You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
71 lines
1.5 KiB
71 lines
1.5 KiB
package breaker
|
|
|
|
import (
|
|
"math"
|
|
"math/rand"
|
|
"sync/atomic"
|
|
"time"
|
|
|
|
"github.com/bilibili/kratos/pkg/ecode"
|
|
"github.com/bilibili/kratos/pkg/log"
|
|
"github.com/bilibili/kratos/pkg/stat/summary"
|
|
)
|
|
|
|
// sreBreaker is a sre CircuitBreaker pattern.
|
|
type sreBreaker struct {
|
|
stat summary.Summary
|
|
|
|
k float64
|
|
request int64
|
|
|
|
state int32
|
|
r *rand.Rand
|
|
}
|
|
|
|
func newSRE(c *Config) Breaker {
|
|
return &sreBreaker{
|
|
stat: summary.New(time.Duration(c.Window), c.Bucket),
|
|
r: rand.New(rand.NewSource(time.Now().UnixNano())),
|
|
|
|
request: c.Request,
|
|
k: c.K,
|
|
state: StateClosed,
|
|
}
|
|
}
|
|
|
|
func (b *sreBreaker) Allow() error {
|
|
success, total := b.stat.Value()
|
|
k := b.k * float64(success)
|
|
if log.V(5) {
|
|
log.Info("breaker: request: %d, succee: %d, fail: %d", total, success, total-success)
|
|
}
|
|
// check overflow requests = K * success
|
|
if total < b.request || float64(total) < k {
|
|
if atomic.LoadInt32(&b.state) == StateOpen {
|
|
atomic.CompareAndSwapInt32(&b.state, StateOpen, StateClosed)
|
|
}
|
|
return nil
|
|
}
|
|
if atomic.LoadInt32(&b.state) == StateClosed {
|
|
atomic.CompareAndSwapInt32(&b.state, StateClosed, StateOpen)
|
|
}
|
|
dr := math.Max(0, (float64(total)-k)/float64(total+1))
|
|
rr := b.r.Float64()
|
|
if log.V(5) {
|
|
log.Info("breaker: drop ratio: %f, real rand: %f, drop: %v", dr, rr, dr > rr)
|
|
}
|
|
if dr <= rr {
|
|
return nil
|
|
}
|
|
return ecode.ServiceUnavailable
|
|
}
|
|
|
|
func (b *sreBreaker) MarkSuccess() {
|
|
b.stat.Add(1)
|
|
}
|
|
|
|
func (b *sreBreaker) MarkFailed() {
|
|
// NOTE: when client reject requets locally, continue add counter let the
|
|
// drop ratio higher.
|
|
b.stat.Add(0)
|
|
}
|
|
|