D-Bus object; only allow a single instance running (bug 62)

Add support for D-Bus to gPodder, and allow only one
instance running (the second invocation sends a D-Bus
message to the running instance to show the window and
then exits).

README

@@ -33,6 +33,7 @@
    * python-gtk2 (minimum 2.6, but >= 2.12 recommended)
    * python-glade2
    * python-feedparser
+   * python-dbus
  
  Additional dependencies for iPod synchronization support:
 

bin/gpodder

@@ -42,6 +42,9 @@ import os.path
 import locale
 import gettext
 
+import dbus
+import dbus.glib
+
 from optparse import OptionParser
 
 try:
@@ -125,6 +128,15 @@ def main( argv = sys.argv):
         from gpodder.liblogger import enable_verbose
         enable_verbose()
 
+    # Try to find an already-running instance of gPodder
+    session_bus = dbus.SessionBus()
+    try:
+        remote_object = session_bus.get_object(gpodder.dbus_bus_name, gpodder.dbus_gui_object_path)
+        from gpodder.liblogger import log
+        log('Found gPodder GUI instance already running')
+    except dbus.exceptions.DBusException:
+        remote_object = None
+
     from gpodder import console
     if options.list:
         console.list_channels()
@@ -140,8 +152,11 @@ def main( argv = sys.argv):
         console.del_channel( options.delete)
     elif options.stats:
         console.sync_stats()
+    elif remote_object is not None:
+        # An instance of GUI is already running
+        remote_object.show_gui_window(dbus_interface=gpodder.dbus_interface)
     else:
-        #default run gui
+        # gPodder is not yet running - create new instance
         from gpodder import gui
         from gpodder.SimpleGladeApp import bindtextdomain
         import gtk.glade
@@ -166,7 +181,6 @@ def main( argv = sys.argv):
         gui.app_version = __version__
         gui.main()
 
-
 if __name__ == "__main__":
     sys.exit( main())
 

src/gpodder/__init__.py

@@ -26,3 +26,8 @@ user_agent = 'gPodder'
 # Are we running in GUI, Maemo or console mode?
 interface = CLI
 
+# D-Bus specific interface names
+dbus_bus_name = 'org.godder'
+dbus_gui_object_path = '/gui'
+dbus_interface = 'org.gpodder.interface'
+

src/gpodder/gui.py

@@ -30,6 +30,10 @@ import time
 import urllib
 import urllib2
 import datetime
+import dbus
+import dbus.service
+import dbus.mainloop
+import dbus.glib
 
 from xml.sax import saxutils
 
@@ -340,9 +344,13 @@ class GladeWidget(SimpleGladeApp.SimpleGladeApp):
         return (result, folder)
 
 
-class gPodder(GladeWidget):
+class gPodder(GladeWidget, dbus.service.Object):
     finger_friendly_widgets = ['btnCancelFeedUpdate', 'label2', 'labelDownloads', 'itemQuit', 'menuPodcasts', 'advanced1', 'menuChannels', 'menuHelp']
     ENTER_URL_TEXT = _('Enter podcast URL...')
+
+    def __init__(self, bus_name):
+        dbus.service.Object.__init__(self, object_path=gpodder.dbus_gui_object_path, bus_name=bus_name)
+        GladeWidget.__init__(self)
     
     def new(self):
         if gpodder.interface == gpodder.MAEMO:
@@ -3015,6 +3023,10 @@ class gPodder(GladeWidget):
         else:
             self.label2.set_text(_('Podcasts'))
 
+    @dbus.service.method(gpodder.dbus_interface)
+    def show_gui_window(self):
+        self.gPodder.present()
+
 class gPodderChannel(GladeWidget):
     finger_friendly_widgets = ['btn_website', 'btnOK', 'channel_description', 'label19', 'label37', 'label31']
     
@@ -4559,7 +4571,10 @@ def main():
     gobject.threads_init()
     gtk.window_set_default_icon_name( 'gpodder')
 
-    gPodder().run()
+    session_bus = dbus.SessionBus(mainloop=dbus.glib.DBusGMainLoop())
+    bus_name = dbus.service.BusName(gpodder.dbus_bus_name, bus=session_bus)
+    gp = gPodder(bus_name)
+    gp.run()