pool.go

package xdb

import (
	"sync"
	"time"
	"fmt"
	"runtime/debug"
	"log"
)

type PoolClient struct {
	sync.RWMutex
	ClientChan chan *Client
	Uri string
	MaxClientCount uint8
	CurrentClientCount uint8
	AvailableCount	uint8
}

var clientPool map[string]*PoolClient

func init()  {
	clientPool = make(map[string]*PoolClient,0)
}

func InitClientPool(name string,uri string,count uint8) error{
	if _,ok:=clientPool[name];!ok{
		clientPool[name] = &PoolClient{
			ClientChan: make(chan *Client, int(count)),
			Uri:uri,
			MaxClientCount: count,
			CurrentClientCount: 0,
			AvailableCount:0,
		}
	}
	return nil
}

func GetClient(name string) (c *Client,err error) {
	if _,ok:=clientPool[name];!ok{
		return nil,fmt.Errorf(name+" not esxit")
	}
	t := clientPool[name]
	t.Lock()
	if t.AvailableCount > 0 {
		t.AvailableCount--
		t.Unlock()
		//这里为什么不需要timeout,是因为前面加了lock 判断空闲连接数
		c = <- t.ClientChan
		return
	}
	if t.MaxClientCount > t.CurrentClientCount{
		t.CurrentClientCount++
		t.Unlock()
		f,stringKey := NewClient(name,t.Uri)
		if f == nil{
			t.Lock()
			t.CurrentClientCount--
			t.Unlock()
		}
		return f,stringKey
	}
	t.Unlock()
	timer := time.NewTimer(5 * time.Second)
	select {
	case c = <-t.ClientChan:
		break
	case <- timer.C:
		break
	}
	timer.Stop()
	if c == nil{
		return nil,fmt.Errorf("get client time out")
	}
	t.Lock()
	t.AvailableCount--
	t.Unlock()
	return
}

func BackCient(name string,c *Client) bool {
	defer func() {
		if err := recover();err !=nil{
			log.Println(string(debug.Stack()))
			return
		}
	}()
	if _,ok:=clientPool[name];!ok{
		return true
	}
	t:=clientPool[name]
	t.Lock()
	if t.CurrentClientCount > t.MaxClientCount{
		t.CurrentClientCount--
		func(){
			defer func() {
				if err := recover();err != nil{
					log.Println(string(debug.Stack()))
					return
				}
			}()
			//调用插件函数,关闭连接,这里防止插件代码写得有问题,抛异常,所以这里需要recover一次
			c.Close()
		}()
	}else{
		t.AvailableCount++
		t.ClientChan <- c
	}
	t.Unlock()
	return true
}