Merge pull request #251 from Monsterovich/master

Make sure that applet.py is running one instance per user

Author: zdohnal

applet.py

@@ -21,6 +21,8 @@
 from functools import reduce
 cups.require ("1.9.42")
 import sys
+import socket
+import getpass
 from debug import *
 
 import dbus
@@ -459,6 +461,16 @@ def check_for_jobs (self, *args):
         except:
             pass
 
+    try:
+        sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+        # Create an abstract socket, by prefixing it with null.
+        sock.bind("\0printer-applet-lock-user-" + getpass.getuser()) 
+    except socket.error as err:
+        error_code = err.args[0]
+        error_string = err.args[1]
+        print("Process already running ({0}:{1}). Exiting.".format(error_code, error_string))
+        sys.exit(0)
+
     loop = GLib.MainLoop ()
     runloop = RunLoop (session_bus, system_bus, loop)
     try: