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267 lines
8.3 KiB
267 lines
8.3 KiB
"""Base classes to manage a Client's interaction with a running kernel"""
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# Copyright (c) Jupyter Development Team.
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# Distributed under the terms of the Modified BSD License.
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import asyncio
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import atexit
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import time
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import typing as t
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from queue import Empty
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from threading import Event
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from threading import Thread
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import zmq.asyncio
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from .channelsabc import HBChannelABC
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from .session import Session
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from jupyter_client import protocol_version_info
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# import ZMQError in top-level namespace, to avoid ugly attribute-error messages
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# during garbage collection of threads at exit
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# -----------------------------------------------------------------------------
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# Constants and exceptions
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# -----------------------------------------------------------------------------
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major_protocol_version = protocol_version_info[0]
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class InvalidPortNumber(Exception):
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pass
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class HBChannel(Thread):
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"""The heartbeat channel which monitors the kernel heartbeat.
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Note that the heartbeat channel is paused by default. As long as you start
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this channel, the kernel manager will ensure that it is paused and un-paused
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as appropriate.
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"""
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session = None
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socket = None
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address = None
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_exiting = False
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time_to_dead: float = 1.0
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_running = None
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_pause = None
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_beating = None
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def __init__(
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self,
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context: t.Optional[zmq.asyncio.Context] = None,
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session: t.Optional[Session] = None,
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address: t.Union[t.Tuple[str, int], str] = "",
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):
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"""Create the heartbeat monitor thread.
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Parameters
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----------
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context : :class:`zmq.asyncio.Context`
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The ZMQ context to use.
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session : :class:`session.Session`
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The session to use.
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address : zmq url
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Standard (ip, port) tuple that the kernel is listening on.
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"""
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super().__init__()
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self.daemon = True
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self.context = context
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self.session = session
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if isinstance(address, tuple):
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if address[1] == 0:
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message = "The port number for a channel cannot be 0."
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raise InvalidPortNumber(message)
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address_str = "tcp://%s:%i" % address
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else:
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address_str = address
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self.address = address_str
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# running is False until `.start()` is called
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self._running = False
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self._exit = Event()
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# don't start paused
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self._pause = False
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self.poller = zmq.Poller()
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@staticmethod
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@atexit.register
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def _notice_exit() -> None:
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# Class definitions can be torn down during interpreter shutdown.
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# We only need to set _exiting flag if this hasn't happened.
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if HBChannel is not None:
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HBChannel._exiting = True
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def _create_socket(self) -> None:
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if self.socket is not None:
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# close previous socket, before opening a new one
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self.poller.unregister(self.socket)
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self.socket.close()
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assert self.context is not None
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self.socket = self.context.socket(zmq.REQ)
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self.socket.linger = 1000
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assert self.address is not None
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self.socket.connect(self.address)
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self.poller.register(self.socket, zmq.POLLIN)
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def run(self) -> None:
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loop = asyncio.new_event_loop()
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asyncio.set_event_loop(loop)
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loop.run_until_complete(self._async_run())
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loop.close()
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async def _async_run(self) -> None:
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"""The thread's main activity. Call start() instead."""
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self._create_socket()
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self._running = True
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self._beating = True
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assert self.socket is not None
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while self._running:
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if self._pause:
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# just sleep, and skip the rest of the loop
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self._exit.wait(self.time_to_dead)
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continue
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since_last_heartbeat = 0.0
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# no need to catch EFSM here, because the previous event was
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# either a recv or connect, which cannot be followed by EFSM
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await self.socket.send(b"ping")
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request_time = time.time()
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# Wait until timeout
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self._exit.wait(self.time_to_dead)
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# poll(0) means return immediately (see http://api.zeromq.org/2-1:zmq-poll)
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self._beating = bool(self.poller.poll(0))
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if self._beating:
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# the poll above guarantees we have something to recv
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await self.socket.recv()
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continue
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elif self._running:
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# nothing was received within the time limit, signal heart failure
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since_last_heartbeat = time.time() - request_time
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self.call_handlers(since_last_heartbeat)
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# and close/reopen the socket, because the REQ/REP cycle has been broken
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self._create_socket()
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continue
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def pause(self) -> None:
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"""Pause the heartbeat."""
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self._pause = True
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def unpause(self) -> None:
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"""Unpause the heartbeat."""
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self._pause = False
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def is_beating(self) -> bool:
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"""Is the heartbeat running and responsive (and not paused)."""
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if self.is_alive() and not self._pause and self._beating:
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return True
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else:
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return False
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def stop(self) -> None:
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"""Stop the channel's event loop and join its thread."""
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self._running = False
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self._exit.set()
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self.join()
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self.close()
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def close(self) -> None:
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if self.socket is not None:
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try:
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self.socket.close(linger=0)
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except Exception:
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pass
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self.socket = None
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def call_handlers(self, since_last_heartbeat: float) -> None:
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"""This method is called in the ioloop thread when a message arrives.
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Subclasses should override this method to handle incoming messages.
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It is important to remember that this method is called in the thread
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so that some logic must be done to ensure that the application level
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handlers are called in the application thread.
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"""
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pass
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HBChannelABC.register(HBChannel)
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class ZMQSocketChannel(object):
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"""A ZMQ socket in an async API"""
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def __init__(self, socket: zmq.asyncio.Socket, session: Session, loop: t.Any = None) -> None:
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"""Create a channel.
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Parameters
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----------
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socket : :class:`zmq.asyncio.Socket`
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The ZMQ socket to use.
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session : :class:`session.Session`
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The session to use.
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loop
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Unused here, for other implementations
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"""
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super().__init__()
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self.socket: t.Optional[zmq.asyncio.Socket] = socket
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self.session = session
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async def _recv(self, **kwargs: t.Any) -> t.Dict[str, t.Any]:
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assert self.socket is not None
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msg = await self.socket.recv_multipart(**kwargs)
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ident, smsg = self.session.feed_identities(msg)
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return self.session.deserialize(smsg)
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async def get_msg(self, timeout: t.Optional[float] = None) -> t.Dict[str, t.Any]:
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"""Gets a message if there is one that is ready."""
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assert self.socket is not None
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if timeout is not None:
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timeout *= 1000 # seconds to ms
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ready = await self.socket.poll(timeout)
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if ready:
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res = await self._recv()
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return res
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else:
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raise Empty
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async def get_msgs(self) -> t.List[t.Dict[str, t.Any]]:
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"""Get all messages that are currently ready."""
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msgs = []
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while True:
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try:
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msgs.append(await self.get_msg())
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except Empty:
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break
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return msgs
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async def msg_ready(self) -> bool:
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"""Is there a message that has been received?"""
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assert self.socket is not None
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return bool(await self.socket.poll(timeout=0))
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def close(self) -> None:
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if self.socket is not None:
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try:
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self.socket.close(linger=0)
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except Exception:
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pass
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self.socket = None
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stop = close
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def is_alive(self) -> bool:
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return self.socket is not None
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def send(self, msg: t.Dict[str, t.Any]) -> None:
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"""Pass a message to the ZMQ socket to send"""
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assert self.socket is not None
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self.session.send(self.socket, msg)
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def start(self) -> None:
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pass
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