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# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
import dbus
import pickle
import logging
from dbus.gobject_service import ExportedGObject
from dbus.service import method, signal
try:
import json
json.dumps
except (ImportError, AttributeError):
import simplejson as json
from sugar.presence import presenceservice
import model
logger = logging.getLogger('flipsticks')
SERVICE = 'org.freedesktop.Telepathy.Tube.Connect'
IFACE = SERVICE
PATH = '/org/freedesktop/Telepathy/Tube/Connect'
class Slot:
def __init__(self, seqno=-1, owner=None):
self.seqno = seqno
self.owner = owner
class Messenger(ExportedGObject):
def __init__(self, tube, initiator, view):
ExportedGObject.__init__(self, tube, PATH)
self.initiator = initiator
self._tube = tube
self._entered = False
self._slots = []
self._view = view
self._view.connect('frame-changed', self._frame_changed_cb)
self._tube.watch_participants(self._participant_change_cb)
def _participant_change_cb(self, added, removed):
if not self._entered and added:
self.me = self._tube.get_unique_name()
for i in range(len(model.keys)):
self._slots.append(Slot())
if self.initiator:
self._tube.add_signal_receiver(self._ping_cb, '_ping', IFACE,
path=PATH, sender_keyword='sender')
for i in self._slots:
i.seqno = 0
i.owner = self.me
else:
self._pong_handle = self._tube.add_signal_receiver(
self._pong_cb, '_pong', IFACE, path=PATH,
sender_keyword='sender')
self._ping()
self._tube.add_signal_receiver(self._notify_cb, '_notify', IFACE,
path=PATH, sender_keyword='sender')
self._entered = True
# incomers' signal to retrieve initial snapshot
@signal(IFACE, signature='')
def _ping(self):
logger.debug('send ping')
pass
# object is ready to post snapshot to incomer
@signal(IFACE, signature='')
def _pong(self):
logger.debug('send pong')
pass
# slot was changed
@signal(IFACE, signature='iiss')
def _notify(self, slot, seqno, sender, raw):
pass
# the whole list of slots for incomers
@method(dbus_interface=IFACE, in_signature='', out_signature='a(iss)',
sender_keyword='sender')
def _snapshot(self, sender=None):
logger.debug('_snapshot requested from %s' % sender)
out = []
for i, slot in enumerate(self._slots):
out.append((slot.seqno, slot.owner,
json.dumps(model.keys[i].collect())))
return out
def _ping_cb(self, sender=None):
if sender == self.me:
return
logger.debug('_ping received from %s' % sender)
self._pong()
def _pong_cb(self, sender=None):
if sender == self.me:
return
logger.debug('_pong sent from %s' % sender)
# we've got source for _snapshot and don't need _pong anymore
self._tube.remove_signal_receiver(self._pong_handle)
self._pong_handle = None
remote = self._tube.get_object(sender, PATH)
rawlist = remote._snapshot()
logger.debug('snapshot received len=%d' % len(rawlist))
for i, (seqno, owner, raw) in enumerate(rawlist):
self._receive(i, seqno, owner, raw, sender)
# we are ready to receive _snapshot requests
self._tube.add_signal_receiver(self._ping_cb, '_ping', IFACE,
path=PATH, sender_keyword='sender')
def _notify_cb(self, slot, seqno, owner, raw, sender=None):
if sender == self.me:
return
logger.debug('_notify requested from %s' % sender)
self._receive(slot, seqno, owner, raw, sender)
def _receive(self, slot, seqno, owner, raw, sender):
cur = self._slots[slot]
new = Slot(seqno, owner)
logger.debug('object received slot=%s seqno=%d owner=%s from %s'
% (slot, new.seqno, new.owner, sender))
if cur.seqno > new.seqno:
logger.debug('trying to rewrite newer value by older one')
return
elif cur.seqno == new.seqno:
# arrived value was sent at the same time as current one
if cur.owner > new.owner:
logger.debug('current value is higher ranked then arrived')
return
if cur.owner == self.me:
# we sent current and arrived value rewrites it
logger.debug('resend current with higher seqno')
self._send(slot)
return
else:
logger.debug('just discard low rank')
return
else:
logger.debug('accept higher seqno')
self._view.props.keyframe = (slot, model.StoredFrame(json.loads(raw)))
self._slots[slot] = new
def _send(self, slot_num):
slot = self._slots[slot_num]
slot.seqno += 1
slot.owner = self.me
self._notify(slot_num, slot.seqno, slot.owner,
json.dumps(model.keys[slot_num].collect()))
logger.debug('_send slot=%s seqno=%d' % (slot_num, slot.seqno))
def _frame_changed_cb(self, sender, slot):
self._send(slot)
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