def _sendfile_cb(self, fut: 'asyncio.Future[None]', out_fd: int,
in_fd: int, offset: int, count: int,
loop: asyncio.AbstractEventLoop,
registered: bool) -> None:
if registered:
loop.remove_writer(out_fd)
if fut.cancelled():
return
try:
n = os.sendfile(out_fd, in_fd, offset, count)
if n == 0: # EOF reached
n = count
except (BlockingIOError, InterruptedError):
n = 0
except Exception as exc:
set_exception(fut, exc)
return
if n < count:
loop.add_writer(out_fd, self._sendfile_cb, fut, out_fd, in_fd,
offset + n, count - n, loop, True)
else:
set_result(fut, None)
async def wait_for_writer(fd: Union[int, io.BufferedWriter], loop: asyncio.AbstractEventLoop) -> None:
f: asyncio.Future = asyncio.Future()
loop.add_writer(fd, f.set_result, None)
f.add_done_callback(lambda f: loop.remove_writer(fd))
await f
