py-libp2p/libp2p/stream_muxer/mplex/mplex.py

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import asyncio
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from .utils import encode_uvarint, decode_uvarint_from_stream
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from .mplex_stream import MplexStream
from ..muxed_connection_interface import IMuxedConn
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class Mplex(IMuxedConn):
# pylint: disable=too-many-instance-attributes
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"""
reference: https://github.com/libp2p/go-mplex/blob/master/multiplex.go
"""
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def __init__(self, conn):
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"""
create a new muxed connection
:param conn: an instance of raw connection
:param initiator: boolean to prevent multiplex with self
"""
self.raw_conn = conn
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self.initiator = conn.initiator
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# Mapping from stream ID -> buffer of messages for that stream
self.buffers = {}
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self.stream_queue = asyncio.Queue()
self.data_buffer = bytearray()
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# The initiator of the raw connection need not read upon construction time.
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# It should read when the user decides that it wants to read from the constructed stream.
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if not self.initiator:
asyncio.ensure_future(self.handle_incoming(None))
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def close(self):
"""
close the stream muxer and underlying raw connection
"""
self.raw_conn.close()
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def is_closed(self):
"""
check connection is fully closed
:return: true if successful
"""
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async def read_buffer(self, stream_id):
"""
Read a message from stream_id's buffer, check raw connection for new messages
:param stream_id: stream id of stream to read from
:return: message read
"""
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# Empty buffer or nonexistent stream
# TODO: propagate up timeout exception and catch
if stream_id not in self.buffers or self.buffers[stream_id].empty():
await self.handle_incoming(stream_id)
if stream_id in self.buffers:
return await self._read_buffer_exists(stream_id)
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return None
async def _read_buffer_exists(self, stream_id):
"""
Reads from raw connection with the assumption that the message buffer for stream_id exsits
:param stream_id: stream id of stream to read from
:return: message read
"""
try:
data = await asyncio.wait_for(self.buffers[stream_id].get(), timeout=5)
return data
except asyncio.TimeoutError:
return None
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async def open_stream(self, protocol_id, peer_id, multi_addr):
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"""
creates a new muxed_stream
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:param protocol_id: protocol_id of stream
:param stream_id: stream_id of stream
:param peer_id: peer_id that stream connects to
:param multi_addr: multi_addr that stream connects to
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:return: a new stream
"""
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stream_id = self.raw_conn.next_stream_id()
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stream = MplexStream(stream_id, multi_addr, self)
self.buffers[stream_id] = asyncio.Queue()
return stream
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async def accept_stream(self):
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"""
accepts a muxed stream opened by the other end
:return: the accepted stream
"""
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# TODO update to pull out protocol_id from message
protocol_id = "/echo/1.0.0"
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stream_id = await self.stream_queue.get()
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stream = MplexStream(stream_id, False, self)
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return stream, stream_id, protocol_id
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async def send_message(self, flag, data, stream_id):
"""
sends a message over the connection
:param header: header to use
:param data: data to send in the message
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:param stream_id: stream the message is in
:return: True if success
"""
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# << by 3, then or with flag
header = (stream_id << 3) | flag
header = encode_uvarint(header)
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if data is None:
data_length = encode_uvarint(0)
_bytes = header + data_length
else:
data_length = encode_uvarint(len(data))
_bytes = header + data_length + data
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return await self.write_to_stream(_bytes)
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async def write_to_stream(self, _bytes):
"""
writes a byte array to a raw connection
:param _bytes: byte array to write
:return: length written
"""
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self.raw_conn.writer.write(_bytes)
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await self.raw_conn.writer.drain()
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return len(_bytes)
async def handle_incoming(self, my_stream_id):
"""
Read a message off of the raw connection and add it to the corresponding message buffer
"""
# TODO Deal with other types of messages using flag (currently _)
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continue_reading = True
i = 0
while continue_reading:
i += 1
stream_id, _, message = await self.read_message()
continue_reading = (stream_id is not None and
stream_id != my_stream_id and
my_stream_id is not None)
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if stream_id not in self.buffers:
self.buffers[stream_id] = asyncio.Queue()
await self.stream_queue.put(stream_id)
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await self.buffers[stream_id].put(message)
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async def read_chunk(self):
"""
Read a chunk of bytes off of the raw connection into data_buffer
"""
# unused now but possibly useful in the future
try:
chunk = await asyncio.wait_for(self.raw_conn.reader.read(-1), timeout=5)
self.data_buffer += chunk
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except asyncio.TimeoutError:
print('timeout!')
return
async def read_message(self):
"""
Read a single message off of the raw connection
:return: stream_id, flag, message contents
"""
# Timeout is set to a relatively small value to alleviate wait time to exit
# loop in handle_incoming
timeout = .1
try:
header = await decode_uvarint_from_stream(self.raw_conn.reader, timeout)
length = await decode_uvarint_from_stream(self.raw_conn.reader, timeout)
message = await asyncio.wait_for(self.raw_conn.reader.read(length), timeout=timeout)
except asyncio.TimeoutError:
return None, None, None
flag = header & 0x07
stream_id = header >> 3
return stream_id, flag, message