Save and restore state of the game

Ability to 'save' (when the user closes the Activity) and 'restore' (when the
user launch it from the Journal or the Home without holding Alt) the state of
the game.

For this ability I had to upgrade 'olpcgames' to 1.6 because
'olpcgames.FILE_READ_REQUEST' and 'olpcgames.FILE_WRITE_REQUEST' events are
added in that version and those events are needed for this.

The data is saved (as JSON, with json module) in the 'event.metadata["state"]' and the timestamp state is saved in 'event.filename'.

This commit solves ticket #2393:
 * http://bugs.sugarlabs.org/ticket/2393

Signed-off-by: Manuel Kaufmann <humitos@gmail.com>
Signed-off-by: Rafael Ortiz <rafael@activitycentral.com>

1 files changed, 310 insertions, 141 deletions

diff --git a/olpcgames/mesh.py b/olpcgames/mesh.py
index fb583bb..1ad4c43 100644
--- a/olpcgames/mesh.py
+++ b/olpcgames/mesh.py
@@ -1,7 +1,125 @@
-'''mesh.py: utilities for wrapping the mesh and making it accessible to Pygame'''
+'''Utilities for wrapping the telepathy network for Pygame
+
+The 'mesh' module allows your Pygame game to be Shared 
+across the OLPC networking infrastructure (D-bus and Tubes).
+It offers a simplified view of the Telepathy system.
+
+All Sugar activities have a 'Share' menu (toolbar) which is 
+intended to allow other people to join the activity instance 
+and collaborate with you. When you select Share, the activity's 
+icon appears on the Neighborhood view of other laptops.
+
+If you do nothing else with networking, this is all that will 
+happen: if anyone selects your shared activity icon, they will 
+just spawn a new instance of the activity, and they will get to 
+play your game alone.
+
+The mesh module automatically sets up a connection from each 
+participant to every other participant.  It provides (string based)
+communications channels that let you either broadcast messages 
+to other users or communicate point-to-point to one other user.
+
+You can use the "handles" which uniquely idenify users to send 
+messages to an individual user (send_to( handle, message )) or 
+broadcast( message ) to send a message to all participants.
+
+More advanced (structured) networking can be handled by using 
+the get_object( handle, path ) function, which looks up an object 
+(by DBUS path) shared by the user "handle" and returns a 
+DBUS/Telepathy proxy for that object.  The object you get back is 
+actually an olpcgames.dbusproxy.DBUSProxy instance, which 
+enforces asynchronous operations and runs your 
+reply_handler/error_handler in the Pygame event loop.
+
+NOTE:
+    You *cannot* make synchronous calls on these objects!  
+    You must use the named arguments:
+
+        reply_handler, error_handler
+
+    for every call which you perform on a shared object (normally 
+    these are ExportedGObject instances).
+
+If you want to run your callbacks in the GTK event loop (for instance 
+because they need to handle GTK-side objects), you can use the 
+dbus_get_object function.  This is *not* recommended for normal 
+usage, as any call to Pygame operations within the GTK event loop 
+can cause a segfault/core of your entire Activity.
+
+Note:
+
+    mesh sets up N**2 connections for each shared activity, obviously 
+    that will not scale to very large shared activities. 
+
+Note: 
+
+    The intention is that mesh will be refactored, possibly as a 
+    new module called "olpcgames.network", which would break out 
+    the various components so that there is no longer an assumed 
+    networking layout.  We will attempt to retain the mesh module's 
+    API as we do so.
+
+Events produced:
+
+    olpcgames.CONNECT -- The tube connection was started. (i.e., the 
+        user clicked Share or started the activity from the Neighborhood 
+        screen).
+        
+        Event properties:
+        
+            id -- a unique identifier for this connection. (shouldn't be needed 
+                for anything)
+
+    olpcgames.PARTICIPANT_ADD -- A participant joined the activity. 
+        This will trigger for the local user as well as any arriving remote 
+        users.  Note that this *only* occurs after the activity is shared, 
+        that is, the local user does not appear until after they have 
+        shared a locally-started activity.
+
+        Event properties:
+
+            handle --  the arriving user's handle (a uniquely identifying string 
+                assigned to the user by the Telepathy system, not human 
+                readable), see lookup_buddy to retrieve human-readable 
+                descriptions of the user.
+
+    olpcgames.PARTICIPANT_REMOVE --  A participant quit the activity.
+    
+        Event properties:
+
+            handle -- the departing user's handle.
+
+    olpcgames.MESSAGE_UNI -- A message was sent to you.
+    
+        Event properties:
+        
+           content --  the content of the message (a string)
+           handle -- the handle of the sending user.
+
+    olpcgames.MESSAGE_MULTI -- A message was sent to everyone.
+
+        Event properties:
+        
+           content -- the content of the message (a string)
+           handle -- the handle of the sending user.
+
+Note:
+
+    Eventually we will stop using top-level Pygame event types for the 
+    various networking message types (currently four of them).  We will 
+    likely use UserEvent with a sub-type specifier for the various events 
+    that OLPCGames produces.
+
+See Also:
+
+    http://blog.vrplumber.com/2016 -- Discussion of how Productive uses 
+        the mesh module and raw Telepathy (ExportedGObject instances)
+'''
 import logging
-log = logging.getLogger('olpcgames.mesh')
-#log.setLevel( logging.DEBUG )
+log = logging.getLogger( 'olpcgames.mesh' )
+##log.setLevel( logging.DEBUG )
+import olpcgames
+from olpcgames.util import get_traceback
 try:
     from sugar.presence.tubeconn import TubeConnection
 except ImportError, err:
@@ -17,45 +135,27 @@ try:
 except ImportError, err:
     telepathy = None
 
