242 lines
7.5 KiB
Python
242 lines
7.5 KiB
Python
"""
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Inter-process comms abstractions
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"""
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from dataclasses import dataclass
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import typing
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from typing import Any, Tuple, Optional
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import msgpack
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import trio
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from async_generator import asynccontextmanager
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from .log import get_logger
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log = get_logger('ipc')
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class StreamQueue:
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"""Stream wrapped as a queue that delivers ``msgpack`` serialized objects.
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"""
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def __init__(self, stream: trio.SocketStream) -> None:
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self.stream = stream
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self._agen = self._iter_packets()
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self._laddr = self.stream.socket.getsockname()[:2]
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self._raddr = self.stream.socket.getpeername()[:2]
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self._send_lock = trio.StrictFIFOLock()
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async def _iter_packets(self) -> typing.AsyncGenerator[dict, None]:
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"""Yield packets from the underlying stream.
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"""
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unpacker = msgpack.Unpacker(raw=False, use_list=False)
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while True:
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try:
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data = await self.stream.receive_some(2**10)
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log.trace(f"received {data}") # type: ignore
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except trio.BrokenResourceError:
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log.error(f"Stream connection {self.raddr} broke")
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return
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if data == b'':
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log.debug(f"Stream connection {self.raddr} was closed")
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return
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unpacker.feed(data)
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for packet in unpacker:
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yield packet
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@property
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def laddr(self) -> Tuple[str, int]:
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return self._laddr
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@property
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def raddr(self) -> Tuple[str, int]:
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return self._raddr
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async def put(self, data: Any) -> int:
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async with self._send_lock:
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return await self.stream.send_all(
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msgpack.dumps(data, use_bin_type=True))
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async def get(self) -> Any:
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return await self._agen.asend(None)
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def __aiter__(self):
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return self._agen
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def connected(self) -> bool:
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return self.stream.socket.fileno() != -1
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class Channel:
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"""A channel to actors in other processes.
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Use this to talk to any micro-service daemon or other client(s) over a
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a transport managed by ``trio``.
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"""
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def __init__(
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self,
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destaddr: Optional[Tuple[str, int]] = None,
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on_reconnect: typing.Callable[..., typing.Awaitable] = None,
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auto_reconnect: bool = False,
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stream: trio.SocketStream = None, # expected to be active
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) -> None:
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self._recon_seq = on_reconnect
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self._autorecon = auto_reconnect
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self.squeue: Optional[StreamQueue] = StreamQueue(
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stream) if stream else None
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if self.squeue and destaddr:
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raise ValueError(
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f"A stream was provided with local addr {self.laddr}"
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)
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self._destaddr = self.squeue.raddr if self.squeue else destaddr
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# set after handshake - always uid of far end
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self.uid: Optional[Tuple[str, str]] = None
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# set if far end actor errors internally
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self._exc: Optional[Exception] = None
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self._agen = self._aiter_recv()
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def __repr__(self) -> str:
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if self.squeue:
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return repr(
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self.squeue.stream.socket._sock).replace(
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"socket.socket", "Channel")
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return object.__repr__(self)
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@property
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def laddr(self) -> Optional[Tuple[str, int]]:
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return self.squeue.laddr if self.squeue else None
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@property
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def raddr(self) -> Optional[Tuple[str, int]]:
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return self.squeue.raddr if self.squeue else None
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async def connect(
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self, destaddr: Tuple[str, int] = None, **kwargs
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) -> trio.SocketStream:
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if self.connected():
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raise RuntimeError("channel is already connected?")
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destaddr = destaddr or self._destaddr
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stream = await trio.open_tcp_stream(*destaddr, **kwargs)
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self.squeue = StreamQueue(stream)
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return stream
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async def send(self, item: Any) -> None:
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log.trace(f"send `{item}`") # type: ignore
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assert self.squeue
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await self.squeue.put(item)
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async def recv(self) -> Any:
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assert self.squeue
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try:
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return await self.squeue.get()
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except trio.BrokenResourceError:
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if self._autorecon:
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await self._reconnect()
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return await self.recv()
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async def aclose(self) -> None:
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log.debug(f"Closing {self}")
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assert self.squeue
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await self.squeue.stream.aclose()
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async def __aenter__(self):
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await self.connect()
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return self
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async def __aexit__(self, *args):
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await self.aclose(*args)
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def __aiter__(self):
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return self._agen
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async def _reconnect(self) -> None:
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"""Handle connection failures by polling until a reconnect can be
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established.
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"""
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down = False
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while True:
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try:
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with trio.move_on_after(3) as cancel_scope:
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await self.connect()
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cancelled = cancel_scope.cancelled_caught
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if cancelled:
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log.warning(
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"Reconnect timed out after 3 seconds, retrying...")
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continue
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else:
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log.warning("Stream connection re-established!")
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# run any reconnection sequence
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on_recon = self._recon_seq
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if on_recon:
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await on_recon(self)
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break
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except (OSError, ConnectionRefusedError):
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if not down:
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down = True
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log.warning(
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f"Connection to {self.raddr} went down, waiting"
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" for re-establishment")
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await trio.sleep(1)
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async def _aiter_recv(
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self
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) -> typing.AsyncGenerator[Any, None]:
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"""Async iterate items from underlying stream.
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"""
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assert self.squeue
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while True:
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try:
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async for item in self.squeue:
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yield item
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# sent = yield item
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# if sent is not None:
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# # optimization, passing None through all the
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# # time is pointless
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# await self.squeue.put(sent)
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except trio.BrokenResourceError:
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if not self._autorecon:
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raise
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await self.aclose()
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if self._autorecon: # attempt reconnect
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await self._reconnect()
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continue
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else:
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return
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def connected(self) -> bool:
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return self.squeue.connected() if self.squeue else False
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@dataclass(frozen=True)
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class Context:
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"""An IAC (inter-actor communication) context.
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Allows maintaining task or protocol specific state between communicating
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actors. A unique context is created on the receiving end for every request
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to a remote actor.
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"""
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chan: Channel
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cid: str
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# TODO: we should probably attach the actor-task
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# cancel scope here now that trio is exposing it
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# as a public object
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async def send_yield(self, data: Any) -> None:
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await self.chan.send({'yield': data, 'cid': self.cid})
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async def send_stop(self) -> None:
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await self.chan.send({'stop': True, 'cid': self.cid})
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@asynccontextmanager
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async def _connect_chan(
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host: str, port: int
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) -> typing.AsyncGenerator[Channel, None]:
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"""Create and connect a channel with disconnect on context manager
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teardown.
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"""
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chan = Channel((host, port))
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await chan.connect()
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yield chan
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await chan.aclose()
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