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selector_events.py
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"""Event loop using a selector and related classes. A selector is a "notify-when-ready" multiplexer. For a subclass which also includes support for signal handling, see the unix_events sub-module. """ __all__ = ['BaseSelectorEventLoop'] import collections import errno import functools import socket import warnings try: import ssl except ImportError: # pragma: no cover ssl = None from . import base_events from . import compat from . import constants from . import events from . import futures from . import selectors from . import transports from . import sslproto from .coroutines import coroutine from .log import logger def _test_selector_event(selector, fd, event): # Test if the selector is monitoring 'event' events # for the file descriptor 'fd'. try: key = selector.get_key(fd) except KeyError: return False else: return bool(key.events & event) class BaseSelectorEventLoop(base_events.BaseEventLoop): """Selector event loop. See events.EventLoop for API specification. """ def __init__(self, selector=None): super().__init__() if selector is None: selector = selectors.DefaultSelector() logger.debug('Using selector: %s', selector.__class__.__name__) self._selector = selector self._make_self_pipe() def _make_socket_transport(self, sock, protocol, waiter=None, *, extra=None, server=None): return _SelectorSocketTransport(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(): return self._make_legacy_ssl_transport( rawsock, protocol, sslcontext, waiter, server_side=server_side, server_hostname=server_hostname, extra=extra, server=server) ssl_protocol = sslproto.SSLProtocol(self, protocol, sslcontext, waiter, server_side, server_hostname) _SelectorSocketTransport(self, rawsock, ssl_protocol, extra=extra, server=server) return ssl_protocol._app_transport def _make_legacy_ssl_transport(self, rawsock, protocol, sslcontext, waiter, *, server_side=False, server_hostname=None, extra=None, server=None): # Use the legacy API: SSL_write, SSL_read, etc. The legacy API is used # on Python 3.4 and older, when ssl.MemoryBIO is not available. return _SelectorSslTransport( self, rawsock, protocol, sslcontext, waiter, server_side, server_hostname, extra, server) def _make_datagram_transport(self, sock, protocol, address=None, waiter=None, extra=None): return _SelectorDatagramTransport(self, sock, protocol, address, waiter, extra) def close(self): if self.is_running(): raise RuntimeError("Cannot close a running event loop") if self.is_closed(): return self._close_self_pipe() super().close() if self._selector is not None: self._selector.close() self._selector = None def _socketpair(self): raise NotImplementedError def _close_self_pipe(self): self.remove_reader(self._ssock.fileno()) 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.add_reader(self._ssock.fileno(), self._read_from_self) def _process_self_data(self, data): pass def _read_from_self(self): while True: try: data = self._ssock.recv(4096) if not data: break self._process_self_data(data) except InterruptedError: continue except BlockingIOError: break 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 not None: 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): self.add_reader(sock.fileno(), self._accept_connection, protocol_factory, sock, sslcontext, server) def _accept_connection(self, protocol_factory, sock, sslcontext=None, server=None): try: conn, addr = sock.accept() if self._debug: logger.debug("%r got a new connection from %r: %r", server, addr, conn) conn.setblocking(False) except (BlockingIOError, InterruptedError, ConnectionAbortedError): pass # False alarm. except OSError as exc: # There's nowhere to send the error, so just log it. if exc.errno in (errno.EMFILE, errno.ENFILE, errno.ENOBUFS, errno.ENOMEM): # Some platforms (e.g. Linux keep reporting the FD as # ready, so we remove the read handler temporarily. # We'll try again in a while. self.call_exception_handler({ 'message': 'socket.accept() out of system resource', 'exception': exc, 'socket': sock, }) self.remove_reader(sock.fileno()) self.call_later(constants.ACCEPT_RETRY_DELAY, self._start_serving, protocol_factory, sock, sslcontext, server) else: raise # The event loop will catch, log and ignore it. else: extra = {'peername': addr} accept = self._accept_connection2(protocol_factory, conn, extra, sslcontext, server) self.create_task(accept) @coroutine def _accept_connection2(self, protocol_factory, conn, extra, sslcontext=None, server=None): protocol = None transport = None try: protocol = protocol_factory() waiter = self.create_future() if sslcontext: transport = self._make_ssl_transport( conn, protocol, sslcontext, waiter=waiter, server_side=True, extra=extra, server=server) else: transport = self._make_socket_transport( conn, protocol, waiter=waiter, extra=extra, server=server) try: yield from waiter except: transport.close() raise # It's now up to the protocol to handle the connection. except Exception as exc: if self._debug: context = { 'message': ('Error on transport creation ' 'for incoming connection'), 'exception': exc, } if protocol is not None: context['protocol'] = protocol if transport is not None: context['transport'] = transport self.call_exception_handler(context) def add_reader(self, fd, callback, *args): """Add a reader callback.""" self._check_closed() handle = events.Handle(callback, args, self) try: key = self._selector.get_key(fd) except KeyError: self._selector.register(fd, selectors.EVENT_READ, (handle, None)) else: mask, (reader, writer) = key.events, key.data self._selector.modify(fd, mask | selectors.EVENT_READ, (handle, writer)) if reader is not None: reader.cancel() def remove_reader(self, fd): """Remove a reader callback.""" if self.is_closed(): return False try: key = self._selector.get_key(fd) except KeyError: return False else: mask, (reader, writer) = key.events, key.data mask &= ~selectors.EVENT_READ if not mask: self._selector.unregister(fd) else: self._selector.modify(fd, mask, (None, writer)) if reader is not None: reader.cancel() return True else: return False def add_writer(self, fd, callback, *args): """Add a writer callback..""" self._check_closed() handle = events.Handle(callback, args, self) try: key = self._selector.get_key(fd) except KeyError: self._selector.register(fd, selectors.EVENT_WRITE, (None, handle)) else: mask, (reader, writer) = key.events, key.data self._selector.modify(fd, mask | selectors.EVENT_WRITE, (reader, handle)) if writer is not None: writer.cancel() def remove_writer(self, fd): """Remove a writer callback.""" if self.is_closed(): return False try: key = self._selector.get_key(fd) except KeyError: return False else: mask, (reader, writer) = key.events, key.data # Remove both writer and connector. mask &= ~selectors.EVENT_WRITE if not mask: self._selector.unregister(fd) else: self._selector.modify(fd, mask, (reader, None)) if writer is not None: writer.cancel() return True else: return False def sock_recv(self, sock, n): """Receive data from the socket. The return value is a bytes object representing the data received. The maximum amount of data to be received at once is specified by nbytes. This method is a coroutine. """ if self._debug and sock.gettimeout() != 0: raise ValueError("the socket must be non-blocking") fut = self.create_future() self._sock_recv(fut, False, sock, n) return fut def _sock_recv(self, fut, registered, sock, n): # _sock_recv() can add itself as an I/O callback if the operation can't # be done immediately. Don't use it directly, call sock_recv(). fd = sock.fileno() if registered: # Remove the callback early. It should be rare that the # selector says the fd is ready but the call still returns # EAGAIN, and I am willing to take a hit in that case in # order to simplify the common case. self.remove_reader(fd) if fut.cancelled(): return try: data = sock.recv(n) except (BlockingIOError, InterruptedError): self.add_reader(fd, self._sock_recv, fut, True, sock, n) except Exception as exc: fut.set_exception(exc) else: fut.set_result(data) def sock_sendall(self, sock, data): """Send data to the socket. The socket must be connected to a remote socket. This method continues to send data from data until either all data has been sent or an error occurs. None is returned on success. On error, an exception is raised, and there is no way to determine how much data, if any, was successfully processed by the receiving end of the connection. This method is a coroutine. """ if self._debug and sock.gettimeout() != 0: raise ValueError("the socket must be non-blocking") fut = self.create_future() if data: self._sock_sendall(fut, False, sock, data) else: fut.set_result(None) return fut def _sock_sendall(self, fut, registered, sock, data): fd = sock.fileno() if registered: self.remove_writer(fd) if fut.cancelled(): return try: n = sock.send(data) except (BlockingIOError, InterruptedError): n = 0 except Exception as exc: fut.set_exception(exc) return if n == len(data): fut.set_result(None) else: if n: data = data[n:] self.add_writer(fd, self._sock_sendall, fut, True, sock, data) @coroutine def sock_connect(self, sock, address): """Connect to a remote socket at address. This method is a coroutine. """ if self._debug and sock.gettimeout() != 0: raise ValueError("the socket must be non-blocking") if not hasattr(socket, 'AF_UNIX') or sock.family != socket.AF_UNIX: resolved = base_events._ensure_resolved(address, loop=self) if not resolved.done(): yield from resolved _, _, _, _, address = resolved.result()[0] fut = self.create_future() self._sock_connect(fut, sock, address) return (yield from fut) def _sock_connect(self, fut, sock, address): fd = sock.fileno() try: sock.connect(address) except (BlockingIOError, InterruptedError): # Issue #23618: When the C function connect() fails with EINTR, the # connection runs in background. We have to wait until the socket # becomes writable to be notified when the connection succeed or # fails. fut.add_done_callback( functools.partial(self._sock_connect_done, fd)) self.add_writer(fd, self._sock_connect_cb, fut, sock, address) except Exception as exc: fut.set_exception(exc) else: fut.set_result(None) def _sock_connect_done(self, fd, fut): self.remove_writer(fd) def _sock_connect_cb(self, fut, sock, address): if fut.cancelled(): return try: err = sock.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR) if err != 0: # Jump to any except clause below. raise OSError(err, 'Connect call failed %s' % (address,)) except (BlockingIOError, InterruptedError): # socket is still registered, the callback will be retried later pass except Exception as exc: fut.set_exception(exc) else: fut.set_result(None) def sock_accept(self, sock): """Accept a connection. The socket must be bound to an address and listening for connections. The return value is a pair (conn, address) where conn is a new socket object usable to send and receive data on the connection, and address is the address bound to the socket on the other end of the connection. This method is a coroutine. """ if self._debug and sock.gettimeout() != 0: raise ValueError("the socket must be non-blocking") fut = self.create_future() self._sock_accept(fut, False, sock) return fut def _sock_accept(self, fut, registered, sock): fd = sock.fileno() if registered: self.remove_reader(fd) if fut.cancelled(): return try: conn, address = sock.accept() conn.setblocking(False) except (BlockingIOError, InterruptedError): self.add_reader(fd, self._sock_accept, fut, True, sock) except Exception as exc: fut.set_exception(exc) else: fut.set_result((conn, address)) def _process_events(self, event_list): for key, mask in event_list: fileobj, (reader, writer) = key.fileobj, key.data if mask & selectors.EVENT_READ and reader is not None: if reader._cancelled: self.remove_reader(fileobj) else: self._add_callback(reader) if mask & selectors.EVENT_WRITE and writer is not None: if writer._cancelled: self.remove_writer(fileobj) else: self._add_callback(writer) def _stop_serving(self, sock): self.remove_reader(sock.fileno()) sock.close() class _SelectorTransport(transports._FlowControlMixin, transports.Transport): max_size = 256 * 1024 # Buffer size passed to recv(). _buffer_factory = bytearray # Constructs initial value for self._buffer. # Attribute used in the destructor: it must be set even if the constructor # is not called (see _SelectorSslTransport which may start by raising an # exception) _sock = None def __init__(self, loop, sock, protocol, extra=None, server=None): super().__init__(extra, loop) self._extra['socket'] = sock self._extra['sockname'] = sock.getsockname() if 'peername' not in self._extra: try: self._extra['peername'] = sock.getpeername() except socket.error: self._extra['peername'] = None self._sock = sock self._sock_fd = sock.fileno() self._protocol = protocol self._protocol_connected = True self._server = server self._buffer = self._buffer_factory() self._conn_lost = 0 # Set when call to connection_lost scheduled. self._closing = False # Set when close() called. if self._server is not None: self._server._attach() def __repr__(self): info = [self.__class__.