1 files changed, 487 insertions, 0 deletions
diff --git a/vendor/github.com/tylerb/graceful/graceful.go b/vendor/github.com/tylerb/graceful/graceful.go
new file mode 100644
index 000000000..a5e2395e0
--- /dev/null
+++ b/vendor/github.com/tylerb/graceful/graceful.go
@@ -0,0 +1,487 @@
+package graceful
+
+import (
+	"crypto/tls"
+	"log"
+	"net"
+	"net/http"
+	"os"
+	"os/signal"
+	"sync"
+	"syscall"
+	"time"
+)
+
+// Server wraps an http.Server with graceful connection handling.
+// It may be used directly in the same way as http.Server, or may
+// be constructed with the global functions in this package.
+//
+// Example:
+//	srv := &graceful.Server{
+//		Timeout: 5 * time.Second,
+//		Server: &http.Server{Addr: ":1234", Handler: handler},
+//	}
+//	srv.ListenAndServe()
+type Server struct {
+	*http.Server
+
+	// Timeout is the duration to allow outstanding requests to survive
+	// before forcefully terminating them.
+	Timeout time.Duration
+
+	// Limit the number of outstanding requests
+	ListenLimit int
+
+	// TCPKeepAlive sets the TCP keep-alive timeouts on accepted
+	// connections. It prunes dead TCP connections ( e.g. closing
+	// laptop mid-download)
+	TCPKeepAlive time.Duration
+
+	// ConnState specifies an optional callback function that is
+	// called when a client connection changes state. This is a proxy
+	// to the underlying http.Server's ConnState, and the original
+	// must not be set directly.
+	ConnState func(net.Conn, http.ConnState)
+
+	// BeforeShutdown is an optional callback function that is called
+	// before the listener is closed. Returns true if shutdown is allowed
+	BeforeShutdown func() bool
+
+	// ShutdownInitiated is an optional callback function that is called
+	// when shutdown is initiated. It can be used to notify the client
+	// side of long lived connections (e.g. websockets) to reconnect.
+	ShutdownInitiated func()
+
+	// NoSignalHandling prevents graceful from automatically shutting down
+	// on SIGINT and SIGTERM. If set to true, you must shut down the server
+	// manually with Stop().
+	NoSignalHandling bool
+
+	// Logger used to notify of errors on startup and on stop.
+	Logger *log.Logger
+
+	// LogFunc can be assigned with a logging function of your choice, allowing
+	// you to use whatever logging approach you would like
+	LogFunc func(format string, args ...interface{})
+
+	// Interrupted is true if the server is handling a SIGINT or SIGTERM
+	// signal and is thus shutting down.
+	Interrupted bool
+
+	// interrupt signals the listener to stop serving connections,
+	// and the server to shut down.
+	interrupt chan os.Signal
+
+	// stopLock is used to protect against concurrent calls to Stop
+	stopLock sync.Mutex
+
+	// stopChan is the channel on which callers may block while waiting for
+	// the server to stop.
+	stopChan chan struct{}
+
+	// chanLock is used to protect access to the various channel constructors.
+	chanLock sync.RWMutex
+
+	// connections holds all connections managed by graceful
+	connections map[net.Conn]struct{}
+
+	// idleConnections holds all idle connections managed by graceful
+	idleConnections map[net.Conn]struct{}
+}
+
+// Run serves the http.Handler with graceful shutdown enabled.
+//
+// timeout is the duration to wait until killing active requests and stopping the server.
+// If timeout is 0, the server never times out. It waits for all active requests to finish.
+func Run(addr string, timeout time.Duration, n http.Handler) {
+	srv := &Server{
+		Timeout:      timeout,
+		TCPKeepAlive: 3 * time.Minute,
+		Server:       &http.Server{Addr: addr, Handler: n},
+		// Logger:       DefaultLogger(),
+	}
+
+	if err := srv.ListenAndServe(); err != nil {
+		if opErr, ok := err.(*net.OpError); !ok || (ok && opErr.Op != "accept") {
+			srv.logf("%s", err)
+			os.Exit(1)
+		}
+	}
+
+}
+
+// RunWithErr is an alternative version of Run function which can return error.
