content: from __future__ import annotations
  
  import contextlib
  import logging
  import random
  import socket
  import struct
  import threading
  import time
  import uuid
  from collections.abc import Iterable, Iterator, Mapping
  from types import TracebackType
  from typing import Any, Literal, overload
  
  from ..exceptions import (
      ConcurrencyError,
      ConnectionClosed,
      ConnectionClosedOK,
      ProtocolError,
  )
  from ..frames import DATA_OPCODES, CloseCode, Frame, Opcode
  from ..http11 import Request, Response
  from ..protocol import CLOSED, OPEN, Event, Protocol, State
  from ..typing import BytesLike, Data, DataLike, LoggerLike, Subprotocol
  from .messages import Assembler
  from .utils import Deadline
  
  
  __all__ = ["Connection"]
  
  
  class Connection:
      """
      :mod:`threading` implementation of a WebSocket connection.
  
      :class:`Connection` provides APIs shared between WebSocket servers and
      clients.
  
      You shouldn't use it directly. Instead, use
      :class:`~websockets.sync.client.ClientConnection` or
      :class:`~websockets.sync.server.ServerConnection`.
  
      """
  
      recv_bufsize = 65536
  
      def __init__(
          self,
          socket: socket.socket,
          protocol: Protocol,
          *,
          ping_interval: float | None = 20,
          ping_timeout: float | None = 20,
          close_timeout: float | None = 10,
          max_queue: int | None | tuple[int | None, int | None] = 16,
      ) -> None:
          self.socket = socket
          self.protocol = protocol
          self.ping_interval = ping_interval
          self.ping_timeout = ping_timeout
          self.close_timeout = close_timeout
          if isinstance(max_queue, int) or max_queue is None:
              max_queue_high, max_queue_low = max_queue, None
          else:
              max_queue_high, max_queue_low = max_queue
  
          # Inject reference to this instance in the protocol's logger.
          self.protocol.logger = logging.LoggerAdapter(
              self.protocol.logger,
              {"websocket": self},
          )
  
          # Copy attributes from the protocol for convenience.
          self.id: uuid.UUID = self.protocol.id
          """Unique identifier of the connection. Useful in logs."""
          self.logger: LoggerLike = self.protocol.logger
          """Logger for this connection."""
          self.debug = self.protocol.debug
  
          # HTTP handshake request and response.
          self.request: Request | None = None
          """Opening handshake request."""
          self.response: Response | None = None
          """Opening handshake response."""
  
          # Mutex serializing interactions with the protocol.
          self.protocol_mutex = threading.Lock()
  
          # Lock stopping reads when the assembler buffer is full.
          self.recv_flow_control = threading.Lock()
  
          # Assembler turning frames into messages and serializing reads.
          self.recv_messages = Assembler(
              max_queue_high,
              max_queue_low,
              pause=self.recv_flow_control.acquire,
              resume=self.recv_flow_control.release,
          )
  
          # Deadline for the closing handshake.
          self.close_deadline: Deadline | None = None
  
          # Whether we are busy sending a fragmented message.
          self.send_in_progress = False
  
          # Mapping of ping IDs to pong waiters, in chronological order.
          self.pending_pings: dict[bytes, tuple[threading.Event, float, bool]] = {}
  
          self.latency: float = 0.0
          """
          Latency of the connection, in seconds.
  
          Latency is defined as the round-trip time of the connection. It is
          measured by sending a Ping frame and waiting for a matching Pong frame.
          Before the first measurement, :attr:`latency` is ``0.0``.
  
