NUT-Monitor: Add automatic reconnection mechanism for Py2Gtk2 as well as Py3Qt{5,6} variants

NEWS.adoc

@@ -246,6 +246,9 @@ https://github.com/networkupstools/nut/milestone/13
     * Fixed Qt tray tooltips to render in plain text, not rich text which
       ended up as literal HTML on KDE Plasma 6; now that rich text formatting
       is only used for main window status labels. [PR #3430]
+    * Fixed both Python 2 and 3 variants to handle automatic client reconnection
+      (e.g. after system suspend/resume, network interruption, or NUT server
+      restart). [issue #3509, PR #3523]
 
  - `upssched` client/tool updates:
     * Added a `clean_exit()` handler similar to that in `upsmon`. [PR #3499]

scripts/python/app/NUT-Monitor-py2gtk2.in

@@ -34,6 +34,7 @@
 
 import gtk, gtk.glade, gobject
 import sys
+import socket
 import base64
 import os, os.path
 import stat
@@ -116,6 +117,7 @@ class interface :
     __ups_rw_vars                    = None
     __gui_thread                     = None
     __current_ups                    = None
+    __reconnect_attempted            = False
 
     def __init__( self ) :
 
@@ -389,8 +391,11 @@ class interface :
     def quit( self, widget=None ) :
         # If we are connected to an UPS, disconnect first...
         if self.__connected :
-            self.gui_status_message( _("Disconnecting from device") )
-            self.disconnect_from_ups()
+            try:
+                self.gui_status_message( _("Disconnecting from device") )
+                self.disconnect_from_ups()
+            except Exception:
+                pass
 
         gtk.main_quit()
 
@@ -705,24 +710,28 @@ class interface :
     # Display a message on the status bar. The message is also set as
     # tooltip to enable users to see long messages.
     def gui_status_message( self, msg="" ) :
-        context_id = self.__widgets["status_bar"].get_context_id("Infos")
-        self.__widgets["status_bar"].pop( context_id )
+        try:
+            context_id = self.__widgets["status_bar"].get_context_id("Infos")
+            self.__widgets["status_bar"].pop( context_id )
 
-        if ( platform.system() == "Windows" ) :
-            text = msg.decode("cp1250").encode("utf8")
-        else :
-            text = msg
+            if ( platform.system() == "Windows" ) :
+                text = msg.decode("cp1250").encode("utf8")
+            else :
+                text = msg
 
-        message_id = self.__widgets["status_bar"].push( context_id, text.replace("\n", "") )
-        self.__widgets["status_bar"].set_tooltip_text( text )
+            message_id = self.__widgets["status_bar"].push( context_id, text.replace("\n", "") )
+            self.__widgets["status_bar"].set_tooltip_text( text )
+        except :
+            pass
 
     #-------------------------------------------------------------------
     # Display a notification using PyNotify with an optional icon
     def gui_status_notification( self, message="", icon_file="" ) :
         # Try to init pynotify
         try :
             import pynotify
-            pynotify.init( "NUT Monitor" )
+            if not pynotify.init( "NUT Monitor" ):
+                return
 
             if ( icon_file != "" ) :
                 icon = "file://%s" % os.path.abspath( os.path.join( self.__resdir, "pixmaps", icon_file ) )
@@ -746,6 +755,7 @@ class interface :
     # Connect to the selected UPS using parameters (host,port,login,pass)
     def connect_to_ups( self, widget=None ) :
 
+        self.__reconnect_attempted = False
         host     = self.__widgets["ups_host_entry"].get_text()
         port     = int( self.__widgets["ups_port_entry"].get_value() )
         login    = None
@@ -862,6 +872,7 @@ class gui_updater( threading.Thread ) :
     __parent_class = None
     __stop_thread  = False
     was_online = True
+    __reconnect_attempted = False
 
     def __init__( self, parent_class ) :
         threading.Thread.__init__( self )
@@ -977,12 +988,88 @@ class gui_updater( threading.Thread ) :
                 # Display UPS status as tooltip for tray icon
                 self.__parent_class._interface__widgets["status_icon"].set_tooltip_markup( status_text )
 
