelValue := range ls {
sum := hashNew()
sum = hashAdd(sum, string(labelName))
sum = hashAddByte(sum, SeparatorByte)
sum = hashAdd(sum, string(labelValue))
result ^= sum
}
return Fingerprint(result)
}
// SignatureForLabels works like LabelsToSignature but takes a Metric as
// parameter (rather than a label map) and only includes the labels with the
// specified LabelNames into the signature calculation. The labels passed in
// will be sorted by this function.
func SignatureForLabels(m Metric, labels ...LabelName) uint64 {
if len(labels) == 0 {
return emptyLabelSignature
}
sort.Sort(LabelNames(labels))
sum := hashNew()
for _, label := range labels {
sum = hashAdd(sum, string(label))
sum = hashAddByte(sum, SeparatorByte)
sum = hashAdd(sum, string(m[label]))
sum = hashAddByte(sum, SeparatorByte)
}
return sum
}
// SignatureWithoutLabels works like LabelsToSignature but takes a Metric as
// parameter (rather than a label map) and excludes the labels with any of the
// specified LabelNames from the signature calculation.
func SignatureWithoutLabels(m Metric, labels map[LabelName]struct{}) uint64 {
if len(m) == 0 {
return emptyLabelSignature
}
labelNames := make(LabelNames, 0, len(m))
for labelName := range m {
if _, exclude := labels[labelName]; !exclude {
labelNames = append(labelNames, labelName)
}
}
if len(labelNames) == 0 {
return emptyLabelSignature
}
sort.Sort(labelNames)
sum := hashNew()
for _, labelName := range labelNames {
sum = hashAdd(sum, string(labelName))
sum = hashAddByte(sum, SeparatorByte)
sum = hashAdd(sum, string(m[labelName]))
sum = hashAddByte(sum, SeparatorByte)
}
return sum
}
|
