Fix races

Signed-off-by: Emile Vauge <emile@vauge.com>

middlewares/handlerSwitcher.go

@@ -1,40 +1,35 @@
 package middlewares
 
 import (
+	"github.com/containous/traefik/safe"
 	"github.com/gorilla/mux"
 	"net/http"
-	"sync"
 )
 
 // HandlerSwitcher allows hot switching of http.ServeMux
 type HandlerSwitcher struct {
-	handler     *mux.Router
-	handlerLock *sync.Mutex
+	handler *safe.Safe
 }
 
 // NewHandlerSwitcher builds a new instance of HandlerSwitcher
 func NewHandlerSwitcher(newHandler *mux.Router) (hs *HandlerSwitcher) {
 	return &HandlerSwitcher{
-		handler:     newHandler,
-		handlerLock: &sync.Mutex{},
+		handler: safe.New(newHandler),
 	}
 }
 
 func (hs *HandlerSwitcher) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
-	hs.handlerLock.Lock()
-	handlerBackup := hs.handler
-	hs.handlerLock.Unlock()
+	handlerBackup := hs.handler.Get().(*mux.Router)
 	handlerBackup.ServeHTTP(rw, r)
 }
 
 // GetHandler returns the current http.ServeMux
 func (hs *HandlerSwitcher) GetHandler() (newHandler *mux.Router) {
-	return hs.handler
+	handler := hs.handler.Get().(*mux.Router)
+	return handler
 }
 
 // UpdateHandler safely updates the current http.ServeMux with a new one
 func (hs *HandlerSwitcher) UpdateHandler(newHandler *mux.Router) {
-	hs.handlerLock.Lock()
-	hs.handler = newHandler
-	defer hs.handlerLock.Unlock()
+	hs.handler.Set(newHandler)
 }