split into small files

+package grace
+
+import "net"
+
+type graceConn struct {
+	net.Conn
+	server *graceServer
+}
+
+func (c graceConn) Close() error {
+	c.server.wg.Done()
+	return c.Conn.Close()
+}

+package grace
+
+import (
+	"net"
+	"os"
+	"syscall"
+	"time"
+)
+
+type graceListener struct {
+	net.Listener
+	stop    chan error
+	stopped bool
+	server  *graceServer
+}
+
+func newGraceListener(l net.Listener, srv *graceServer) (el *graceListener) {
+	el = &graceListener{
+		Listener: l,
+		stop:     make(chan error),
+		server:   srv,
+	}
+	go func() {
+		_ = <-el.stop
+		el.stopped = true
+		el.stop <- el.Listener.Close()
+	}()
+	return
+}
+
+func (gl *graceListener) Accept() (c net.Conn, err error) {
+	tc, err := gl.Listener.(*net.TCPListener).AcceptTCP()
+	if err != nil {
+		return
+	}
+
+	tc.SetKeepAlive(true)
+	tc.SetKeepAlivePeriod(3 * time.Minute)
+
+	c = graceConn{
+		Conn:   tc,
+		server: gl.server,
+	}
+
+	gl.server.wg.Add(1)
+	return
+}
+
+func (el *graceListener) Close() error {
+	if el.stopped {
+		return syscall.EINVAL
+	}
+	el.stop <- nil
+	return <-el.stop
+}
+
+func (el *graceListener) File() *os.File {
+	// returns a dup(2) - FD_CLOEXEC flag *not* set
+	tl := el.Listener.(*net.TCPListener)
+	fl, _ := tl.File()
+	return fl
+}

