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accesscontrol.go
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accesscontrol.go
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// Copyright 2018 Blockchain-CN . All rights reserved.
// https://github.com/Blockchain-CN
package httpsvr
import (
"errors"
"sync"
"time"
"sync/atomic"
)
// Access 接入控制
type Access struct {
maxAccess int
// 桶,用来限制最大并发数
bucket chan struct{}
// 用来判断何时桶内已空,否则需要循环判断
wg sync.WaitGroup
closed int32
}
// NewAccessor ...
func NewAccessor(i int) *Access {
var ac Access
ac.closed = 0
ac.maxAccess = i
// 10ms 准入超时计时器,时间窗口
ac.bucket = make(chan struct{}, i)
return &ac
}
// Stop 优雅退出
func (a *Access) Stop() {
if !atomic.CompareAndSwapInt32(&a.closed, 0, 1) {
return
}
// 第一种判断桶内为空
a.wg.Wait()
/*第二种判断桶内为空
for {
if len(a.bucket)== 0 {
return
}
}*/
}
// InControl 入口控制
func (a *Access) InControl() error {
if atomic.LoadInt32(&a.closed) == 1 {
return errors.New("server is closing")
}
select {
case a.bucket <- struct{}{}:
a.wg.Add(1)
case <-time.After(time.Millisecond * 100):
return errors.New("server is busy please try later")
}
return nil
}
// OutControl 出口注销
func (a *Access) OutControl() {
<-a.bucket
a.wg.Done()
}