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71 lines
1.5 KiB
71 lines
1.5 KiB
package breaker
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import (
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"math"
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"math/rand"
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"sync/atomic"
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"time"
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"github.com/bilibili/Kratos/pkg/ecode"
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"github.com/bilibili/Kratos/pkg/log"
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"github.com/bilibili/Kratos/pkg/stat/summary"
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)
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// sreBreaker is a sre CircuitBreaker pattern.
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type sreBreaker struct {
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stat summary.Summary
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k float64
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request int64
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state int32
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r *rand.Rand
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}
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func newSRE(c *Config) Breaker {
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return &sreBreaker{
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stat: summary.New(time.Duration(c.Window), c.Bucket),
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r: rand.New(rand.NewSource(time.Now().UnixNano())),
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request: c.Request,
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k: c.K,
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state: StateClosed,
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}
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}
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func (b *sreBreaker) Allow() error {
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success, total := b.stat.Value()
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k := b.k * float64(success)
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if log.V(5) {
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log.Info("breaker: request: %d, succee: %d, fail: %d", total, success, total-success)
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}
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// check overflow requests = K * success
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if total < b.request || float64(total) < k {
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if atomic.LoadInt32(&b.state) == StateOpen {
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atomic.CompareAndSwapInt32(&b.state, StateOpen, StateClosed)
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}
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return nil
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}
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if atomic.LoadInt32(&b.state) == StateClosed {
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atomic.CompareAndSwapInt32(&b.state, StateClosed, StateOpen)
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}
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dr := math.Max(0, (float64(total)-k)/float64(total+1))
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rr := b.r.Float64()
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if log.V(5) {
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log.Info("breaker: drop ratio: %f, real rand: %f, drop: %v", dr, rr, dr > rr)
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}
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if dr <= rr {
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return nil
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}
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return ecode.ServiceUnavailable
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}
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func (b *sreBreaker) MarkSuccess() {
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b.stat.Add(1)
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}
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func (b *sreBreaker) MarkFailed() {
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// NOTE: when client reject requets locally, continue add counter let the
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// drop ratio higher.
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b.stat.Add(0)
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}
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