          By default, websockets enables a :ref:`keepalive <keepalive>` mechanism
          that sends Ping frames automatically at regular intervals. You can also
          send Ping frames and measure latency with :meth:`ping`.
          """
  
          # Thread that sends keepalive pings. None when ping_interval is None.
          self.keepalive_thread: threading.Thread | None = None
  
          # Exception raised while reading from the connection, to be chained to
          # ConnectionClosed in order to show why the TCP connection dropped.
          self.recv_exc: BaseException | None = None
  
          # Receiving events from the socket. This thread is marked as daemon to
          # allow creating a connection in a non-daemon thread and using it in a
          # daemon thread. This mustn't prevent the interpreter from exiting.
          self.recv_events_thread = threading.Thread(
              target=self.recv_events,
              daemon=True,
          )
  
          # Start recv_events only after all attributes are initialized.
          self.recv_events_thread.start()
  
      # Public attributes
  
      @property
      def local_address(self) -> Any:
          """
          Local address of the connection.
  
          For IPv4 connections, this is a ``(host, port)`` tuple.
  
          The format of the address depends on the address family.
          See :meth:`~socket.socket.getsockname`.
  
          """
          return self.socket.getsockname()
  
      @property
      def remote_address(self) -> Any:
          """
          Remote address of the connection.
  
          For IPv4 connections, this is a ``(host, port)`` tuple.
  
          The format of the address depends on the address family.
          See :meth:`~socket.socket.getpeername`.
  
          """
          return self.socket.getpeername()
  
      @property
      def state(self) -> State:
          """
          State of the WebSocket connection, defined in :rfc:`6455`.
  
          This attribute is provided for completeness. Typical applications
          shouldn't check its value. Instead, they should call :meth:`~recv` or
          :meth:`send` and handle :exc:`~websockets.exceptions.ConnectionClosed`
          exceptions.
  
          """
          return self.protocol.state
  
      @property
      def subprotocol(self) -> Subprotocol | None:
          """
          Subprotocol negotiated during the opening handshake.
  
          :obj:`None` if no subprotocol was negotiated.
  
          """
          return self.protocol.subprotocol
  
      @property
      def close_code(self) -> int | None:
          """
          State of the WebSocket connection, defined in :rfc:`6455`.
  
          This attribute is provided for completeness. Typical applications
          shouldn't check its value. Instead, they should inspect attributes
          of :exc:`~websockets.exceptions.ConnectionClosed` exceptions.
  
          """
          return self.protocol.close_code
  
      @property
      def close_reason(self) -> str | None:
          """
          State of the WebSocket connection, defined in :rfc:`6455`.
  
          This attribute is provided for completeness. Typical applications
          shouldn't check its value. Instead, they should inspect attributes
          of :exc:`~websockets.exceptions.ConnectionClosed` exceptions.
  
          """
          return self.protocol.close_reason
  
      # Public methods
  
      def __enter__(self) -> Connection:
          return self
  
      def __exit__(
          self,
          exc_type: type[BaseException] | None,
          exc_value: BaseException | None,
          traceback: TracebackType | None,
      ) -> None:
          if exc_type is None:
              self.close()
          else:
              self.close(CloseCode.INTERNAL_ERROR)
  
      def __iter__(self) -> Iterator[Data]:
          """
          Iterate on incoming messages.
  
          The iterator calls :meth:`recv` and yields messages in an infinite loop.
  
          It exits when the connection is closed normally. It raises a
          :exc:`~websockets.exceptions.ConnectionClosedError` exception after a
          protocol error or a network failure.
  
          """
          try:
              while True:
                  yield self.recv()
          except ConnectionClosedOK:
              return
  
      # This overload structure is required to avoid the error:
      # "parameter without a default follows parameter with a default"
  
      @overload
      def recv(self, timeout: float | None, decode: Literal[True]) -> str: ...
  
      @overload
      def recv(self, timeout: float | None, decode: Literal[False]) -> bytes: ...
  
      @overload
      def recv(self, timeout: float | None = None, *, decode: Literal[True]) -> str: ...
  
      @overload
      def recv(
          self, timeout: float | None = None, *, decode: Literal[False]
      ) -> bytes: ...
  
