/usr/share/sugar/activities/Physics.activity/olpcgames/mesh.py is in sugar-physics-activity 7+dfsg-1.1.
This file is owned by root:root, with mode 0o644.
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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 )
import olpcgames
from olpcgames.util import get_traceback
try:
from sugar.presence.tubeconn import TubeConnection
except ImportError, err:
TubeConnection = object
try:
from dbus.gobject_service import ExportedGObject
except ImportError, err:
ExportedGObject = object
from dbus.service import method, signal
try:
import telepathy
except ImportError, err:
telepathy = None
try:
import sugar.presence.presenceservice
except Exception, err:
pass
import pygame.event as PEvent
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_SERVICE = None
### NEW PYGAME EVENTS ###
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!
pygametubes = []
text_chan, tubes_chan = (None, None)
conn = None
initiating = False
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
of when the Tube is ready.'''
global connect_callback
connect_callback = cb
def activity_shared(activity):
'''Called when the user clicks Share.'''
global initiating
initiating = True
_setup(activity)
log.debug('This is my activity: making a tube...')
channel = tubes_chan[telepathy.CHANNEL_TYPE_TUBES]
if hasattr( channel, 'OfferDBusTube' ):
id = channel.OfferDBusTube(
DBUS_SERVICE, {})
else:
id = channel.OfferTube(
telepathy.TUBE_TYPE_DBUS, DBUS_SERVICE, {})
global connect_callback
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.'''
# Find out who's already in the shared activity:
log.debug('Joined an existing shared 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(
reply_handler=_list_tubes_reply_cb,
error_handler=_list_tubes_error_cb)
global connect_callback
if connect_callback is not None:
connect_callback()
def _getConn( activity ):
log.debug( '_getConn' )
global 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):
'''Determines text and tube channels for the current Activity. If no tube
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"
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"
# Make sure we have a Tubes channel - PS doesn't yet provide one
if tubes_chan is None:
log.debug("Didn't find our Tubes channel, requesting one...")
tubes_chan = conn.request_channel(telepathy.CHANNEL_TYPE_TUBES,
telepathy.HANDLE_TYPE_ROOM, room, True)
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 )
else:
channel.AcceptTube(id)
tube_conn = TubeConnection(conn,
tubes_chan[telepathy.CHANNEL_TYPE_TUBES],
id, group_iface=text_chan[telepathy.CHANNEL_INTERFACE_GROUP])
global pygametubes, initiating
pygametubes.append(PygameTube(tube_conn, initiating, len(pygametubes)))
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 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' )
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)
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( ):
"""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...
"""
log.debug( """About to import sugar.presence.presenceservice""" )
try:
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]
class PygameTube(ExportedGObject):
'''The object whose instance is shared across D-bus
Call instance() to get the instance of this object for your activity service.
Its 'tube' property contains the underlying D-bus Connection.
'''
def __init__(self, tube, is_initiator, tube_id):
super(PygameTube, self).__init__(tube, DBUS_PATH)
log.info( 'PygameTube init' )
self.tube = tube
self.is_initiator = is_initiator
self.entered = False
self.ordered_bus_names = []
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 )
for handle, bus_name in added:
dbus_handle = self.tube.participants[handle]
self.ordered_bus_names.append(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)
PEvent.post(PEvent.Event(PARTICIPANT_REMOVE, handle=dbus_handle))
if self.is_initiator:
if not self.entered:
# Initiator will broadcast a new ordered_bus_names each time
# a participant joins.
self.ordered_bus_names = [self.tube.get_unique_name()]
self.NewParticipants(self.ordered_bus_names)
self.entered = True
@signal(dbus_interface=DBUS_IFACE, signature='as')
def NewParticipants(self, ordered_bus_names):
'''This is the NewParticipants signal, sent when the authoritative list of ordered_bus_names changes.'''
log.debug("sending NewParticipants: %s" % ordered_bus_names)
pass
@signal(dbus_interface=DBUS_IFACE, signature='s')
def Broadcast(self, content):
'''This is the Broadcast signal; it sends a message to all other activity participants.'''
pass
@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.'''
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.'''
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.'''
log.debug("new participant. new bus names %s, old %s" % (new_bus_names, self.ordered_bus_names))
if self.ordered_bus_names != new_bus_names:
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 )
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 )
instance().Broadcast(content)
def my_handle():
'''Returns the handle of this user
Note, you can get a DBusException from this if you have
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' )
return instance().tube.get_unique_name()
def is_initiator():
'''Returns the handle of this user.'''
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' )
try:
return instance().ordered_bus_names[:]
except IndexError, err:
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
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. 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( %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
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