+try:
+    import sugar.presence.presenceservice
+except Exception, err:
+    pass
+import pygame.event as PEvent
 
-class OfflineError(Exception):
+class OfflineError( Exception ):
     """Raised when we cannot complete an operation due to being offline"""
 
-DBUS_IFACE = "org.laptop.games.pygame"
-DBUS_PATH = "/org/laptop/games/pygame"
+DBUS_IFACE="org.laptop.games.pygame"
+DBUS_PATH="/org/laptop/games/pygame"
 DBUS_SERVICE = None
 
 
 ### NEW PYGAME EVENTS ###
 
-'''The tube connection was started. (i.e., the user clicked Share or started
-the activity from the Neighborhood screen).
-Event properties:
-  id: a unique identifier for this connection. (shouldn't be needed for anything)'''
-CONNECT = 9912
-
-'''A participant joined the activity. This will trigger for the local user
-as well as any arriving remote users.
-Event properties:
-  handle: the arriving user's handle.'''
-PARTICIPANT_ADD = 9913
-
-'''A participant quit the activity.
-Event properties:
-  handle: the departing user's handle.'''
-PARTICIPANT_REMOVE = 9914
-
-'''A message was sent to you.
-Event properties:
-   content: the content of the message (a string)
-   handle: the handle of the sending user.'''
-MESSAGE_UNI = 9915
-
-'''A message was sent to everyone.
-Event properties:
-   content: the content of the message (a string)
-   handle: the handle of the sending user.'''
-MESSAGE_MULTI = 9916
+CONNECT            = olpcgames.CONNECT
+PARTICIPANT_ADD    = olpcgames.PARTICIPANT_ADD
+PARTICIPANT_REMOVE = olpcgames.PARTICIPANT_REMOVE
+MESSAGE_UNI        = olpcgames.MESSAGE_UNI
+MESSAGE_MULTI      = olpcgames.MESSAGE_MULTI
 
 
 # Private objects for useful purposes!
@@ -67,21 +167,18 @@ joining = False
 
 connect_callback = None
 
-
 def is_initiating():
     '''A version of is_initiator that's a bit less goofy, and can be used
     before the Tube comes up.'''
     global initiating
     return initiating
 
-
 def is_joining():
     '''Returns True if the activity was started up by means of the
     Neighbourhood mesh view.'''
     global joining
     return joining
 
-
 def set_connect_callback(cb):
     '''Just the same as the Pygame event loop can listen for CONNECT,
     this is just an ugly callback that the glib side can use to be aware
@@ -89,7 +186,6 @@ def set_connect_callback(cb):
     global connect_callback
     connect_callback = cb
 
-
 def activity_shared(activity):
     '''Called when the user clicks Share.'''
 