+//
+// Unlike Run this version will not exit the program if an error is encountered but will
+// return it instead.
+func RunWithErr(addr string, timeout time.Duration, n http.Handler) error {
+	srv := &Server{
+		Timeout:      timeout,
+		TCPKeepAlive: 3 * time.Minute,
+		Server:       &http.Server{Addr: addr, Handler: n},
+		Logger:       DefaultLogger(),
+	}
+
+	return srv.ListenAndServe()
+}
+
+// ListenAndServe is equivalent to http.Server.ListenAndServe with graceful shutdown enabled.
+//
+// timeout is the duration to wait until killing active requests and stopping the server.
+// If timeout is 0, the server never times out. It waits for all active requests to finish.
+func ListenAndServe(server *http.Server, timeout time.Duration) error {
+	srv := &Server{Timeout: timeout, Server: server, Logger: DefaultLogger()}
+	return srv.ListenAndServe()
+}
+
+// ListenAndServe is equivalent to http.Server.ListenAndServe with graceful shutdown enabled.
+func (srv *Server) ListenAndServe() error {
+	// Create the listener so we can control their lifetime
+	addr := srv.Addr
+	if addr == "" {
+		addr = ":http"
+	}
+	conn, err := srv.newTCPListener(addr)
+	if err != nil {
+		return err
+	}
+
+	return srv.Serve(conn)
+}
+
+// ListenAndServeTLS is equivalent to http.Server.ListenAndServeTLS with graceful shutdown enabled.
+//
+// timeout is the duration to wait until killing active requests and stopping the server.
+// If timeout is 0, the server never times out. It waits for all active requests to finish.
+func ListenAndServeTLS(server *http.Server, certFile, keyFile string, timeout time.Duration) error {
+	srv := &Server{Timeout: timeout, Server: server, Logger: DefaultLogger()}
+	return srv.ListenAndServeTLS(certFile, keyFile)
+}
+
+// ListenTLS is a convenience method that creates an https listener using the
+// provided cert and key files. Use this method if you need access to the
+// listener object directly. When ready, pass it to the Serve method.
+func (srv *Server) ListenTLS(certFile, keyFile string) (net.Listener, error) {
+	// Create the listener ourselves so we can control its lifetime
+	addr := srv.Addr
+	if addr == "" {
+		addr = ":https"
+	}
+
+	config := &tls.Config{}
+	if srv.TLSConfig != nil {
+		*config = *srv.TLSConfig
+	}
+
+	var err error
+	config.Certificates = make([]tls.Certificate, 1)
+	config.Certificates[0], err = tls.LoadX509KeyPair(certFile, keyFile)
+	if err != nil {
+		return nil, err
+	}
+
+	// Enable http2
+	enableHTTP2ForTLSConfig(config)
+
+	conn, err := srv.newTCPListener(addr)
+	if err != nil {
+		return nil, err
+	}
+
+	srv.TLSConfig = config
+
+	tlsListener := tls.NewListener(conn, config)
+	return tlsListener, nil
+}
+
+// Enable HTTP2ForTLSConfig explicitly enables http/2 for a TLS Config. This is due to changes in Go 1.7 where
+// http servers are no longer automatically configured to enable http/2 if the server's TLSConfig is set.
+// See https://github.com/golang/go/issues/15908
+func enableHTTP2ForTLSConfig(t *tls.Config) {
+
+	if TLSConfigHasHTTP2Enabled(t) {
+		return
+	}
+
+	t.NextProtos = append(t.NextProtos, "h2")
+}
+
+// TLSConfigHasHTTP2Enabled checks to see if a given TLS Config has http2 enabled.
+func TLSConfigHasHTTP2Enabled(t *tls.Config) bool {
+	for _, value := range t.NextProtos {
+		if value == "h2" {
+			return true
+		}
+	}
+	return false
+}
+
+// ListenAndServeTLS is equivalent to http.Server.ListenAndServeTLS with graceful shutdown enabled.
