func (server *UmgmtServer) Serve() error {
relog.Info("started umgmt server: %v", server.listener.Addr())
for {
conn, err := server.listener.Accept()
if err != nil {
server.Lock()
if server.quit {
server.Unlock()
return nil
}
server.Unlock()
if err == syscall.EINVAL {
return err
}
// syscall.EMFILE, syscall.ENFILE could happen here if you run out of file descriptors
relog.Error("accept error %v", err)
continue
}
server.Lock()
server.connMap[conn] = true
server.Unlock()
rpc.ServeConn(conn)
server.Lock()
delete(server.connMap, conn)
server.Unlock()
}
return nil
}
func (service *UmgmtService) closeListeners() (err error) {
service.mutex.Lock()
defer service.mutex.Unlock()
for _, l := range service.listeners {
addr := l.Addr()
closeErr := l.Close()
if closeErr != nil {
err := fmt.Errorf("failed to close listener on %v err:%v", addr, closeErr)
// just return that at least one error happened, the log will reveal the rest
relog.Error("%s", err)
}
relog.Info("closed listener %v", addr)
}
for _, f := range service.closeCallbacks {
go f()
}
// Prevent duplicate execution.
service.listeners = service.listeners[:0]
return
}
func ListenAndServe(addr string) error {
rpc.Register(defaultService)
server := &UmgmtServer{connMap: make(map[net.Conn]bool)}
defer server.Close()
var umgmtClient *Client
for i := 2; i > 0; i-- {
l, e := net.Listen("unix", addr)
if e != nil {
if umgmtClient != nil {
umgmtClient.Close()
}
if checkError(e, syscall.EADDRINUSE) {
var clientErr error
umgmtClient, clientErr = Dial(addr)
if clientErr == nil {
closeErr := umgmtClient.CloseListeners()
if closeErr != nil {
relog.Error("closeErr:%v", closeErr)
}
// wait for rpc to finish
rebindDelay := defaultService.rebindDelay()
if rebindDelay > 0.0 {
relog.Info("delaying rebind: %vs", rebindDelay)
time.Sleep(rebindDelay)
}
continue
} else if checkError(clientErr, syscall.ECONNREFUSED) {
if unlinkErr := syscall.Unlink(addr); unlinkErr != nil {
relog.Error("can't unlink %v err:%v", addr, unlinkErr)
}
} else {
return e
}
} else {
return e
}
} else {
server.listener = l
break
}
}
if server.listener == nil {
panic("unable to rebind umgmt socket")
}
// register the umgmt server itself for dropping - this seems like
// the common case. i can't see when you *wouldn't* want to drop yourself
defaultService.addListener(server)
defaultService.addShutdownCallback(func() {
server.handleGracefulShutdown()
})
// fire off the startup callbacks. if these bind ports, they should
// call AddListener.
for _, f := range defaultService.startupCallbacks {
f()
}
if umgmtClient != nil {
go func() {
time.Sleep(defaultService.lameDuckPeriod())
umgmtClient.GracefulShutdown()
umgmtClient.Close()
}()
}
err := server.Serve()
// If we exitted gracefully, wait for the service to finish callbacks.
if err == nil {
<-defaultService.done
}
return err
}