-
Notifications
You must be signed in to change notification settings - Fork 450
/
round_robin.go
61 lines (53 loc) · 1.78 KB
/
round_robin.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
// Copyright 2021 OpenSSF Scorecard 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 tokens
import (
"sync/atomic"
"time"
)
const expiryTimeInSec = 30
// roundRobinAccessor implements TokenAccessor.
type roundRobinAccessor struct {
accessTokens []string
accessState []int64
counter uint64
}
// Next implements TokenAccessor.Next.
func (tokens *roundRobinAccessor) Next() (uint64, string) {
c := atomic.AddUint64(&tokens.counter, 1)
l := len(tokens.accessTokens)
index := c % uint64(l)
// If selected accessToken is unavailable, wait.
for !atomic.CompareAndSwapInt64(&tokens.accessState[index], 0, time.Now().Unix()) {
currVal := atomic.LoadInt64(&tokens.accessState[index])
expired := time.Now().After(time.Unix(currVal, 0).Add(expiryTimeInSec * time.Second))
if !expired {
continue
}
if atomic.CompareAndSwapInt64(&tokens.accessState[index], currVal, time.Now().Unix()) {
break
}
}
return index, tokens.accessTokens[index]
}
// Release implements TokenAccessor.Release.
func (tokens *roundRobinAccessor) Release(id uint64) {
atomic.SwapInt64(&tokens.accessState[id], 0)
}
func makeRoundRobinAccessor(accessTokens []string) TokenAccessor {
return &roundRobinAccessor{
accessTokens: accessTokens,
accessState: make([]int64, len(accessTokens)),
}
}