GIN+GORILLA=A GOLANG WEBSOCKET SERVER

　　　鉴于聊天已然成为大部分app的基础功能,而大部分app用户基数有没有辣么大,常用的聊天server架构如xmpp或者消息队列实现之类的用起来还挺麻烦的,有比较难跟网页端做交互,加之H5标准落地,所以websocket已然成为一个轻巧可用性高的聊天server实现方法;

　　　websocket的server常见的是用nodejs或者java的netty框架实现,netty相对重一点,direct buffer的内存泄露调起来比较麻烦,试了一下go,轻巧,稳定性不错,性能不错,所以用go实现了一下;

　　　websocket的协议标准和基本概念网上一搜一片,这里不赘述;

　　　http server用gin来做,websocket的handler则用gorilla,由于不重复造轮子,所以整个搭建的过程很快;

　　　

import (
    "util"
    "os"
    "fmt"
    "github.com/DeanThompson/ginpprof"
    "github.com/gin-gonic/gin"
    "runtime"
)
var (
    logger * util.LogHelper
)
func main() {
    runtime.GOMAXPROCS(runtime.NumCPU())
    logFile,err := os.OpenFile("/var/log/gows.log",os.O_CREATE|os.O_RDWR,0777)
    if err!=nil {
        fmt.Println(err.Error())
        os.Exit(0)
    }
    defer logFile.Close()
    logger = util.NewLogger(logFile)
    logger.Info("Starting system...")
    wsHandler := new(WebSocketHandler)
    gin.SetMode(gin.ReleaseMode)
    r := gin.Default()
    r.GET("/", func(c *gin.Context) {
        wsHandler.HandleConn(c.Writer, c.Request)
    })
    ginpprof.Wrapper(r)//调试用 可以看到堆栈状态和所有goroutine状态
    //err = r.Run(listenPath, certPath, keyPath) 这样可以支持wss
    err = r.Run("127.0.0.1:8888")
    if err != nil {
        fmt.Println(err)
    }
}

这样我们的入口就有了~

websocket的模式大概是 onopen onmessage onerror onclose四个callback来覆盖整个通信流程

所以我们来看下简易版本的websockethandler的实现

package main

import (
    "bytes"
    "compress/gzip"
    "encoding/json"
    "errors"
    "net/http"
    "strconv"
    "time"
    "util"
    "github.com/gorilla/websocket"
)

var (
    ctxHashMap  = util.NewConcurrentMap()
)
//用来升级http协议到ws协议
type WebSocketHandler struct {
    wsupgrader websocket.Upgrader
}

func (wsh *WebSocketHandler) NewWebSocketHandler() {
    wsh.wsupgrader = websocket.Upgrader{
        ReadBufferSize:  4096,
        WriteBufferSize: 4096,
    }
}

func (wsh *WebSocketHandler) onMessage(conn *websocket.Conn, ctx *ConnContext, msg []byte, msgType int) {
    //处理文本消息 或者 2进制消息 2进制通常是些 gzip的文本 语音或者图片视频之类的一般会用其他云服务不然带宽会爆掉
    if msgType == websocket.TextMessage {
        wsh.processIncomingTextMsg(conn, ctx, msg)
    }
    if msgType == websocket.BinaryMessage {

    }
}

func (wsh *WebSocketHandler) onOpen(conn *websocket.Conn, r *http.Request) (ctx *ConnContext, err error) {
    if err := r.ParseForm(); err != nil {
        return nil, errors.New("参数校验错误")
    }
    specialKey := r.FormValue("specialKey")
    supportGzip := r.FormValue("support_gzip")
    
    ctx = &ConnContext{specialKey, supportGzip}
    //用来标识一个tcp链接
    keyString := ctx.AsHashKey()

    if oldConn, ok := ctxHashMap.Get(keyString); ok {
            wsh.onClose(oldConn.(*websocket.Conn), ctx)
            oldConn.(*websocket.Conn).Close()
    }
    ctxHashMap.Set(keyString, conn)
    return ctx, nil
}

func (wsh *WebSocketHandler) onClose(conn *websocket.Conn, ctx *ConnContext) {
    logger.Info("client close itself as " + ctx.String())
    wsh.closeConnWithCtx(ctx)
    return
}