-            except :
-                self.__parent_class.gui_status_message( _("Error from '{0}' ({1})").format( ups, sys.exc_info()[1] ) )
-                self.__parent_class.gui_status_notification( _("Error from '{0}'\n{1}").format( ups, sys.exc_info()[1] ), "warning.png" )
+            except (socket.error, EOFError, PyNUT.PyNUTError) as e:
+                # Connection error detected - attempt automatic reconnection
+                if not self.__reconnect_attempted and self.__parent_class._interface__connected:
+                    self.__reconnect_attempted = True
+                    self.__parent_class.gui_status_message( _("Connection lost - attempting to reconnect...") )
+                    self.__parent_class.gui_status_notification( _("Connection lost"), "warning.png" )
+
+                    # Close the socket to avoid "Broken pipe" in subsequent calls if any
+                    if self.__parent_class._interface__ups_handler:
+                        self.__parent_class._interface__ups_handler.disconnect()
+
+                    # Wait for 2 seconds before attempting reconnection
+                    time.sleep( 2 )
+                    self.__attempt_reconnect()
+                else:
+                    self.__parent_class.gui_status_message( _("Error from '{0}' ({1})").format( ups, sys.exc_info()[1] ) )
+                    self.__parent_class.gui_status_notification( _("Error from '{0}'\n{1}").format( ups, sys.exc_info()[1] ), "warning.png" )
 
             time.sleep( 1 )
 
+    def __attempt_reconnect( self ) :
+        """Attempt to reconnect to the UPS after a connection loss."""
+        if self.__stop_thread:
+            return
+
+        try:
+            # Get connection parameters from the parent class
+            host = self.__parent_class._interface__widgets["ups_host_entry"].get_text()
+            port = int(self.__parent_class._interface__widgets["ups_port_entry"].get_value())
+            login = None
+            password = None
+
+            if self.__parent_class._interface__widgets["ups_authentication_check"].get_active():
+                login = self.__parent_class._interface__widgets["ups_authentication_login"].get_text()
+                password = self.__parent_class._interface__widgets["ups_authentication_password"].get_text()
+
+            # Teardown old connection handler properly
+            old_handler = self.__parent_class._interface__ups_handler
+            if old_handler is not None:
+                old_handler.disconnect()
+                del old_handler
+
+            # Create a new connection handler
+            ups_handler = PyNUT.PyNUTClient(host=host, port=port, login=login, password=password)
+
+            # Verify the UPS is available
+            ups = self.__parent_class._interface__current_ups
+            srv_upses = ups_handler.GetUPSList()
+
+            if ups not in srv_upses:
+                self.__parent_class.gui_status_message( _("UPS '{0}' not found after reconnection").format(ups) )
+                self.__reconnect_attempted = False
+                return
+
+            if not ups_handler.CheckUPSAvailable(ups):
+                self.__parent_class.gui_status_message( _("UPS '{0}' is still not reachable").format(ups) )
+                self.__reconnect_attempted = False
+                return
+
+            # Connection successful - update the parent class
+            self.__parent_class._interface__ups_handler = ups_handler
+            self.__parent_class._interface__connected = True
+            self.__reconnect_attempted = False
+
+            # Refresh UPS data
+            commands = ups_handler.GetUPSCommands(ups)
+            self.__parent_class._interface__ups_commands = list(commands.keys())
+            self.__parent_class._interface__ups_commands.sort()
+
+            self.__parent_class._interface__ups_vars = ups_handler.GetUPSVars(ups)
+            self.__parent_class._interface__ups_rw_vars = ups_handler.GetRWVars(ups)
+
+            # Update the GUI (must be done on the main thread in GTK)
+            gobject.idle_add( self.__parent_class._interface__gui_update_ups_vars_view )
+            gobject.idle_add( self.__parent_class.change_status_icon, "on_line", False )
+            self.__parent_class.gui_status_message( _("Reconnected to '{0}' on {1}").format(ups, host) )
+            self.__parent_class.gui_status_notification( _("Reconnected to UPS"), "on_line.png" )
+
+        except (socket.error, EOFError, PyNUT.PyNUTError) as e:
+            self.__parent_class.gui_status_message( _("Reconnection failed: {0}").format(str(e)) )
+            self.__reconnect_attempted = False
+
     def stop_thread( self ) :
         self.__stop_thread = True
 