+package grace
+
+import (
+	"crypto/tls"
+	"fmt"
+	"log"
+	"net"
+	"net/http"
+	"os"
+	"os/exec"
+	"os/signal"
+	"strings"
+	"sync"
+	"syscall"
+	"time"
+)
+
+type graceServer struct {
+	*http.Server
+	GraceListener    net.Listener
+	SignalHooks      map[int]map[os.Signal][]func()
+	tlsInnerListener *graceListener
+	wg               sync.WaitGroup
+	sigChan          chan os.Signal
+	isChild          bool
+	state            uint8
+	Network          string
+}
+
+// Serve accepts incoming connections on the Listener l,
+// creating a new service goroutine for each.
+// The service goroutines read requests and then call srv.Handler to reply to them.
+func (srv *graceServer) Serve() (err error) {
+	srv.state = STATE_RUNNING
+	err = srv.Server.Serve(srv.GraceListener)
+	log.Println(syscall.Getpid(), "Waiting for connections to finish...")
+	srv.wg.Wait()
+	srv.state = STATE_TERMINATE
+	return
+}
+
+// ListenAndServe listens on the TCP network address srv.Addr and then calls Serve
+// to handle requests on incoming connections. If srv.Addr is blank, ":http" is
+// used.
+func (srv *graceServer) ListenAndServe() (err error) {
+	addr := srv.Addr
+	if addr == "" {
+		addr = ":http"
+	}
+
+	go srv.handleSignals()
+
+	l, err := srv.getListener(addr)
+	if err != nil {
+		log.Println(err)
+		return err
+	}
+
+	srv.GraceListener = newGraceListener(l, srv)
+
+	if srv.isChild {
+		process, err := os.FindProcess(os.Getppid())
+		if err != nil {
+			log.Println(err)
+			return err
+		}
+		err = process.Kill()
+		if err != nil {
+			return err
+		}
+	}
+
+	log.Println(os.Getpid(), srv.Addr)
+	return srv.Serve()
+}
+
+// ListenAndServeTLS listens on the TCP network address srv.Addr and then calls
+// Serve to handle requests on incoming TLS connections.
+//
+// Filenames containing a certificate and matching private key for the server must
+// be provided. If the certificate is signed by a certificate authority, the
+// certFile should be the concatenation of the server's certificate followed by the
+// CA's certificate.
+//
+// If srv.Addr is blank, ":https" is used.
+func (srv *graceServer) ListenAndServeTLS(certFile, keyFile string) (err error) {
+	addr := srv.Addr
+	if addr == "" {
+		addr = ":https"
+	}
+
+	config := &tls.Config{}
+	if srv.TLSConfig != nil {
+		*config = *srv.TLSConfig
+	}
+	if config.NextProtos == nil {
+		config.NextProtos = []string{"http/1.1"}
+	}
+
+	config.Certificates = make([]tls.Certificate, 1)
+	config.Certificates[0], err = tls.LoadX509KeyPair(certFile, keyFile)
+	if err != nil {
+		return
+	}
+
+	go srv.handleSignals()
+
+	l, err := srv.getListener(addr)
+	if err != nil {
+		log.Println(err)
+		return err
+	}
+
+	srv.tlsInnerListener = newGraceListener(l, srv)
+	srv.GraceListener = tls.NewListener(srv.tlsInnerListener, config)
+
+	if srv.isChild {
+		process, err := os.FindProcess(os.Getppid())
+		if err != nil {
+			log.Println(err)
+			return err
+		}
+		err = process.Kill()
+		if err != nil {
+			return err
+		}
+	}
+	log.Println(os.Getpid(), srv.Addr)
+	return srv.Serve()
+}
+
+// getListener either opens a new socket to listen on, or takes the acceptor socket
+// it got passed when restarted.
+func (srv *graceServer) getListener(laddr string) (l net.Listener, err error) {
+	if srv.isChild {
+		var ptrOffset uint = 0
+		if len(socketPtrOffsetMap) > 0 {
+			ptrOffset = socketPtrOffsetMap[laddr]
+			log.Println("laddr", laddr, "ptr offset", socketPtrOffsetMap[laddr])
+		}
+
+		f := os.NewFile(uintptr(3+ptrOffset), "")
+		l, err = net.FileListener(f)
+		if err != nil {
+			err = fmt.Errorf("net.FileListener error: %v", err)
+			return
+		}
+	} else {
+		l, err = net.Listen(srv.Network, laddr)
+		if err != nil {
+			err = fmt.Errorf("net.Listen error: %v", err)
+			return
+		}
+	}
+	return
+}
+
+// handleSignals listens for os Signals and calls any hooked in function that the
+// user had registered with the signal.
+func (srv *graceServer) handleSignals() {
+	var sig os.Signal
+
+	signal.Notify(
+		srv.sigChan,
+		syscall.SIGHUP,
+		syscall.SIGINT,
+		syscall.SIGTERM,
+	)
+
+	pid := syscall.Getpid()
+	for {
+		sig = <-srv.sigChan
+		srv.signalHooks(PRE_SIGNAL, sig)
+		switch sig {
+		case syscall.SIGHUP:
+			log.Println(pid, "Received SIGHUP. forking.")
+			err := srv.fork()
+			if err != nil {
+				log.Println("Fork err:", err)
+			}
+		case syscall.SIGINT:
+			log.Println(pid, "Received SIGINT.")
+			srv.shutdown()
+		case syscall.SIGTERM:
+			log.Println(pid, "Received SIGTERM.")
+			srv.shutdown()
+		default:
+			log.Printf("Received %v: nothing i care about...\n", sig)
+		}
+		srv.signalHooks(POST_SIGNAL, sig)
+	}
+}
+
+func (srv *graceServer) signalHooks(ppFlag int, sig os.Signal) {
+	if _, notSet := srv.SignalHooks[ppFlag][sig]; !notSet {
+		return
+	}
+	for _, f := range srv.SignalHooks[ppFlag][sig] {
+		f()
+	}
+	return
+}
+
+// shutdown closes the listener so that no new connections are accepted. it also
+// starts a goroutine that will serverTimeout (stop all running requests) the server
+// after DefaultTimeout.
+func (srv *graceServer) shutdown() {
+	if srv.state != STATE_RUNNING {
+		return
+	}
+
+	srv.state = STATE_SHUTTING_DOWN
+	if DefaultTimeout >= 0 {
+		go srv.serverTimeout(DefaultTimeout)
+	}
+	err := srv.GraceListener.Close()
+	if err != nil {
+		log.Println(syscall.Getpid(), "Listener.Close() error:", err)
+	} else {
+		log.Println(syscall.Getpid(), srv.GraceListener.Addr(), "Listener closed.")
+	}
+}
+
+// serverTimeout forces the server to shutdown in a given timeout - whether it
+// finished outstanding requests or not. if Read/WriteTimeout are not set or the
+// max header size is very big a connection could hang
+func (srv *graceServer) serverTimeout(d time.Duration) {
+	defer func() {
+		if r := recover(); r != nil {
+			log.Println("WaitGroup at 0", r)
+		}
+	}()
+	if srv.state != STATE_SHUTTING_DOWN {
+		return
+	}
+	time.Sleep(d)
+	log.Println("[STOP - Hammer Time] Forcefully shutting down parent")
+	for {
+		if srv.state == STATE_TERMINATE {
+			break
+		}
+		srv.wg.Done()
+	}
+}
+
+func (srv *graceServer) fork() (err error) {
+	regLock.Lock()
+	defer regLock.Unlock()
+	if runningServersForked {
+		return
+	}
+	runningServersForked = true
+
+	var files = make([]*os.File, len(runningServers))
+	var orderArgs = make([]string, len(runningServers))
+	for _, srvPtr := range runningServers {
+		switch srvPtr.GraceListener.(type) {
+		case *graceListener:
+			files[socketPtrOffsetMap[srvPtr.Server.Addr]] = srvPtr.GraceListener.(*graceListener).File()
+		default:
+			files[socketPtrOffsetMap[srvPtr.Server.Addr]] = srvPtr.tlsInnerListener.File()
+		}
+		orderArgs[socketPtrOffsetMap[srvPtr.Server.Addr]] = srvPtr.Server.Addr
+	}
+
+	log.Println(files)
+	path := os.Args[0]
+	var args []string
+	if len(os.Args) > 1 {
+		for _, arg := range os.Args[1:] {
+			if arg == "-graceful" {
+				break
+			}
+			args = append(args, arg)
+		}
+	}
+	args = append(args, "-graceful")
+	if len(runningServers) > 1 {
+		args = append(args, fmt.Sprintf(`-socketorder=%s`, strings.Join(orderArgs, ",")))
+		log.Println(args)
+	}
+	cmd := exec.Command(path, args...)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	cmd.ExtraFiles = files
+	err = cmd.Start()
+	if err != nil {
+		log.Fatalf("Restart: Failed to launch, error: %v", err)
+	}
+
+	return
+}