108 lines
2.3 KiB
Go
108 lines
2.3 KiB
Go
package pubsub
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import (
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"context"
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"fmt"
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"math/rand"
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"sync"
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"time"
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"github.com/libp2p/go-libp2p/core/peer"
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)
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const (
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MinBackoffDelay = 100 * time.Millisecond
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MaxBackoffDelay = 10 * time.Second
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TimeToLive = 10 * time.Minute
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BackoffCleanupInterval = 1 * time.Minute
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BackoffMultiplier = 2
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MaxBackoffJitterCoff = 100
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MaxBackoffAttempts = 4
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)
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type backoffHistory struct {
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duration time.Duration
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lastTried time.Time
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attempts int
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}
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type backoff struct {
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mu sync.Mutex
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info map[peer.ID]*backoffHistory
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ct int // size threshold that kicks off the cleaner
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ci time.Duration // cleanup intervals
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maxAttempts int // maximum backoff attempts prior to ejection
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}
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func newBackoff(ctx context.Context, sizeThreshold int, cleanupInterval time.Duration, maxAttempts int) *backoff {
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b := &backoff{
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mu: sync.Mutex{},
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ct: sizeThreshold,
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ci: cleanupInterval,
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maxAttempts: maxAttempts,
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info: make(map[peer.ID]*backoffHistory),
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}
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rand.Seed(time.Now().UnixNano()) // used for jitter
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go b.cleanupLoop(ctx)
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return b
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}
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func (b *backoff) updateAndGet(id peer.ID) (time.Duration, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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h, ok := b.info[id]
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switch {
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case !ok || time.Since(h.lastTried) > TimeToLive:
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// first request goes immediately.
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h = &backoffHistory{
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duration: time.Duration(0),
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attempts: 0,
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}
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case h.attempts >= b.maxAttempts:
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return 0, fmt.Errorf("peer %s has reached its maximum backoff attempts", id)
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case h.duration < MinBackoffDelay:
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h.duration = MinBackoffDelay
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case h.duration < MaxBackoffDelay:
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jitter := rand.Intn(MaxBackoffJitterCoff)
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h.duration = (BackoffMultiplier * h.duration) + time.Duration(jitter)*time.Millisecond
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if h.duration > MaxBackoffDelay || h.duration < 0 {
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h.duration = MaxBackoffDelay
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}
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}
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h.attempts += 1
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h.lastTried = time.Now()
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b.info[id] = h
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return h.duration, nil
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}
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func (b *backoff) cleanup() {
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b.mu.Lock()
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defer b.mu.Unlock()
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for id, h := range b.info {
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if time.Since(h.lastTried) > TimeToLive {
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delete(b.info, id)
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}
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}
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}
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func (b *backoff) cleanupLoop(ctx context.Context) {
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ticker := time.NewTicker(b.ci)
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defer ticker.Stop()
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for {
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select {
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case <-ctx.Done():
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return // pubsub shutting down
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case <-ticker.C:
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b.cleanup()
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}
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}
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}
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