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)
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