def _process_queue(self):
"""
Runs a thread for processing the packets in the packet queue.
"""
while True:
packet = self._packet_queue.get()
if not packet:
# Stop the network
self._stop_thread = True
break
# Artificially delay the network
if self.delay > 0:
time.sleep(self.delay)
# Simulate packet loss
packet_drop_var = random.random()
if packet_drop_var > (1 - self.packet_drop_rate):
Logger.get_instance().log("PACKET DROPPED")
if packet.payload_type == Constants.QUANTUM:
packet.payload.release()
continue
sender, receiver = packet.sender, packet.receiver
if packet.payload_type == Constants.QUANTUM:
if not self._route_quantum_info(sender, receiver,
[packet.payload]):
continue
try:
if packet.protocol == Constants.RELAY and not self.use_hop_by_hop:
full_route = packet.route
route = full_route[full_route.index(sender):]
else:
if packet.protocol == Constants.REC_EPR:
route = self.get_classical_route(sender, receiver)
else:
route = self.get_classical_route(sender, receiver)
if len(route) < 2:
raise Exception('No route exists')
elif len(route) == 2:
if packet.protocol != Constants.RELAY:
if packet.protocol == Constants.REC_EPR:
host_sender = self.get_host(sender)
q = host_sender \
.backend \
.create_EPR(host_sender.host_id,
receiver,
q_id=packet.payload['q_id'],
block=packet.payload['blocked'])
host_sender.add_epr(receiver, q)
self.ARP[receiver].rec_packet(packet)
else:
self.ARP[receiver].rec_packet(packet.payload)
else:
if packet.protocol == Constants.REC_EPR:
q_id = packet.payload['q_id']
blocked = packet.payload['blocked']
q_route = self.get_quantum_route(sender, receiver)
if self.use_ent_swap:
DaemonThread(self._entanglement_swap,
args=(sender, receiver, q_route, q_id,
packet.seq_num, blocked))
else:
DaemonThread(self._establish_epr,
args=(sender, receiver, q_id,
packet.seq_num, blocked))
else:
network_packet = self._encode(route, packet)
self.ARP[route[1]].rec_packet(network_packet)
except nx.NodeNotFound:
Logger.get_instance().error(
"route couldn't be calculated, node doesn't exist")
except ValueError:
Logger.get_instance().error(
"route couldn't be calculated, value error")
except Exception as e:
Logger.get_instance().error('Error in network: ' + str(e))
def _entanglement_swap(self, sender, receiver, route, q_id, o_seq_num,
blocked):
"""
Performs a chain of entanglement swaps with the hosts between sender and receiver to create a shared EPR pair
between sender and receiver.
Args:
sender (Host): Sender of the EPR pair
receiver (Host): Receiver of the EPR pair
route (list): Route between the sender and receiver
q_id (str): Qubit ID of the sent EPR pair
o_seq_num (int): The original sequence number
blocked (bool): If the pair being distributed is blocked or not
"""
host_sender = self.get_host(sender)
def establish_epr(net, s, r):
if not net.shares_epr(s, r):
self.get_host(s).send_epr(r, q_id, await_ack=True)
else:
old_id = self.get_host(s).change_epr_qubit_id(r, q_id)
net.get_host(r).change_epr_qubit_id(route[i], q_id, old_id)
# Create EPR pairs on the route, where all EPR qubits have the id q_id
threads = []
for i in range(len(route) - 1):
threads.append(
DaemonThread(establish_epr,
args=(self, route[i], route[i + 1])))
for t in threads:
t.join()
for i in range(len(route) - 2):
host = self.get_host(route[i + 1])
q = host.get_epr(route[0], q_id, wait=10)
if q is None:
print("Host is %s" % host.host_id)
print("Search host is %s" % route[0])
print("Search id is %s" % q_id)
print("EPR storage is")
print(host.EPR_store)
Logger.get_instance().error('Entanglement swap failed')
return
data = {
'q': q,
'eq_id': q_id,
'node': sender,
'o_seq_num': o_seq_num,
'type': Constants.EPR
}
if route[i + 2] == route[-1]:
data = {
'q': q,
'eq_id': q_id,
'node': sender,
'ack': True,
'o_seq_num': o_seq_num,
'type': Constants.EPR
}
host.send_teleport(route[i + 2],
None,
await_ack=True,
payload=data,
generate_epr_if_none=False)
# Change in the storage that the EPR qubit is shared with the receiver
q2 = host_sender.get_epr(route[1], q_id=q_id)
host_sender.add_epr(receiver, q2, q_id, blocked)
Logger.get_instance().log(
'Entanglement swap was successful for pair with id ' + q_id +
' between ' + sender + ' and ' + receiver)
