def write(self, data):
"""
Arranges to have data sent.
@type data: str or bytearray
"""
data = bytearray(data)
if self.retransmission_mode == RTM_NONE:
self.tx_requests.appendleft(Packet(data, self.channel_id, 0))
elif self.retransmission_mode in (RTM_AUTO, RTM_AUTO_ORDERED):
self.buffer.appendleft(data)
elif self.retransmission_mode == RTM_MANUAL:
self.buffer.clear()
self.buffer.appendleft(data)
else:
raise LNX2Exception, 'Invalid retransmission mode'
def on_sendable(self):
"""
Called when something can be sent.
Returns a packet when it wants something to be sent,
or raises L{lnx2.NothingToSend} if nothing is to be sent
@return: L{lnx2.Packet}
"""
# tx_requests take precedence
# RTM_NONE write()s directly to tx_requests
if len(self.tx_requests) > 0:
return self.tx_requests.pop()
if self.retransmission_mode == RTM_MANUAL:
# Two cases are possible: either a new packet
# can be dispatched, or retransmission should be considered
if len(self.packs_in_transit) == 0:
# It seems that a new packet can be sent
if len(self.buffer) == 0:
# There's nothing to send
raise NothingToSend
# A packet can be sent
data = self.buffer.pop()
pk = Packet(data, self.channel_id, self.next_send_window_id)
self.next_send_window_id = (self.next_send_window_id + 1) % 64
self.packs_in_transit[pk.window_id] = time.time(), pk
return pk
else:
# Consider a retransmission
ctime = time.time()
time_sent, pack = self.packs_in_transit.itervalues().next()
if ctime - time_sent > self.retransmission_timeout:
# Yes, a retransmission is in works
if len(self.buffer) > 0:
# User ordered a change to packet in meantime
pack = Packet(self.buffer.pop(), \
self.channel_id, pack.window_id)
self.packs_in_transit[pack.window_id] = ctime, pack
return pack
raise NothingToSend # no retransmission needed
elif self.retransmission_mode in (RTM_AUTO, RTM_AUTO_ORDERED):
if len(self.buffer) > 0:
# We can consider sending a new packet
if len(self.packs_in_transit) < self.max_bundle_size:
# We seem to be allowed to sent a new packet
nwid = self.next_send_window_id
# Check if there's an unsent window ID that has not
# been confirmed
naxid = nwid - self.max_bundle_size
if naxid < 0: naxid += 64
if naxid not in self.packs_in_transit:
# there are no missing windows. Go on.
self.next_send_window_id = (self.next_send_window_id +
1) % 64
pk = Packet(self.buffer.pop(), self.channel_id, nwid)
self.packs_in_transit[nwid] = time.time(), pk
return pk
ctime = time.time()
# Check for retransmissions then
for time_sent, pack in self.packs_in_transit.itervalues():
if ctime - time_sent > self.retransmission_timeout:
# A retransmission needs to be made
self.packs_in_transit[pack.window_id] = ctime, pack
return pack
raise NothingToSend