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proactor_events.py
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"""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): self._pending_data = None self._paused = True super().__init__(loop, sock, protocol, waiter, extra, server) 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) data = self._pending_data self._pending_data = None if data is not None: # Call the protocol methode after calling _loop_reading(), # since the protocol can decide to pause reading again. self._loop.call_soon(self._data_received, data) 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): 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 is None self._pending_data = data return if not data: 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): 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 data = fut.result() 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 data = None return if data == b'': # we got end-of-file so no need to reschedule a new read 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(self._sock, 32768) 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 data is not None: self._data_received(data) 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): # 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): 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()