def read(receiver):
received = []
max_index = -1
stream_id = get_stream_id(receiver)
total_len = get_stream_length(stream_id, receiver)
while len(received) != total_len:
try:
raw_payload, addr = receiver.recvfrom(1024)
packet = get_packet(raw_payload)
index = packet["index"]
if packet["stream_id"] == stream_id and packet[
"type"] == "DATA" and is_valid(
raw_payload) and random.random() > 0.3:
receiver.sendto(
make_payload(stream_id, "CONTROL", "ACK", index), addr)
if index > max_index:
max_index = index
if not is_index_in_chunks(received, index):
received.append((packet["data"], index))
else:
receiver.sendto(
make_payload(stream_id, "CONTROL", "NACK", index), addr)
except:
for i in range(max_index + 1):
if not is_index_in_chunks(received, i):
receiver.sendto(
make_payload(stream_id, "CONTROL", "NACK", i), addr)
return join_chunks(received)
def write(val, sender):
stream_id = str(uuid.uuid4())
receiver = sender.connection
msgs = split2chunks(val)
data2send = create_packets(msgs, stream_id)
window = 1
pointer = 0
waiting = set()
ssthresh = 6
init_write(stream_id, sender, receiver)
init_stream_len(stream_id, len(data2send), sender, receiver)
while pointer < len(data2send) or len(waiting) != 0:
while len(waiting) < window and pointer < len(data2send):
if pointer != 3 and pointer != 5 and pointer != 15:
sender.sendto(data2send[pointer], receiver)
waiting.add(pointer)
pointer += 1
with suppress(BlockingIOError):
while True:
payload, addr = sender.recvfrom(1024, socket.MSG_DONTWAIT)
packet = get_packet(payload)
if packet["type"] == "CONTROL" and packet["data"] == "NACK":
index = packet["index"]
sender.sendto(data2send[index], receiver)
window *= 2 / 3
elif packet["type"] == "CONTROL" and packet["data"] == "ACK":
index = packet["index"]
if index in waiting:
waiting.remove(index)
window = window + 1 if window < ssthresh else window + 0.5
def get_stream_length(stream_id, receiver):
while True:
with suppress(BlockingIOError):
payload, addrs = receiver.recvfrom(1024)
packet = get_packet(payload)
if is_valid(payload) and packet["type"] == "LENGTH":
receiver.sendto(make_payload(stream_id, "LENGTH", "ACK", 0),
addrs)
return int(packet["data"])
def init_write(stream_id, sender, receiver):
sender.sendto(make_payload(stream_id, "INIT", stream_id, 0), receiver)
while True:
try:
resp, addr = sender.recvfrom(1024)
packet = get_packet(resp)
if packet["type"] == "INIT" and packet["data"] == "ACK":
break
except:
sender.sendto(make_payload(stream_id, "INIT", stream_id, 0),
receiver)
continue
def get_stream_id(receiver):
while True:
with suppress(BlockingIOError):
payload, addrs = receiver.recvfrom(1024)
packet = get_packet(payload)
if is_valid(payload) and packet["type"] == "INIT":
stream_id = packet["data"]
receiver.sendto(make_payload(stream_id, "INIT", "ACK", 0),
addrs)
return stream_id
def init_stream_len(stream_id, length, sender, receiver):
sender.sendto(make_payload(stream_id, "LENGTH", str(length), 0), receiver)
while True:
try:
resp, addr = sender.recvfrom(1024)
packet = get_packet(resp)
if packet["type"] == "LENGTH" and packet["data"] == "ACK":
break
except:
sender.sendto(
make_payload(stream_id, "LENGTH", str(len(data2send)), 0),
receiver)
continue