123 lines
2.3 KiB
Go
123 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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// reconnectBackoff 按 DEVELOPMENT 第 9 节：1s 起、加倍、上限 30s、±30% 抖动；
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// 稳定在线 60s 后恢复到 1s。
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type reconnectBackoff struct {
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mu sync.Mutex
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base time.Duration
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onlineAt time.Time
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online bool
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stable bool
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timer *time.Timer
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}
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func newReconnectBackoff() *reconnectBackoff {
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return &reconnectBackoff{base: time.Second}
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}
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func (b *reconnectBackoff) Func(attempt int) time.Duration {
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b.mu.Lock()
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defer b.mu.Unlock()
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if attempt <= 0 {
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return 0
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}
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d := b.base
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for i := 1; i < attempt; i++ {
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d *= 2
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if d > 30*time.Second {
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d = 30 * time.Second
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break
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}
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}
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return withJitter(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.stable = false
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if b.timer != nil {
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b.timer.Stop()
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}
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b.timer = time.AfterFunc(60*time.Second, func() {
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b.mu.Lock()
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defer b.mu.Unlock()
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if b.online {
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b.stable = true
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b.base = time.Second
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}
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})
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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.timer != nil {
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b.timer.Stop()
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b.timer = nil
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}
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wasOnline := b.online
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b.online = false
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if !wasOnline {
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// 连接尚未成功就失败：在 Func 内已按 attempt 加倍，这里把 base 提到下次周期的起点。
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next := b.base * 2
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if next > 30*time.Second {
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next = 30 * time.Second
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}
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if next < time.Second {
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next = time.Second
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}
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b.base = next
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return
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}
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if b.stable || time.Since(b.onlineAt) >= 60*time.Second {
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b.base = time.Second
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b.stable = false
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return
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}
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next := b.base * 2
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if next > 30*time.Second {
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next = 30 * time.Second
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}
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b.base = next
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b.stable = false
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}
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func (b *reconnectBackoff) Base() time.Duration {
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b.mu.Lock()
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defer b.mu.Unlock()
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return b.base
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}
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func withJitter(d time.Duration) time.Duration {
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// ±30%
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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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// computeBackoffDelay 供单测：无 attempt 与 base 计算无抖动前的标称延迟。
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func computeBackoffDelay(base time.Duration, attempt int) time.Duration {
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if attempt <= 0 {
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return 0
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}
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d := base
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for i := 1; i < attempt; 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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if d > 30*time.Second {
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return 30 * time.Second
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}
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return d
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}
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