@@ -98,9 +194,10 @@ def activity_shared(activity):
 
     _setup(activity)
 
+
     log.debug('This is my activity: making a tube...')
     channel = tubes_chan[telepathy.CHANNEL_TYPE_TUBES]
-    if hasattr(channel, 'OfferDBusTube'):
+    if hasattr( channel, 'OfferDBusTube' ):
         id = channel.OfferDBusTube(
             DBUS_SERVICE, {})
     else:
@@ -111,7 +208,6 @@ def activity_shared(activity):
     if connect_callback is not None:
         connect_callback()
 
-
 def activity_joined(activity):
     '''Called at the startup of our Activity, when the user started it via Neighborhood intending to join an existing activity.'''
 
@@ -121,11 +217,13 @@ def activity_joined(activity):
     for buddy in activity._shared_activity.get_joined_buddies():
         log.debug('Buddy %s is already in the activity' % buddy.props.nick)
 
+
     global initiating
     global joining
     initiating = False
     joining = True
 
+
     _setup(activity)
 
     tubes_chan[telepathy.CHANNEL_TYPE_TUBES].ListTubes(
@@ -136,14 +234,24 @@ def activity_joined(activity):
     if connect_callback is not None:
         connect_callback()
 
-
-def _getConn():
-    log.info('_getConn')
-    pservice = _get_presence_service()
-    name, path = pservice.get_preferred_connection()
+def _getConn( activity ):
+    log.debug( '_getConn' )
     global conn
-    conn = telepathy.client.Connection(name, path)
-    return conn
+    if conn:
+        return conn
+    else:
+        if hasattr( activity._shared_activity, 'telepathy_conn' ):
+            log.debug( '''new-style api for retrieving telepathy connection present''' )
+            conn = activity._shared_activity.telepathy_conn
+        else:
+            pservice = _get_presence_service()
+            log.debug( '_get_presence_service -> %s', pservice )
+            name, path = pservice.get_preferred_connection()
+            log.debug( '_get_presence_service -> %s, %s', name, path)
+            conn = telepathy.client.Connection(name, path)
+        log.debug( 'Telepathy Client Connection: %s', conn )
+        return conn
+
 
 
 def _setup(activity):
@@ -152,37 +260,48 @@ channel present, creates one. Updates text_chan and tubes_chan.
 
 setup(sugar.activity.Activity, telepathy.client.Connection)'''
     global text_chan, tubes_chan, DBUS_SERVICE
+    log.info( 'Setup for %s', activity )
     if not DBUS_SERVICE:
         DBUS_SERVICE = activity.get_bundle_id()
     if not activity.get_shared():
         log.error('Failed to share or join activity')
         raise "Failure"
 
