-
Notifications
You must be signed in to change notification settings - Fork 4.4k
/
callcounter.go
66 lines (59 loc) · 2.12 KB
/
callcounter.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
/*
*
* Copyright 2022 gRPC 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 outlierdetection
import (
"sync/atomic"
"unsafe"
)
type bucket struct {
numSuccesses uint32
numFailures uint32
}
func newCallCounter() *callCounter {
return &callCounter{
activeBucket: unsafe.Pointer(&bucket{}),
inactiveBucket: &bucket{},
}
}
// callCounter has two buckets, which each count successful and failing RPC's.
// The activeBucket is used to actively count any finished RPC's, and the
// inactiveBucket is populated with this activeBucket's data every interval for
// use by the Outlier Detection algorithm.
type callCounter struct {
// activeBucket updates every time a call finishes (from picker passed to
// Client Conn), so protect pointer read with atomic load of unsafe.Pointer
// so picker does not have to grab a mutex per RPC, the critical path.
activeBucket unsafe.Pointer // bucket
inactiveBucket *bucket
}
func (cc *callCounter) clear() {
atomic.StorePointer(&cc.activeBucket, unsafe.Pointer(&bucket{}))
cc.inactiveBucket = &bucket{}
}
// "When the timer triggers, the inactive bucket is zeroed and swapped with the
// active bucket. Then the inactive bucket contains the number of successes and
// failures since the last time the timer triggered. Those numbers are used to
// evaluate the ejection criteria." - A50.
func (cc *callCounter) swap() {
ib := cc.inactiveBucket
*ib = bucket{}
ab := (*bucket)(atomic.SwapPointer(&cc.activeBucket, unsafe.Pointer(ib)))
cc.inactiveBucket = &bucket{
numSuccesses: atomic.LoadUint32(&ab.numSuccesses),
numFailures: atomic.LoadUint32(&ab.numFailures),
}
}