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server.go
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server.go
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package main
import (
"fmt"
"log"
"net"
"os"
"os/signal"
"strconv"
"sync"
"syscall"
"time"
)
type server struct {
listener net.Listener
tcpListener *net.TCPListener
chStop chan bool
conns map[net.Conn]struct{}
muConns sync.RWMutex
isStop bool
muStop sync.RWMutex
wg sync.WaitGroup
}
func (s *server) checkError(str string, err error) {
if err != nil {
log.Println("Error, ", str, ", ", err)
panic(err)
}
}
func (s *server) setEnv(env string, value string) {
err := os.Setenv(env, value)
s.checkError(fmt.Sprintf("Setenv %s %s", env, value), err)
}
func (s *server) hupSignal() {
c := make(chan os.Signal, 1)
signal.Notify(c, syscall.SIGHUP)
go func() {
<-c
s.muStop.Lock()
s.isStop = true
s.muStop.Unlock()
s.tcpListener.SetDeadline(time.Now()) // 停止接受客户端请求
listenerFile, err := s.tcpListener.File()
s.checkError("get listener file", err)
s.setEnv("GRACEFUL_RESTART", "true")
s.setEnv("GRACEFUL_RESTART_FILES", strconv.Itoa(4+len(s.conns)))
execSpec := &syscall.ProcAttr{
Env: os.Environ(),
Files: nil,
}
execSpec.Files = make([]uintptr, 4+len(s.conns))
copy(execSpec.Files[0:5], []uintptr{
os.Stdin.Fd(),
os.Stdout.Fd(),
os.Stderr.Fd(),
listenerFile.Fd(), // 发送监听套接字到子进程
})
s.muConns.RLock()
pos := 5
for conn, _ := range s.conns { // 发送长连接套接字到子进程
file, err := conn.(*net.TCPConn).File()
s.checkError("get TCPConn file", err)
execSpec.Files[pos] = file.Fd()
pos++
}
s.muConns.RUnlock()
pid, err := syscall.ForkExec(os.Args[0], os.Args, execSpec) // 启动新进程
log.Println("pid of new process is", pid, err)
s.chStop <- true
}()
}
func (s *server) isRun() bool {
s.muStop.RLock()
isrun := (s.isStop == false)
s.muStop.RUnlock()
return isrun
}
func (s *server) closeDeleteConn(conn net.Conn) {
s.muConns.Lock()
delete(s.conns, conn)
s.muConns.Unlock()
conn.Close()
}
func (s *server) handle(conn net.Conn) {
defer s.wg.Done()
s.muConns.Lock()
s.conns[conn] = struct{}{}
s.muConns.Unlock()
s.wg.Add(1)
buf := make([]byte, 512)
for s.isRun() {
_, err := conn.Read(buf)
if err != nil {
log.Println("Error reading", err.Error())
s.closeDeleteConn(conn)
return
}
log.Printf("Received data: %v", string(buf))
}
}
func (s *server) setTcpListener() {
tcpListener, ok := s.listener.(*net.TCPListener)
if !ok {
log.Fatal("Error tcpListener")
}
s.tcpListener = tcpListener
}
func (s *server) startFromFork() {
file := os.NewFile(3, "/tmp/graceful_reload")
var err error
s.listener, err = net.FileListener(file)
s.checkError("get network listener", err)
s.setTcpListener()
uLimit, err := strconv.Atoi(os.Getenv("GRACEFUL_RESTART_FILES"))
s.checkError("atoi GRACEFUL_RESTART_FILES", err)
for fd := 4; fd < uLimit; fd++ {
file := os.NewFile((uintptr)(fd), "/tmp/"+strconv.Itoa(fd))
conn, err := net.FileConn(file)
s.checkError("get network connection", err)
go s.handle(conn)
}
}
func (s *server) startFromPort() {
var err error
s.listener, err = net.Listen("tcp", "localhost:8080")
s.checkError("listen", err)
s.setTcpListener()
}
func main() {
log.Println("Starting the server ...")
s := &server{
chStop: make(chan bool),
conns: make(map[net.Conn]struct{}, 10000),
}
if os.Getenv("GRACEFUL_RESTART") == "true" {
s.startFromFork()
} else {
s.startFromPort()
}
s.hupSignal()
for {
conn, err := s.listener.Accept()
if err != nil {
if nerr, ok := err.(net.Error); ok && nerr.Timeout() {
break
} else {
log.Fatal("Error accepting", err.Error())
}
}
go s.handle(conn)
}
log.Println("not accept anymore")
go func() {
s.wg.Wait()
s.chStop <- true
}()
select { // 等待旧服务不再处理连接
case <-s.chStop:
log.Println("server stop")
case <-time.After(time.Second * 5):
log.Println("timeout, server stop")
}
}