-    bus_name, conn_path, channel_paths = activity._shared_activity.get_channels()
-    _getConn()
-
-    # Work out what our room is called and whether we have Tubes already
-    room = None
-    tubes_chan = None
-    text_chan = None
-    for channel_path in channel_paths:
-        channel = telepathy.client.Channel(bus_name, channel_path)
-        htype, handle = channel.GetHandle()
-        if htype == telepathy.HANDLE_TYPE_ROOM:
-            log.debug('Found our room: it has handle#%d "%s"',
-                handle, conn.InspectHandles(htype, [handle])[0])
-            room = handle
-            ctype = channel.GetChannelType()
-            if ctype == telepathy.CHANNEL_TYPE_TUBES:
-                log.debug('Found our Tubes channel at %s', channel_path)
-                tubes_chan = channel
-            elif ctype == telepathy.CHANNEL_TYPE_TEXT:
-                log.debug('Found our Text channel at %s', channel_path)
-                text_chan = channel
-
-    if room is None:
-        log.error("Presence service didn't create a room")
-        raise "Failure"
+    if hasattr( activity._shared_activity, 'telepathy_tubes_chan' ):
+        log.debug( '''Improved channel setup API available''' )
+        _getConn( activity )
+        conn = activity._shared_activity.telepathy_conn
+        tubes_chan = activity._shared_activity.telepathy_tubes_chan
+        text_chan = activity._shared_activity.telepathy_text_chan
+    else:
+        log.debug( '''Old-style setup API''' )
+        bus_name, conn_path, channel_paths = activity._shared_activity.get_channels()
+        _getConn( activity )
+
+        # Work out what our room is called and whether we have Tubes already
+        room = None
+        tubes_chan = None
+        text_chan = None
+        for channel_path in channel_paths:
+            log.debug( 'Testing channel path: %s', channel_path)
+            channel = telepathy.client.Channel(bus_name, channel_path)
+            htype, handle = channel.GetHandle()
+            log.debug( '  Handle Type: %s  Handle: %s', htype, handle)
+            if htype == telepathy.HANDLE_TYPE_ROOM:
+                log.debug('Found our room: it has handle#%d "%s"',
+                    handle, conn.InspectHandles(htype, [handle])[0])
+                room = handle
+                ctype = channel.GetChannelType()
+                if ctype == telepathy.CHANNEL_TYPE_TUBES:
+                    log.debug('Found our Tubes channel at %s', channel_path)
+                    tubes_chan = channel
+                elif ctype == telepathy.CHANNEL_TYPE_TEXT:
+                    log.debug('Found our Text channel at %s', channel_path)
+                    text_chan = channel
+
+        if room is None:
+            log.error("Presence service didn't create a room")
+            raise "Failure"
     if text_chan is None:
         log.error("Presence service didn't create a text channel")
         raise "Failure"
@@ -196,16 +315,16 @@ setup(sugar.activity.Activity, telepathy.client.Connection)'''
     tubes_chan[telepathy.CHANNEL_TYPE_TUBES].connect_to_signal('NewTube',
         new_tube_cb)
 
+    log.info( 'Setup for %s complete', activity )
     return (text_chan, tubes_chan)
 
-
 def new_tube_cb(id, initiator, type, service, params, state):
     log.debug("New_tube_cb called: %s %s %s" % (id, initiator, type))
     if (type == telepathy.TUBE_TYPE_DBUS and service == DBUS_SERVICE):
         if state == telepathy.TUBE_STATE_LOCAL_PENDING:
             channel = tubes_chan[telepathy.CHANNEL_TYPE_TUBES]
-            if hasattr(channel, 'AcceptDBusTube'):
-                channel.AcceptDBusTube(id)
+            if hasattr( channel, 'AcceptDBusTube' ):
+                channel.AcceptDBusTube( id )
             else:
                 channel.AcceptTube(id)
 
@@ -221,59 +340,98 @@ def _list_tubes_reply_cb(tubes):
     for tube_info in tubes:
         new_tube_cb(*tube_info)
 
-
 def _list_tubes_error_cb(e):
     log.error('ListTubes() failed: %s', e)
 
