cpython/Lib/asyncio/proactor_events.py
Ben Darnell ea5a6363c3
bpo-39010: Fix errors logged on proactor loop restart (#22017)
Stopping and restarting a proactor event loop on windows can lead to
spurious errors logged (ConnectionResetError while reading from the
self pipe). This fixes the issue by ensuring that we don't attempt
to start multiple copies of the self-pipe reading loop.
2020-08-31 12:57:52 -07:00

862 lines
31 KiB
Python

"""Event loop using a proactor and related classes.
A proactor is a "notify-on-completion" multiplexer. Currently a
proactor is only implemented on Windows with IOCP.
"""
__all__ = 'BaseProactorEventLoop',
import io
import os
import socket
import warnings
import signal
import threading
import collections
from . import base_events
from . import constants
from . import futures
from . import exceptions
from . import protocols
from . import sslproto
from . import transports
from . import trsock
from .log import logger
def _set_socket_extra(transport, sock):
transport._extra['socket'] = trsock.TransportSocket(sock)
try:
transport._extra['sockname'] = sock.getsockname()
except socket.error:
if transport._loop.get_debug():
logger.warning(
"getsockname() failed on %r", sock, exc_info=True)
if 'peername' not in transport._extra:
try:
transport._extra['peername'] = sock.getpeername()
except socket.error:
# UDP sockets may not have a peer name
transport._extra['peername'] = None
class _ProactorBasePipeTransport(transports._FlowControlMixin,
transports.BaseTransport):
"""Base class for pipe and socket transports."""
def __init__(self, loop, sock, protocol, waiter=None,
extra=None, server=None):
super().__init__(extra, loop)
self._set_extra(sock)
self._sock = sock
self.set_protocol(protocol)
self._server = server
self._buffer = None # None or bytearray.
self._read_fut = None
self._write_fut = None
self._pending_write = 0
self._conn_lost = 0
self._closing = False # Set when close() called.
self._eof_written = False
if self._server is not None:
self._server._attach()
self._loop.call_soon(self._protocol.connection_made, self)
if waiter is not None:
# only wake up the waiter when connection_made() has been called
self._loop.call_soon(futures._set_result_unless_cancelled,
waiter, None)
def __repr__(self):
info = [self.__class__.__name__]
if self._sock is None:
info.append('closed')
elif self._closing:
info.append('closing')
if self._sock is not None:
info.append(f'fd={self._sock.fileno()}')
if self._read_fut is not None:
info.append(f'read={self._read_fut!r}')
if self._write_fut is not None:
info.append(f'write={self._write_fut!r}')
if self._buffer:
info.append(f'write_bufsize={len(self._buffer)}')
if self._eof_written:
info.append('EOF written')
return '<{}>'.format(' '.join(info))
def _set_extra(self, sock):
self._extra['pipe'] = sock
def set_protocol(self, protocol):
self._protocol = protocol
def get_protocol(self):
return self._protocol
def is_closing(self):
return self._closing
def close(self):
if self._closing:
return
self._closing = True
self._conn_lost += 1
if not self._buffer and self._write_fut is None:
self._loop.call_soon(self._call_connection_lost, None)
if self._read_fut is not None:
self._read_fut.cancel()
self._read_fut = None
def __del__(self, _warn=warnings.warn):
if self._sock is not None:
_warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
self.close()
def _fatal_error(self, exc, message='Fatal error on pipe transport'):
try:
if isinstance(exc, OSError):
if self._loop.get_debug():
logger.debug("%r: %s", self, message, exc_info=True)
else:
self._loop.call_exception_handler({
'message': message,
'exception': exc,
'transport': self,
'protocol': self._protocol,
})
finally:
self._force_close(exc)
def _force_close(self, exc):
if self._empty_waiter is not None and not self._empty_waiter.done():
if exc is None:
self._empty_waiter.set_result(None)
else:
self._empty_waiter.set_exception(exc)
if self._closing:
return
self._closing = True
self._conn_lost += 1
if self._write_fut:
self._write_fut.cancel()
self._write_fut = None
if self._read_fut:
self._read_fut.cancel()
self._read_fut = None
self._pending_write = 0
self._buffer = None
self._loop.call_soon(self._call_connection_lost, exc)
def _call_connection_lost(self, exc):
try:
self._protocol.connection_lost(exc)
finally:
