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@ -3,6 +3,7 @@ package breaker |
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import ( |
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"math" |
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"math/rand" |
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"sync" |
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"sync/atomic" |
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"time" |
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@ -11,6 +12,12 @@ import ( |
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"github.com/bilibili/kratos/pkg/stat/metric" |
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) |
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var ( |
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// rand.New(...) returns a non thread safe object
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random = rand.New(rand.NewSource(time.Now().UnixNano())) |
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lock sync.Mutex |
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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 metric.RollingCounter |
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@ -19,7 +26,6 @@ type sreBreaker struct { |
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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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@ -30,7 +36,6 @@ func newSRE(c *Config) Breaker { |
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stat := metric.NewRollingCounter(counterOpts) |
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return &sreBreaker{ |
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stat: stat, |
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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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@ -69,14 +74,14 @@ func (b *sreBreaker) Allow() error { |
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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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drop := trueOnProba(dr) |
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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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log.Info("breaker: drop ratio: %f, drop: %t", dr, drop) |
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} |
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if drop { |
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return ecode.ServiceUnavailable |
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} |
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return nil |
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} |
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func (b *sreBreaker) MarkSuccess() { |
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@ -88,3 +93,10 @@ func (b *sreBreaker) MarkFailed() { |
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// drop ratio higher.
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b.stat.Add(0) |
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} |
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func trueOnProba(proba float64) (truth bool) { |
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lock.Lock() |
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truth = random.Float64() < proba |
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lock.Unlock() |
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return |
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} |
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