-
-def get_buddy(dbus_handle):
-    """Get a Buddy from a handle."""
+def lookup_buddy( dbus_handle, callback, errback=None ):
+    """Do a lookup on the buddy information, callback with the information
+    
+    Calls callback( buddy ) with the result of the lookup, or errback( error ) with 
+    a dbus description of the error in the lookup process.
+    
+    returns None
+    """
     log.debug('Trying to find owner of handle %s...', dbus_handle)
     cs_handle = instance().tube.bus_name_to_handle[dbus_handle]
     log.debug('Trying to find my handle in %s...', cs_handle)
     group = text_chan[telepathy.CHANNEL_INTERFACE_GROUP]
-    log.debug('Calling GetSelfHandle')
-    my_csh = group.GetSelfHandle()
-    log.debug('My handle in that group is %s', my_csh)
-    if my_csh == cs_handle:
-        handle = conn.GetSelfHandle()
-        log.debug('CS handle %s belongs to me, %s', cs_handle, handle)
-    elif group.GetGroupFlags() & telepathy.CHANNEL_GROUP_FLAG_CHANNEL_SPECIFIC_HANDLES:
-        handle = group.GetHandleOwners([cs_handle])[0]
-        log.debug('CS handle %s belongs to %s', cs_handle, handle)
-    else:
-        handle = cs_handle
-        log.debug('non-CS handle %s belongs to itself', handle)
+    log.debug( 'Calling GetSelfHandle' )
+    if not errback:
+        def errback( error ):
+            log.error( """Failure retrieving handle for buddy lookup: %s""", error )
+    def with_my_csh( my_csh ):
+        log.debug('My handle in that group is %s', my_csh)
+        def _withHandle( handle ):
+            """process the results of the handle values"""
+            # XXX: we're assuming that we have Buddy objects for all contacts -
+            # this might break when the server becomes scalable.
+            pservice = _get_presence_service()
+            name, path = pservice.get_preferred_connection()
+            callback( pservice.get_buddy_by_telepathy_handle(name, path, handle) )
+        if my_csh == cs_handle:
+            conn.GetSelfHandle(reply_handler = _withHandle, error_handler=errback)
+            log.debug('CS handle %s belongs to me, looking up with GetSelfHandle', cs_handle)
+        elif group.GetGroupFlags() & telepathy.CHANNEL_GROUP_FLAG_CHANNEL_SPECIFIC_HANDLES:
+            handle = group.GetHandleOwners([cs_handle])[0]
+            log.debug('CS handle %s belongs to %s', cs_handle, handle)
+            _withHandle( handle )
+        else:
+            handle = cs_handle
+            log.debug('non-CS handle %s belongs to itself', handle)
+            _withHandle( handle )
+    group.GetSelfHandle( reply_handler = with_my_csh, error_handler = errback)
 
-    # XXX: we're assuming that we have Buddy objects for all contacts -
-    # this might break when the server becomes scalable.
-    pservice = _get_presence_service()
-    name, path = pservice.get_preferred_connection()
-    return pservice.get_buddy_by_telepathy_handle(name, path, handle)
+    
 
+def get_buddy(dbus_handle):
+    """DEPRECATED: Get a Buddy from a handle
+    
+    THIS API WAS NOT THREAD SAFE!  It has been removed to avoid
+    extremely hard-to-debug failures in activities.  Use lookup_buddy 
+    instead!
+    
+    Code that read:
+    
+        get_buddy( handle )
+        doSomething( handle, buddy )
+        doSomethingElse( buddy )
+        
+    Translates to:
+        
+        def withBuddy( buddy ):
+            doSomething( handle, buddy )
+            doSomethingElse( buddy )
+        lookup_buddy( handle, callback=withBuddy )
+    """
+    raise RuntimeError(
+        """get_buddy is not thread safe and will crash your activity (hard).  Use lookup_buddy."""
+    )
 
-def _get_presence_service():
+def _get_presence_service( ):
     """Attempt to retrieve the presence service (check for offline condition)
 