# XXX If there is a pending overlapped read on the other
# end then it may fail with ERROR_NETNAME_DELETED if we
# just close our end. First calling shutdown() seems to
# cure it, but maybe using DisconnectEx() would be better.
if hasattr(self._sock, 'shutdown'):
self._sock.shutdown(socket.SHUT_RDWR)
self._sock.close()
self._sock = None
server = self._server
if server is not None:
server._detach()
self._server = None
def get_write_buffer_size(self):
size = self._pending_write
if self._buffer is not None:
size += len(self._buffer)
return size
class _ProactorReadPipeTransport(_ProactorBasePipeTransport,
transports.ReadTransport):
"""Transport for read pipes."""
def __init__(self, loop, sock, protocol, waiter=None,
extra=None, server=None, buffer_size=65536):
self._pending_data_length = -1
self._paused = True
super().__init__(loop, sock, protocol, waiter, extra, server)
self._data = bytearray(buffer_size)
self._loop.call_soon(self._loop_reading)
self._paused = False
def is_reading(self):
return not self._paused and not self._closing
def pause_reading(self):
if self._closing or self._paused:
return
self._paused = True
# bpo-33694: Don't cancel self._read_fut because cancelling an
# overlapped WSASend() loss silently data with the current proactor
# implementation.
#
# If CancelIoEx() fails with ERROR_NOT_FOUND, it means that WSASend()
# completed (even if HasOverlappedIoCompleted() returns 0), but
# Overlapped.cancel() currently silently ignores the ERROR_NOT_FOUND
# error. Once the overlapped is ignored, the IOCP loop will ignores the
# completion I/O event and so not read the result of the overlapped
# WSARecv().
if self._loop.get_debug():
logger.debug("%r pauses reading", self)
def resume_reading(self):
if self._closing or not self._paused:
return
self._paused = False
if self._read_fut is None:
self._loop.call_soon(self._loop_reading, None)
length = self._pending_data_length
self._pending_data_length = -1
if length > -1:
# Call the protocol methode after calling _loop_reading(),
# since the protocol can decide to pause reading again.
self._loop.call_soon(self._data_received, self._data[:length], length)
if self._loop.get_debug():
logger.debug("%r resumes reading", self)
def _eof_received(self):
if self._loop.get_debug():
logger.debug("%r received EOF", self)
try:
keep_open = self._protocol.eof_received()
except (SystemExit, KeyboardInterrupt):
raise
except BaseException as exc:
self._fatal_error(
exc, 'Fatal error: protocol.eof_received() call failed.')
return
if not keep_open:
self.close()
def _data_received(self, data, length):
if self._paused:
# Don't call any protocol method while reading is paused.
# The protocol will be called on resume_reading().
assert self._pending_data_length == -1
self._pending_data_length = length
return
if length == 0:
self._eof_received()
return
if isinstance(self._protocol, protocols.BufferedProtocol):
try:
protocols._feed_data_to_buffered_proto(self._protocol, data)
except (SystemExit, KeyboardInterrupt):
raise
except BaseException as exc:
self._fatal_error(exc,
'Fatal error: protocol.buffer_updated() '
'call failed.')
return
else:
self._protocol.data_received(data)
def _loop_reading(self, fut=None):
length = -1
data = None
try:
if fut is not None:
assert self._read_fut is fut or (self._read_fut is None and
self._closing)
self._read_fut = None
if fut.done():
# deliver data later in "finally" clause
length = fut.result()
if length == 0:
# we got end-of-file so no need to reschedule a new read
return
data = self._data[:length]
else:
# the future will be replaced by next proactor.recv call
fut.cancel()
if self._closing:
