1 files changed, 127 insertions, 0 deletions

diff --git a/src/lib/daemon_quiesce.c b/src/lib/daemon_quiesce.c
new file mode 100644
index 00000000..31104a7d
--- /dev/null
+++ b/src/lib/daemon_quiesce.c
@@ -0,0 +1,127 @@
+/*
+  This file is part of libmicrohttpd
+  Copyright (C) 2007-2018 Daniel Pittman and Christian Grothoff
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+/**
+ * @file lib/daemon.c
+ * @brief main functions to quiesce a daemon
+ * @author Christian Grothoff
+ */
+#include "internal.h"
+
+
+/**
+ * Stop accepting connections from the listening socket.  Allows
+ * clients to continue processing, but stops accepting new
+ * connections.  Note that the caller is responsible for closing the
+ * returned socket; however, if MHD is run using threads (anything but
+ * external select mode), it must not be closed until AFTER
+ * #MHD_stop_daemon has been called (as it is theoretically possible
+ * that an existing thread is still using it).
+ *
+ * Note that some thread modes require the caller to have passed
+ * #MHD_USE_ITC when using this API.  If this daemon is
+ * in one of those modes and this option was not given to
+ * #MHD_start_daemon, this function will return #MHD_INVALID_SOCKET.
+ *
+ * @param daemon daemon to stop accepting new connections for
+ * @return old listen socket on success, #MHD_INVALID_SOCKET if
+ *         the daemon was already not listening anymore, or
+ *         was never started
+ * @ingroup specialized
+ */
+MHD_socket
+MHD_daemon_quiesce (struct MHD_Daemon *daemon)
+{
+  MHD_socket listen_socket;
+
+  if (MHD_INVALID_SOCKET == (listen_socket = daemon->listen_socket))
+    return MHD_INVALID_SOCKET;
+  if ( (daemon->disable_itc) &&
+       (MHD_TM_EXTERNAL_EVENT_LOOP != daemon->threading_model) )
+    {
+#ifdef HAVE_MESSAGES
+      MHD_DLOG (daemon,
+                MHD_SC_SYSCALL_QUIESCE_REQUIRES_ITC,
+                "Using MHD_quiesce_daemon in this mode requires ITC\n");
+#endif
+      return MHD_INVALID_SOCKET;
+    }
+
+  if (NULL != daemon->worker_pool)
+    {
+      unsigned int i;
+
+      for (i = 0; i < daemon->threading_model; i++)
+        {
+          struct MHD_Daemon *worker = &daemon->worker_pool[i];
+          
+          worker->was_quiesced = true;
+#ifdef EPOLL_SUPPORT
+          if ( (MHD_ELS_EPOLL == daemon->event_loop_syscall) &&
+               (-1 != worker->epoll_fd) &&
+               (worker->listen_socket_in_epoll) )
+            {
+              if (0 != epoll_ctl (worker->epoll_fd,
+                                  EPOLL_CTL_DEL,
+                                  listen_socket,
+                                  NULL))
+                MHD_PANIC (_("Failed to remove listen FD from epoll set\n"));
+              worker->listen_socket_in_epoll = false;
+            }
+          else
+#endif
+            if (MHD_ITC_IS_VALID_(worker->itc))
+              {
+                if (! MHD_itc_activate_ (worker->itc,
+                                         "q"))
+                  MHD_PANIC (_("Failed to signal quiesce via inter-thread communication channel"));
+              }
+        }
+      daemon->was_quiesced = true;
+#ifdef EPOLL_SUPPORT
+      if ( (MHD_ELS_EPOLL == daemon->event_loop_syscall) &&
+           (-1 != daemon->epoll_fd) &&
+           (daemon->listen_socket_in_epoll) )
+        {
+          if (0 != epoll_ctl (daemon->epoll_fd,
+                              EPOLL_CTL_DEL,
+                              listen_socket,
+                              NULL))
+            MHD_PANIC ("Failed to remove listen FD from epoll set\n");
+          daemon->listen_socket_in_epoll = false;
+        }
+#endif
+    }
+  
+  if ( (MHD_ITC_IS_VALID_(daemon->itc)) &&
+       (! MHD_itc_activate_ (daemon->itc,
+                             "q")) )
+    MHD_PANIC (_("Failed to signal quiesce via inter-thread communication channel"));
+
+  /* FIXME: we might want some bi-directional communication here
+     (in both the thread-pool and single-thread case!) 
+     to be sure that the threads have stopped using the listen
+     socket, otherwise there is still the possibility of a race
+     between a thread accept()ing and the caller closing and
+     re-binding the socket. */
+  
+  return listen_socket;
+}
+
+