Golang 业务限流器

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package rate

import (
    "math/rand"
    "sync"
    "sync/atomic"
    "time"
)

//使用cas 锁来实现、减少开销
//业务限流器
const (
    Normal = iota
    AbNormal
)

//标示, 可以是appId  uid 唯一性的代表值
type Limit float64

type Limiter struct {
    limit     Limit
    EventName string
    //cas
    done uint32

    //时间
    retryTime int
    //重试次数
    retryLen int

    //最大缓冲时间
    maxTime int64
    //最小缓冲时间
    minTime int64

    mu sync.Mutex
    // last is the last time the limiter's tokens field was updated
    last time.Time
    // lastEvent is the latest time of a rate-limited event (past or future)
    lastEvent time.Time
}

func NewLimiter(r Limit, n string) *Limiter {

    return &Limiter{
        limit:     r,
        EventName: n,
    }
}

func DefaultLimiter(r Limit, n string) *Limiter {
    return &Limiter{
        limit:     r,
        EventName: n,
        maxTime:   1000,
        minTime:   100,
    }
}

func (lim *Limiter) Allow() bool {
    //no limit rate
    if atomic.LoadUint32(&lim.done) == Normal {
        return true
    }
    //rand sleep, avoid conflict
    randTime := rand.Int63n(lim.maxTime-lim.minTime) + lim.minTime
    time.Sleep(time.Duration(randTime) * time.Millisecond)
    return false
}

//where use stop
func (lim *Limiter) Stop() bool {
    lim.mu.Lock()
    defer lim.mu.Unlock()
    if lim.done == Normal {
        defer atomic.StoreUint32(&lim.done, AbNormal)
    }

    return true
}

func (lim *Limiter) Recover() {

    if atomic.LoadUint32(&lim.done) == AbNormal {
        return
    }
    lim.mu.Lock()
    defer lim.mu.Unlock()
    if lim.done == AbNormal {
        defer atomic.StoreUint32(&lim.done, Normal)
    }
}

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