__name__] if self._sock is None: info.append('closed') elif self._closing: info.append('closing') info.append('fd=%s' % self._sock_fd) # test if the transport was closed if self._loop is not None and not self._loop.is_closed(): polling = _test_selector_event(self._loop._selector, self._sock_fd, selectors.EVENT_READ) if polling: info.append('read=polling') else: info.append('read=idle') polling = _test_selector_event(self._loop._selector, self._sock_fd, selectors.EVENT_WRITE) if polling: state = 'polling' else: state = 'idle' bufsize = self.get_write_buffer_size() info.append('write=<%s, bufsize=%s>' % (state, bufsize)) return '<%s>' % ' '.join(info) def abort(self): self._force_close(None) def is_closing(self): return self._closing def close(self): if self._closing: return self._closing = True self._loop.remove_reader(self._sock_fd) if not self._buffer: self._conn_lost += 1 self._loop.remove_writer(self._sock_fd) self._loop.call_soon(self._call_connection_lost, 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._sock.close() def _fatal_error(self, exc, message='Fatal error on transport'): # Should be called from exception handler only. 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._conn_lost: return if self._buffer: self._buffer.clear() self._loop.remove_writer(self._sock_fd) if not self._closing: self._closing = True self._loop.remove_reader(self._sock_fd) self._conn_lost += 1 self._loop.call_soon(self._call_connection_lost, exc) def _call_connection_lost(self, exc): try: if self._protocol_connected: self._protocol.connection_lost(exc) finally: self._sock.close() self._sock = None self._protocol = None self._loop = None server = self._server if server is not None: server._detach() self._server = None def get_write_buffer_size(self): return len(self._buffer) class _SelectorSocketTransport(_SelectorTransport): def __init__(self, loop, sock, protocol, waiter=None, extra=None, server=None): super().__init__(loop, sock, protocol, extra, server) self._eof = False self._paused = False self._loop.call_soon(self._protocol.connection_made, self) # only start reading when connection_made() has been called self._loop.call_soon(self._loop.add_reader, self._sock_fd, self._read_ready) 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 pause_reading(self): if self._closing: raise RuntimeError('Cannot pause_reading() when closing') if self._paused: raise RuntimeError('Already paused') self._paused = True self._loop.remove_reader(self._sock_fd) 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.add_reader(self._sock_fd, self._read_ready) if self._loop.get_debug(): logger.debug("%r resumes reading", self) def _read_ready(self): if self._conn_lost: return try: data = self._sock.recv(self.max_size) except (BlockingIOError, InterruptedError): pass except Exception as exc: self._fatal_error(exc, 'Fatal read error on socket transport') else: if data: self._protocol.data_received(data) else: if self._loop.get_debug(): logger.debug("%r received EOF", self) keep_open = self._protocol.eof_received() if keep_open: # We're keeping the connection open so the # protocol can write more, but we still can't # receive more, so remove the reader callback. self._loop.remove_reader(self._sock_fd) else: self.close() def write(self, data): if not isinstance(data, (bytes, bytearray, memoryview)): raise TypeError('data argument must be a bytes-like object, ' 'not %r' % type(data).__name__) if self._eof: raise RuntimeError('Cannot call write() after write_eof()') 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 if not self._buffer: # Optimization: try to send now. try: n = self._sock.send(data) except (BlockingIOError, InterruptedError): pass except Exception as exc: self._fatal_error(exc, 'Fatal write error on socket transport') return else: data = data[n:] if not data: return # Not all was written; register write handler. self._loop.add_writer(self._sock_fd, self._write_ready) # Add it to the buffer. self._buffer.extend(data) self._maybe_pause_protocol() def _write_ready(self): assert self._buffer, 'Data should not be empty' if self._conn_lost: return try: n = self._sock.send(self._buffer) except (BlockingIOError, InterruptedError): pass except Exception as exc: self._loop.remove_writer(self._sock_fd) self._buffer.clear() self._fatal_error(exc, 'Fatal write error on socket transport') else: if n: del self._buffer[:n] self._maybe_resume_protocol() # May