      @overload
      def recv(
          self, timeout: float | None = None, decode: bool | None = None
      ) -> Data: ...
  
      def recv(self, timeout: float | None = None, decode: bool | None = None) -> Data:
          """
          Receive the next message.
  
          When the connection is closed, :meth:`recv` raises
          :exc:`~websockets.exceptions.ConnectionClosed`. Specifically, it raises
          :exc:`~websockets.exceptions.ConnectionClosedOK` after a normal closure
          and :exc:`~websockets.exceptions.ConnectionClosedError` after a protocol
          error or a network failure. This is how you detect the end of the
          message stream.
  
          If ``timeout`` is :obj:`None`, block until a message is received. If
          ``timeout`` is set, wait up to ``timeout`` seconds for a message to be
          received and return it, else raise :exc:`TimeoutError`. If ``timeout``
          is ``0`` or negative, check if a message has been received already and
          return it, else raise :exc:`TimeoutError`.
  
          When the message is fragmented, :meth:`recv` waits until all fragments
          are received, reassembles them, and returns the whole message.
  
          Args:
              timeout: Timeout for receiving a message in seconds.
              decode: Set this flag to override the default behavior of returning
                  :class:`str` or :class:`bytes`. See below for details.
  
          Returns:
              A string (:class:`str`) for a Text_ frame or a bytestring
              (:class:`bytes`) for a Binary_ frame.
  
              .. _Text: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6
              .. _Binary: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6
  
              You may override this behavior with the ``decode`` argument:
  
              * Set ``decode=False`` to disable UTF-8 decoding of Text_ frames and
                return a bytestring (:class:`bytes`). This improves performance
                when decoding isn't needed, for example if the message contains
                JSON and you're using a JSON library that expects a bytestring.
              * Set ``decode=True`` to force UTF-8 decoding of Binary_ frames and
                return strings (:class:`str`). This may be useful for servers that
                send binary frames instead of text frames.
  
          Raises:
              ConnectionClosed: When the connection is closed.
              ConcurrencyError: If two threads call :meth:`recv` or
                  :meth:`recv_streaming` concurrently.
  
          """
          try:
              return self.recv_messages.get(timeout, decode)
          except EOFError:
              pass
              # fallthrough
          except ConcurrencyError:
              raise ConcurrencyError(
                  "cannot call recv while another thread "
                  "is already running recv or recv_streaming"
              ) from None
          except UnicodeDecodeError as exc:
              with self.send_context():
                  self.protocol.fail(
                      CloseCode.INVALID_DATA,
                      f"{exc.reason} at position {exc.start}",
                  )
              # fallthrough
  
          # Wait for the protocol state to be CLOSED before accessing close_exc.
          self.recv_events_thread.join()
          raise self.protocol.close_exc from self.recv_exc
  
      @overload
      def recv_streaming(self, decode: Literal[True]) -> Iterator[str]: ...
  
      @overload
      def recv_streaming(self, decode: Literal[False]) -> Iterator[bytes]: ...
  
      @overload
      def recv_streaming(self, decode: bool | None = None) -> Iterator[Data]: ...
  
      def recv_streaming(self, decode: bool | None = None) -> Iterator[Data]:
          """
          Receive the next message frame by frame.
  
          This method is designed for receiving fragmented messages. It returns an
          iterator that yields each fragment as it is received. This iterator must
          be fully consumed. Else, future calls to :meth:`recv` or
          :meth:`recv_streaming` will raise
          :exc:`~websockets.exceptions.ConcurrencyError`, making the connection
          unusable.
  
          :meth:`recv_streaming` raises the same exceptions as :meth:`recv`.
  
          Args:
              decode: Set this flag to override the default behavior of returning
                  :class:`str` or :class:`bytes`. See below for details.
  
          Returns:
              An iterator of strings (:class:`str`) for a Text_ frame or
              bytestrings (:class:`bytes`) for a Binary_ frame.
  
