Merge lp:~kaihengfeng/ubiquity/fix-usd-scaling into lp:ubiquity

[Kai-Heng Feng]

[Kai-Heng Feng (kaihengfeng)]

This commit needs [1] to behave correctly.

http://bazaar.launchpad.net/~unity-settings-daemon-team/unity-settings-daemon/trunk/revision/4147

[Mathieu Trudel-Lapierre (cyphermox)]

Looks generally fine; have you built this locally and tested it on a live image?

review: Needs Information

[Kai-Heng Feng (kaihengfeng)]

Yes. It depends on the dbus-monitor output format, but I think it won't change anytime soon.

[Mathieu Trudel-Lapierre (cyphermox)]

Looks fine this way; thanks!

review: Approve

[Iain Lane (laney)]

IMHO calling out to an external program like this is bad form in terms of efficiency and using the right tools for the job (the regex in particular has a bad smell).

There are APIs to talk to DBus directly which you can use from python. I recommend using GDBus via g-i. Something like---

  from gi.repository import Gio
  loop = Glib.MainLoop()
  connection = Gio.bus_get (Gio.BusType.SESSION, None, on_got_bus, loop)
  loop.run()

  # on_got_bus
  connection.signal_subscribe (sender, interface, "PluginActivated", object_path, None, Gio.DBusSignalFlags.NONE, on_xsettings_active, loop)
  # add a timeout for safety
  # start u-s-d

  # on_xsettings_active
  # check the signal parameter
  loop.quit()

review: Disapprove

[Kai-Heng Feng (kaihengfeng)]

Yea I think your solution is better. I didn't know that Glib.MainLoop.run() will block until quit() is called, so I came up with current solution.

I'll update one accordingly.

[Kai-Heng Feng (kaihengfeng)]

It can't receive signals even if it does use connection.signal_subscribe()... Does it require something more than Glib.MainLoop()?

=== modified file 'bin/ubiquity-dm'
--- bin/ubiquity-dm	2016-06-13 10:47:25 +0000
+++ bin/ubiquity-dm	2016-06-24 09:05:30 +0000
@@ -461,10 +461,29 @@
                         preexec_fn=self.drop_privileges))
 
                 elif osextras.find_on_path(usd):
+                    # Wait until xsettings plugin is activated
+                    import re
+                    regexp = re.compile(
+                        r'signal.*SettingsDaemon.*PluginActivated')
+
+                    dbus_monitor = subprocess.Popen(
+                       '/usr/bin/dbus-monitor', stdin=null,
+                       stdout=subprocess.PIPE, stderr=subprocess.PIPE,
+                       universal_newlines=True,
+                       preexec_fn=self.drop_privileges)
+
                     extras.append(subprocess.Popen(
                         [usd], stdin=null, stdout=logfile, stderr=logfile,
                         preexec_fn=self.drop_privileges))
 
+                    while True:
+                        line = dbus_monitor.stdout.readline()
+                        if regexp.match(line) is not None:
+                            nextline = dbus_monitor.stdout.readline()
+                            if 'xsettings' in nextline:
+                                dbus_monitor.terminate()
+                                break
+
                 elif osextras.find_on_path(gsd):
                     extras.append(subprocess.Popen(
                         [gsd], stdin=null, stdout=logfile, stderr=logfile,