package server

import (
    "net"
    "time"
    "sync"
    "crypto/tls"
    log "github.com/sirupsen/logrus"
    "runtime"
    "bufio"
    "strings"
    "io"
    "sibo/protocol"
    "sibo/share"
    "errors"
    "fmt"
    "sibo/proto"
    "github.com/robfig/cron"
    "path"
    "github.com/lestrrat/go-file-rotatelogs"
 

    "github.com/rifflock/lfshook"
)
var ErrServerClosed = errors.New("sibo: Server closed")

var shutdownPollInterval = 500 * time.Millisecond
var schuduleInterval = 1 * time.Minute

// 讀寫緩衝區大小
const (
    ReaderBufferSize = 1024
    WriterBufferSize = 1024
)

type Server struct {
    ln                   net.Listener
    readTimeout          time.Duration
    writeTimeout         time.Duration

    mu            sync.RWMutex
    activeSession map
 
[ISession]struct{} // 全域性連線管理器
    doneChan      chan struct{} //
    inShutdown    int32 // 監聽server的關閉狀態

    // TLSConfig for creating tls tcp connection.
    tlsConfig *tls.Config // tls配置
    waitGroup *sync.WaitGroup

    cron *cron.Cron // 定時任務
    scheduleSaveDuration time.Duration // 記憶體資料儲存到資料庫的定時任務的週期
}

func
 
 NewServer() *Server {
    return &Server{
        waitGroup:            &sync.WaitGroup{},
        cron:                 cron.New(),
        scheduleSaveDuration: schuduleInterval,
    }
}
// 返回伺服器地址
func (s *Server) Address() net.Addr {
    s.mu.RLock()
    defer s.mu.RUnlock()
    if s.ln == nil {
        return nil
    }
    return s.ln.Addr()
}

// 設定定時任務週期
func (s *Server) SetScheduleSaveDuration(t time.Duration) {
    s.scheduleSaveDuration = t
}

func (s *Server) Serve(network, address string) (err error) {
    var ln net.Listener
    if s.tlsConfig == nil {
        ln, err = net.Listen("tcp", address)
    } else {
        ln, err = tls.Listen("tcp", address, s.tlsConfig)
    }
    s.cron.Start()
    s.scheduleSavePlayer2DB() // start save job
    return s.serveListener(ln)
}

func (s *Server) serveListener(ln net.Listener) error {
    var tempDelay time.Duration

    s.mu.Lock()
    s.ln = ln
    if s.activeSession == nil {
        s.activeSession = make(map[ISession]struct{})
    }
    s.mu.Unlock()

    // 死迴圈監聽來自client的連線
    for {
        conn, e := ln.Accept()
        if e != nil {
            select {
            case <-s.doneChan:
                return ErrServerClosed
            default:
            }
            if ne, ok := e.(net.Error); ok && ne.Temporary() { // temporary error, retry in one second
                if tempDelay == 0 {
                    tempDelay = 5 * time.Millisecond
                } else {
                    tempDelay *= 2
                }
                if max := 1 * time.Second; tempDelay > max {
                    tempDelay = max
                }
                log.Printf("sibo: Accept error: %v; retrying in %v", e, tempDelay)
                time.Sleep(tempDelay)
                continue
            }
            log.Println("closed listener")
            return e
        }
        tempDelay = 0

        if tc, ok := conn.(*net.TCPConn); ok {
            tc.SetKeepAlive(true)
            tc.SetKeepAlivePeriod(3 * time.Minute)
        }

        s.mu.Lock()
        session := NewSession(conn)
        s.activeSession[session] = struct{}{}
        s.mu.Unlock()
        go s.serveSession(session) // 每個連線對應一個goroutine
    }
}

