nghttpx: Fix shutdown too early with QUIT signal if num_worker == 1

src/shrpx.cc

@@ -406,6 +406,10 @@ void graceful_shutdown_signal_cb(struct ev_loop *loop, ev_signal *w,
                                  int revents) {
   auto conn_handler = static_cast<ConnectionHandler *>(w->data);
 
+  if (worker_config->graceful_shutdown) {
+    return;
+  }
+
   LOG(NOTICE) << "Graceful shutdown signal received";
 
   worker_config->graceful_shutdown = true;
@@ -419,6 +423,10 @@ void graceful_shutdown_signal_cb(struct ev_loop *loop, ev_signal *w,
 
   conn_handler->graceful_shutdown_worker();
 
+  if (get_config()->num_worker == 1) {
+    return;
+  }
+
   // We have accepted all pending connections.  Shutdown main event
   // loop.
   ev_break(loop);