py-libp2p/libp2p/stream_muxer/mplex/mplex_stream.py
2019-08-28 21:43:34 +08:00

176 lines
5.7 KiB
Python

import asyncio
from libp2p.stream_muxer.abc import IMuxedConn, IMuxedStream
from .constants import HeaderTags
from .datastructures import StreamID
class MplexStream(IMuxedStream):
"""
reference: https://github.com/libp2p/go-mplex/blob/master/stream.go
"""
name: str
stream_id: StreamID
mplex_conn: IMuxedConn
read_deadline: int
write_deadline: int
local_closed: bool
remote_closed: bool
stream_lock: asyncio.Lock
_buf: bytearray
def __init__(self, name: str, stream_id: StreamID, mplex_conn: IMuxedConn) -> None:
"""
create new MuxedStream in muxer
:param stream_id: stream id of this stream
:param mplex_conn: muxed connection of this muxed_stream
"""
self.name = name
self.stream_id = stream_id
self.mplex_conn = mplex_conn
self.read_deadline = None
self.write_deadline = None
self.local_closed = False
self.remote_closed = False
self.stream_lock = asyncio.Lock()
self._buf = bytearray()
@property
def is_initiator(self) -> bool:
return self.stream_id.is_initiator
async def read(self, n: int = -1) -> bytes:
"""
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.
:param n: number of bytes to read
:return: bytes actually read
"""
# TODO: Handle `StreamNotFound` raised in `self.mplex_conn.read_buffer`.
# TODO: Add exceptions and handle/raise them in this class.
if n < 0 and n != -1:
raise ValueError(
f"the number of bytes to read `n` must be positive or -1 to indicate read until EOF"
)
# 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))
# 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)
async def write(self, data: bytes) -> int:
"""
write to stream
:return: number of bytes written
"""
flag = (
HeaderTags.MessageInitiator
if self.is_initiator
else HeaderTags.MessageReceiver
)
return await self.mplex_conn.send_message(flag, data, self.stream_id)
async def close(self) -> bool:
"""
Closing a stream closes it for writing and closes the remote end for reading
but allows writing in the other direction.
:return: true if successful
"""
# TODO error handling with timeout
# TODO understand better how mutexes are used from go repo
flag = (
HeaderTags.CloseInitiator if self.is_initiator else HeaderTags.CloseReceiver
)
await self.mplex_conn.send_message(flag, None, self.stream_id)
remote_lock = False
async with self.stream_lock:
if self.local_closed:
return True
self.local_closed = True
remote_lock = self.remote_closed
if remote_lock:
# 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
return True
async def reset(self) -> bool:
"""
closes both ends of the stream
tells this remote side to hang up
:return: true if successful
"""
# TODO understand better how mutexes are used here
# TODO understand the difference between close and reset
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.is_initiator
else HeaderTags.ResetReceiver
)
await self.mplex_conn.send_message(flag, None, self.stream_id)
self.local_closed = True
self.remote_closed = True
# 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
return True
# TODO deadline not in use
def set_deadline(self, ttl: int) -> bool:
"""
set deadline for muxed stream
:return: True if successful
"""
self.read_deadline = ttl
self.write_deadline = ttl
return True
def set_read_deadline(self, ttl: int) -> bool:
"""
set read deadline for muxed stream
:return: True if successful
"""
self.read_deadline = ttl
return True
def set_write_deadline(self, ttl: int) -> bool:
"""
set write deadline for muxed stream
:return: True if successful
"""
self.write_deadline = ttl
return True