+func (srv *Server) ListenAndServeTLS(certFile, keyFile string) error {
+	l, err := srv.ListenTLS(certFile, keyFile)
+	if err != nil {
+		return err
+	}
+
+	return srv.Serve(l)
+}
+
+// ListenAndServeTLSConfig can be used with an existing TLS config and is equivalent to
+// http.Server.ListenAndServeTLS with graceful shutdown enabled,
+func (srv *Server) ListenAndServeTLSConfig(config *tls.Config) error {
+	addr := srv.Addr
+	if addr == "" {
+		addr = ":https"
+	}
+
+	conn, err := srv.newTCPListener(addr)
+	if err != nil {
+		return err
+	}
+
+	srv.TLSConfig = config
+
+	tlsListener := tls.NewListener(conn, config)
+	return srv.Serve(tlsListener)
+}
+
+// Serve is equivalent to http.Server.Serve with graceful shutdown enabled.
+//
+// timeout is the duration to wait until killing active requests and stopping the server.
+// If timeout is 0, the server never times out. It waits for all active requests to finish.
+func Serve(server *http.Server, l net.Listener, timeout time.Duration) error {
+	srv := &Server{Timeout: timeout, Server: server, Logger: DefaultLogger()}
+
+	return srv.Serve(l)
+}
+
+// Serve is equivalent to http.Server.Serve with graceful shutdown enabled.
+func (srv *Server) Serve(listener net.Listener) error {
+
+	if srv.ListenLimit != 0 {
+		listener = LimitListener(listener, srv.ListenLimit)
+	}
+
+	// Make our stopchan
+	srv.StopChan()
+
+	// Track connection state
+	add := make(chan net.Conn)
+	idle := make(chan net.Conn)
+	active := make(chan net.Conn)
+	remove := make(chan net.Conn)
+
+	srv.Server.ConnState = func(conn net.Conn, state http.ConnState) {
+		switch state {
+		case http.StateNew:
+			add <- conn
+		case http.StateActive:
+			active <- conn
+		case http.StateIdle:
+			idle <- conn
+		case http.StateClosed, http.StateHijacked:
+			remove <- conn
+		}
+
+		srv.stopLock.Lock()
+		defer srv.stopLock.Unlock()
+
+		if srv.ConnState != nil {
+			srv.ConnState(conn, state)
+		}
+	}
+
+	// Manage open connections
+	shutdown := make(chan chan struct{})
+	kill := make(chan struct{})
+	go srv.manageConnections(add, idle, active, remove, shutdown, kill)
+
+	interrupt := srv.interruptChan()
+	// Set up the interrupt handler
+	if !srv.NoSignalHandling {
+		signal.Notify(interrupt, syscall.SIGINT, syscall.SIGTERM)
+	}
+	quitting := make(chan struct{})
+	go srv.handleInterrupt(interrupt, quitting, listener)
+
+	// Serve with graceful listener.
+	// Execution blocks here until listener.Close() is called, above.
+	err := srv.Server.Serve(listener)
+	if err != nil {
+		// If the underlying listening is closed, Serve returns an error
+		// complaining about listening on a closed socket. This is expected, so
+		// let's ignore the error if we are the ones who explicitly closed the
+		// socket.
+		select {
+		case <-quitting:
+			err = nil
+		default:
+		}
+	}
+
+	srv.shutdown(shutdown, kill)
+
+	return err
+}
+
+// Stop instructs the type to halt operations and close
+// the stop channel when it is finished.
+//
+// timeout is grace period for which to wait before shutting
+// down the server. The timeout value passed here will override the
+// timeout given when constructing the server, as this is an explicit
+// command to stop the server.
+func (srv *Server) Stop(timeout time.Duration) {
+	srv.stopLock.Lock()
+	defer srv.stopLock.Unlock()
+
+	srv.Timeout = timeout
+	interrupt := srv.interruptChan()
+	interrupt <- syscall.SIGINT
+}
+
+// StopChan gets the stop channel which will block until
+// stopping has completed, at which point it is closed.
+// Callers should never close the stop channel.
+func (srv *Server) StopChan() <-chan struct{} {
+	srv.chanLock.Lock()
+	defer srv.chanLock.Unlock()
+
+	if srv.stopChan == nil {
+		srv.stopChan = make(chan struct{})
+	}
+	return srv.stopChan
+}
+
+// DefaultLogger returns the logger used by Run, RunWithErr, ListenAndServe, ListenAndServeTLS and Serve.