func (s *Server) serveSession(session ISession) {
    log.Println("serve session -> ", session.SessionId())
    player := NewPlayer(session)
    // 客戶端與伺服器斷開連線時執行
    defer func() { // execute when client disconnect from server
        if err := recover(); err != nil {
            const size = 64 << 10
            buf := make([]byte, size)
            ss := runtime.Stack(buf, false)
            if ss > size {
                ss = size
            }
            buf = buf[:ss]
            log.Printf("serving %s panic error: %s, stack:\n %s", session.Conn().RemoteAddr(), err, buf)
        }
        s.mu.Lock()
        delete(s.activeSession, session)
        s.mu.Unlock()
        session.Close(func() {
            log.Println("exec on session close.")
            /*player.Logout(func() {
                log.Println("exec on player logout.")
            })*/
        })
    }()

    if tlsConn, ok := session.Conn().(*tls.Conn); ok {
        if d := s.readTimeout; d != 0 {
            session.Conn().SetReadDeadline(time.Now().Add(d))
        }
        if d := s.writeTimeout; d != 0 {
            session.Conn().SetWriteDeadline(time.Now().Add(d))
        }
        if err := tlsConn.Handshake(); err != nil {
            log.Printf("sibo: TLS handshake error from %s: %v", session.Conn().RemoteAddr(), err)
            return
        }
    }
    r := bufio.NewReaderSize(session.Conn(), ReaderBufferSize)

    // client與server建立連線後，迴圈接受來自客戶端的請求資料
    for {
        t0 := time.Now()
        if s.readTimeout != 0 {
            session.Conn().SetReadDeadline(t0.Add(s.readTimeout))
        }
        req, err := session.ReadRequest(r)
        if err != nil {
            if err == io.EOF { // client close conn
                //player.SaveAll()
                log.Printf("client has closed this connection: %s", session.Conn().RemoteAddr().String())
            } else if strings.Contains(err.Error(), "use of closed network connection") { // (伺服器主動關閉conn)conn已被conn.Close()關閉,從conn讀取會報這個錯誤
                log.Printf("sibo: connection %s is closed", session.Conn().RemoteAddr().String())
            } else {
                log.Printf("sibo: failed to read request: %v", err)
            }
            player.Logout(func() {
                log.Println("player logout on session close")
            })
            /*session.Close(func() {
                player.SaveAll()
                log.Println("session close : " + session.SessionId())
            })*/
            return
        }
        if s.writeTimeout != 0 {
            session.Conn().SetWriteDeadline(t0.Add(s.writeTimeout))
        }

        // 業務邏輯用單獨的goroutine處理以防請求被阻塞(此處後期可使用類似fasthttp的goroutine池來優化)
        go func() {
            if req.IsHeartbeat() {
                req.SetMessageType(protocol.Response)
                session.SendResponse(req)
                return
            }

            res, err := s.handleRequest(player, req)
            if err != nil {
                log.Printf("sibo: failed to handle request: %v", err)
            }
            if !req.IsOneway() {
                session.SendResponse(res)
            }
            protocol.FreeMsg(req)
            protocol.FreeMsg(res)
        }()
    }
}
// 請求處理（業務邏輯）
func (s *Server) handleRequest(player IPlayer, req *protocol.Message) (res *protocol.Message, err error) {
    res = req.Clone()
    res.SetMessageType(protocol.Response)

    codec, ok := share.Codecs[req.SerializeType()]
    if !ok {
        err = fmt.Errorf("can not find codec for %d", req.SerializeType())
        handleError(res, err)
        return res, err
    }
    compression, ok := share.Compression[req.CompressType()]
    if !ok {
        err = fmt.Errorf("can not find compress type for %d", req.CompressType())
        handleError(res, err)
        return res, err
    }

    payload, err := compression.Decompress(req.Payload)
    if err != nil {
        err = fmt.Errorf("UnZip error for compress type %d", req.CompressType())
        handleError(res, err)
        return res, err
    }

