134 lines
2.3 KiB
Go
134 lines
2.3 KiB
Go
package nixmsg
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import (
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"math/rand"
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"sync"
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"time"
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)
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// 重连 / 限速重交共用标称间隔：第 n 次 min(1s×2^(n-1), 30s)，n≥1。
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func nominalDelay(n int) time.Duration {
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if n < 1 {
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return 0
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}
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if n > 6 {
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return 30 * time.Second
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}
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d := time.Second
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for i := 1; i < n; i++ {
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d *= 2
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if d >= 30*time.Second {
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return 30 * time.Second
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}
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}
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return d
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}
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var backoffJitter = withJitter
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func withJitter(d time.Duration) time.Duration {
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if d <= 0 {
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return 0
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}
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f := 0.7 + rand.Float64()*0.6
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return time.Duration(float64(d) * f)
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}
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// reconnectBackoff 只维护一个连续失败计数 n。
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// 应用调用 Connect 后的第一次连接不等待；之后第 n 次等待 nominalDelay(n)×抖动。
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type reconnectBackoff struct {
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mu sync.Mutex
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n int
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skipFirst bool
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online bool
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onlineAt time.Time
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counted bool
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}
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func newReconnectBackoff() *reconnectBackoff {
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return &reconnectBackoff{skipFirst: true}
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}
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// Func 供 autopaho；忽略其 attempt，只用本对象的 n。
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func (b *reconnectBackoff) Func(attempt int) time.Duration {
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_ = attempt
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return b.NextWait()
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}
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func (b *reconnectBackoff) NextWait() time.Duration {
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return b.nextWait(true)
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}
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func (b *reconnectBackoff) nextWait(jitter bool) time.Duration {
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b.mu.Lock()
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defer b.mu.Unlock()
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b.counted = false
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if b.skipFirst {
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b.skipFirst = false
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return 0
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}
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n := b.n
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if n < 1 {
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n = 1
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}
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d := nominalDelay(n)
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if jitter {
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return backoffJitter(d)
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}
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return d
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}
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func (b *reconnectBackoff) MarkOnline() {
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b.mu.Lock()
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defer b.mu.Unlock()
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b.online = true
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b.onlineAt = time.Now()
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b.counted = false
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}
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func (b *reconnectBackoff) MarkOffline() {
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b.mu.Lock()
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defer b.mu.Unlock()
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if b.counted {
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return
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}
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b.counted = true
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was := b.online
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onlineAt := b.onlineAt
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b.online = false
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if !was {
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b.n++
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if b.n < 1 {
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b.n = 1
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}
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return
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}
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if time.Since(onlineAt) >= 60*time.Second {
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b.n = 1
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return
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}
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b.n++
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if b.n < 1 {
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b.n = 1
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}
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}
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func (b *reconnectBackoff) N() int {
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b.mu.Lock()
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defer b.mu.Unlock()
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return b.n
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}
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func (b *reconnectBackoff) setOnlineAtForTest(t time.Time) {
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b.mu.Lock()
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defer b.mu.Unlock()
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b.online = true
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b.onlineAt = t
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}
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// computeBackoffDelay 保留给旧单测：忽略 base，按 n 计算标称延迟。
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func computeBackoffDelay(base time.Duration, n int) time.Duration {
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_ = base
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return nominalDelay(n)
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}
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