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

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import asyncio
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from libp2p.stream_muxer.abc import IMuxedConn, IMuxedStream
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from .constants import HeaderTags
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class MplexStream(IMuxedStream):
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"""
reference: https://github.com/libp2p/go-mplex/blob/master/stream.go
"""
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stream_id: int
initiator: bool
mplex_conn: IMuxedConn
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read_deadline: int
write_deadline: int
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local_closed: bool
remote_closed: bool
stream_lock: asyncio.Lock
_buf: bytearray
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def __init__(self, stream_id: int, initiator: bool, mplex_conn: IMuxedConn) -> None:
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"""
create new MuxedStream in muxer
:param stream_id: stream stream id
:param initiator: boolean if this is an initiator
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:param mplex_conn: muxed connection of this muxed_stream
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"""
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self.stream_id = stream_id
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self.initiator = initiator
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self.mplex_conn = mplex_conn
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self.read_deadline = None
self.write_deadline = None
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self.local_closed = False
self.remote_closed = False
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self.stream_lock = asyncio.Lock()
self._buf = bytearray()
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async def read(self, n: int = -1) -> bytes:
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"""
Read up to n bytes. Read possibly returns fewer than `n` bytes,
if there are not enough bytes in the Mplex buffer.
If `n == -1`, read until EOF.
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:param n: number of bytes to read
:return: bytes actually read
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"""
if n < 0 and n != -1:
raise ValueError("`n` can only be -1 if it is negative")
# If the buffer is empty at first, blocking wait for data.
if len(self._buf) == 0:
self._buf.extend(await self.mplex_conn.read_buffer(self.stream_id))
# Sanity check: `self._buf` should never be empty here.
if self._buf is None or len(self._buf) == 0:
raise Exception("`self._buf` should never be empty here")
# FIXME: If `n == -1`, we should blocking read until EOF, instead of returning when
# no message is available.
# If `n >= 0`, read up to `n` bytes.
# Else, read until no message is available.
while len(self._buf) < n or n == -1:
new_bytes = await self.mplex_conn.read_buffer_nonblocking(self.stream_id)
if new_bytes is None:
# Nothing to read in the `MplexConn` buffer
break
self._buf.extend(new_bytes)
payload: bytearray
if n == -1:
payload = self._buf
else:
payload = self._buf[:n]
self._buf = self._buf[len(payload) :]
return bytes(payload)
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async def write(self, data: bytes) -> int:
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"""
write to stream
:return: number of bytes written
"""
flag = (
HeaderTags.MessageInitiator
if self.initiator
else HeaderTags.MessageReceiver
)
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return await self.mplex_conn.send_message(flag, data, self.stream_id)
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async def close(self) -> bool:
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"""
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Closing a stream closes it for writing and closes the remote end for reading
but allows writing in the other direction.
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:return: true if successful
"""
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# TODO error handling with timeout
# TODO understand better how mutexes are used from go repo
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flag = HeaderTags.CloseInitiator if self.initiator else HeaderTags.CloseReceiver
await self.mplex_conn.send_message(flag, None, self.stream_id)
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remote_lock = False
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async with self.stream_lock:
if self.local_closed:
return True
self.local_closed = True
remote_lock = self.remote_closed
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if remote_lock:
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# FIXME: mplex_conn has no conn_lock!
async with self.mplex_conn.conn_lock: # type: ignore
# FIXME: Don't access to buffers directly
self.mplex_conn.buffers.pop(self.stream_id) # type: ignore
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return True
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async def reset(self) -> bool:
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"""
closes both ends of the stream
tells this remote side to hang up
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:return: true if successful
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"""
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# TODO understand better how mutexes are used here
# TODO understand the difference between close and reset
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async with self.stream_lock:
if self.remote_closed and self.local_closed:
return True
if not self.remote_closed:
flag = (
HeaderTags.ResetInitiator
if self.initiator
else HeaderTags.ResetInitiator
)
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await self.mplex_conn.send_message(flag, None, self.stream_id)
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self.local_closed = True
self.remote_closed = True
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# FIXME: mplex_conn has no conn_lock!
async with self.mplex_conn.conn_lock: # type: ignore
# FIXME: Don't access to buffers directly
self.mplex_conn.buffers.pop(self.stream_id, None) # type: ignore
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return True
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# TODO deadline not in use
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def set_deadline(self, ttl: int) -> bool:
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"""
set deadline for muxed stream
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:return: True if successful
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"""
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self.read_deadline = ttl
self.write_deadline = ttl
return True
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def set_read_deadline(self, ttl: int) -> bool:
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"""
set read deadline for muxed stream
:return: True if successful
"""
self.read_deadline = ttl
return True
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def set_write_deadline(self, ttl: int) -> bool:
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"""
set write deadline for muxed stream
:return: True if successful
"""
self.write_deadline = ttl
return True