    mmId := req.ModuleMessageID()
    if _, ok := proto.RequestMap[mmId]; !ok {
        handleError(res, errors.New("messageID not exist"))
    }
    request := proto.RequestMap[mmId]()
    err = codec.Decode(payload, request)
    if err != nil {
        return handleError(res, err)
    }
    responsePayload, err := ProcessorMap[mmId].Process(player, request)

    if !req.IsOneway() {
        data, err := codec.Encode(responsePayload)
        if err != nil {
            handleError(res, err)
            return res, err
        }
        payload, err := compression.Compress(data)
        if err != nil {
            handleError(res, err)
            return res, err
        }
        res.Payload = payload
    }
    return res, nil
}
// 關閉伺服器
func (s *Server) Close() error {
    s.mu.Lock()
    s.closeDoneChan()
    var err error
    if s.ln != nil {
        err = s.ln.Close()
    }
    s.mu.Unlock()

    s.cron.Stop() // stop schedule job
    s.saveAllPlayer2DB() // 儲存資料
    s.closeSessions() //關閉所有連線
    s.waitGroup.Wait()
    return err
}
// 關閉所有已建立的連線
func (s *Server) closeSessions() {
    s.mu.Lock()
    defer s.mu.Unlock()
    for session := range s.activeSession {
        session.Close(func() {
            log.Println("session close on by server: " + session.SessionId())
        })
        delete(s.activeSession, session)
    }
}

// 定時任務儲存玩家資料
func (s *Server) scheduleSavePlayer2DB() {
    //spec := "0 */2 * * * ?"
    s.cron.Schedule(cron.Every(s.scheduleSaveDuration), new(SavePlayerJob))
}

// 儲存玩家資料到資料庫，shutdown graceful
func (s *Server) saveAllPlayer2DB() {
    if PlayerId2PlayerMap.Len() > 0 {
        for _, player := range PlayerId2PlayerMap.Values() {
            //player, ok := PlayerId2PlayerMap.Get(k)
            s.waitGroup.Add(1)
            go func(player IPlayer) {  // 此處每個玩家使用一個goroutine，玩家數多可能有問題，可修改為一個goroutine處理多個玩家
                defer s.waitGroup.Done()
                log.Println("task start")
                //time.Sleep(2 * time.Second) 模仿資料儲存
                player.SaveAll()
                log.Println("task end")
            }(player)
        }
        PlayerId2PlayerMap.Clear()
    }
}
// 這裡使用了一點程式碼的trick將chan當作sync.Cond使用
func (s *Server) closeDoneChan() {
    if s.doneChan == nil {
        s.doneChan = make(chan struct{})
    }
    select {
    case <-s.doneChan:
        // Already closed. Don't close again.
    default:
        // Safe to close here. We're the only closer, guarded
        // by s.mu.
        close(s.doneChan)
    }
}
// 日誌配置
func (s *Server) ConfigLocalFilesystemLogger(logPath, logFileName string, maxAge time.Duration, rotationTime time.Duration) {
    baseLogPaht := path.Join(logPath, logFileName)
    writer, err := rotatelogs.New(
        baseLogPaht+".%Y%m%d%H%M",
        rotatelogs.WithLinkName(baseLogPaht), // 生成軟鏈，指向最新日誌檔案
        rotatelogs.WithMaxAge(maxAge), // 檔案最大儲存時間
        rotatelogs.WithRotationTime(rotationTime), // 日誌切割時間間隔
    )
    if err != nil {
        log.Errorf("config local file system logger error. %+v", err)
    }
    lfHook := lfshook.NewHook(lfshook.WriterMap{
        log.DebugLevel: writer, // 為不同級別設定不同的輸出目的
        log.InfoLevel:  writer,
        log.WarnLevel:  writer,
        log.ErrorLevel: writer,
        log.FatalLevel: writer,
        log.PanicLevel: writer,
    })
    log.AddHook(lfHook)
}

func handleError(res *protocol.Message, err error) (*protocol.Message, error) {
    res.SetMessageStatusType(protocol.Error)
    return res, err
}

原始碼地址