# since close() has been called we ignore any read data
return
# bpo-33694: buffer_updated() has currently no fast path because of
# a data loss issue caused by overlapped WSASend() cancellation.
if not self._paused:
# reschedule a new read
self._read_fut = self._loop._proactor.recv_into(self._sock, self._data)
except ConnectionAbortedError as exc:
if not self._closing:
self._fatal_error(exc, 'Fatal read error on pipe transport')
elif self._loop.get_debug():
logger.debug("Read error on pipe transport while closing",
exc_info=True)
except ConnectionResetError as exc:
self._force_close(exc)
except OSError as exc:
self._fatal_error(exc, 'Fatal read error on pipe transport')
except exceptions.CancelledError:
if not self._closing:
raise
else:
if not self._paused:
self._read_fut.add_done_callback(self._loop_reading)
finally:
if length > -1:
self._data_received(data, length)
class _ProactorBaseWritePipeTransport(_ProactorBasePipeTransport,
transports.WriteTransport):
"""Transport for write pipes."""
_start_tls_compatible = True
def __init__(self, *args, **kw):
super().__init__(*args, **kw)
self._empty_waiter = None
def write(self, data):
if not isinstance(data, (bytes, bytearray, memoryview)):
raise TypeError(
f"data argument must be a bytes-like object, "
f"not {type(data).__name__}")
if self._eof_written:
raise RuntimeError('write_eof() already called')
if self._empty_waiter is not None:
raise RuntimeError('unable to write; sendfile is in progress')
if not data:
return
if self._conn_lost:
if self._conn_lost >= constants.LOG_THRESHOLD_FOR_CONNLOST_WRITES:
logger.warning('socket.send() raised exception.')
self._conn_lost += 1
return
# Observable states:
# 1. IDLE: _write_fut and _buffer both None
# 2. WRITING: _write_fut set; _buffer None
# 3. BACKED UP: _write_fut set; _buffer a bytearray
# We always copy the data, so the caller can't modify it
# while we're still waiting for the I/O to happen.
if self._write_fut is None: # IDLE -> WRITING
assert self._buffer is None
# Pass a copy, except if it's already immutable.
self._loop_writing(data=bytes(data))
elif not self._buffer: # WRITING -> BACKED UP
# Make a mutable copy which we can extend.
self._buffer = bytearray(data)
self._maybe_pause_protocol()
else: # BACKED UP
# Append to buffer (also copies).
self._buffer.extend(data)
self._maybe_pause_protocol()
def _loop_writing(self, f=None, data=None):
try:
if f is not None and self._write_fut is None and self._closing:
# XXX most likely self._force_close() has been called, and
# it has set self._write_fut to None.
return
assert f is self._write_fut
self._write_fut = None
self._pending_write = 0
if f:
f.result()
if data is None:
data = self._buffer
self._buffer = None
if not data:
if self._closing:
self._loop.call_soon(self._call_connection_lost, None)
if self._eof_written:
self._sock.shutdown(socket.SHUT_WR)