     The presence service, when offline, has no preferred connection type,
     so we check that before returning the object...
     """
-    import sugar.presence.presenceservice
-    pservice = sugar.presence.presenceservice.get_instance()
+    log.debug( """About to import sugar.presence.presenceservice""" )
     try:
-        name, path = pservice.get_preferred_connection()
-    except (TypeError, ValueError), err:
-        log.warn('Working in offline mode, cannot retrieve buddy information for %s: %s', handle, err)
-        raise OfflineError("""Unable to retrieve buddy information, currently offline""")
-    else:
-        return pservice
-
+        log.debug( 'About to retrieve presence service instance' )
+        pservice = sugar.presence.presenceservice.get_instance()
+        try:
+            log.debug( '  Retrieved presence service instance: %s', pservice )
+            name, path = pservice.get_preferred_connection()
+            log.debug( '  Name = %s  Path = %s', name, path )
+        except (TypeError,ValueError), err:
+            log.warn('Working in offline mode, cannot retrieve buddy information for %s: %s', handle, err )
+            raise OfflineError( """Unable to retrieve buddy information, currently offline""" )
+        else:
+            return pservice
+    except Exception, err:
+        log.error( """Failure in _get_presence_service: %s""", get_traceback( err ))
 
 def instance(idx=0):
     return pygametubes[idx]
 
-import eventwrap, pygame.event as PEvent
-
 
 class PygameTube(ExportedGObject):
     '''The object whose instance is shared across D-bus
@@ -283,36 +441,30 @@ class PygameTube(ExportedGObject):
     '''
     def __init__(self, tube, is_initiator, tube_id):
         super(PygameTube, self).__init__(tube, DBUS_PATH)
-        log.info('PygameTube init')
+        log.info( 'PygameTube init' )
         self.tube = tube
         self.is_initiator = is_initiator
         self.entered = False
         self.ordered_bus_names = []
-        eventwrap.post(PEvent.Event(CONNECT, id=tube_id))
+        PEvent.post(PEvent.Event(CONNECT, id=tube_id))
 
         if not self.is_initiator:
             self.tube.add_signal_receiver(self.new_participant_cb, 'NewParticipants', DBUS_IFACE, path=DBUS_PATH)
         self.tube.watch_participants(self.participant_change_cb)
         self.tube.add_signal_receiver(self.broadcast_cb, 'Broadcast', DBUS_IFACE, path=DBUS_PATH, sender_keyword='sender')
 
-    def participant_change_cb(self, added, removed):
-        log.debug('participant_change_cb: %s %s', added, removed)
-        
-        def nick(buddy):
-            if buddy is not None:
-                return buddy.props.nick
-            else:
-                return 'Unknown'
 
+    def participant_change_cb(self, added, removed):
+        log.debug( 'participant_change_cb: %s %s', added, removed )
         for handle, bus_name in added:
             dbus_handle = self.tube.participants[handle]
             self.ordered_bus_names.append(dbus_handle)
-            eventwrap.post(PEvent.Event(PARTICIPANT_ADD, handle=dbus_handle))
+            PEvent.post(PEvent.Event(PARTICIPANT_ADD, handle=dbus_handle))
 
         for handle in removed:
             dbus_handle = self.tube.participants[handle]
             self.ordered_bus_names.remove(dbus_handle)
-            eventwrap.post(PEvent.Event(PARTICIPANT_REMOVE, handle=dbus_handle))
+            PEvent.post(PEvent.Event(PARTICIPANT_REMOVE, handle=dbus_handle))
 
         if self.is_initiator:
             if not self.entered:
@@ -337,11 +489,11 @@ class PygameTube(ExportedGObject):
     @method(dbus_interface=DBUS_IFACE, in_signature='s', out_signature='', sender_keyword='sender')
     def Tell(self, content, sender=None):
         '''This is the targeted-message interface; called when a message is received that was sent directly to me.'''
-        eventwrap.post(PEvent.Event(MESSAGE_UNI, handle=sender, content=content))
+        PEvent.post(PEvent.Event(MESSAGE_UNI, handle=sender, content=content))
 
     def broadcast_cb(self, content, sender=None):
         '''This is the Broadcast callback, fired when someone sends a Broadcast signal along the bus.'''
-        eventwrap.post(PEvent.Event(MESSAGE_MULTI, handle=sender, content=content))
+        PEvent.post(PEvent.Event(MESSAGE_MULTI, handle=sender, content=content))
 
     def new_participant_cb(self, new_bus_names):
         '''This is the NewParticipants callback, fired when someone joins or leaves.'''
@@ -350,28 +502,22 @@ class PygameTube(ExportedGObject):
             log.warn("ordered bus names out of sync with server, resyncing")
             self.ordered_bus_names = new_bus_names
 