append to buffer. if not self._buffer: self._loop.remove_writer(self._sock_fd) if self._closing: self._call_connection_lost(None) elif self._eof: self._sock.shutdown(socket.SHUT_WR) def write_eof(self): if self._eof: return self._eof = True if not self._buffer: self._sock.shutdown(socket.SHUT_WR) def can_write_eof(self): return True class _SelectorSslTransport(_SelectorTransport): _buffer_factory = bytearray def __init__(self, loop, rawsock, protocol, sslcontext, waiter=None, server_side=False, server_hostname=None, extra=None, server=None): if ssl is None: raise RuntimeError('stdlib ssl module not available') if not sslcontext: sslcontext = sslproto._create_transport_context(server_side, server_hostname) wrap_kwargs = { 'server_side': server_side, 'do_handshake_on_connect': False, } if server_hostname and not server_side: wrap_kwargs['server_hostname'] = server_hostname sslsock = sslcontext.wrap_socket(rawsock, **wrap_kwargs) super().__init__(loop, sslsock, protocol, extra, server) # the protocol connection is only made after the SSL handshake self._protocol_connected = False self._server_hostname = server_hostname self._waiter = waiter self._sslcontext = sslcontext self._paused = False # SSL-specific extra info. (peercert is set later) self._extra.update(sslcontext=sslcontext) if self._loop.get_debug(): logger.debug("%r starts SSL handshake", self) start_time = self._loop.time() else: start_time = None self._on_handshake(start_time) def _wakeup_waiter(self, exc=None): if self._waiter is None: return if not self._waiter.cancelled(): if exc is not None: self._waiter.set_exception(exc) else: self._waiter.set_result(None) self._waiter = None def _on_handshake(self, start_time): try: self._sock.do_handshake() except ssl.SSLWantReadError: self._loop.add_reader(self._sock_fd, self._on_handshake, start_time) return except ssl.SSLWantWriteError: self._loop.add_writer(self._sock_fd, self._on_handshake, start_time) return except BaseException as exc: if self._loop.get_debug(): logger.warning("%r: SSL handshake failed", self, exc_info=True) self._loop.remove_reader(self._sock_fd) self._loop.remove_writer(self._sock_fd) self._sock.close() self._wakeup_waiter(exc) if isinstance(exc, Exception): return else: raise self._loop.remove_reader(self._sock_fd) self._loop.remove_writer(self._sock_fd) peercert = self._sock.getpeercert() if not hasattr(self._sslcontext, 'check_hostname'): # Verify hostname if requested, Python 3.4+ uses check_hostname # and checks the hostname in do_handshake() if (self._server_hostname and self._sslcontext.verify_mode != ssl.CERT_NONE): try: ssl.match_hostname(peercert, self._server_hostname) except Exception as exc: if self._loop.get_debug(): logger.warning("%r: SSL handshake failed " "on matching the hostname", self, exc_info=True) self._sock.close() self._wakeup_waiter(exc) return # Add extra info that becomes available after handshake. self._extra.update(peercert=peercert, cipher=self._sock.cipher(), compression=self._sock.compression(), ssl_object=self._sock, ) self._read_wants_write = False self._write_wants_read = False self._loop.add_reader(self._sock_fd, self._read_ready) self._protocol_connected = True self._loop.call_soon(self._protocol.connection_made, self) # only wake up the waiter when connection_made() has been called self._loop.call_soon(self._wakeup_waiter) if self._loop.get_debug(): dt = self._loop.time() - start_time logger.debug("%r: SSL handshake took %.1f ms", self, dt * 1e3) def pause_reading(self): # XXX This is a bit icky, given the comment at the top of # _read_ready(). Is it possible to evoke a deadlock? I don't # know, although it doesn't look like it; write() will still # accept more data for the buffer and eventually the app will # call resume_reading() again, and things will flow again. if self._closing: raise RuntimeError('Cannot pause_reading() when closing') if self._paused: raise RuntimeError('Already paused') self._paused = True self._loop.remove_reader(self._sock_fd) 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.add_reader(self._sock_fd, self._read_ready) if self._loop.get_debug(): logger.debug("%r resumes reading", self) def _read_ready(self): if self._conn_lost: return if self._write_wants_read: self._write_wants_read = False self._write_ready() if self._buffer: self._loop.add_writer(self._sock_fd, self._write_ready) try: data = self._sock.recv(self.max_size) except (BlockingIOError, InterruptedError, ssl.SSLWantReadError): pass except ssl.SSLWantWriteError: self._read_wants_write = True self._loop.remove_reader(self._sock_fd) self._loop.add_writer(self._sock_fd, self._write_ready) except Exception as exc: self._fatal_error(exc, 'Fatal read error on SSL transport') else: if data: self._protocol.data_received(data) else: try: if self._loop.get_debug(): logger.debug("%r received EOF", self) keep_open = self._protocol.eof_received() if keep_open: logger.warning('returning true from eof_received() ' 'has no effect when using ssl') finally: self.close() def _write_ready(self): if self._conn_lost: return if self._read_wants_write: self._read_wants_write = False self._read_ready() if not (self._paused or self._closing): self._loop.add_reader(self._sock_fd, self._read_ready) if self._buffer: try: n = self._sock.send(self._buffer) except (BlockingIOError, InterruptedError, ssl.SSLWantWriteError): n = 0 except ssl.SSLWantReadError: n = 0 self._loop.remove_writer(self._sock_fd) self._write_wants_read = True except Exception as exc: self._loop.remove_writer(self._sock_fd) self._buffer.clear() self._fatal_error(exc, 'Fatal write error on SSL transport') return if n: del self._buffer[:n] self._maybe_resume_protocol() # May append to buffer. if not self._buffer: self._loop.remove_writer(self._sock_fd) if self._closing: self._call_connection_lost(None) def write(self, data): if not isinstance(data, (bytes, bytearray, memoryview)): raise TypeError('data argument must be a bytes-like object, ' 'not %r' % type(data).__name__) 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 if not self._buffer: self._loop.add_writer(self._sock_fd, self._write_ready) # Add it to the buffer. self._buffer.extend(data) self._maybe_pause_protocol() def can_write_eof(self): return False class _SelectorDatagramTransport(_SelectorTransport): _buffer_factory = collections.deque def __init__(self, loop, sock, protocol, address=None, waiter=None, extra=None): super().__init__(loop, sock, protocol, extra) self._address = address self._loop.call_soon(self._protocol.connection_made, self) # only start reading when connection_made() has been called self._loop.call_soon(self._loop.add_reader, self._sock_fd, self._read_ready) 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 get_write_buffer_size(self): return sum(len(data) for data, _ in self._buffer) def _read_ready(self): if self._conn_lost: return try: data, addr = self._sock.recvfrom(self.max_size) except (BlockingIOError, InterruptedError): pass except OSError as exc: self._protocol.error_received(exc) except Exception as exc: self._fatal_error(exc, 'Fatal read error on datagram transport') else: self._protocol.datagram_received(data, addr) def sendto(self, data, addr=None): if not isinstance(data, (bytes, bytearray, memoryview)): raise TypeError('data argument must be a bytes-like object, ' 'not %r' % type(data).__name__) if not data: return if self._address and addr not in (None, self._address): raise ValueError('Invalid address: must be None or %s' % (self._address,)) if self._conn_lost and self._address: if self._conn_lost >= constants.LOG_THRESHOLD_FOR_CONNLOST_WRITES: logger.warning('socket.send() raised exception.') self._conn_lost += 1 return if not self._buffer: # Attempt to send it right away first. try: if self._address: self._sock.send(data) else: self._sock.sendto(data, addr) return except (BlockingIOError, InterruptedError): self._loop.add_writer(self._sock_fd, self._sendto_ready) except OSError as exc: self._protocol.error_received(exc) return except Exception as exc: self._fatal_error(exc, 'Fatal write error on datagram transport') return # Ensure that what we buffer is immutable. self._buffer.append((bytes(data), addr)) self._maybe_pause_protocol() def _sendto_ready(self): while self._buffer: data, addr = self._buffer.popleft() try: if self._address: self._sock.send(data) else: self._sock.sendto(data, addr) except (BlockingIOError, InterruptedError): self._buffer.appendleft((data, addr)) # Try again later. break except OSError as exc: self._protocol.error_received(exc) return except Exception as exc: self._fatal_error(exc, 'Fatal write error on datagram transport') return self._maybe_resume_protocol() # May append to buffer. if not self._buffer: self._loop.remove_writer(self._sock_fd) if self._closing: self._call_connection_lost(None)