scripts/python/app/NUT-Monitor-py3qt5.in

@@ -43,6 +43,7 @@ from PyQt5.QtCore import *
 from PyQt5.QtGui import *
 from PyQt5.QtWidgets import *
 import sys
+import socket
 import base64
 import os, os.path
 import stat
@@ -53,6 +54,7 @@ import optparse
 import configparser
 import locale
 import gettext
+import PyNUT
 
 # Try local development/accompanying packaging first,
 # then system installation
@@ -407,8 +409,11 @@ class interface :
     def quit( self, widget=None ) :
         # If we are connected to an UPS, disconnect first...
         if self.__connected :
-            self.gui_status_message( _("Disconnecting from device") )
-            self.disconnect_from_ups()
+            try:
+                self.gui_status_message( _("Disconnecting from device") )
+                self.disconnect_from_ups()
+            except RuntimeError:
+                pass  # widgets may already be deleted during shutdown
 
         self.__app.quit()
 
@@ -748,20 +753,28 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
     # Display a message on the status bar. The message is also set as
     # tooltip to enable users to see long messages.
     def gui_status_message( self, msg="" ) :
-        text = msg
-
-        message_id = self.__widgets["status_bar"].showMessage( text.replace("\n", "") )
-        self.__widgets["status_bar"].setToolTip( text )
+        try:
+            text = msg
+            if self.__widgets.get("status_bar"):
+                self.__widgets["status_bar"].showMessage( text.replace("\n", "") )
+                self.__widgets["status_bar"].setToolTip( text )
+        except Exception:
+            pass
 
     #-------------------------------------------------------------------
     # Display a notification using QSystemTrayIcon with an optional icon
     def gui_status_notification( self, message="", icon_file="" ) :
-        if ( icon_file != "" ) :
-            icon = QIcon( os.path.abspath( self.__find_res_file( "pixmaps", icon_file ) ) )
-        else :
-            icon = None
-
-        self.__widgets["status_icon"].showMessage( "NUT Monitor", message, icon )
+        try:
+            if not self.__widgets.get("status_icon"):
+                return
+            if ( icon_file != "" ) :
+                icon = QIcon( os.path.abspath( self.__find_res_file( "pixmaps", icon_file ) ) )
+            else :
+                icon = None
+
+            self.__widgets["status_icon"].showMessage( "NUT Monitor", message, icon )
+        except Exception:
+            pass
 
     #-------------------------------------------------------------------
     # Connect to the selected UPS using parameters (host,port,login,pass)
@@ -895,6 +908,7 @@ class gui_updater :
     __parent_class = None
     __stop_thread  = False
     was_online = True
+    __reconnect_attempted = False
 
     def __init__( self, parent_class ) :
         threading.Thread.__init__( self )
@@ -1031,12 +1045,101 @@ class gui_updater :
                 # Display UPS status as tooltip for tray icon
                 self.__parent_class._interface__widgets["status_icon"].setToolTip( "\n".join( tooltip_lines ) )
 