-
 def send_to(handle, content=""):
     '''Sends the given message to the given buddy identified by handle.'''
-    log.debug('send_to: %s %s', handle, content)
+    log.debug( 'send_to: %s %s', handle, content )
     remote_proxy = dbus_get_object(handle, DBUS_PATH)
     remote_proxy.Tell(content, reply_handler=dbus_msg, error_handler=dbus_err)
 
-
 def dbus_msg():
     log.debug("async reply to send_to")
-
-
 def dbus_err(e):
     log.error("async error: %s" % e)
 
-
 def broadcast(content=""):
     '''Sends the given message to all participants.'''
-    log.debug('Broadcast: %s', content)
+    log.debug( 'Broadcast: %s', content )
     instance().Broadcast(content)
 
-
 def my_handle():
     '''Returns the handle of this user
     
@@ -379,36 +525,59 @@ def my_handle():
     not yet got a unique ID assigned by the bus.  You may need 
     to delay calling until you are sure you are connected.
     '''
-    log.debug('my handle')
+    log.debug( 'my handle' )
     return instance().tube.get_unique_name()
 
-
 def is_initiator():
     '''Returns the handle of this user.'''
-    log.debug('is initiator')
+    log.debug( 'is initiator' )
     return instance().is_initiator
 
-
 def get_participants():
     '''Returns the list of active participants, in order of arrival.
     List is maintained by the activity creator; if that person leaves it may not stay in sync.'''
-    log.debug('get_participants')
+    log.debug( 'get_participants' )
     try:
         return instance().ordered_bus_names[:]
     except IndexError, err:
-        return []  # no participants yet, as we don't yet have a connection
+        return [] # no participants yet, as we don't yet have a connection
 
+def dbus_get_object(handle, path, warning=True):
+    '''Get a D-bus object from another participant
 
-def dbus_get_object(handle, path):
-    '''Get a D-bus object from another participant.
+    Note: this *must* be called *only* from the GTK mainloop, calling 
+    it from Pygame will cause crashes!  If you are *sure* you only ever 
+    want to call methods on this proxy from GTK, you can use 
+    warning=False to silence the warning log message.
+    '''
+    if warning:
+        log.warn( 'Use of dbus_get_object is only safe from the GTK mainloop, use dbus_get_object_proxy instead: %s %s', handle, path )
+    return instance().tube.get_object(handle, path)
+
+def get_object(handle, path):
+    '''Get a D-BUS proxy object from another participant for use in Pygame
 
     This is how you can communicate with other participants using
     arbitrary D-bus objects without having to manage the participants
-    yourself.
+    yourself.  You can use the returned proxy's methods from Pygame,
+    with your callbacks occuring in the Pygame thread, rather than 
+    in the DBUS/GTK event loop.
 
     Simply define a D-bus class with an interface and path that you
     choose; when you want a reference to the corresponding remote
     object on a participant, call this method.
+    
+    returns an olpcgames.dbusproxy.DBUSProxy( ) object wrapping 
+    the DBUSProxy object.
+    
+    The dbus_get_object_proxy name is deprecated
     '''
-    log.debug('dbus_get_object: %s %s', handle, path)
-    return instance().tube.get_object(handle, path)
+    log.debug( 'DBUS get_object( %r %r )', handle, path )
+    from olpcgames import dbusproxy
+    return dbusproxy.DBUSProxy( 
+        instance().tube.get_object( handle, path), 
+        tube=instance().tube, 
+        path=path 
+    )
+
+dbus_get_object_proxy = get_object