"""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._called_connection_lost = False
self._eof_written = False
if self._server is not None:
self._server._attach(self)
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._sock.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 and self._called_connection_lost:
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):
if self._called_connection_lost:
return
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') and self._sock.fileno() != -1:
self._sock.shutdown(socket.SHUT_RDWR)
self._sock.close()
self._sock = None
server = self._server
if server is not None:
server._detach(self)
self._server = None
self._called_connection_lost = True
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 method 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
# It's a new slice so make it immutable so protocols upstream don't have problems
data = bytes(memoryview(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,
transports.DatagramTransport):
max_size = 256 * 1024
def __init__(self, loop, sock, protocol, address=None,
waiter=None, extra=None):
self._address = address
self._empty_waiter = None
self._buffer_size = 0
# 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 self._buffer_size
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 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))
self._buffer_size += len(data) + 8 # include header bytes
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()
self._buffer_size -= len(data)
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_shutdown_timeout=None):
ssl_protocol = sslproto.SSLProtocol(
self, protocol, sslcontext, waiter,
server_side, server_hostname,
ssl_handshake_timeout=ssl_handshake_timeout,
ssl_shutdown_timeout=ssl_shutdown_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_recvfrom(self, sock, bufsize):
return await self._proactor.recvfrom(sock, bufsize)
async def sock_recvfrom_into(self, sock, buf, nbytes=0):
if not nbytes:
nbytes = len(buf)
return await self._proactor.recvfrom_into(sock, buf, nbytes)
async def sock_sendall(self, sock, data):
return await self._proactor.send(sock, data)
async def sock_sendto(self, sock, data, address):
return await self._proactor.sendto(sock, data, 0, address)
async def sock_connect(self, sock, address):
if self._debug and sock.gettimeout() != 0:
raise ValueError("the socket must be non-blocking")
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):
# This may be called from a different thread, possibly after
# _close_self_pipe() has been called or even while it is
# running. Guard for self._csock being None or closed. When
# a socket is closed, send() raises OSError (with errno set to
# EBADF, but let's not rely on the exact error code).
csock = self._csock
if csock is None:
return
try:
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,
ssl_shutdown_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,
ssl_shutdown_timeout=ssl_shutdown_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()
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cpython