mgo连接池

package main

import (
    "log"
    "sync"
    "time"

    "gopkg.in/mgo.v2"
)

var sizeMax = 50
var size = 0
var sizeMu = sync.Mutex{}
var pool = make(chan *mgo.Session, sizeMax)

func getConn() *mgo.Session {
    sizeMu.Lock()
    defer sizeMu.Unlock()
    select {
    case conn := <-pool:
        log.Println("get conn from pool start")
        if conn.Ping() == nil {
            log.Println("get conn from pool success")
            return conn
        } else {
            size--
        }
    default:
    }
    if size >= sizeMax {
        log.Println("继续从连接池获取连接")
        conn := <-pool
        if conn.Ping() == nil {
            return conn
        } else {
            size--
        }
    }
    log.Println("get conn from new")
    session, err := mgo.Dial("localhost")
    if err != nil {
        log.Fatal(err)
    }
    log.Println("get conn from new success")
    size++
    return session
}

func putConn(conn *mgo.Session) {
    pool <- conn
}

func main() {
    wg := sync.WaitGroup{}
    for i := 0; i < 100; i++ {
        wg.Add(1)
        if i == 3 {
        }
        go func(n int) {
            log.Println("n:", n, "开始连接")
            conn := getConn()
            time.Sleep(time.Second)
            putConn(conn)
            log.Println("n:", n, "释放连接")
            wg.Done()
        }(i)
    }
    wg.Wait()
    log.Println("连接池数量:", len(pool))
}

2018/12/07 22:30:48 n: 1 开始连接
2018/12/07 22:30:48 get conn from new
2018/12/07 22:30:48 n: 0 开始连接
2018/12/07 22:30:48 n: 2 开始连接
2018/12/07 22:30:48 get conn from new success
2018/12/07 22:30:48 n: 1 释放连接
2018/12/07 22:30:48 get conn from new
2018/12/07 22:30:48 get conn from new success
2018/12/07 22:30:48 n: 0 释放连接
2018/12/07 22:30:48 继续从连接池获取连接
2018/12/07 22:30:48 n: 2 释放连接
2018/12/07 22:30:49 n: 9 开始连接
2018/12/07 22:30:49 n: 4 开始连接
2018/12/07 22:30:49 n: 5 开始连接
2018/12/07 22:30:49 get conn from pool start
2018/12/07 22:30:49 get conn from pool start
2018/12/07 22:30:49 n: 6 开始连接
2018/12/07 22:30:49 n: 7 开始连接
2018/12/07 22:30:49 n: 8 开始连接
2018/12/07 22:30:49 n: 3 开始连接
2018/12/07 22:30:49 继续从连接池获取连接
2018/12/07 22:30:49 get conn from pool success
2018/12/07 22:30:49 n: 4 释放连接
2018/12/07 22:30:49 n: 5 释放连接
2018/12/07 22:30:49 继续从连接池获取连接
2018/12/07 22:30:49 n: 6 释放连接
2018/12/07 22:30:49 get conn from pool success
2018/12/07 22:30:49 n: 9 释放连接
2018/12/07 22:30:49 继续从连接池获取连接
2018/12/07 22:30:49 n: 7 释放连接
2018/12/07 22:30:49 继续从连接池获取连接
2018/12/07 22:30:49 n: 8 释放连接
2018/12/07 22:30:49 继续从连接池获取连接
2018/12/07 22:30:49 n: 3 释放连接
2018/12/07 22:30:49 连接池数量: 2