# Now that we've reduced the buffer size, tell the
# protocol to resume writing if it was paused. Note that
# we do this last since the callback is called immediately
# and it may add more data to the buffer (even causing the
# protocol to be paused again).
self._maybe_resume_protocol()
else:
self._write_fut = self._loop._proactor.send(self._sock, data)
if not self._write_fut.done():
assert self._pending_write == 0
self._pending_write = len(data)
self._write_fut.add_done_callback(self._loop_writing)
self._maybe_pause_protocol()
else:
self._write_fut.add_done_callback(self._loop_writing)
if self._empty_waiter is not None and self._write_fut is None:
self._empty_waiter.set_result(None)
except ConnectionResetError as exc:
self._force_close(exc)
except OSError as exc:
self._fatal_error(exc, 'Fatal write error on pipe transport')
def can_write_eof(self):
return True
def write_eof(self):
self.close()
def abort(self):
self._force_close(None)
def _make_empty_waiter(self):
if self._empty_waiter is not None:
raise RuntimeError("Empty waiter is already set")
self._empty_waiter = self._loop.create_future()
if self._write_fut is None:
self._empty_waiter.set_result(None)
return self._empty_waiter
def _reset_empty_waiter(self):
self._empty_waiter = None
class _ProactorWritePipeTransport(_ProactorBaseWritePipeTransport):
def __init__(self, *args, **kw):
super().__init__(*args, **kw)
self._read_fut = self._loop._proactor.recv(self._sock, 16)
self._read_fut.add_done_callback(self._pipe_closed)
def _pipe_closed(self, fut):
if fut.cancelled():
# the transport has been closed
return
assert fut.result() == b''
if self._closing:
assert self._read_fut is None
return
assert fut is self._read_fut, (fut, self._read_fut)
self._read_fut = None
if self._write_fut is not None:
self._force_close(BrokenPipeError())
else:
self.close()
class _ProactorDatagramTransport(_ProactorBasePipeTransport):
max_size = 256 * 1024
def __init__(self, loop, sock, protocol, address=None,
waiter=None, extra=None):
self._address = address
self._empty_waiter = None
# We don't need to call _protocol.connection_made() since our base
# constructor does it for us.
super().__init__(loop, sock, protocol, waiter=waiter, extra=extra)
# The base constructor sets _buffer = None, so we set it here
self._buffer = collections.deque()
self._loop.call_soon(self._loop_reading)
def _set_extra(self, sock):
_set_socket_extra(self, sock)
def get_write_buffer_size(self):
return sum(len(data) for data, _ in self._buffer)
def abort(self):
self._force_close(None)
def sendto(self, data, addr=None):
if not isinstance(data, (bytes, bytearray, memoryview)):
raise TypeError('data argument must be bytes-like object (%r)',
type(data))
if not data:
return
if self._address is not None and addr not in (None, self._address):
raise ValueError(
f'Invalid address: must be None or {self._address}')
if self._conn_lost and self._address:
if self._conn_lost >= constants.LOG_THRESHOLD_FOR_CONNLOST_WRITES:
logger.warning('socket.sendto() raised exception.')
self._conn_lost += 1
return
# Ensure that what we buffer is immutable.
self._buffer.append((bytes(data), addr))
if self._write_fut is None:
# No current write operations are active, kick one off
self._loop_writing()
# else: A write operation is already kicked off
self._maybe_pause_protocol()
def _loop_writing(self, fut=None):
try:
if self._conn_lost:
return
assert fut is self._write_fut
self._write_fut = None
if fut:
# We are in a _loop_writing() done callback, get the result
fut.result()
if not self._buffer or (self._conn_lost and self._address):
# The connection has been closed
if self._closing:
self._loop.call_soon(self._call_connection_lost, None)
return
data, addr = self._buffer.popleft()
if self._address is not None:
self._write_fut = self._loop._proactor.send(self._sock,
data)
else:
self._write_fut = self._loop._proactor.sendto(self._sock,
data,
addr=addr)
except OSError as exc:
self._protocol.error_received(exc)
except Exception as exc:
self._fatal_error(exc, 'Fatal write error on datagram transport')
else:
self._write_fut.add_done_callback(self._loop_writing)
self._maybe_resume_protocol()
def _loop_reading(self, fut=None):
data = None
try:
if self._conn_lost:
return
assert self._read_fut is fut or (self._read_fut is None and
self._closing)
self._read_fut = None
if fut is not None:
res = fut.result()
if self._closing:
# since close() has been called we ignore any read data
data = None
return
if self._address is not None:
data, addr = res, self._address
else:
data, addr = res
if self._conn_lost:
return
if self._address is not None:
self._read_fut = self._loop._proactor.recv(self._sock,
self.max_size)
else:
self._read_fut = self._loop._proactor.recvfrom(self._sock,
self.max_size)
except OSError as exc:
self._protocol.error_received(exc)
except exceptions.CancelledError:
if not self._closing:
raise
else:
if self._read_fut is not None:
self._read_fut.add_done_callback(self._loop_reading)
finally:
if data:
self._protocol.datagram_received(data, addr)
class _ProactorDuplexPipeTransport(_ProactorReadPipeTransport,
_ProactorBaseWritePipeTransport,
transports.Transport):
"""Transport for duplex pipes."""
def can_write_eof(self):
return False
def write_eof(self):
raise NotImplementedError
class _ProactorSocketTransport(_ProactorReadPipeTransport,
_ProactorBaseWritePipeTransport,
transports.Transport):
"""Transport for connected sockets."""
