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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 socket import warnings from . import base_events from . import compat from . import constants from . import futures from . import sslproto from . import transports from .log import logger 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._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('fd=%s' % self._sock.fileno()) if self._read_fut is not None: info.append('read=%s' % self._read_fut) if self._write_fut is not None: info.append("write=%r" % self._write_fut) if self._buffer: bufsize = len(self._buffer) info.append('write_bufsize=%s' % bufsize) if self._eof_written: info.append('EOF written') return '<%s>' % ' '.join(info) def _set_extra(self, sock): self._extra['pipe'] = sock 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 # On Python 3.3 and older, objects with a destructor part of a reference # cycle are never destroyed. It's not more the case on Python 3.4 thanks # to the PEP 442. if compat.PY34: def __del__(self): if self._sock is not None: warnings.warn("unclosed transport %r" % self, ResourceWarning) self.close() def _fatal_error(self, exc, message='Fatal error on pipe transport'): if isinstance(exc, base_events._FATAL_ERROR_IGNORE): 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, }) self._force_close(exc) def _force_close(self, 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): super().__init__(loop, sock, protocol, waiter, extra, server) self._paused = False self._loop.call_soon(self._loop_reading) def pause_reading(self): if self._closing: raise RuntimeError('Cannot pause_reading() when closing') if self._paused: raise RuntimeError('Already paused') self._paused = True if self._loop.get_debug(): logger.debug("%r pauses reading", self) def resume_reading(self): if not self._paused: raise RuntimeError('Not paused') self._paused = False if self._closing: return self._loop.call_soon(self._loop_reading, self._read_fut) if self._loop.get_debug(): logger.debug("%r resumes reading", self) def _loop_reading(self, fut=None): if self._paused: return 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 data = fut.result() # deliver data later in "finally" clause 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 # reschedule a new read self._read_fut = self._loop._proactor.recv(self._sock, 4096) 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 futures.CancelledError: if not self._closing: raise else: self._read_fut.add_done_callback(self._loop_reading) finally: if data: self._protocol.data_received(data) elif data is not None: if self._loop.get_debug(): logger.debug("%r received EOF", self) keep_open = self._protocol.eof_received() if not keep_open: self.close() class _ProactorBaseWritePipeTransport(_ProactorBasePipeTransport, transports.WriteTransport): """Transport for write pipes.""" def write(self, data): if not isinstance(data, (bytes, bytearray, memoryview)): raise TypeError('data argument must be byte-ish (%r)', type(data)) if self._eof_written: raise RuntimeError('write_eof() already called') 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: 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) 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) 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 _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.""" def _set_extra(self, sock): self._extra['socket'] = sock try: self._extra['sockname'] = sock.getsockname() except (socket.error, AttributeError): if self._loop.get_debug(): logger.warning("getsockname() failed on %r", sock, exc_info=True) if 'peername' not in self._extra: try: self._extra['peername'] = sock.getpeername() except (socket.error, AttributeError): if self._loop.get_debug(): logger.warning("getpeername() failed on %r", sock, exc_info=True) 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() 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): if not sslproto._is_sslproto_available(): raise NotImplementedError("Proactor event loop requires Python 3.5" " or newer (ssl.MemoryBIO) to support " "SSL") ssl_protocol = sslproto.SSLProtocol(self, protocol, sslcontext, waiter, server_side, server_hostname) _ProactorSocketTransport(self, rawsock, ssl_protocol, extra=extra, server=server) return ssl_protocol._app_transport 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 # 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() def sock_recv(self, sock, n): return self._proactor.recv(sock, n) def sock_sendall(self, sock, data): return self._proactor.send(sock, data) def sock_connect(self, sock, address): return self._proactor.connect(sock, address) def sock_accept(self, sock): return self._proactor.accept(sock) def _socketpair(self): raise NotImplementedError 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 = self._socketpair() self._ssock.setblocking(False) self._csock.setblocking(False) self._internal_fds += 1 self.call_soon(self._loop_self_reading) def _loop_self_reading(self, f=None): try: if f is not None: f.result() # may raise f = self._proactor.recv(self._ssock, 4096) except futures.CancelledError: # _close_self_pipe() has been called, stop waiting for data return except Exception 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): self._csock.send(b'\0') def _start_serving(self, protocol_factory, sock, sslcontext=None, server=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) 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': sock, }) sock.close() elif self._debug: logger.debug("Accept failed on socket %r", sock, exc_info=True) except futures.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): self._stop_accept_futures() self._proactor._stop_serving(sock) sock.close()