-
Notifications
You must be signed in to change notification settings - Fork 22
/
ratelimit.go
89 lines (75 loc) · 1.97 KB
/
ratelimit.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
// Copyright (C) 2023 Gobalsky Labs Limited
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package ratelimit
import (
"encoding/base64"
)
type Key []byte
func (k Key) String() string {
return base64.StdEncoding.EncodeToString(k)
}
type Rates struct {
block int
requests int
perNBlocks int
entries map[string][]int
}
func New(requests, perNBlocks int) *Rates {
return &Rates{
block: 0,
requests: requests,
perNBlocks: perNBlocks,
entries: map[string][]int{},
}
}
// Count returns the number of requests recorded for a given key
// It returns -1 if the key has been not recorded or evicted.
func (r *Rates) Count(key string) int {
entry, ok := r.entries[key]
if !ok {
return -1
}
var count int
for _, n := range entry {
count += n
}
return count
}
func (r *Rates) NextBlock() {
// compute the next block index
r.block = (r.block + 1) % (r.perNBlocks)
// reset the counters for that particular block index
for _, c := range r.entries {
c[r.block] = 0
}
// We clean up the entries after finishing the block round
if r.block != 0 {
return
}
for key := range r.entries {
if r.Count(key) == 0 {
delete(r.entries, key)
}
}
}
func (r *Rates) Allow(key string) bool {
entry, ok := r.entries[key]
if !ok {
entry = make([]int, r.perNBlocks)
r.entries[key] = entry
}
entry[r.block]++
return r.Count(key) < r.requests
}