func (wsh *WebSocketHandler) onError(errMsg string) {
    logger.Error(errMsg)
}
func (wsh *WebSocketHandler) HandleConn(w http.ResponseWriter, r *http.Request) {
    wsh.wsupgrader.CheckOrigin = func(r *http.Request) bool { return true }
    conn, err := wsh.wsupgrader.Upgrade(w, r, nil)
    if err != nil {
        logger.Error("Failed to set websocket upgrade: " + err.Error())
        return
    }
    defer conn.Close()
    if ctx, err := wsh.onOpen(conn, r); err != nil {
        logger.Error("Open connection failed " + err.Error() + r.URL.RawQuery)
        return
    } else {
        conn.SetPingHandler(func(message string) error {
            conn.WriteControl(websocket.PongMessage, []byte(message), time.Now().Add(time.Second))
            return nil
        })
        for {
            t, msg, err := conn.ReadMessage()
            if err != nil {
                logger.Error("READ ERR FROM " + ctx.String() + " ERR " + err.Error())
                wsh.onClose(conn, ctx)
                return
            }

            switch t {
            case websocket.TextMessage, websocket.BinaryMessage:
                wsh.onMessage(conn, ctx, msg, t)
            case websocket.CloseMessage:
                wsh.onClose(conn, ctx)
                return
            case websocket.PingMessage:
            case websocket.PongMessage:
            }

        }
    }
}

func (wsh *WebSocketHandler) closeConnWithCtx(ctx *ConnContext) {
    keyString := ctx.AsHashKey()
    ctxHashMap.Remove(keyString)
    return
}
func (wsh *WebSocketHandler) processIncomingTextMsg(conn *websocket.Conn, ctx *ConnContext, msg []byte) {
    logger.Debug("CLIENT SAID " + string(msg))
    sendMessageToAll(msg)
}

func (wsh *WebSocketHandler) sendMessageToAll(msg []byte]) {
    var gzMsg bytes.Buffer
    gzWriter := gzip.NewWriter(&gzMsg)
    gzWriter.Write(msg)
    gzWriter.Flush()
    gzWriter.Close()
    for key, conn := range ctxHashMap.Items() {
        if ctx, err := HashKeyAsCtx(key.(string)); err != nil {
            wsh.onError(err.Error())
        } else {
            if ctx.supportGzip == "1" {
                err = conn.(*websocket.Conn).WriteMessage(websocket.BinaryMessage, gzMsg.Bytes())
                logger.Debug("send binary msg to " + ctx.String())
            } else {
                err = conn.(*websocket.Conn).WriteMessage(websocket.TextMessage, []byte(msg))
                logger.Debug("send text msg to " + ctx.String())
            }
            if err != nil {
                wsh.onClose(conn.(*websocket.Conn), ctx)
                conn.(*websocket.Conn).Close()
                wsh.onError("WRITE ERR TO " + key.(string) + " ERR:" + err.Error())
            }
        }
    }

}

因为删了一些线上代码的敏感信息 所以未必编译的过,不过差不多一个意思,主要看气质

里面的一个莫名其妙的叫做ctx的东西出现了很多次其实是connectionContext的缩写,一般链接形如ws://ip:port/?param=value&param1=value1之类的形式,当然会加密,所以在onopen的时候会对url做一次基础校验,并且回记录url的一些关键参数标记,以用来确认消息到底要发送给谁

一个简单connContext实现如下

// connContext.go
package main

import (
    "errors"
    "strings"
    "util"
)

type ConnContext struct {
    specialKey    string
    supportGzip string 
}
func HashKeyAsCtx(hashKey string) (*ConnContext,error){
    values := strings.Split(hashKey,":")
    if(len(values)!=2){
        return nil,errors.New("艾玛 key不对: "+hashKey)
    }else{
        return &ConnContext{values[0],values[1]},nil
    }    
}
func (ctx *ConnContext) AsHashKey() string{
    return strings.Join([]string{ctx.specialKey, ctx.supportGzip},":")
}
func (ctx * ConnContext) String () string{
    return util.NewStringBuilder("specialkey: ",ctx.specialkey, " gzip ",ctx.supportGzip).String()
}

以上 一个简易的websocket server 就这样完成了 可喜可贺

有事儿寻这儿

http://weibo.com/SandCu