_sendfile_compatible = constants._SendfileMode.TRY_NATIVE
def __init__(self, loop, sock, protocol, waiter=None,
extra=None, server=None):
super().__init__(loop, sock, protocol, waiter, extra, server)
base_events._set_nodelay(sock)
def _set_extra(self, sock):
_set_socket_extra(self, sock)
def can_write_eof(self):
return True
def write_eof(self):
if self._closing or self._eof_written:
return
self._eof_written = True
if self._write_fut is None:
self._sock.shutdown(socket.SHUT_WR)
class BaseProactorEventLoop(base_events.BaseEventLoop):
def __init__(self, proactor):
super().__init__()
logger.debug('Using proactor: %s', proactor.__class__.__name__)
self._proactor = proactor
self._selector = proactor # convenient alias
self._self_reading_future = None
self._accept_futures = {} # socket file descriptor => Future
proactor.set_loop(self)
self._make_self_pipe()
if threading.current_thread() is threading.main_thread():
# wakeup fd can only be installed to a file descriptor from the main thread
signal.set_wakeup_fd(self._csock.fileno())
def _make_socket_transport(self, sock, protocol, waiter=None,
extra=None, server=None):
return _ProactorSocketTransport(self, sock, protocol, waiter,
extra, server)
def _make_ssl_transport(
self, rawsock, protocol, sslcontext, waiter=None,
*, server_side=False, server_hostname=None,
extra=None, server=None,
ssl_handshake_timeout=None):
ssl_protocol = sslproto.SSLProtocol(
self, protocol, sslcontext, waiter,
server_side, server_hostname,
ssl_handshake_timeout=ssl_handshake_timeout)
_ProactorSocketTransport(self, rawsock, ssl_protocol,
extra=extra, server=server)
return ssl_protocol._app_transport
def _make_datagram_transport(self, sock, protocol,
address=None, waiter=None, extra=None):
return _ProactorDatagramTransport(self, sock, protocol, address,
waiter, extra)
def _make_duplex_pipe_transport(self, sock, protocol, waiter=None,
extra=None):
return _ProactorDuplexPipeTransport(self,
sock, protocol, waiter, extra)
def _make_read_pipe_transport(self, sock, protocol, waiter=None,
extra=None):
return _ProactorReadPipeTransport(self, sock, protocol, waiter, extra)
def _make_write_pipe_transport(self, sock, protocol, waiter=None,
extra=None):
# We want connection_lost() to be called when other end closes
return _ProactorWritePipeTransport(self,
sock, protocol, waiter, extra)
def close(self):
if self.is_running():
raise RuntimeError("Cannot close a running event loop")
if self.is_closed():
return
if threading.current_thread() is threading.main_thread():
signal.set_wakeup_fd(-1)
