xfy
c6bb75cffe
- Zero-lock atomic EWMA implementation using fixed-point arithmetic - Supports header_time and last_byte_time tracking - Concurrent-safe with CAS retry loop
61 lines
1.3 KiB
Go
61 lines
1.3 KiB
Go
package loadbalance
|
||
|
||
import (
|
||
"sync/atomic"
|
||
"time"
|
||
)
|
||
|
||
// EWMAStats 使用原子操作实现的 EWMA（指数加权移动平均）统计器。
|
||
type EWMAStats struct {
|
||
headerTime atomic.Int64 // 首字节时间的 EWMA（纳秒）
|
||
lastByteTime atomic.Int64 // 完整响应时间的 EWMA（纳秒）
|
||
sampleCount atomic.Int64 // 样本计数
|
||
}
|
||
|
||
const defaultAlphaScale = 300 // alpha = 0.3
|
||
|
||
func NewEWMAStats() *EWMAStats {
|
||
return &EWMAStats{}
|
||
}
|
||
|
||
func (e *EWMAStats) Record(headerTime, lastByteTime time.Duration) {
|
||
e.recordAtomic(&e.headerTime, headerTime)
|
||
e.recordAtomic(&e.lastByteTime, lastByteTime)
|
||
e.sampleCount.Add(1)
|
||
}
|
||
|
||
func (e *EWMAStats) recordAtomic(ptr *atomic.Int64, newValue time.Duration) {
|
||
newNano := newValue.Nanoseconds()
|
||
for {
|
||
old := ptr.Load()
|
||
if old == 0 {
|
||
if ptr.CompareAndSwap(0, newNano) {
|
||
return
|
||
}
|
||
continue
|
||
}
|
||
updated := (defaultAlphaScale*newNano + (1000-defaultAlphaScale)*old) / 1000
|
||
if ptr.CompareAndSwap(old, updated) {
|
||
return
|
||
}
|
||
}
|
||
}
|
||
|
||
func (e *EWMAStats) HeaderTime() time.Duration {
|
||
return time.Duration(e.headerTime.Load())
|
||
}
|
||
|
||
func (e *EWMAStats) LastByteTime() time.Duration {
|
||
return time.Duration(e.lastByteTime.Load())
|
||
}
|
||
|
||
func (e *EWMAStats) SampleCount() int64 {
|
||
return e.sampleCount.Load()
|
||
}
|
||
|
||
func (e *EWMAStats) Reset() {
|
||
e.headerTime.Store(0)
|
||
e.lastByteTime.Store(0)
|
||
e.sampleCount.Store(0)
|
||
}
|