              .. _Text: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6
              .. _Binary: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6
  
              You may override this behavior with the ``decode`` argument:
  
              * Set ``decode=False`` to disable UTF-8 decoding of Text_ frames and
                yield bytestrings (:class:`bytes`). This improves performance
                when decoding isn't needed.
              * Set ``decode=True`` to force UTF-8 decoding of Binary_ frames and
                yield strings (:class:`str`). This may be useful for servers that
                send binary frames instead of text frames.
  
          Raises:
              ConnectionClosed: When the connection is closed.
              ConcurrencyError: If two threads call :meth:`recv` or
                  :meth:`recv_streaming` concurrently.
  
          """
          try:
              yield from self.recv_messages.get_iter(decode)
              return
          except EOFError:
              pass
              # fallthrough
          except ConcurrencyError:
              raise ConcurrencyError(
                  "cannot call recv_streaming while another thread "
                  "is already running recv or recv_streaming"
              ) from None
          except UnicodeDecodeError as exc:
              with self.send_context():
                  self.protocol.fail(
                      CloseCode.INVALID_DATA,
                      f"{exc.reason} at position {exc.start}",
                  )
              # fallthrough
  
          # Wait for the protocol state to be CLOSED before accessing close_exc.
          self.recv_events_thread.join()
          raise self.protocol.close_exc from self.recv_exc
  
      def send(
          self,
          message: DataLike | Iterable[DataLike],
          text: bool | None = None,
      ) -> None:
          """
          Send a message.
  
          A string (:class:`str`) is sent as a Text_ frame. A bytestring or
          bytes-like object (:class:`bytes`, :class:`bytearray`, or
          :class:`memoryview`) is sent as a Binary_ frame.
  
          .. _Text: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6
          .. _Binary: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6
  
          You may override this behavior with the ``text`` argument:
  
          * Set ``text=True`` to send an UTF-8 bytestring or bytes-like object
            (:class:`bytes`, :class:`bytearray`, or :class:`memoryview`) in a
            Text_ frame. This improves performance when the message is already
            UTF-8 encoded, for example if the message contains JSON and you're
            using a JSON library that produces a bytestring.
          * Set ``text=False`` to send a string (:class:`str`) in a Binary_
            frame. This may be useful for servers that expect binary frames
            instead of text frames.
  
          :meth:`send` also accepts an iterable of strings, bytestrings, or
          bytes-like objects to enable fragmentation_. Each item is treated as a
          message fragment and sent in its own frame. All items must be of the
          same type, or else :meth:`send` will raise a :exc:`TypeError` and the
          connection will be closed.
  
          .. _fragmentation: https://datatracker.ietf.org/doc/html/rfc6455#section-5.4
  
          :meth:`send` rejects dict-like objects because this is often an error.
          (If you really want to send the keys of a dict-like object as fragments,
          call its :meth:`~dict.keys` method and pass the result to :meth:`send`.)
  
          When the connection is closed, :meth:`send` raises
          :exc:`~websockets.exceptions.ConnectionClosed`. Specifically, it
          raises :exc:`~websockets.exceptions.ConnectionClosedOK` after a normal
          connection closure and
          :exc:`~websockets.exceptions.ConnectionClosedError` after a protocol
          error or a network failure.
  
          Args:
              message: Message to send.
  
          Raises:
              ConnectionClosed: When the connection is closed.
              ConcurrencyError: If the connection is sending a fragmented message.
              TypeError: If ``message`` doesn't have a supported type.
  
