-
Notifications
You must be signed in to change notification settings - Fork 451
/
sampler.go
99 lines (85 loc) · 2.64 KB
/
sampler.go
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
// Copyright (c) 2018 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package sampler
import (
"fmt"
"go.uber.org/atomic"
)
// Rate is a sample rate.
type Rate float64
// Value returns the float64 sample rate value.
func (r Rate) Value() float64 {
return float64(r)
}
// Validate validates a sample rate.
func (r Rate) Validate() error {
if r < 0.0 || r > 1.0 {
return fmt.Errorf("invalid sample rate: actual=%f, valid=[0.0,1.0]", r)
}
return nil
}
// UnmarshalYAML unmarshals a sample rate.
func (r *Rate) UnmarshalYAML(unmarshal func(interface{}) error) error {
var value float64
if err := unmarshal(&value); err != nil {
return err
}
parsed := Rate(value)
if err := parsed.Validate(); err != nil {
return err
}
*r = parsed
return nil
}
// Sampler samples the requests, out of 100 sample calls,
// 100*sampleRate calls will be sampled.
type Sampler struct {
sampleRate Rate
sampleEvery int32
numTried *atomic.Int32
}
// NewSampler creates a new sampler with a sample rate.
func NewSampler(sampleRate Rate) (*Sampler, error) {
if err := sampleRate.Validate(); err != nil {
return nil, err
}
if sampleRate == 0 {
return &Sampler{
sampleRate: sampleRate,
sampleEvery: 0,
}, nil
}
return &Sampler{
sampleRate: sampleRate,
numTried: atomic.NewInt32(0),
sampleEvery: int32(1.0 / sampleRate),
}, nil
}
// Sample returns true when the call is sampled.
func (t *Sampler) Sample() bool {
if t.sampleEvery == 0 {
return false
}
return (t.numTried.Inc()-1)%t.sampleEvery == 0
}
// SampleRate returns the effective sample rate.
func (t *Sampler) SampleRate() Rate {
return t.sampleRate
}