-            except :
-                self.__parent_class.gui_status_message( _("Error from '{0}' ({1})").format( ups, sys.exc_info()[1] ) )
-                self.__parent_class.gui_status_notification( _("Error from '{0}'\n{1}").format( ups, sys.exc_info()[1] ), "warning.png" )
+            except (socket.error, ConnectionError, EOFError, OSError, PyNUT.PyNUTError) as e:
+                # Connection error detected — attempt automatic reconnection
+                if not self.__reconnect_attempted and self.__parent_class._interface__connected:
+                    self.__reconnect_attempted = True
+                    self.__parent_class.gui_status_message( _("Connection lost — attempting to reconnect...") )
+                    self.__parent_class.gui_status_notification( _("Connection lost"), "warning.png" )
+
+                    # Stop the current timer
+                    self.__timer.stop()
+
+                    # Close the socket to avoid "Broken pipe" in subsequent calls if any
+                    if self.__parent_class._interface__ups_handler:
+                        self.__parent_class._interface__ups_handler.disconnect()
+
+                    # Schedule reconnection attempt after 2 seconds
+                    QTimer.singleShot(2000, self.__attempt_reconnect)
+                elif self.__reconnect_attempted:
+                    # Reconnection already in progress, just ignore this update
+                    pass
+                else:
+                    self.__parent_class.gui_status_message( _("Error from '{0}' ({1})").format( ups, sys.exc_info()[1] ) )
+                    self.__parent_class.gui_status_notification( _("Error from '{0}'\n{1}").format( ups, sys.exc_info()[1] ), "warning.png" )
+
+    def __attempt_reconnect( self ) :
+        """Attempt to reconnect to the UPS after a connection loss."""
+        if self.__stop_thread:
+            return
+
+        try:
+            # Get connection parameters from the parent class
+            host = self.__parent_class._interface__widgets["ups_host_entry"].text()
+            port = int(self.__parent_class._interface__widgets["ups_port_entry"].value())
+            login = None
+            password = None
+
+            if self.__parent_class._interface__widgets["ups_authentication_check"].isChecked():
+                login = self.__parent_class._interface__widgets["ups_authentication_login"].text()
+                password = self.__parent_class._interface__widgets["ups_authentication_password"].text()
+
+            # Teardown old connection handler properly
+            old_handler = self.__parent_class._interface__ups_handler
+            if old_handler is not None:
+                old_handler.disconnect()
+                del old_handler
+
+            # Create a new connection handler
+            ups_handler = PyNUT.PyNUTClient(host=host, port=port, login=login, password=password)
+
+            # Verify the UPS is available
+            ups = self.__parent_class._interface__current_ups
+            srv_upses = ups_handler.GetUPSList()
+
+            if ups.encode('ascii') not in srv_upses:
+                self.__parent_class.gui_status_message( _("UPS '{0}' not found after reconnection").format(ups) )
+                self.__reconnect_attempted = False
+                # Restart the timer to continue polling
+                self.__timer.start(1000)
+                return
+
+            if not ups_handler.CheckUPSAvailable(ups):
+                self.__parent_class.gui_status_message( _("UPS '{0}' is still not reachable").format(ups) )
+                self.__reconnect_attempted = False
+                self.__timer.start(1000)
+                return
+
+            # Connection successful — update the parent class
+            self.__parent_class._interface__ups_handler = ups_handler
+            self.__parent_class._interface__connected = True
+            self.__reconnect_attempted = False
+
+            # Refresh UPS data
+            commands = ups_handler.GetUPSCommands(ups)
+            self.__parent_class._interface__ups_commands = list(commands.keys())
+            self.__parent_class._interface__ups_commands.sort()
+
+            self.__parent_class._interface__ups_vars = ups_handler.GetUPSVars(ups)
+            self.__parent_class._interface__ups_rw_vars = ups_handler.GetRWVars(ups)
+
+            # Update the GUI
+            self.__parent_class._interface__gui_update_ups_vars_view()
+            self.__parent_class.change_status_icon("on_line", blink=False)
+            self.__parent_class.gui_status_message( _("Reconnected to '{0}' on {1}").format(ups, host) )
+            self.__parent_class.gui_status_notification( _("Reconnected to UPS"), "on_line.png" )
+
+        except (socket.error, ConnectionError, EOFError, OSError, PyNUT.PyNUTError) as e:
+            self.__parent_class.gui_status_message( _("Reconnection failed: {0}").format(str(e)) )
+            self.__reconnect_attempted = False
+
+        # Restart the timer to continue polling
+        self.__timer.start(1000)
 
     def stop_thread( self ) :
-        self.__timer.stop()
+        self.__stop_thread = True
+        if hasattr(self, '_gui_updater__timer'):
+            self.__timer.stop()
 
 
 #-----------------------------------------------------------------------