          """
          # Unfragmented message -- this case must be handled first because
          # strings and bytes-like objects are iterable.
  
          if isinstance(message, str):
              with self.send_context():
                  if self.send_in_progress:
                      raise ConcurrencyError(
                          "cannot call send while another thread is already running send"
                      )
                  if text is False:
                      self.protocol.send_binary(message.encode())
                  else:
                      self.protocol.send_text(message.encode())
  
          elif isinstance(message, BytesLike):
              with self.send_context():
                  if self.send_in_progress:
                      raise ConcurrencyError(
                          "cannot call send while another thread is already running send"
                      )
                  if text is True:
                      self.protocol.send_text(message)
                  else:
                      self.protocol.send_binary(message)
  
          # Catch a common mistake -- passing a dict to send().
  
          elif isinstance(message, Mapping):
              raise TypeError("data is a dict-like object")
  
          # Fragmented message -- regular iterator.
  
          elif isinstance(message, Iterable):
              chunks = iter(message)
              try:
                  chunk = next(chunks)
              except StopIteration:
                  return
  
              try:
                  # First fragment.
                  if isinstance(chunk, str):
                      with self.send_context():
                          if self.send_in_progress:
                              raise ConcurrencyError(
                                  "cannot call send while another thread "
                                  "is already running send"
                              )
                          self.send_in_progress = True
                          if text is False:
                              self.protocol.send_binary(chunk.encode(), fin=False)
                          else:
                              self.protocol.send_text(chunk.encode(), fin=False)
                      encode = True
                  elif isinstance(chunk, BytesLike):
                      with self.send_context():
                          if self.send_in_progress:
                              raise ConcurrencyError(
                                  "cannot call send while another thread "
                                  "is already running send"
                              )
                          self.send_in_progress = True
                          if text is True:
                              self.protocol.send_text(chunk, fin=False)
                          else:
                              self.protocol.send_binary(chunk, fin=False)
                      encode = False
                  else:
                      raise TypeError("iterable must contain bytes or str")
  
                  # Other fragments
                  for chunk in chunks:
                      if isinstance(chunk, str) and encode:
                          with self.send_context():
                              assert self.send_in_progress
                              self.protocol.send_continuation(chunk.encode(), fin=False)
                      elif isinstance(chunk, BytesLike) and not encode:
                          with self.send_context():
                              assert self.send_in_progress
                              self.protocol.send_continuation(chunk, fin=False)
                      else:
                          raise TypeError("iterable must contain uniform types")
  
                  # Final fragment.
                  with self.send_context():
                      self.protocol.send_continuation(b"", fin=True)
                      self.send_in_progress = False
  
              except ConcurrencyError:
                  # We didn't start sending a fragmented message.
                  # The connection is still usable.
                  raise
  
              except Exception:
                  # We're half-way through a fragmented message and we can't
                  # complete it. This makes the connection unusable.
                  with self.send_context():
                      self.protocol.fail(
                          CloseCode.INTERNAL_ERROR,
                          "error in fragmented message",
                      )
                  raise
  
          else:
              raise TypeError("data must be str, bytes, or iterable")
  
      def close(
          self,
          code: CloseCode | int = CloseCode.NORMAL_CLOSURE,
          reason: str = "",
      ) -> None:
          """
          Perform the closing handshake.
  
          :meth:`close` waits for the other end to complete the handshake and
          for the TCP connection to terminate.
  
          :meth:`close` is idempotent: it doesn't do anything once the
          connection is closed.
  
          Args:
              code: WebSocket close code.
              reason: WebSocket close reason.
  
          """
          try:
              # The context manager takes care of waiting for the TCP connection
              # to terminate after calling a method that sends a close frame.
              with self.send_context():
                  if self.send_in_progress:
                      self.protocol.fail(
                          CloseCode.INTERNAL_ERROR,
                          "close during fragmented message",
                      )
                  else:
                      self.protocol.send_close(code, reason)
          except ConnectionClosed:
              # Ignore ConnectionClosed exceptions raised from send_context().
              # They mean that the connection is closed, which was the goal.
              pass
  
      def ping(
          self,
          data: DataLike | None = None,
          ack_on_close: bool = False,
      ) -> threading.Event:
          """
          Send a Ping_.
  
