Async refresh

Move refresh of google music content to an extra thread.
This fixes two problems:

1. Very long startup times on small systems, like the raspberry pi
2. Remote changes to the content, like new/changed playlists

mopidy_gmusic/__init__.py

@@ -24,6 +24,7 @@ def get_config_schema(self):
         schema['password'] = config.Secret()
         schema['deviceid'] = config.String(optional=True)
         schema['all_access'] = config.Boolean(optional=True)
+        schema['refresh_playlists'] = config.Integer(minimum=-1, optional=True)
         return schema
 
     def setup(self, registry):

mopidy_gmusic/actor.py

@@ -1,5 +1,10 @@
 from __future__ import unicode_literals
 
+import logging
+import time
+
+from threading import Timer
+
 from mopidy import backend
 
 import pykka
@@ -9,11 +14,14 @@
 from .playlists import GMusicPlaylistsProvider
 from .session import GMusicSession
 
+logger = logging.getLogger(__name__)
+
 
 class GMusicBackend(pykka.ThreadingActor, backend.Backend):
     def __init__(self, config, audio):
         super(GMusicBackend, self).__init__()
 
+        self._refresh_timer = None
         self.config = config
 
         self.library = GMusicLibraryProvider(backend=self)
@@ -28,8 +36,28 @@ def on_start(self):
                            self.config['gmusic']['password'],
                            self.config['gmusic']['deviceid'])
         self.library.set_all_access(self.config['gmusic']['all_access'])
-        self.library.refresh()
-        self.playlists.refresh()
+        # wait a few seconds to let mopidy settle
+        # then refresh google music content asynchronously
+        self._sched_refresh(5.0)
 
     def on_stop(self):
+        if self._refresh_timer:
+            self._refresh_timer.cancel()
+            self._refresh_timer = None
         self.session.logout()
+
+    def _refresh_content(self):
+        logger.debug('Start refreshing gmusic content')
+        t0 = round(time.time())
+        self.library.refresh()
+        self.playlists.refresh()
+        # schedule next refresh
+        refresh_playlists = self.config['gmusic']['refresh_playlists']
+        if refresh_playlists > 0:
+            self._sched_refresh(refresh_playlists * 60.0)
+        t1 = round(time.time())
+        logger.debug('Finished refreshing gmusic content, took %ds', t1 - t0)
+
+    def _sched_refresh(self, seconds):
+        self._refresh_timer = Timer(seconds, self._refresh_content)
+        self._refresh_timer.start()

mopidy_gmusic/ext.conf

@@ -4,3 +4,4 @@ username =
 password =
 deviceid =
 all_access = false
+refresh_playlists = 60