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
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
|
// Copyright 2017, OpenCensus 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 tag
import (
"bytes"
"context"
"fmt"
"sort"
)
// Tag is a key value pair that can be propagated on wire.
type Tag struct {
Key Key
Value string
}
// Map is a map of tags. Use New to create a context containing
// a new Map.
type Map struct {
m map[Key]string
}
// Value returns the value for the key if a value for the key exists.
func (m *Map) Value(k Key) (string, bool) {
if m == nil {
return "", false
}
v, ok := m.m[k]
return v, ok
}
func (m *Map) String() string {
if m == nil {
return "nil"
}
keys := make([]Key, 0, len(m.m))
for k := range m.m {
keys = append(keys, k)
}
sort.Slice(keys, func(i, j int) bool { return keys[i].Name() < keys[j].Name() })
var buffer bytes.Buffer
buffer.WriteString("{ ")
for _, k := range keys {
buffer.WriteString(fmt.Sprintf("{%v %v}", k.name, m.m[k]))
}
buffer.WriteString(" }")
return buffer.String()
}
func (m *Map) insert(k Key, v string) {
if _, ok := m.m[k]; ok {
return
}
m.m[k] = v
}
func (m *Map) update(k Key, v string) {
if _, ok := m.m[k]; ok {
m.m[k] = v
}
}
func (m *Map) upsert(k Key, v string) {
m.m[k] = v
}
func (m *Map) delete(k Key) {
delete(m.m, k)
}
func newMap() *Map {
return &Map{m: make(map[Key]string)}
}
// Mutator modifies a tag map.
type Mutator interface {
Mutate(t *Map) (*Map, error)
}
// Insert returns a mutator that inserts a
// value associated with k. If k already exists in the tag map,
// mutator doesn't update the value.
func Insert(k Key, v string) Mutator {
return &mutator{
fn: func(m *Map) (*Map, error) {
if !checkValue(v) {
return nil, errInvalidValue
}
m.insert(k, v)
return m, nil
},
}
}
// Update returns a mutator that updates the
// value of the tag associated with k with v. If k doesn't
// exists in the tag map, the mutator doesn't insert the value.
func Update(k Key, v string) Mutator {
return &mutator{
fn: func(m *Map) (*Map, error) {
if !checkValue(v) {
return nil, errInvalidValue
}
m.update(k, v)
return m, nil
},
}
}
// Upsert returns a mutator that upserts the
// value of the tag associated with k with v. It inserts the
// value if k doesn't exist already. It mutates the value
// if k already exists.
func Upsert(k Key, v string) Mutator {
return &mutator{
fn: func(m *Map) (*Map, error) {
if !checkValue(v) {
return nil, errInvalidValue
}
m.upsert(k, v)
return m, nil
},
}
}
// Delete returns a mutator that deletes
// the value associated with k.
func Delete(k Key) Mutator {
return &mutator{
fn: func(m *Map) (*Map, error) {
m.delete(k)
return m, nil
},
}
}
// New returns a new context that contains a tag map
// originated from the incoming context and modified
// with the provided mutators.
func New(ctx context.Context, mutator ...Mutator) (context.Context, error) {
m := newMap()
orig := FromContext(ctx)
if orig != nil {
for k, v := range orig.m {
if !checkKeyName(k.Name()) {
return ctx, fmt.Errorf("key:%q: %v", k, errInvalidKeyName)
}
if !checkValue(v) {
return ctx, fmt.Errorf("key:%q value:%q: %v", k.Name(), v, errInvalidValue)
}
m.insert(k, v)
}
}
var err error
for _, mod := range mutator {
m, err = mod.Mutate(m)
if err != nil {
return ctx, err
}
}
return NewContext(ctx, m), nil
}
// Do is similar to pprof.Do: a convenience for installing the tags
// from the context as Go profiler labels. This allows you to
// correlated runtime profiling with stats.
//
// It converts the key/values from the given map to Go profiler labels
// and calls pprof.Do.
//
// Do is going to do nothing if your Go version is below 1.9.
func Do(ctx context.Context, f func(ctx context.Context)) {
do(ctx, f)
}
type mutator struct {
fn func(t *Map) (*Map, error)
}
func (m *mutator) Mutate(t *Map) (*Map, error) {
return m.fn(t)
}
|