+// The logger outputs to STDERR by default.
+func DefaultLogger() *log.Logger {
+	return log.New(os.Stderr, "[graceful] ", 0)
+}
+
+func (srv *Server) manageConnections(add, idle, active, remove chan net.Conn, shutdown chan chan struct{}, kill chan struct{}) {
+	var done chan struct{}
+	srv.connections = map[net.Conn]struct{}{}
+	srv.idleConnections = map[net.Conn]struct{}{}
+	for {
+		select {
+		case conn := <-add:
+			srv.connections[conn] = struct{}{}
+		case conn := <-idle:
+			srv.idleConnections[conn] = struct{}{}
+		case conn := <-active:
+			delete(srv.idleConnections, conn)
+		case conn := <-remove:
+			delete(srv.connections, conn)
+			delete(srv.idleConnections, conn)
+			if done != nil && len(srv.connections) == 0 {
+				done <- struct{}{}
+				return
+			}
+		case done = <-shutdown:
+			if len(srv.connections) == 0 && len(srv.idleConnections) == 0 {
+				done <- struct{}{}
+				return
+			}
+			// a shutdown request has been received. if we have open idle
+			// connections, we must close all of them now. this prevents idle
+			// connections from holding the server open while waiting for them to
+			// hit their idle timeout.
+			for k := range srv.idleConnections {
+				if err := k.Close(); err != nil {
+					srv.logf("[ERROR] %s", err)
+				}
+			}
+		case <-kill:
+			srv.stopLock.Lock()
+			defer srv.stopLock.Unlock()
+
+			srv.Server.ConnState = nil
+			for k := range srv.connections {
+				if err := k.Close(); err != nil {
+					srv.logf("[ERROR] %s", err)
+				}
+			}
+			return
+		}
+	}
+}
+
+func (srv *Server) interruptChan() chan os.Signal {
+	srv.chanLock.Lock()
+	defer srv.chanLock.Unlock()
+
+	if srv.interrupt == nil {
+		srv.interrupt = make(chan os.Signal, 1)
+	}
+
+	return srv.interrupt
+}
+
+func (srv *Server) handleInterrupt(interrupt chan os.Signal, quitting chan struct{}, listener net.Listener) {
+	for _ = range interrupt {
+		if srv.Interrupted {
+			srv.logf("already shutting down")
+			continue
+		}
+		srv.logf("shutdown initiated")
+		srv.Interrupted = true
+		if srv.BeforeShutdown != nil {
+			if !srv.BeforeShutdown() {
+				srv.Interrupted = false
+				continue
+			}
+		}
+
+		close(quitting)
+		srv.SetKeepAlivesEnabled(false)
+		if err := listener.Close(); err != nil {
+			srv.logf("[ERROR] %s", err)
+		}
+
+		if srv.ShutdownInitiated != nil {
+			srv.ShutdownInitiated()
+		}
+	}
+}
+
+func (srv *Server) logf(format string, args ...interface{}) {
+	if srv.LogFunc != nil {
+		srv.LogFunc(format, args...)
+	} else if srv.Logger != nil {
+		srv.Logger.Printf(format, args...)
+	}
+}
+
+func (srv *Server) shutdown(shutdown chan chan struct{}, kill chan struct{}) {
+	// Request done notification
+	done := make(chan struct{})
+	shutdown <- done
+
+	if srv.Timeout > 0 {
+		select {
+		case <-done:
+		case <-time.After(srv.Timeout):
+			close(kill)
+		}
+	} else {
+		<-done
+	}
+	// Close the stopChan to wake up any blocked goroutines.
+	srv.chanLock.Lock()
+	if srv.stopChan != nil {
+		close(srv.stopChan)
+	}
+	srv.chanLock.Unlock()
+}
+
+func (srv *Server) newTCPListener(addr string) (net.Listener, error) {
+	conn, err := net.Listen("tcp", addr)
+	if err != nil {
+		return conn, err
+	}
+	if srv.TCPKeepAlive != 0 {
+		conn = keepAliveListener{conn, srv.TCPKeepAlive}
+	}
+	return conn, nil
+}