137 lines
4.0 KiB
Python
137 lines
4.0 KiB
Python
"""
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Inter-process comms abstractions
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"""
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from typing import Coroutine
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import msgpack
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import trio
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from .log import get_logger
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log = get_logger('broker.core')
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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):
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self.stream = stream
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self.peer = stream.socket.getpeername()
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self._agen = self._iter_packets()
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async def _iter_packets(self):
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"""Yield packets from the underlying stream.
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"""
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unpacker = msgpack.Unpacker(raw=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"Data is {data}")
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except trio.BrokenStreamError:
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log.error(f"Stream connection {self.peer} broke")
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return
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if data == b'':
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log.debug("Stream connection 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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async def put(self, data):
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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):
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return await self._agen.asend(None)
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async def __aiter__(self):
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return self._agen
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class Client:
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"""The most basic client.
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Use this to talk to any micro-service daemon or other client(s) over a
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TCP socket managed by ``trio``.
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"""
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def __init__(
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self, sockaddr: tuple,
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on_reconnect: Coroutine,
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auto_reconnect: bool = True,
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):
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self.sockaddr = sockaddr
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self._recon_seq = on_reconnect
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self._autorecon = auto_reconnect
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self.squeue = None
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async def connect(self, sockaddr: tuple = None, **kwargs):
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sockaddr = sockaddr or self.sockaddr
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stream = await trio.open_tcp_stream(*sockaddr, **kwargs)
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self.squeue = StreamQueue(stream)
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return stream
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async def send(self, item):
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await self.squeue.put(item)
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async def recv(self):
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try:
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return await self.squeue.get()
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except trio.BrokenStreamError as err:
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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, *args):
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await self.squeue.stream.aclose()
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async def __aenter__(self):
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await self.connect(self.sockaddr)
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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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async def _reconnect(self):
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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.warn(
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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.warn("Stream connection re-established!")
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# run any reconnection sequence
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await self._recon_seq(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.warn(
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f"Connection to {self.sockaddr} 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(self):
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"""Async iterate items from underlying stream.
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"""
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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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except trio.BrokenStreamError as err:
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if not self._autorecon:
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raise
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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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