# Call these methods before closing the event loop (before calling
# BaseEventLoop.close), because they can schedule callbacks with
# call_soon(), which is forbidden when the event loop is closed.
self._stop_accept_futures()
self._close_self_pipe()
self._proactor.close()
self._proactor = None
self._selector = None
# Close the event loop
super().close()
async def sock_recv(self, sock, n):
return await self._proactor.recv(sock, n)
async def sock_recv_into(self, sock, buf):
return await self._proactor.recv_into(sock, buf)
async def sock_sendall(self, sock, data):
return await self._proactor.send(sock, data)
async def sock_connect(self, sock, address):
return await self._proactor.connect(sock, address)
async def sock_accept(self, sock):
return await self._proactor.accept(sock)
async def _sock_sendfile_native(self, sock, file, offset, count):
try:
fileno = file.fileno()
except (AttributeError, io.UnsupportedOperation) as err:
raise exceptions.SendfileNotAvailableError("not a regular file")
try:
fsize = os.fstat(fileno).st_size
except OSError:
raise exceptions.SendfileNotAvailableError("not a regular file")
blocksize = count if count else fsize
if not blocksize:
return 0 # empty file
blocksize = min(blocksize, 0xffff_ffff)
end_pos = min(offset + count, fsize) if count else fsize
offset = min(offset, fsize)
total_sent = 0
try:
while True:
blocksize = min(end_pos - offset, blocksize)
if blocksize <= 0:
return total_sent
await self._proactor.sendfile(sock, file, offset, blocksize)
offset += blocksize
total_sent += blocksize
finally:
if total_sent > 0:
file.seek(offset)
async def _sendfile_native(self, transp, file, offset, count):
resume_reading = transp.is_reading()
transp.pause_reading()
await transp._make_empty_waiter()
try:
return await self.sock_sendfile(transp._sock, file, offset, count,
fallback=False)
finally:
transp._reset_empty_waiter()
if resume_reading:
transp.resume_reading()
def _close_self_pipe(self):
if self._self_reading_future is not None:
self._self_reading_future.cancel()
self._self_reading_future = None
self._ssock.close()
self._ssock = None
self._csock.close()
self._csock = None
self._internal_fds -= 1
def _make_self_pipe(self):
# A self-socket, really. :-)
self._ssock, self._csock = socket.socketpair()
self._ssock.setblocking(False)
self._csock.setblocking(False)
self._internal_fds += 1
def _loop_self_reading(self, f=None):
try:
if f is not None:
f.result() # may raise
if self._self_reading_future is not f:
# When we scheduled this Future, we assigned it to
# _self_reading_future. If it's not there now, something has
# tried to cancel the loop while this callback was still in the
# queue (see windows_events.ProactorEventLoop.run_forever). In
# that case stop here instead of continuing to schedule a new
# iteration.
return
f = self._proactor.recv(self._ssock, 4096)
except exceptions.CancelledError:
# _close_self_pipe() has been called, stop waiting for data
return
except (SystemExit, KeyboardInterrupt):
raise
except BaseException as exc:
self.call_exception_handler({
'message': 'Error on reading from the event loop self pipe',
'exception': exc,
'loop': self,
})
else:
self._self_reading_future = f
f.add_done_callback(self._loop_self_reading)
def _write_to_self(self):
try:
self._csock.send(b'\0')
except OSError:
if self._debug:
logger.debug("Fail to write a null byte into the "
"self-pipe socket",
exc_info=True)
def _start_serving(self, protocol_factory, sock,
sslcontext=None, server=None, backlog=100,
ssl_handshake_timeout=None):
def loop(f=None):
try:
if f is not None:
conn, addr = f.result()
if self._debug:
logger.debug("%r got a new connection from %r: %r",
server, addr, conn)
protocol = protocol_factory()
if sslcontext is not None:
self._make_ssl_transport(
conn, protocol, sslcontext, server_side=True,
extra={'peername': addr}, server=server,
ssl_handshake_timeout=ssl_handshake_timeout)
else:
self._make_socket_transport(
conn, protocol,
extra={'peername': addr}, server=server)
if self.is_closed():
return
f = self._proactor.accept(sock)
except OSError as exc:
if sock.fileno() != -1:
self.call_exception_handler({
'message': 'Accept failed on a socket',
'exception': exc,
'socket': trsock.TransportSocket(sock),
})
sock.close()
elif self._debug:
logger.debug("Accept failed on socket %r",
sock, exc_info=True)
except exceptions.CancelledError:
sock.close()
else:
self._accept_futures[sock.fileno()] = f
f.add_done_callback(loop)
self.call_soon(loop)
def _process_events(self, event_list):
# Events are processed in the IocpProactor._poll() method
pass
def _stop_accept_futures(self):
for future in self._accept_futures.values():
future.cancel()
self._accept_futures.clear()
def _stop_serving(self, sock):
future = self._accept_futures.pop(sock.fileno(), None)
if future:
future.cancel()
self._proactor._stop_serving(sock)
sock.close()