          .. _Ping: https://datatracker.ietf.org/doc/html/rfc6455#section-5.5.2
  
          A ping may serve as a keepalive or as a check that the remote endpoint
          received all messages up to this point
  
          Args:
              data: Payload of the ping. A :class:`str` will be encoded to UTF-8.
                  If ``data`` is :obj:`None`, the payload is four random bytes.
              ack_on_close: when this option is :obj:`True`, the event will also
                  be set when the connection is closed. While this avoids getting
                  stuck waiting for a pong that will never arrive, it requires
                  checking that the state of the connection is still ``OPEN`` to
                  confirm that a pong was received, rather than the connection
                  being closed.
  
          Returns:
              An event that will be set when the corresponding pong is received.
              You can ignore it if you don't intend to wait.
  
              ::
  
                  pong_received = ws.ping()
                  # only if you want to wait for the corresponding pong
                  pong_received.wait()
  
          Raises:
              ConnectionClosed: When the connection is closed.
              ConcurrencyError: If another ping was sent with the same data and
                  the corresponding pong wasn't received yet.
  
          """
          if isinstance(data, BytesLike):
              data = bytes(data)
          elif isinstance(data, str):
              data = data.encode()
          elif data is not None:
              raise TypeError("data must be str or bytes-like")
  
          with self.send_context():
              # Protect against duplicates if a payload is explicitly set.
              if data in self.pending_pings:
                  raise ConcurrencyError("already waiting for a pong with the same data")
  
              # Generate a unique random payload otherwise.
              while data is None or data in self.pending_pings:
                  data = struct.pack("!I", random.getrandbits(32))
  
              pong_received = threading.Event()
              ping_timestamp = time.monotonic()
              self.pending_pings[data] = (pong_received, ping_timestamp, ack_on_close)
              self.protocol.send_ping(data)
              return pong_received
  
      def pong(self, data: DataLike = b"") -> None:
          """
          Send a Pong_.
  
          .. _Pong: https://datatracker.ietf.org/doc/html/rfc6455#section-5.5.3
  
          An unsolicited pong may serve as a unidirectional heartbeat.
  
          Args:
              data: Payload of the pong. A :class:`str` will be encoded to UTF-8.
  
          Raises:
              ConnectionClosed: When the connection is closed.
  
          """
          if isinstance(data, BytesLike):
              data = bytes(data)
          elif isinstance(data, str):
              data = data.encode()
          else:
              raise TypeError("data must be str or bytes-like")
  
          with self.send_context():
              self.protocol.send_pong(data)
  
      # Private methods
  
      def process_event(self, event: Event) -> None:
          """
          Process one incoming event.
  
          This method is overridden in subclasses to handle the handshake.
  
          """
          assert isinstance(event, Frame)
          if event.opcode in DATA_OPCODES:
              self.recv_messages.put(event)
  
          if event.opcode is Opcode.PONG:
              self.acknowledge_pings(bytes(event.data))
  
      def acknowledge_pings(self, data: bytes) -> None:
          """
          Acknowledge pings when receiving a pong.
  
          """
          with self.protocol_mutex:
              # Ignore unsolicited pong.
              if data not in self.pending_pings:
                  return
  
              pong_timestamp = time.monotonic()
  
              # Sending a pong for only the most recent ping is legal.
              # Acknowledge all previous pings too in that case.
              ping_id = None
              ping_ids = []
              for ping_id, (
                  pong_received,
                  ping_timestamp,
                  _ack_on_close,
              ) in self.pending_pings.items():
                  ping_ids.append(ping_id)
                  pong_received.set()
                  if ping_id == data:
                      self.latency = pong_timestamp - ping_timestamp
                      break
              else:
                  raise AssertionError("solicited pong not found in pings")
  
              # Remove acknowledged pings from self.pending_pings.
              for ping_id in ping_ids:
                  del self.pending_pings[ping_id]
  
      def terminate_pending_pings(self) -> None:
          """
          Acknowledge pending pings when the connection is closed.
  
