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
|
// Copyright (c) 2017 Uber Technologies, Inc.
//
// 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 metrics
import (
"fmt"
"reflect"
"strconv"
"strings"
)
// MustInit initializes the passed in metrics and initializes its fields using the passed in factory.
//
// It uses reflection to initialize a struct containing metrics fields
// by assigning new Counter/Gauge/Timer values with the metric name retrieved
// from the `metric` tag and stats tags retrieved from the `tags` tag.
//
// Note: all fields of the struct must be exported, have a `metric` tag, and be
// of type Counter or Gauge or Timer.
//
// Errors during Init lead to a panic.
func MustInit(metrics interface{}, factory Factory, globalTags map[string]string) {
if err := Init(metrics, factory, globalTags); err != nil {
panic(err.Error())
}
}
// Init does the same as Init, but returns an error instead of
// panicking.
func Init(m interface{}, factory Factory, globalTags map[string]string) error {
// Allow user to opt out of reporting metrics by passing in nil.
if factory == nil {
factory = NullFactory
}
counterPtrType := reflect.TypeOf((*Counter)(nil)).Elem()
gaugePtrType := reflect.TypeOf((*Gauge)(nil)).Elem()
timerPtrType := reflect.TypeOf((*Timer)(nil)).Elem()
histogramPtrType := reflect.TypeOf((*Histogram)(nil)).Elem()
v := reflect.ValueOf(m).Elem()
t := v.Type()
for i := 0; i < t.NumField(); i++ {
tags := make(map[string]string)
for k, v := range globalTags {
tags[k] = v
}
var buckets []float64
field := t.Field(i)
metric := field.Tag.Get("metric")
if metric == "" {
return fmt.Errorf("Field %s is missing a tag 'metric'", field.Name)
}
if tagString := field.Tag.Get("tags"); tagString != "" {
tagPairs := strings.Split(tagString, ",")
for _, tagPair := range tagPairs {
tag := strings.Split(tagPair, "=")
if len(tag) != 2 {
return fmt.Errorf(
"Field [%s]: Tag [%s] is not of the form key=value in 'tags' string [%s]",
field.Name, tagPair, tagString)
}
tags[tag[0]] = tag[1]
}
}
if bucketString := field.Tag.Get("buckets"); bucketString != "" {
if field.Type.AssignableTo(timerPtrType) {
// TODO: Parse timer duration buckets
return fmt.Errorf(
"Field [%s]: Buckets are not currently initialized for timer metrics",
field.Name)
} else if field.Type.AssignableTo(histogramPtrType) {
bucketValues := strings.Split(bucketString, ",")
for _, bucket := range bucketValues {
b, err := strconv.ParseFloat(bucket, 64)
if err != nil {
return fmt.Errorf(
"Field [%s]: Bucket [%s] could not be converted to float64 in 'buckets' string [%s]",
field.Name, bucket, bucketString)
}
buckets = append(buckets, b)
}
} else {
return fmt.Errorf(
"Field [%s]: Buckets should only be defined for Timer and Histogram metric types",
field.Name)
}
}
help := field.Tag.Get("help")
var obj interface{}
if field.Type.AssignableTo(counterPtrType) {
obj = factory.Counter(Options{
Name: metric,
Tags: tags,
Help: help,
})
} else if field.Type.AssignableTo(gaugePtrType) {
obj = factory.Gauge(Options{
Name: metric,
Tags: tags,
Help: help,
})
} else if field.Type.AssignableTo(timerPtrType) {
// TODO: Add buckets once parsed (see TODO above)
obj = factory.Timer(TimerOptions{
Name: metric,
Tags: tags,
Help: help,
})
} else if field.Type.AssignableTo(histogramPtrType) {
obj = factory.Histogram(HistogramOptions{
Name: metric,
Tags: tags,
Help: help,
Buckets: buckets,
})
} else {
return fmt.Errorf(
"Field %s is not a pointer to timer, gauge, or counter",
field.Name)
}
v.Field(i).Set(reflect.ValueOf(obj))
}
return nil
}
|
