An elegant stop program in the Go language

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/**go language in the implementation of graceful stop program main Goroutine listen to the operating system messages, received system Stop message after shutting down the server Chan, all the sub-process detected Chan closed, then all exit **/package mainimport ("Log" "" NET " "OS" "Os/signal" "Sync" "Syscall" "Time")//an uninteresting Service.type service struct {ch Chan boolwaitgroup *sync.w aitgroup}//make a new Service.func NewService () *service {return &service{ch:make (chan bool), Waitgroup: & Sync.  waitgroup{},}}//Accept connections and spawn a goroutine to serve each one. Stop listening//If anything is received on the service ' s Channel.func (S *service) Serve (Listener *net. TcpListener) {S.waitgroup.add (1) Defer s.waitgroup.done () for {select {case <-s.ch:log. PRINTLN ("Stopping listening on", listener. ADDR ()) listener. Close () Returndefault:}listener. Setdeadline (time. Now (). ADD (1E9)) conn, err: = Listener. ACCEPTTCP () if nil! = Err {//Determine if the error type is net. Operrorif Operr, OK: = Err. (*net. OPERROR); OK && operr.timeout () {Continue}log. PRINTLN (Err)}log. PRINTLN (Conn. Remoteaddr (), "Connected") go S.serve (conn)}}//Stop the service byClosing the service ' s channel. Block until the service//is really stopped.func (s *service) Stop () {Close (s.ch) s.waitgroup.wait ()}//Serve a connection  By reading and writing who was read.  That's right, this//are an echo service. Stop Reading and writing if anything is received on the//service ' s channel, only after writing what was Read.func (s * Service) Serve (conn *net. Tcpconn) {Defer conn. Close () S.waitgroup.add (1) Defer s.waitgroup.done () for {select {case <-s.ch:log. Println ("disconnecting", Conn. Remoteaddr ()) Returndefault:}conn. Setdeadline (time. Now (). ADD (1E9)) BUF: = Make ([]byte, 4096) If _, err: = conn. Read (BUF); Nil! = Err {if operr, OK: = Err. ( *net. OPERROR); OK && operr.timeout () {Continue}log. PRINTLN (Err) Return}if _, Err: = conn. Write (BUF); Nil! = Err {log.  PRINTLN (Err) Return}}}func main () {//Listen on 127.0.0.1:48879. That's my favorite port number because in//hex 48879 is 0xbeef.laddr, err: = Net. RESOLVETCPADDR ("TCP", "127.0.0.1:48879") if nil! = Err {log. FataLln (Err)}listener, err: = Net. LISTENTCP ("TCP", LADDR) if nil! = Err {log. Fatalln (Err)}log. Println ("Listening on", listener. ADDR ())//Make a new service and send it into the background.service: = NewService () Go service. Serve (Listener)//Handle SIGINT and sigterm.ch: = Make (chan os. Signal) Signal. Notify (CH, syscall. SIGINT, Syscall. SIGTERM) log. PRINTLN ("Signal:", <-ch)//Stop the Service Gracefully.service.Stop ()}