          """
          assert self.protocol_mutex.locked()
          assert self.protocol.state is CLOSED
  
          for pong_received, _ping_timestamp, ack_on_close in self.pending_pings.values():
              if ack_on_close:
                  pong_received.set()
  
          self.pending_pings.clear()
  
      def keepalive(self) -> None:
          """
          Send a Ping frame and wait for a Pong frame at regular intervals.
  
          """
          assert self.ping_interval is not None
          try:
              while True:
                  # If self.ping_timeout > self.latency > self.ping_interval,
                  # pings will be sent immediately after receiving pongs.
                  # The period will be longer than self.ping_interval.
                  self.recv_events_thread.join(self.ping_interval - self.latency)
                  if not self.recv_events_thread.is_alive():
                      break
  
                  try:
                      pong_received = self.ping(ack_on_close=True)
                  except ConnectionClosed:
                      break
                  if self.debug:
                      self.logger.debug("% sent keepalive ping")
  
                  if self.ping_timeout is not None:
                      if pong_received.wait(self.ping_timeout):
                          if self.debug:
                              self.logger.debug("% received keepalive pong")
                      else:
                          if self.debug:
                              self.logger.debug("- timed out waiting for keepalive pong")
                          with self.send_context():
                              self.protocol.fail(
                                  CloseCode.INTERNAL_ERROR,
                                  "keepalive ping timeout",
                              )
                          break
          except Exception:
              self.logger.error("keepalive ping failed", exc_info=True)
  
      def start_keepalive(self) -> None:
          """
          Run :meth:`keepalive` in a thread, unless keepalive is disabled.
  
          """
          if self.ping_interval is not None:
              # This thread is marked as daemon like self.recv_events_thread.
              self.keepalive_thread = threading.Thread(
                  target=self.keepalive,
                  daemon=True,
              )
              self.keepalive_thread.start()
  
      def recv_events(self) -> None:
          """
          Read incoming data from the socket and process events.
  
          Run this method in a thread as long as the connection is alive.
  
          ``recv_events()`` exits immediately when ``self.socket`` is closed.
  
          """
          try:
              while True:
                  try:
                      # If the assembler buffer is full, block until it drains.
                      with self.recv_flow_control:
                          pass
                      if self.close_deadline is not None:
                          self.socket.settimeout(self.close_deadline.timeout())
                      data = self.socket.recv(self.recv_bufsize)
                  except Exception as exc:
                      if self.debug:
                          self.logger.debug(
                              "! error while receiving data",
                              exc_info=True,
                          )
                      # When the closing handshake is initiated by our side,
                      # recv() may block until send_context() closes the socket.
                      # In that case, send_context() already set recv_exc.
                      # Calling set_recv_exc() avoids overwriting it.
                      with self.protocol_mutex:
                          self.set_recv_exc(exc)
                      break
  
                  if data == b"":
                      break
  
                  # Acquire the connection lock.
                  with self.protocol_mutex:
                      # Feed incoming data to the protocol.
                      self.protocol.receive_data(data)
  
                      # This isn't expected to raise an exception.
                      events = self.protocol.events_received()
  
                      # Write outgoing data to the socket.
                      try:
                          self.send_data()
                      except Exception as exc:
                          if self.debug:
                              self.logger.debug(
                                  "! error while sending data",
                                  exc_info=True,
                              )
                          # Similarly to the above, avoid overriding an exception
                          # set by send_context(), in case of a race condition
                          # i.e. send_context() closes the socket after recv()
                          # returns above but before send_data() calls send().
                          self.set_recv_exc(exc)
                          break
  
                      # If needed, set the close deadline based on the close timeout.
                      if self.protocol.close_expected():
                          if self.close_deadline is None:
                              self.close_deadline = Deadline(self.close_timeout)
  
                  # Unlock conn_mutex before processing events. Else, the
                  # application can't send messages in response to events.
  
  