name : base_protocol.py import asyncio from typing import Optional, cast from .tcp_helpers import tcp_nodelay class BaseProtocol(asyncio.Protocol): __slots__ = ( "_loop", "_paused", "_drain_waiter", "_connection_lost", "_reading_paused", "transport", ) def __init__(self, loop: asyncio.AbstractEventLoop) -> None: self._loop: asyncio.AbstractEventLoop = loop self._paused = False self._drain_waiter: Optional[asyncio.Future[None]] = None self._reading_paused = False self.transport: Optional[asyncio.Transport] = None @property def connected(self) -> bool: """Return True if the connection is open.""" return self.transport is not None def pause_writing(self) -> None: assert not self._paused self._paused = True def resume_writing(self) -> None: assert self._paused self._paused = False waiter = self._drain_waiter if waiter is not None: self._drain_waiter = None if not waiter.done(): waiter.set_result(None) def pause_reading(self) -> None: if not self._reading_paused and self.transport is not None: try: self.transport.pause_reading() except (AttributeError, NotImplementedError, RuntimeError): pass self._reading_paused = True def resume_reading(self) -> None: if self._reading_paused and self.transport is not None: try: self.transport.resume_reading() except (AttributeError, NotImplementedError, RuntimeError): pass self._reading_paused = False def connection_made(self, transport: asyncio.BaseTransport) -> None: tr = cast(asyncio.Transport, transport) tcp_nodelay(tr, True) self.transport = tr def connection_lost(self, exc: Optional[BaseException]) -> None: # Wake up the writer if currently paused. self.transport = None if not self._paused: return waiter = self._drain_waiter if waiter is None: return self._drain_waiter = None if waiter.done(): return if exc is None: waiter.set_result(None) else: waiter.set_exception(exc) async def _drain_helper(self) -> None: if not self.connected: raise ConnectionResetError("Connection lost") if not self._paused: return waiter = self._drain_waiter if waiter is None: waiter = self._loop.create_future() self._drain_waiter = waiter await asyncio.shield(waiter)